Conservation Ecology of the Nile Crocodile
The major conflict between man and Nile crocodile over living space is investigated and it's possible to prevent. The community members create disturbances to crocodile life. The project activities estimated crocodile population, disturbance, habitat suitability, nesting ecology, Lake Nasser fishery, and Morphometric measurements, to estimate the health of the lake Nasser ecosystem; furthermore, a great deal make to enhance the awareness toward the Nile crocodile
الثلاثاء، 11 يناير 2011
Notes about "Conservation Ecology of the Nile crocodile and Community Environmental Education" project
Conservation Ecology of the Nile crocodile and Community Environmental Education to resolve the conflicts between the Nile Crocodiles and Man, in Lake Nasser –EGYPT
The project activities that carried in and out Lake Nasser upon the Nile crocodile described in detail in the project report on the other hand due to the larger size and a lot of format in this report we divided the report into 9 chapters included 3 chapters with two parts We uploaded all of these parts separately as a PDF format as well as word document but in two compressed part in section of Media coverage of this project, so for further detail please try to look up this section and read as you can in that section.But we will try to summarize the project activities according to the following sentences.
First the project inclouded these titles
In Chapter I, the author gives a review upon what was published in articles about the Nile crocodile in Egypt and Africa and he also summarized the Nile crocodile history and evaluation and role in the ecosystem, and now have a look up on part of this chapter A REVIEW OF SCIENTIFIC STUDY FOCUSING ON THE NILE CROCODILENile crocodile (CROCODYLUS NILOTICUS) IN AFRICA and EGYPTNile crocodile history, evaluation and role in the ecosystemFossil relics of primitive crocodilians, of thecodonts ancestry, come out in the Upper Triassic period some 200 million years ago. In this era, the wiped out thecodonts, the dinosaurs, the pterosaurs, or flying reptiles and the ancestors of the birds as reported by (Gatesy et al. 2003). The most advanced kind were Crocodilians, the Eusuchians first appeared some 140 to 65 million years ago and the crocodilians of today all belong to this suborder. King and Burke 1989 reported that thee are of about 23 species found throughout the world today belonging to Family Crocodylidae which is further divided into 3 subfamilies a) Crocodylinae, b) the Alligatorinae and c) the Gavialinae. On the other hand, Crocodilians exist throughout the tropics and are considered “keystone species” that generally maintain ecosystem structure and function and recycling nutrients and maintenance of wet refuge in droughts as reported by (Thorbjarnarson 1992).Cott 1961; Pooley 1982 and Thorbjarnarson 1992 reported that these include selective predation on fish species.Crocodilian populations are threatened by overexploitation, hunting, skin trades, habitat loss and pollution (Thorbjarnarson, 1992). On the other hand, many species wide-reaching are exploited for their skins and many populations are threatened due to hunting for trade. Ross 1998 explained that the loss of any species of crocodilian would correspond to a significant loss of biodiversity, economic potential and economic stability.Nile crocodile and the history of EgyptThe Nile crocodile has traditionally played a very important role in the history of Egypt and the Nile River. The god Sobek, with the body of a man and head of a crocodile, was worshipped to venerate the strength of the crocodile while preventing “evil” interactions. In his honor, temples at Fayoum and Kom Ombo (Aswan) were erected during the Greek-Roman Period 200 B.CAncient Egyptians would keep crocodiles in pools and temples. They ornamented the crocodiles with jewels in honor of their beloved god, Sobek. The people of ancient Egypt worshiped Sobek in order to appease him, the crocodiles, and to insure the fertility of their people and crops.The Nile was very important to the people of Egypt, and so that Sobek was called the Lord of Faiyum, and was considered the god who controlled the waters. Water was necessary for the survival of crops, the success of trade, and the livelihood of fishing. These waters were filled with crocodile, so it was a matter of common sense to appease them through the worship of their leader, Sobek.
Nile crocodile history: Nile valley and Lake Nasser
Historically, the Nile crocodile was found throughout the Nile River and its tributaries, including the Rosetta Branch at El-Rahmaniya village (Flower 1933); however, its modern occurrence has been heavily impacted by the expansion of human populations and the creation of the Aswan Dam. While there are no formal reports, unreliable information suggests that in the 1950's professional hunters decimated crocodile populations for the unregulated skin trade, resulting in a very patchy distribution, even fears of extinction, throughout Egypt in the 1960's and 1970's (Ross 1998, Pooley 1980). While the construction of the Dam at Aswan negatively impacted the ability of the crocodiles to utilize the Nile River, the resulting formation of the Lake Nasser opened available habitat and crocodiles were colonizing the lake. It was a surprise for scientists to observe crocodiles spreading in the Lake and increasing in number, year after year. This may be because the Lake is now banked on both sides by the desert, and the human population has been thinned, and the environment became suitable and favourable for living and breeding of crocodiles. The question of where the crocodiles came from, whether it was from the upper Nile in Sudan or the lower Nile towards the
In Chapter 2, the author gives detailed information upon the Lake Nasser habitat and ecosystem try to have a look on some of what he wrote.
Chapter II General Characteristics of Lake Nasser
The flood, which arrives at Aswan from Khartoum within one month before the High Dam was built, covers now the same distance in not less than 5 months but sometimes probably more than 12 months depending on Lake level and the strength of the flood.
In chapter 3 the author study lake Nasser shoreline vegetation and he also identify the role of these vegetation types in relation to Nile crocodile life, have a look upon this chapter 3 Chapter IIIGRADIENT OF LAKE NASSER SHORELINE VEGETATION AND THEIR AND THEIR ROLE FOR NILE CROCODILE HABITATSABSTRACT. A delicate plant cover has developed during the last few decades along the shores of Lake Nasser, on the hand, the use of statistical methods ordination and classification techniques emphasize the groups of species and their distribution along the shoreline of Lake Nasser affected by the prevailing environmental conditions that in the same time affected on the lake Nasser ecosystem. Mainly the distribution of these species is robustly related to the moisture gradient as well as Lake Nasser water level. RESULTS AND DISCUSSION Vegetation analysis Identification of clusters (groups)According to TWINSPAN classification of the stands surveyed in the present study, four clusters of stands their vegetation, are objectively identified. Each cluster is named after the dominant species and identified according to its associated species as described below.Cluster I: Hyoscyamus muticus - Tamarix nilotica - and Glinus lotoides. The dominant species are Hyoscyamus muticus (P = 100%), Tamarix nilotica (P = 85 %), Citrullus colocynthis and Glinus lotoides (P = 57.1%). Other characteristic are Salsola imbricata, Pulicaria crispa (P = 42.5%).Cluster II: Tamarix nilotica - Glinus lotoides - Cynodon dactylon - Fimbristylis bis-umbellata. The dominant species are Tamarix nilotica (P= 100%), Glinus lotoides (P = 76.5%) and Cynodon dactylon, Fimbristylis bis-umbellata, Crypsis schoenoides and Heliotropium supinum. Cluster III: Tamarix nilotica - Phragmites australis and Rumex dentatus, and Heliotropium supinum. The dominant species are Tamarix nilotica (P= 100%). Cluster IV: Tamarix nilotica - Eragrostis aegyptiaca, Senecio aegyptius, Fimbristylis bisumbellata, and Cyperus laevigatus -. The dominant species are Tamarix nilotica (P= 100%). Based on the water supply and moisture content which controlling the vegetation distribution along the shoreline. CA analysis of the species in relation to the moisture content obviously indicates the arrangement of the species along the moisture gradient. AHC analysis separates the groups of species in relation to the moisture gradient which is recognizable in nature. A sequence in the arrangement of the groups of the species indicates the altitudinal zonation of the vegetation. Starting from lower to upper area or from lower slope to higher we can classily the vegetation structure into the following groups based on the soil moisture. The first group of species and that is characterized the stands that characterized by wet conditions (Amaranthus lividus, Crypsis schoenoides and Echiurn rauwolfii, Cynodon dactylon). The second group comprises the mesophytic species (Hyoscyamus muticus, Glinus lotoides, Amaranthus sp and Heliotropium supinum) associated with the mesic (these area that having or characterized by moderate or a well-balanced supply of moisture) conditions on the moisture gradient. The third group (Eragrostis aegyptiaca, Senecio aegyptius, Fimbristylis bisumbellata, and Cyperus laevigatus) is distributed along the moisture gradient from little mesic to mesic-dry conditions this come in harmony with (Springuel et al.1991). The fourth group (Tamarix nilotica, Phragmites australis and Rumex dentatus) occupies the dry end on the moisture gradient of Lake Nasser shoreline. These species typically grow on the upper part of the shores, subjected to epigrammatic inundations occurring less frequently than once a year on the other hand, these species looks like border along the shoreline and help Nile crocodiles for nesting and may they used as shelters and they moderate some time the nesting temperature or say they protect nests form the sun.Finally the desert perennials (Salsola imbricata and Pulicaria crispa) have a special position out of the recognized moisture gradient. They are native plants in the desert around the Lake and their growth seems to depend on the seed bank rather than on other factors. Along the shores of the lake both plants are present only in isolated locations and do not form a continuous zone.We conclude that the ordination and classification analyses used in the present study elucidate that the water regime of the Lake is the main factor controlling the growth of the plants and zonation of shoreline vegetation on the other hand the soil parameters have little effect of the spatial variation of vegetation and geographical gradient is less marked as reported by (Springuel et al.1991).According to the above data as well as the landsat ETM+ supervised classification that carried out in the previous chapter, Tamarix nilotica, Phragmites australis, Salsola imbricata and Pulicaria crispa are the most important plants for crocodiles nesting and they play a good role as shelters furthermore most crocodile nests located in/beside these vegetation, where moderate nests temperature. Vegetation types, role and dominant vegetation types Vegetation cover along the lake Nasser was analysis of the vegetation type which screened the nest site directly from the water only and which grows parallel to the stream. Vegetation cover around the nest was analyzed as the vegetation which occurred around the nest site .The vegetation cover surrounds the nest site and does not cover the actual nest chamber as that needs to be exposed to the sun for egg Incubation. The vegetation character along the lake Nasser shoreline or the lake banks, are fairly uniform and are not composed of a large diversity of plants. Based on our investigation and literature review species of vegetation around nesting sites play also an importance role where when the vegetation presence, that means the vegetation save the shade that it will cast over the nest causing it to cool down and try to moderate the air temperature . Vegetation also provides shade for the female crocodile that has to regulate her body temperature while guarding the nest against predators. Pooley (1969) reported that that soil temperatures in direct sunlight became unbearably high, thus shade becomes important for the survival of the female crocodile. Nevertheless, too much shade over the nesting site may alter the incubation temperature which will affect sex ratios in the nest, on the other hand at sites that the vegetation rare to occur and no shade, crocodile female, depend on, to wet her body then quickly go toward the nest and wet the sand, such that operation repeated more than time along the day, this come based on the author investigation and felid work in the lake. Also based up on our investigation the shape and the deep of the nests whole depend up on the soil substrata, which according to our survey where classified on sand, sandy rocky, sandy muddy or with alluvial deposits, and gravelly alluvial deposits, this point need more research in the future
In chapter 4: the author discuses the Nile crocodile estimation in lake Nasser in details under this chapter and used the spot light methodology and double observer nocturnal spotlight count survey methods on the other hand we will try to give a shot summary about this chapter and we will discuss his result as follow in this part for further details please go to chapter 4 and chapter 4 part 2 in section of media coverage in this web site.Chapter IV: Nocturnal spotlight count survey methods for the estimation of abundance, distribution and population trend analysis of the Nile crocodile, Crocodylus niloticus, in Lake Nasser- Egypt
Spot light survey estimation In accordance with (Bayliss et al. 1986; Hutton and Woolhouse, 1989; Brown et al., 2004; Combrink, 2004) Spotlight surveys have usually been used to assess and observe populations by providing indices of population size and density. On the other hand, the spotlight counts are innately inaccurate due to the visibility biases, and observers during the survey routes do not see all of the crocodiles present during a survey. (Messel et al. 1977) reported that the spotlight count method of surveying crocodilians was standardized in 1977 and has proved to be a very successful and dependable method over the last three decades (Letnic and Connors 2006). On the other hand, this method is the most frequently working technique to estimate crocodilian population trends as reported by (Bayliss et al. 1986; Thorbjarnarson et al. 2000). As a result of a reflective layer in the eye known as the Tapetum lucidum (Grenard 1991), crocodilian eyes reflect any bright light shone into them and exposed crocodiles can be located for distances in excess of 100 m. On the other hand, the probability of detection of crocodiles in lake Nasser influenced by several factors include the type and structure of vegetation along the shoreline of lake Nasser between the observer and the crocodile, khors width in lake Nasser, frequency of bends position of the crocodile – submerged, on land, the orientation of the crocodile, and the wariness of the crocodile. As well as the shoreline type sandy, rocky or whatever. All these factor influencing Nile crocodile estimation, and also we not forget the weather condition and waves level. Large crocodile tend to be more wary than smaller animals as reported by (Ron et al. 1998). Over a significant period of time, from October 2009 - August 2010. The spotlight counts of all encounters with crocodiles in the lake Nasser resulted in a reliable population structure and size class distribution pattern. During the last 10 years ago, three surveys have been conducted for crocodiles in Lake Nasser. As reported by Ibrahim 1998 the first was conducted by the Lake Nasser Authority over 3 trips during February and March 1998 reaching no further than 20km of the High Dam and they cover some areas of Khor El Ramla. The surveys carried out using crocodile counts and “Eyelids of Morning”. In total, 13 crocodiles were detected ranging in size from < 2.5 – 5m, and from this they estimated the total Lake Nasser population size to be no more than 1000 crocodiles. The second was conducted by the South Area Protectorates, Nature Conservation Sector, EEAA over a 6 day period when the team travelled from the High Dam south to Khor Korosko via the west bank and returned north via the east bank covering over 50% of the lake shoreline (Salem and Asran 2006). 19 individual crocodiles were detected ranging in size from 2-4m, and from this they estimated the population to be less than 2000 individuals for the entirety of Lake Nasser, the third also conducted by the EEAA south area protectorates and estimated the total count of Lake Nasser Nile crocodile by more 3000- 30000. Generally the above three surveys were conducted exclusively during the day and were created with technical errors. Additionally, resulting estimates of population size were calculated using elementary relationships of detections/unit area extrapolated to the area of the entire lake (i.e. not just suitable habitat).Generally, although these surveys provide little in the way of precious quantitative data, they do provide insights regarding the distribution of Nile crocodiles and perceptions of threats to the Lake Nasser fishing community. the previous mentioned duo to a lot of reasons, such as an error methods of survey technique of survey, and the use of detection/ the unit area of Lake Nasser which mainly not suitable habitats for the occurrence of Nile Crocodile or said nesting of Nile crocodile, deep water and so on.In accordance to our recent surveys, it was observed that the density (Crocodile/km) of Nile crocodile varies from location to the others and from time to other which means that Lake Nasser had a great variation in shorelines topography, habitats and degree of disturbances. Based on the trip/ time and location variations, for instances in total of 148Km (trip 5) were surveyed at Khors of El Madiq area of lake Nasser 100 crocodiles were observed, (the encounter rate or the total abundance=0.676 crocodiles/km, and the corrected abundance =0.680 crocodiles/km.and of 109 Km (trip1) were surveyed at Khor abuo Al hadid part 1at Dahmit area, Khor El magharby, khor Ambercab and Khor Ahmed Badawy at Dahmit east 70 crocodiles were observed, (the encounter rate or the total abundance=0.642 crocodiles/km, and the corrected abundance =0.349 crocodiles/km.and of 107 Km (trip 2) were surveyed at (Khor near al hadide_ Dahmit west, Khor Rahma part 1 and 2, Mirwaw West (khor hag Araby) and Khor AL Manam_ Dabod part1) 59 crocodiles were observed, (the encounter rate or the total abundance=0.551 crocodiles/km, and the corrected abundance =0.234 crocodiles/km That means although trip four was carried out in Eastern part of Lake Nasser shoreline at Khors of El Madiq area, which characterized by rocky cliffs and steeply sloping, rocky shorelines, though, interspersed can be found patches of habitat similar to the western shore of the lake or said suitable habitat for Nile crocodile and resembles areas of trip 1 that carried out at Khor abuo Al hadid part 1at Dahmit area, Khor El magharby, khor In contrast in, (Khor Al– Allaqi in trip 3 and 4) showed low density of Nile crocodile (0.260 and 0.140 respectively), although these area in general view suitable than the above, By working to discover the reasons, it was observed that this location characterized by high density of fishermen, motor boat and by agricultures or reclamation land, which means that the location more crowded enough for crocodiles occurrence. Furthermore the last location was surveyed in winter where the water temperature low, also this reasons may play a significant role for less crocodile investigation at this site, and this site was famous by some hunters of Nile crocodile who used this trend for gain money from crocodile skin trade. The low density location have a resembles reasons (generally we will discuss the suitability of habitat and habitat disturbance for Nile crocodile in a separate chapter). generally we observed that larger crocodiles over four meter are extremely wary to fewer of them being counted during surveys furthermore they submerged at the first sign of being approached which, in turn will explain the low percentage of animals reported in this size class. However we can safely assume that about 10% of Lake Nasser crocodiles are larger than 4 meter. But mainly the main reasons for the low percentages of crocodiles that over than 4 m. due to professional hunters of crocodile populations for illegal skin trade, hunting sports, although that sport at very low scale, and may carried out by very rich men, and by lake Nasser fishermen whom said that crocodiles cause negative impacts on the livelihoods of them and herders and cause extensive damage to fishing nets and to deplete the fishery by over consumption of the resource. So there is a trend to kill crocodile for the above reasons in some areas along Lake Nasser, which that mean, it should for the EEAA decisions makers and researchers to increase their public awareness for the importance of Nile Crocodile in lake Nasser and enhance that way along Lake Nasser fishermen. The size frequency distributions of Nile crocodile populations exhibit a more or less inverse- J- shaped or positively skewed size frequency distribution, which may represent rapidly growing population with high reproductive capacity. Such distributions may indicate also a high hatchling/juvenile mortality as well (Harper 1977), but nevertheless they seem to represent long-term stability, since in most stable populations; one would expect an excess of juvenile over mature individuals, Goldberg and Turner 1986. In these populations, the younger individuals are preponderant than older ones, which is an indication of strength and success of the species, it is mostly due to victorious growing and survival of individuals (Salem 2006). In accordance of a total estimation of Nile crocodile in Lake Nasser the detectability was ≈ 0.96 in between the forty two (42) locations and thus the total estimated count of about 412 crocodiles. According to the variation of Lake Nasser shoreline length by the water fluctuation, of a total 528 Nile crocodile were observed along our survey of about 1261.3 km of survey route the total abundance or "the encounter rate" (0.419 crocodiles/km) and the corrected abundance(0.304 crocodile/km). It was noted that a considerable variation in the total abundance and in the in counter rate in between 42 location see above tables). A chi-square goodness of fit test (χ2= 254.2, df =41; P<0.0001), which indicated that crocodiles were not randomly distributed in between habitats along lake Nasser shoreline and their estimation or there count depend upon several factor that was discussed above. According to the area estimated and counted or determined on using supervised classification and 3D modeling of the suitability of habitat, there are of about 900 to 1000 km of Lake Nasser shoreline not suitable habitat for Nile crocodile at low water level, this will be discussed in chapter of habitat suitability, but mainly this will reduce the estimate of Nile crocodile by about 300:400 crocodile according to table 11. According to table11 the mean number estimated of crocodile at the given water level 172.5 will be 2262.5±237.8 crocodile and at 175 the mean estimated will be as 3029.3±551.5However it will be at 170 only 1529.1±278.4. Based on our investigation the most correctly mean estimation will be most of our work done around it, I mean the given water level 172.5 so the mean estimation number of Lake Nasser crocodile is 2262.5±237.8. Based on the suitability factor this number will reduced by 300-400 crocodile of the mean estimated number so, the mean estimated will be ranged in between 1962.5±237.8 to 1862.5±237.8 at water level 172.5 In accidence to the assumption discussed by (Bayliss et al. 1986; Hutton and Woolhouse 1989) for estimation of the total count, 38 % of crocodiles may be underwater. Because large crocodilians tend to be more wary than the smaller size classes and often submerge when approached (Webb and Messel, 1979; Ron et al., 1998). Spotlight counts therefore represent an index of the total population and without an idea of how many animals there are in the system, there is no way to check on the relationship between spotlight counts and total population size (Woodward and Moore, 1993). However, in combination with population estimates, correction factors can be applied to spotlight count data to improve the accuracy thereof. Nevertheless, for trend analysis without the knowledge of population size, the assumption is made that the relationship between total population size and spotlight count density remains constant (Woodward and Moore, 1993).Therefore the total count on using the above assumption will be increased by about 38 % of crocodiles than that was estimated before. Now, the following what the newspapers published on the Nile crocodile in EgyptSome comments upon what has been written in the Egyptian newspaper about the Nile crocodile in the recent year, starting by what written in Al-Ahram news paper which is one of the famous new paper in Egypt in September 05, 2001 Published an article titled "A farm to crocodiles in Egypt, in Lake Nasser" The first farm for breeding crocodiles will be erected in Egypt, in Lake Nasser which will be auspice by the touristic wildlife parks association on an area of 500 acres on the western shores of Lake Nasser located 15 km away from Aswan-Abu Simbel road. Additionally the project will comprise an open zoo of the endemic species of animals, a Nubian village, golf tracks and gardens. General / Samir Youssef –Aswan governor- demanded the permission of the ministry of state of Environmental Affairs which inhibits Nile crocodiles hunting in order to solve the problem that the fishermen are facing, on the other hand by the end this project faced a lot of complicated cases and finally the project not carried out. our comments on what was published that there was interest in imminent danger of the Nile crocodile by our responsibility and this is what appeared in the request by the governor of Aswan to invite the EEAA in the intervention and try to find a solution of the over hunting of Nile crocodile in lake Nasser at that time.On contrast Al-Wafd newspaper in August 10,2002, Published an article titled by "Egypt's lakes in danger, crocodiles are aggrieved" Professor Helmy Bishai ensured that according to their studies in Lake Nasser that it is a big mistake to say that crocodiles consume big quantities of fishes ,but on the contraire ,they provide a big benefit for fishes farms through eating insects, crustaceans, fishes breeding on the small fishes and the dead animals in the Lake and so crocodiles get the lake rid of those harmful species .The proof is the increasing fishery harvesting in the lakes in which crocodiles were protected.Since then, Lake Nasser and the Nile crocodile, fishermen and the government in the ongoing conflict and the largest examples of this was published in the newspapers the following,Al-Ahram news paper in Feb.02, 2006, Published an article titled by "60 thousands crocodiles in the High Dam Lake" According to some experts, the population of crocodiles in the High Dam was estimated to be not less than 60 thousands crocodiles, every one eats between 5-9 kg of fishes per day and so crocodiles consume 110 thousand tons of fishes approximately every year. I recommended who write this essay to try to read carefully the lake Nasser fishery production and then try to write his essay again, I think he will change his opinion upon the Nile crocodile.As the same continue the attack on the Nile crocodile and forget the problem Electronic Banking, fishermen, smuggling and pricing constraint on the fish, the Nile crocodile. Another journalist wrote in Al-Wafd newspaper in November 22, 2008 Published an article titled "20 thousands crocodiles swallow 70 thousand tons of fishes every year." The newspaper mentioned that according to a report prepared by Misr-Aswan company for fishing in cooperation with the Danish company " Micofish" and experts from Denmark and Uganda ,they all confirmed the increasing population of crocodiles in Lake Nasser and the number is estimated to be 20 thousands crocodiles swallow 70 thousand tons of fishes every year and the report recommends decreasing the population of crocodiles to be 5000 only in order to keep the fishes stock and to achieve the balance between the crocodiles and the fishes and this will lead to attain 50 thousand tons of fish yield every year. * The committee recommended the following: 1- Getting use of the crocodile's skin commercially quickly, 2- Organizing trips for hunting crocodiles of the lake and 3- Adopting the appropriate measures for inhibiting fishing the small size fishes.Here we recommend that each one who wrote on the Nile crocodile in lake Nasser, more reading and accuracy and not to rely on guesswork and palmistry, as they say in Egypt, not the process earn the scoop, but the people want the truth and I believe that truth is what comes from scientific research not only.Pressure is mounting on the Nile crocodile and the situation may change and perhaps we cannot protect the kind of risk over-fishing problem in Egypt and the skin trade and collection of the young/ hatchling and the other, and then we call for more research and more protection for this type, and finally we should say that no relation in between the Nile crocodile in between man, or lake Nasser fishery production, but the main problem in lake Nasser is the man himself.
In chapter 5: The author discuses the: MORPHOMETRIC AND FELID ESTIMATION OF THE SIZE OF NILE CROCODILE IN LAKE NASSER- EGYPT And try to have a look up on some results and discussion in this chapter Morphometric data A total of 528 + 81*hatchling individual crocodiles were sighting 61 individuals crocodiles were captured between October 2009 and august 2010. Yearlings made up the majority of the individuals, reflecting their natural dominance in the population (Table 1) Male and female hatchlings were pooled due to the difficulties. In sexing hatchlings in the field using non-lethal techniques Table 1. Number of individuals captured per size class from 2009/2010 from Lake Nasser region, using nocturnal, and boat based techniques. Hatchlings could not be sexed reliably in the field using non-lethal methods. Regression analysisThe following were measured on every crocodile: head length (HL), snout-vent length (SVL), total length (TL), right hind foot length (HFL), neck girth (NG), tail girth (TG), chest girth (CG), and mass. HL was measured dorsally, while SVL and TL and vent were measured ventrally. Simple linear regression and logarithmic equations expressing the relationship between TL and VL,HFL,NG,TG,CG,HD vent and Body mass, and SVL and TL, HFL, HFL,NG,TG,CG,HD vent and Body mass by using the flowing equations (y = a + bx).Snout-vent length relationships: Total length According to our study, hatchlings were removed from the analysis due to their less increased in snout-vent length with increasing total length than the other size classes. On the study of the relationship in between total length and snot vent length relationship, the slope of other size show highly significantrelationship (r= 0.996 , P<0.001), which indicating a significantly higher increase in SVL relative to the increase in TL as animals grew longer. Generally male and female adults showed significantly different rates of increase and intercepts, with males showing a relatively higher increase of SVL: TL than females. The intercept for females was, however, non-significant.Snout-vent length relationships: Head length The lake Nasser population showed a significant relationship between head length and snout-vent length for all size, with HL increasing at a higher rate relative to SVL in smaller animals (Fig. 2). The slope of the HL: SVL regression decreased step-wise as crocodiles grew, with adults having the lowest head-length increase relative to SVL (r =0. 986, p < 0.001). Hatchling head length measurements showed more variation than other size and so the intercept for this regression was not significant
Snout-vent length: Head width There was a significant relationship in between the SVL: HW of Nile crocodile in Regression analysis of Lake Nasser, in according to fig. 1 (r=0.989, p< 0.001).On the other hand, the slope of regression in between SVL: NG, show high significant relationship, which means as the animals increase in snout vent length the Neck girth increased rapidly, however that may depend on some factor such nutrients, but in our case the nutrients in lake Nasser play a significant role and not contributed by any problem in animals growth.Snout-vent length relationships: Head depthThe slope of the regression of HD: SVL increases more rapidly as crocodile length (SVL) increases, showing that larger animals have significantly deeper heads relative to their length than smaller animals (r =0.987, p < 0.001 ). The regression trends for juvenile and subadults sizes show significant variation in the rate of increase of HD with increasing SVL. The rate of increase of HD with increasing SVL did not differ between sexes (p > 0.05). Snout-vent length: Head width There was a significant relationship in between the SVL: HW of Nile crocodile in Regression analysis of Lake Nasser, in according to fig. 1 (r=0.989, p< 0.001).On the other hand, the slope of regression in between SVL: NG, show high significant relationship, which means as the animals increase in snout vent length the Neck girth increased rapidly, however that may depend on some factor such nutrients, but in our case the nutrients in lake Nasser play a significant role and not contributed by any problem in animals growth.Snout-vent length relationships: Head depthThe slope of the regression of HD: SVL increases more rapidly as crocodile length (SVL) increases, showing that larger animals have significantly deeper heads relative to their length than smaller animals (r =0.987, p < 0.001 ). The regression trends for juvenile and subadults sizes show significant variation in the rate of increase of HD with increasing SVL. The rate of increase of HD with increasing SVL did not differ between sexes (p > 0.05). Snout-vent length: Tail girth, the slope of regression analysis of the relation in between the Tail Girth: Snout-vent length, show high significant relationship where (r=0.989, p< 0.001).Snout-vent length: Chest girth The slope of regression analysis of the relation in between the Chest girth: Snout-vent length, exhibited high significant relationship where (r=0.983, p< 0.001).Snout-vent length: Body mass The slope of regression analysis of the relation in between the Body mass: Snout-vent lengthexhibited high significant relationship where (r=0.921, p< 0.001), this relation as we discussed before that may dependant up on the nutrients and the amount of stomach food, so may the relation from animals to other and may also dependant on the time of feeding, so we think that this relation may also dependant also on the location, or said that the location and time play a significant role in that relation.Snout-vent length: VentThe slope of regression analysis of the relation in between the Vent: Snout-vent length exhibited slightly significant relationship where (r=0.885, p< 0.001) on the other hand Hind foot length: Snout-vent, show a moderate relationship (r=0.754, p< 0.001), see fig 2, table 2). Total length with the other parameters relationship The table below table 3 illustrating the regression relationship in between the Total length and the parameters (Neck girth, Chest girth, Body mass, Tail girth, head length, hind foot length, head depth and head width, vent, and the slope of the regression illustrated as in the following table 3.Total length: Head length Lake Nasser population showed a significant relationship between head length and Total length for all size, with HL increasing at a higher rate relative to HL in smaller animals (Fig.3). The slope of the HL: HL regression decreased step-wise as crocodiles grew, with adults having the lowest head-length increase relative to HL (r =0.994, p < 0.001). Hatchling head length measurements showed more variation than other size and so the intercept for this regression was not significant.Total length: Head widthThere was a significant relationship in between the TL: HW of Nile crocodile in Regression analysis of Lake Nasser, in according to fig. 3 (r=0.990, p< 0.001).On the other hand, the slope of regression in between TL: NG, (r = 0.989, p< 0.001) show high significant relationship, which means as the animals increase in total length , the Neck girth increased rapidly, however that may depend on some factor such nutrients, but in our case the nutrients in lake Nasser play a significant role and not contributed any problem in animals growth.Total length: Tail Girth The slope of regression analysis of the relation in between the Tail Girth: Total length, show high significant relationship where (r=0.991, p< 0.001) on the other hand, Total length: Chest girth, show a high regression analysis slope ((r=0.984, p< 0.001), as well as the relation in between the Total Length and Vent and hind foot length and (r= 0.873, p< 0.001, r=0.740, p< 0.001) respectively, as expressed the Hind foot print show moderately significant relationship and slightly high relationship in case of the vent relationship, and high relationship in case of the body mass (r= 0.923, p< 0.001), which means the no problem in the nutrients/food sources for crocodile in lake Nasser as well as may slightly difference in between location, but still no variation in between location as well as by time see table 3 and fig.3). DISCUSSION Morphometric According to our study it was noted that as crocodiles increase in length, the rate at which snout-vent length increases relative to total length, this may be an indication of their behavior, so that small crocodiles have relatively longer tails than large crocodiles. On the other hand, that can be illustrated due to the need to be vastly mobile to capture fast-moving invertebrate prey (so to be faster than the prey to capture), as well to being able or to have the ability for quickly and efficiently to avoid capture by predators. As they increase in size, the numbers of prospective predators decreases to eventually just humans and other crocodiles. Large crocodiles feed less often, on fewer, larger prey items and do not need to feed as regularly as smaller crocodiles that feed constantly throughout the year in Lake Nasser which come in harmony with (Wallace and Leslie 2007). According to our study and on using simple linear regression it was observed that the larger animals grow in girth at a much faster rate relative to an increase in length than do smaller animals, and that was clearly observed according to the close relationship and the close correlation in between the total length and tail girth, as well the close correlation in between the snout-vent length and the tail girth (see graphic), and so that added girth and mass is an adaptation that is required to control large mammalian prey. Lake Nasser water system characterized by a constant flowing current especially in the khors system but the small increase in tail length may possibly provide an animal with a unique swimming advantage, or run quickly from predators in Lake Nasser, or to avoid themselves from Lake Nasser fishermen in hydro-vegetation. The proportional rate of growth of HD to SVL decreased in hatchling and yearling animals was isometric in juveniles and subadult animals and then increased again in adult animals. The predominance of fish in the diet of juvenile and subadult animals (Hutton, 1987a) this may be illustrated that these animals do not need the additional strengthening of the jaw brought about by the allometric increase of the depth of the jaw. The associated increase in surface area for muscle-attachment with increased head depth would give larger animals a distinct benefit to handle larger mammalian prey, as well as providing the extra Strength/power to withstand powerful knocks to the skull by these preys. The swift ontogenetic shift in skull morphology does therefore not seem to be restricted to smaller animals (HW and HL), but also occurs at the onset of sexual maturity (HD) to prepare adults for larger prey. It was observed that the lack of adult captures reflects the ability of larger animals to avoid capture, mainly it was recognized that larger animals more sensitive than smaller animals in the wild habitat. The Nile crocodile growth rates are extremely changeable and thus, to predict the age of individuals on use the size-age curves a larger error will be resulted as reported by (Hutton, 1987c). However, given the variability in growth rates of juvenile animals, it is not possible to accurately estimate age using regression methods. Brandt (1989) found this in A. mississippiensis, Games (1990) in C. niloticus and Webb et al. (1978) and in C. porosus.Body condition indices Occasionally, as (Webb and Messel 1978a) noted that SVL was used as the basic index of body size because TL relied on the assumption that the tail was undamaged. However, this was not always the case. On the other hand, Webb and Messel (1978a) found that tail length was slightly sexually dimorphic. So we see that the accurate relationship to compare SVL with other parameters based on that the SVL as the basic index of body size. But mainly body mass varies with the amount of food in the stomach, and therefore not a reliable indicator of growth of animals in lake Nasser furthermore, the habitat type and whether conditions and seasonal variations and we also recognized that slopes also play a vital role and that come in harmony with the suggestion that given by (Webb et al. 1978). While SVL growth of Lake Nasser crocodiles was, for the most part, significantly correlated to the proportion of time spent in above average water temperature, the increase in condition for hatchling, yearling and juvenile animals was positively correlated to a rise in water level and negatively correlated to time spent in above-average water and air temperatures, we need to say that also water temperature play the vital role in Lake Nasser crocodiles life history, where the increase of feeding by the suitable temperature and the opposite is right. Interestingly an increased proportion of time spent in warmer than average water and air temperature decreased the RCF, while the proportion of time spent in above-average water level increased the RCF. This was probably due to the fact that in above average temperatures, energy was being put into active growth of the crocodiles, whereas in the high - water season, the over-abundance of food allowed the crocodiles to improve physical condition, Games (1990), found that juvenile crocodiles did not differ significantly in RCF values between sex, age, differing parasitic loads or the timing of the hot, wet season. However, RCF values differed between cool and warm periods. These findings showed that RCF values for juveniles were higher in the cool, dry period, due to higher water levels allowing crocodiles to exploit new food sources as well as in khors in lake Nasser than the open areas, where a high amount of food than, on the other hand, (Webb et al. 1991) suggested that the quantity and variety an the type of prey ingested has direct consequences for body condition. On the other hand, he also emphases that according to Crocodylus porosus juveniles showed similar growth rates, in different studies, when they had similar diets without changes.This illustrated that lake Nasser ecosystem enable crocodiles with high value of RFC and it varies from site to other and from khor to the others based on the food sources and types and quantity
CONCLUSION
A number of biotic and a biotic factor interact to determine growth rates, morphometrics and body condition indices of crocodilians. In the lake Nasser, the most significant influences were water level and temperature, diet and possibly the fast-flowing nature of the lake Nasser itself or said water fluctuation. While these influences were not unique to this crocodilian population, their combined effects may distinguish the physical characteristics of the individuals making up the lake Nasser population from other populations. The body design of crocodilians, while showing extreme conservation throughout their evolution, is phenotypically flexible which may allow for minor adjustments in response to environmental stimuli, as demonstrated by extant genera (Richardson et al. 2002).The close significant correlation and relationship in between parameters, exhibits the health of Nile crocodiles as well as the health of lake Nasser ecosystem during the time of the study although, lake Nasser ecosystem affected by several types of pollutants, which mean that Nile crocodile need further research to estimate its relationship with the lake Nasser pollutants and their effect on its life history and at what degree as well as the close relation in between parameters illustrated that no problems in the nutrients and food sources in lake Nasser.
In chapter 7: the author try to give detailed information about nesting ecology as possible as he can in Lake Nasser, try to have a look for this chapter.During their range, crocodilian populations in the entire world are in danger and threatened by overexploitation, hunting, habitat loss and pollution, human disturbance and all of the control ways of life as reported (Thorbjarnarson 1992). On the other hand, Ross (1998) reported that numerous species worldwide are subjugated for their skins and many populations are threatened due to hunting for trade and in specific word skin trade. The crocodile skin trade generates an international income of about $ 500 million annually. Furthermore he reported also that not only skin trade and hunting but also the Crocodile ranching and farming has the prospective and potential to harm populations if it is not managed correctly, in other words Ross (1998) reported the loss of any species of crocodilian would represent a significant loss of biodiversity as well as an economic prospective. The study of Crocodilians ecology certain information emphasized that Crocodilians are long-lived animals with very high mortality rates in their first year of life because of predation, on the other hand considered as the largest predators in their aquatic environments without any exception.Crocodilians can stand a broad diversity of habitat types including small brackish streams, fast flowingrivers, swamps, lakes….etc, as reported by (Leslie 1997) on the other hand, Crocodiles are ectothermicanimal and they adaptable their body temperature according to their behavior by moving in between sun-exposed sandy banks of rivers, lakes, and the water. According to (Blake and Jacobsen 1992), there are three species of crocodilians occur in Africa, the slender-snouted crocodile (Mecistopscataphractus), the Dwarf crocodile (Osteolaemus tetraspis) and the Nile crocodile (C. niloticus), on the other hand they also reported that one of the most important Crocodilians species is the Nile crocodile; of these three species, the Nile crocodile is the only one to have established itself in the eastern half of the subcontinent. Its sexual maturity is reached by females over a moderately large size range and is locality-dependent. According to Graham (1968) they attain sexual maturity at 232 cm total length as he discussed on his study on South African Nile crocodile. The Nile crocodile breeding in summer at the end of dry season, where the presence of sandy banks as well as when these sandy areas exposed to the highly summer temperature Cott (1961). In general word these nests occur or located in behind the permanent freshwater rivers, lakes ….etc. Graham (1968) reported that the nests cavities were occurred in varies types of substrates, from clay to course-grain sandy area, or mat river sand, after which the eggs (40-80) are laid in the chamber and then covered with sand and incubate for an average of 90 days. The author discuses, crocodile nesting habitat, THE CHARACTERISTICS NESTING SITE, Once a nest was located a set of environmental parameters were recorded. These included, 1-Date and nest number, 2-Location name and position were recorded with GPS e Trix H as UTM WGS 1984, 3- a general habitat description of ground-cover on other hand, the vegetation type, types of plants and their densities, were estimated visually surrounding each nest site, 4-distances to water, 5-the height above water was measured using a standard flexible tape-measure (m), 6-The amount of direct sunlight received by each nest was estimated as the percentage of direct sunlight on the nest at day of investigation, 7- depth to first egg by cm and Depth and breadth of the hole also was estimated and finally 8- soil substrates.· Nesting criteria· Census crocodile nesting · Distance to water and its effects · Nest height above water level · Exposure of the nest to direct sunlight · Vegetation types, role and dominant vegetation types · Shoreline slope
Workshops that had been carried out on the behalf of Nile crocodile comminutes environmental education program. The Nile crocodile project has organized three effective workshops targeted several groups, mostly students from schools, colleges, and nature conservation sector employers , teachers, educational sector of Aswan Aimed was to raise the environmental awareness among all target groups, this has resulted in workshops and achieved desired their objectives. § The first workshop carried out at 24 Jan. 2010 and held in Aswan. The workshop aimed to arise the efficiency of the nature conservation sector and Aswan branch of Egyptian environmental affairs employers to the importance of the Nile crocodile, Lake Nasser and the extent of the risks faced by this object as well as lengthy presentation to the formation of Lake Nasser from 1964/1966 and its stages for filling as well as the different stages of lake Nasser fisheries production since the formation of the High dam Lake. § The second workshop carried out at 10 March and held in Aswan, nature conservation sector, included a felid trip to Saluga and Gazal islands (the workshop report included). § The third workshop carried out in Aswan, nature conservation sector, included a felid trip to a felid trip to Saluga and Gazal islands 26 April 2010 (the report included).
finally try read the above chapters in details in section of media caverages in this web site
end
The project activities that carried in and out Lake Nasser upon the Nile crocodile described in detail in the project report on the other hand due to the larger size and a lot of format in this report we divided the report into 9 chapters included 3 chapters with two parts We uploaded all of these parts separately as a PDF format as well as word document but in two compressed part in section of Media coverage of this project, so for further detail please try to look up this section and read as you can in that section.But we will try to summarize the project activities according to the following sentences.
First the project inclouded these titles
In Chapter I, the author gives a review upon what was published in articles about the Nile crocodile in Egypt and Africa and he also summarized the Nile crocodile history and evaluation and role in the ecosystem, and now have a look up on part of this chapter A REVIEW OF SCIENTIFIC STUDY FOCUSING ON THE NILE CROCODILENile crocodile (CROCODYLUS NILOTICUS) IN AFRICA and EGYPTNile crocodile history, evaluation and role in the ecosystemFossil relics of primitive crocodilians, of thecodonts ancestry, come out in the Upper Triassic period some 200 million years ago. In this era, the wiped out thecodonts, the dinosaurs, the pterosaurs, or flying reptiles and the ancestors of the birds as reported by (Gatesy et al. 2003). The most advanced kind were Crocodilians, the Eusuchians first appeared some 140 to 65 million years ago and the crocodilians of today all belong to this suborder. King and Burke 1989 reported that thee are of about 23 species found throughout the world today belonging to Family Crocodylidae which is further divided into 3 subfamilies a) Crocodylinae, b) the Alligatorinae and c) the Gavialinae. On the other hand, Crocodilians exist throughout the tropics and are considered “keystone species” that generally maintain ecosystem structure and function and recycling nutrients and maintenance of wet refuge in droughts as reported by (Thorbjarnarson 1992).Cott 1961; Pooley 1982 and Thorbjarnarson 1992 reported that these include selective predation on fish species.Crocodilian populations are threatened by overexploitation, hunting, skin trades, habitat loss and pollution (Thorbjarnarson, 1992). On the other hand, many species wide-reaching are exploited for their skins and many populations are threatened due to hunting for trade. Ross 1998 explained that the loss of any species of crocodilian would correspond to a significant loss of biodiversity, economic potential and economic stability.Nile crocodile and the history of EgyptThe Nile crocodile has traditionally played a very important role in the history of Egypt and the Nile River. The god Sobek, with the body of a man and head of a crocodile, was worshipped to venerate the strength of the crocodile while preventing “evil” interactions. In his honor, temples at Fayoum and Kom Ombo (Aswan) were erected during the Greek-Roman Period 200 B.CAncient Egyptians would keep crocodiles in pools and temples. They ornamented the crocodiles with jewels in honor of their beloved god, Sobek. The people of ancient Egypt worshiped Sobek in order to appease him, the crocodiles, and to insure the fertility of their people and crops.The Nile was very important to the people of Egypt, and so that Sobek was called the Lord of Faiyum, and was considered the god who controlled the waters. Water was necessary for the survival of crops, the success of trade, and the livelihood of fishing. These waters were filled with crocodile, so it was a matter of common sense to appease them through the worship of their leader, Sobek.
Nile crocodile history: Nile valley and Lake Nasser
Historically, the Nile crocodile was found throughout the Nile River and its tributaries, including the Rosetta Branch at El-Rahmaniya village (Flower 1933); however, its modern occurrence has been heavily impacted by the expansion of human populations and the creation of the Aswan Dam. While there are no formal reports, unreliable information suggests that in the 1950's professional hunters decimated crocodile populations for the unregulated skin trade, resulting in a very patchy distribution, even fears of extinction, throughout Egypt in the 1960's and 1970's (Ross 1998, Pooley 1980). While the construction of the Dam at Aswan negatively impacted the ability of the crocodiles to utilize the Nile River, the resulting formation of the Lake Nasser opened available habitat and crocodiles were colonizing the lake. It was a surprise for scientists to observe crocodiles spreading in the Lake and increasing in number, year after year. This may be because the Lake is now banked on both sides by the desert, and the human population has been thinned, and the environment became suitable and favourable for living and breeding of crocodiles. The question of where the crocodiles came from, whether it was from the upper Nile in Sudan or the lower Nile towards the
Chapter II General Characteristics of Lake Nasser
LOCATION
The Aswan Dam was built in 1902 and heightened twice in 1912 and 1934 to increase its storage capacity. Nevertheless/ the stored water was not adequate for agricultural development and great amounts of flood water were released annually into the Mediterranean Sea. In 1959, the construction of a rock-filled dam started on the River Nile, 17 km south of Aswan, 900 km from Cairo, which created one of the largest man-made lakes in Africa - the High Dam Lake (Fig. 1). The Lake extends from the dam itself in the north to the Cataract at Dal, Sudan in the south. The major portion of the Lake lies in Egypt and is known as Lake Nasser and Lake Nubia on the Sudanese side. Lake Nasser extends between latitudes 22° 00' - 23" 58' N and longitudes 31° 19'- 33° 19' E. The purpose of constructing the Aswan High Dam (AHD) was primarily to benefit the downstream side by controlling annual floods, provide irrigation to about two million feddans and generate electricity. Indirectly, however, the upstream side has also benefited because of the formation of the lake, which has created great possibilities for fisheries, navigation, agricultural production and even tourism. The region from Aswan to Adindan, which was previously an undeveloped desert, is already developed by controlled use of water from the reservoir (Bishi 2000).
LAKE NASSER MORPHOMETRY The whole reservoir extends about 496 km, 292 km for Lake Nasser and 204 km for Lake Nubia. The area of the reservoir at 180 m level is about 6275 km2 of which Lake Nasser occupies about 5248 km2. The mean depth of Lake Nasser at 160 m level is 21.5 m as compared with about 25.2 m at 180 m level.The mean width of the Lake at 160 m level is 8.9 km, and 18.0 km when the water level reaches 180 m. Morphometric data of Lake Nasser at water levels of 160 and 180 m are presented in Tables 1 and 2.the deepest part of the Lake is the ancient river bed south the adjacent strips of cultivated land forming together the original river valley, called the central area of the Lake with its bottom elevation between 85 and 150 m above sea level. The side areas lie between 150 and 180 m a. s. l. The central part is considered as a flowing river-lake where the speed of the current is fast at the southern end of the Nubian gorge region (100-150 cm/sec). This speed is gradually reduced within a few kms to 10-20 cm/sec and in Lake Nasser to 0-3 cm/sec. The mean depth of this central part is gradually increasing from 10 m at the southern end to 70 m in the north. The bulk of the water masses coming from the south are passing through the central part, which forms about half of the total volume of the Lake (Entz and Latif 1974 and Entz 1976). The flood, which arrives at Aswan from Khartoum within one month before the High Dam was built, covers now the same distance in not less than 5 months but sometimes probably more than 12 months depending on Lake level and the strength of the flood.
In chapter 3 the author study lake Nasser shoreline vegetation and he also identify the role of these vegetation types in relation to Nile crocodile life, have a look upon this chapter 3 Chapter IIIGRADIENT OF LAKE NASSER SHORELINE VEGETATION AND THEIR AND THEIR ROLE FOR NILE CROCODILE HABITATSABSTRACT. A delicate plant cover has developed during the last few decades along the shores of Lake Nasser, on the hand, the use of statistical methods ordination and classification techniques emphasize the groups of species and their distribution along the shoreline of Lake Nasser affected by the prevailing environmental conditions that in the same time affected on the lake Nasser ecosystem. Mainly the distribution of these species is robustly related to the moisture gradient as well as Lake Nasser water level. RESULTS AND DISCUSSION Vegetation analysis Identification of clusters (groups)According to TWINSPAN classification of the stands surveyed in the present study, four clusters of stands their vegetation, are objectively identified. Each cluster is named after the dominant species and identified according to its associated species as described below.Cluster I: Hyoscyamus muticus - Tamarix nilotica - and Glinus lotoides. The dominant species are Hyoscyamus muticus (P = 100%), Tamarix nilotica (P = 85 %), Citrullus colocynthis and Glinus lotoides (P = 57.1%). Other characteristic are Salsola imbricata, Pulicaria crispa (P = 42.5%).Cluster II: Tamarix nilotica - Glinus lotoides - Cynodon dactylon - Fimbristylis bis-umbellata. The dominant species are Tamarix nilotica (P= 100%), Glinus lotoides (P = 76.5%) and Cynodon dactylon, Fimbristylis bis-umbellata, Crypsis schoenoides and Heliotropium supinum. Cluster III: Tamarix nilotica - Phragmites australis and Rumex dentatus, and Heliotropium supinum. The dominant species are Tamarix nilotica (P= 100%). Cluster IV: Tamarix nilotica - Eragrostis aegyptiaca, Senecio aegyptius, Fimbristylis bisumbellata, and Cyperus laevigatus -. The dominant species are Tamarix nilotica (P= 100%). Based on the water supply and moisture content which controlling the vegetation distribution along the shoreline. CA analysis of the species in relation to the moisture content obviously indicates the arrangement of the species along the moisture gradient. AHC analysis separates the groups of species in relation to the moisture gradient which is recognizable in nature. A sequence in the arrangement of the groups of the species indicates the altitudinal zonation of the vegetation. Starting from lower to upper area or from lower slope to higher we can classily the vegetation structure into the following groups based on the soil moisture. The first group of species and that is characterized the stands that characterized by wet conditions (Amaranthus lividus, Crypsis schoenoides and Echiurn rauwolfii, Cynodon dactylon). The second group comprises the mesophytic species (Hyoscyamus muticus, Glinus lotoides, Amaranthus sp and Heliotropium supinum) associated with the mesic (these area that having or characterized by moderate or a well-balanced supply of moisture) conditions on the moisture gradient. The third group (Eragrostis aegyptiaca, Senecio aegyptius, Fimbristylis bisumbellata, and Cyperus laevigatus) is distributed along the moisture gradient from little mesic to mesic-dry conditions this come in harmony with (Springuel et al.1991). The fourth group (Tamarix nilotica, Phragmites australis and Rumex dentatus) occupies the dry end on the moisture gradient of Lake Nasser shoreline. These species typically grow on the upper part of the shores, subjected to epigrammatic inundations occurring less frequently than once a year on the other hand, these species looks like border along the shoreline and help Nile crocodiles for nesting and may they used as shelters and they moderate some time the nesting temperature or say they protect nests form the sun.Finally the desert perennials (Salsola imbricata and Pulicaria crispa) have a special position out of the recognized moisture gradient. They are native plants in the desert around the Lake and their growth seems to depend on the seed bank rather than on other factors. Along the shores of the lake both plants are present only in isolated locations and do not form a continuous zone.We conclude that the ordination and classification analyses used in the present study elucidate that the water regime of the Lake is the main factor controlling the growth of the plants and zonation of shoreline vegetation on the other hand the soil parameters have little effect of the spatial variation of vegetation and geographical gradient is less marked as reported by (Springuel et al.1991).According to the above data as well as the landsat ETM+ supervised classification that carried out in the previous chapter, Tamarix nilotica, Phragmites australis, Salsola imbricata and Pulicaria crispa are the most important plants for crocodiles nesting and they play a good role as shelters furthermore most crocodile nests located in/beside these vegetation, where moderate nests temperature. Vegetation types, role and dominant vegetation types Vegetation cover along the lake Nasser was analysis of the vegetation type which screened the nest site directly from the water only and which grows parallel to the stream. Vegetation cover around the nest was analyzed as the vegetation which occurred around the nest site .The vegetation cover surrounds the nest site and does not cover the actual nest chamber as that needs to be exposed to the sun for egg Incubation. The vegetation character along the lake Nasser shoreline or the lake banks, are fairly uniform and are not composed of a large diversity of plants. Based on our investigation and literature review species of vegetation around nesting sites play also an importance role where when the vegetation presence, that means the vegetation save the shade that it will cast over the nest causing it to cool down and try to moderate the air temperature . Vegetation also provides shade for the female crocodile that has to regulate her body temperature while guarding the nest against predators. Pooley (1969) reported that that soil temperatures in direct sunlight became unbearably high, thus shade becomes important for the survival of the female crocodile. Nevertheless, too much shade over the nesting site may alter the incubation temperature which will affect sex ratios in the nest, on the other hand at sites that the vegetation rare to occur and no shade, crocodile female, depend on, to wet her body then quickly go toward the nest and wet the sand, such that operation repeated more than time along the day, this come based on the author investigation and felid work in the lake. Also based up on our investigation the shape and the deep of the nests whole depend up on the soil substrata, which according to our survey where classified on sand, sandy rocky, sandy muddy or with alluvial deposits, and gravelly alluvial deposits, this point need more research in the future
Spot light survey estimation In accordance with (Bayliss et al. 1986; Hutton and Woolhouse, 1989; Brown et al., 2004; Combrink, 2004) Spotlight surveys have usually been used to assess and observe populations by providing indices of population size and density. On the other hand, the spotlight counts are innately inaccurate due to the visibility biases, and observers during the survey routes do not see all of the crocodiles present during a survey. (Messel et al. 1977) reported that the spotlight count method of surveying crocodilians was standardized in 1977 and has proved to be a very successful and dependable method over the last three decades (Letnic and Connors 2006). On the other hand, this method is the most frequently working technique to estimate crocodilian population trends as reported by (Bayliss et al. 1986; Thorbjarnarson et al. 2000). As a result of a reflective layer in the eye known as the Tapetum lucidum (Grenard 1991), crocodilian eyes reflect any bright light shone into them and exposed crocodiles can be located for distances in excess of 100 m. On the other hand, the probability of detection of crocodiles in lake Nasser influenced by several factors include the type and structure of vegetation along the shoreline of lake Nasser between the observer and the crocodile, khors width in lake Nasser, frequency of bends position of the crocodile – submerged, on land, the orientation of the crocodile, and the wariness of the crocodile. As well as the shoreline type sandy, rocky or whatever. All these factor influencing Nile crocodile estimation, and also we not forget the weather condition and waves level. Large crocodile tend to be more wary than smaller animals as reported by (Ron et al. 1998). Over a significant period of time, from October 2009 - August 2010. The spotlight counts of all encounters with crocodiles in the lake Nasser resulted in a reliable population structure and size class distribution pattern. During the last 10 years ago, three surveys have been conducted for crocodiles in Lake Nasser. As reported by Ibrahim 1998 the first was conducted by the Lake Nasser Authority over 3 trips during February and March 1998 reaching no further than 20km of the High Dam and they cover some areas of Khor El Ramla. The surveys carried out using crocodile counts and “Eyelids of Morning”. In total, 13 crocodiles were detected ranging in size from < 2.5 – 5m, and from this they estimated the total Lake Nasser population size to be no more than 1000 crocodiles. The second was conducted by the South Area Protectorates, Nature Conservation Sector, EEAA over a 6 day period when the team travelled from the High Dam south to Khor Korosko via the west bank and returned north via the east bank covering over 50% of the lake shoreline (Salem and Asran 2006). 19 individual crocodiles were detected ranging in size from 2-4m, and from this they estimated the population to be less than 2000 individuals for the entirety of Lake Nasser, the third also conducted by the EEAA south area protectorates and estimated the total count of Lake Nasser Nile crocodile by more 3000- 30000. Generally the above three surveys were conducted exclusively during the day and were created with technical errors. Additionally, resulting estimates of population size were calculated using elementary relationships of detections/unit area extrapolated to the area of the entire lake (i.e. not just suitable habitat).Generally, although these surveys provide little in the way of precious quantitative data, they do provide insights regarding the distribution of Nile crocodiles and perceptions of threats to the Lake Nasser fishing community. the previous mentioned duo to a lot of reasons, such as an error methods of survey technique of survey, and the use of detection/ the unit area of Lake Nasser which mainly not suitable habitats for the occurrence of Nile Crocodile or said nesting of Nile crocodile, deep water and so on.In accordance to our recent surveys, it was observed that the density (Crocodile/km) of Nile crocodile varies from location to the others and from time to other which means that Lake Nasser had a great variation in shorelines topography, habitats and degree of disturbances. Based on the trip/ time and location variations, for instances in total of 148Km (trip 5) were surveyed at Khors of El Madiq area of lake Nasser 100 crocodiles were observed, (the encounter rate or the total abundance=0.676 crocodiles/km, and the corrected abundance =0.680 crocodiles/km.and of 109 Km (trip1) were surveyed at Khor abuo Al hadid part 1at Dahmit area, Khor El magharby, khor Ambercab and Khor Ahmed Badawy at Dahmit east 70 crocodiles were observed, (the encounter rate or the total abundance=0.642 crocodiles/km, and the corrected abundance =0.349 crocodiles/km.and of 107 Km (trip 2) were surveyed at (Khor near al hadide_ Dahmit west, Khor Rahma part 1 and 2, Mirwaw West (khor hag Araby) and Khor AL Manam_ Dabod part1) 59 crocodiles were observed, (the encounter rate or the total abundance=0.551 crocodiles/km, and the corrected abundance =0.234 crocodiles/km That means although trip four was carried out in Eastern part of Lake Nasser shoreline at Khors of El Madiq area, which characterized by rocky cliffs and steeply sloping, rocky shorelines, though, interspersed can be found patches of habitat similar to the western shore of the lake or said suitable habitat for Nile crocodile and resembles areas of trip 1 that carried out at Khor abuo Al hadid part 1at Dahmit area, Khor El magharby, khor In contrast in, (Khor Al– Allaqi in trip 3 and 4) showed low density of Nile crocodile (0.260 and 0.140 respectively), although these area in general view suitable than the above, By working to discover the reasons, it was observed that this location characterized by high density of fishermen, motor boat and by agricultures or reclamation land, which means that the location more crowded enough for crocodiles occurrence. Furthermore the last location was surveyed in winter where the water temperature low, also this reasons may play a significant role for less crocodile investigation at this site, and this site was famous by some hunters of Nile crocodile who used this trend for gain money from crocodile skin trade. The low density location have a resembles reasons (generally we will discuss the suitability of habitat and habitat disturbance for Nile crocodile in a separate chapter). generally we observed that larger crocodiles over four meter are extremely wary to fewer of them being counted during surveys furthermore they submerged at the first sign of being approached which, in turn will explain the low percentage of animals reported in this size class. However we can safely assume that about 10% of Lake Nasser crocodiles are larger than 4 meter. But mainly the main reasons for the low percentages of crocodiles that over than 4 m. due to professional hunters of crocodile populations for illegal skin trade, hunting sports, although that sport at very low scale, and may carried out by very rich men, and by lake Nasser fishermen whom said that crocodiles cause negative impacts on the livelihoods of them and herders and cause extensive damage to fishing nets and to deplete the fishery by over consumption of the resource. So there is a trend to kill crocodile for the above reasons in some areas along Lake Nasser, which that mean, it should for the EEAA decisions makers and researchers to increase their public awareness for the importance of Nile Crocodile in lake Nasser and enhance that way along Lake Nasser fishermen. The size frequency distributions of Nile crocodile populations exhibit a more or less inverse- J- shaped or positively skewed size frequency distribution, which may represent rapidly growing population with high reproductive capacity. Such distributions may indicate also a high hatchling/juvenile mortality as well (Harper 1977), but nevertheless they seem to represent long-term stability, since in most stable populations; one would expect an excess of juvenile over mature individuals, Goldberg and Turner 1986. In these populations, the younger individuals are preponderant than older ones, which is an indication of strength and success of the species, it is mostly due to victorious growing and survival of individuals (Salem 2006). In accordance of a total estimation of Nile crocodile in Lake Nasser the detectability was ≈ 0.96 in between the forty two (42) locations and thus the total estimated count of about 412 crocodiles. According to the variation of Lake Nasser shoreline length by the water fluctuation, of a total 528 Nile crocodile were observed along our survey of about 1261.3 km of survey route the total abundance or "the encounter rate" (0.419 crocodiles/km) and the corrected abundance(0.304 crocodile/km). It was noted that a considerable variation in the total abundance and in the in counter rate in between 42 location see above tables). A chi-square goodness of fit test (χ2= 254.2, df =41; P<0.0001), which indicated that crocodiles were not randomly distributed in between habitats along lake Nasser shoreline and their estimation or there count depend upon several factor that was discussed above. According to the area estimated and counted or determined on using supervised classification and 3D modeling of the suitability of habitat, there are of about 900 to 1000 km of Lake Nasser shoreline not suitable habitat for Nile crocodile at low water level, this will be discussed in chapter of habitat suitability, but mainly this will reduce the estimate of Nile crocodile by about 300:400 crocodile according to table 11. According to table11 the mean number estimated of crocodile at the given water level 172.5 will be 2262.5±237.8 crocodile and at 175 the mean estimated will be as 3029.3±551.5However it will be at 170 only 1529.1±278.4. Based on our investigation the most correctly mean estimation will be most of our work done around it, I mean the given water level 172.5 so the mean estimation number of Lake Nasser crocodile is 2262.5±237.8. Based on the suitability factor this number will reduced by 300-400 crocodile of the mean estimated number so, the mean estimated will be ranged in between 1962.5±237.8 to 1862.5±237.8 at water level 172.5 In accidence to the assumption discussed by (Bayliss et al. 1986; Hutton and Woolhouse 1989) for estimation of the total count, 38 % of crocodiles may be underwater. Because large crocodilians tend to be more wary than the smaller size classes and often submerge when approached (Webb and Messel, 1979; Ron et al., 1998). Spotlight counts therefore represent an index of the total population and without an idea of how many animals there are in the system, there is no way to check on the relationship between spotlight counts and total population size (Woodward and Moore, 1993). However, in combination with population estimates, correction factors can be applied to spotlight count data to improve the accuracy thereof. Nevertheless, for trend analysis without the knowledge of population size, the assumption is made that the relationship between total population size and spotlight count density remains constant (Woodward and Moore, 1993).Therefore the total count on using the above assumption will be increased by about 38 % of crocodiles than that was estimated before. Now, the following what the newspapers published on the Nile crocodile in EgyptSome comments upon what has been written in the Egyptian newspaper about the Nile crocodile in the recent year, starting by what written in Al-Ahram news paper which is one of the famous new paper in Egypt in September 05, 2001 Published an article titled "A farm to crocodiles in Egypt, in Lake Nasser" The first farm for breeding crocodiles will be erected in Egypt, in Lake Nasser which will be auspice by the touristic wildlife parks association on an area of 500 acres on the western shores of Lake Nasser located 15 km away from Aswan-Abu Simbel road. Additionally the project will comprise an open zoo of the endemic species of animals, a Nubian village, golf tracks and gardens. General / Samir Youssef –Aswan governor- demanded the permission of the ministry of state of Environmental Affairs which inhibits Nile crocodiles hunting in order to solve the problem that the fishermen are facing, on the other hand by the end this project faced a lot of complicated cases and finally the project not carried out. our comments on what was published that there was interest in imminent danger of the Nile crocodile by our responsibility and this is what appeared in the request by the governor of Aswan to invite the EEAA in the intervention and try to find a solution of the over hunting of Nile crocodile in lake Nasser at that time.On contrast Al-Wafd newspaper in August 10,2002, Published an article titled by "Egypt's lakes in danger, crocodiles are aggrieved" Professor Helmy Bishai ensured that according to their studies in Lake Nasser that it is a big mistake to say that crocodiles consume big quantities of fishes ,but on the contraire ,they provide a big benefit for fishes farms through eating insects, crustaceans, fishes breeding on the small fishes and the dead animals in the Lake and so crocodiles get the lake rid of those harmful species .The proof is the increasing fishery harvesting in the lakes in which crocodiles were protected.Since then, Lake Nasser and the Nile crocodile, fishermen and the government in the ongoing conflict and the largest examples of this was published in the newspapers the following,Al-Ahram news paper in Feb.02, 2006, Published an article titled by "60 thousands crocodiles in the High Dam Lake" According to some experts, the population of crocodiles in the High Dam was estimated to be not less than 60 thousands crocodiles, every one eats between 5-9 kg of fishes per day and so crocodiles consume 110 thousand tons of fishes approximately every year. I recommended who write this essay to try to read carefully the lake Nasser fishery production and then try to write his essay again, I think he will change his opinion upon the Nile crocodile.As the same continue the attack on the Nile crocodile and forget the problem Electronic Banking, fishermen, smuggling and pricing constraint on the fish, the Nile crocodile. Another journalist wrote in Al-Wafd newspaper in November 22, 2008 Published an article titled "20 thousands crocodiles swallow 70 thousand tons of fishes every year." The newspaper mentioned that according to a report prepared by Misr-Aswan company for fishing in cooperation with the Danish company " Micofish" and experts from Denmark and Uganda ,they all confirmed the increasing population of crocodiles in Lake Nasser and the number is estimated to be 20 thousands crocodiles swallow 70 thousand tons of fishes every year and the report recommends decreasing the population of crocodiles to be 5000 only in order to keep the fishes stock and to achieve the balance between the crocodiles and the fishes and this will lead to attain 50 thousand tons of fish yield every year. * The committee recommended the following: 1- Getting use of the crocodile's skin commercially quickly, 2- Organizing trips for hunting crocodiles of the lake and 3- Adopting the appropriate measures for inhibiting fishing the small size fishes.Here we recommend that each one who wrote on the Nile crocodile in lake Nasser, more reading and accuracy and not to rely on guesswork and palmistry, as they say in Egypt, not the process earn the scoop, but the people want the truth and I believe that truth is what comes from scientific research not only.Pressure is mounting on the Nile crocodile and the situation may change and perhaps we cannot protect the kind of risk over-fishing problem in Egypt and the skin trade and collection of the young/ hatchling and the other, and then we call for more research and more protection for this type, and finally we should say that no relation in between the Nile crocodile in between man, or lake Nasser fishery production, but the main problem in lake Nasser is the man himself.
See chapter 4 part2 to see location maps and tracking routes and crocodile sighting.
CONCLUSION
A number of biotic and a biotic factor interact to determine growth rates, morphometrics and body condition indices of crocodilians. In the lake Nasser, the most significant influences were water level and temperature, diet and possibly the fast-flowing nature of the lake Nasser itself or said water fluctuation. While these influences were not unique to this crocodilian population, their combined effects may distinguish the physical characteristics of the individuals making up the lake Nasser population from other populations. The body design of crocodilians, while showing extreme conservation throughout their evolution, is phenotypically flexible which may allow for minor adjustments in response to environmental stimuli, as demonstrated by extant genera (Richardson et al. 2002).The close significant correlation and relationship in between parameters, exhibits the health of Nile crocodiles as well as the health of lake Nasser ecosystem during the time of the study although, lake Nasser ecosystem affected by several types of pollutants, which mean that Nile crocodile need further research to estimate its relationship with the lake Nasser pollutants and their effect on its life history and at what degree as well as the close relation in between parameters illustrated that no problems in the nutrients and food sources in lake Nasser.
In chapter 7: the author try to give detailed information about nesting ecology as possible as he can in Lake Nasser, try to have a look for this chapter.During their range, crocodilian populations in the entire world are in danger and threatened by overexploitation, hunting, habitat loss and pollution, human disturbance and all of the control ways of life as reported (Thorbjarnarson 1992). On the other hand, Ross (1998) reported that numerous species worldwide are subjugated for their skins and many populations are threatened due to hunting for trade and in specific word skin trade. The crocodile skin trade generates an international income of about $ 500 million annually. Furthermore he reported also that not only skin trade and hunting but also the Crocodile ranching and farming has the prospective and potential to harm populations if it is not managed correctly, in other words Ross (1998) reported the loss of any species of crocodilian would represent a significant loss of biodiversity as well as an economic prospective. The study of Crocodilians ecology certain information emphasized that Crocodilians are long-lived animals with very high mortality rates in their first year of life because of predation, on the other hand considered as the largest predators in their aquatic environments without any exception.Crocodilians can stand a broad diversity of habitat types including small brackish streams, fast flowingrivers, swamps, lakes….etc, as reported by (Leslie 1997) on the other hand, Crocodiles are ectothermicanimal and they adaptable their body temperature according to their behavior by moving in between sun-exposed sandy banks of rivers, lakes, and the water. According to (Blake and Jacobsen 1992), there are three species of crocodilians occur in Africa, the slender-snouted crocodile (Mecistopscataphractus), the Dwarf crocodile (Osteolaemus tetraspis) and the Nile crocodile (C. niloticus), on the other hand they also reported that one of the most important Crocodilians species is the Nile crocodile; of these three species, the Nile crocodile is the only one to have established itself in the eastern half of the subcontinent. Its sexual maturity is reached by females over a moderately large size range and is locality-dependent. According to Graham (1968) they attain sexual maturity at 232 cm total length as he discussed on his study on South African Nile crocodile. The Nile crocodile breeding in summer at the end of dry season, where the presence of sandy banks as well as when these sandy areas exposed to the highly summer temperature Cott (1961). In general word these nests occur or located in behind the permanent freshwater rivers, lakes ….etc. Graham (1968) reported that the nests cavities were occurred in varies types of substrates, from clay to course-grain sandy area, or mat river sand, after which the eggs (40-80) are laid in the chamber and then covered with sand and incubate for an average of 90 days. The author discuses, crocodile nesting habitat, THE CHARACTERISTICS NESTING SITE, Once a nest was located a set of environmental parameters were recorded. These included, 1-Date and nest number, 2-Location name and position were recorded with GPS e Trix H as UTM WGS 1984, 3- a general habitat description of ground-cover on other hand, the vegetation type, types of plants and their densities, were estimated visually surrounding each nest site, 4-distances to water, 5-the height above water was measured using a standard flexible tape-measure (m), 6-The amount of direct sunlight received by each nest was estimated as the percentage of direct sunlight on the nest at day of investigation, 7- depth to first egg by cm and Depth and breadth of the hole also was estimated and finally 8- soil substrates.· Nesting criteria· Census crocodile nesting · Distance to water and its effects · Nest height above water level · Exposure of the nest to direct sunlight · Vegetation types, role and dominant vegetation types · Shoreline slope
In chapter 5 part 2 the author give a detailed information about the
Capture recapture and release technique methods try to have alook on this chapter in section of media caverages
In chapter 6: the author discuses the habitat vulnerability in lake Nasser as well as he disused in details human disturbances in lake Nasser then try to indentify habitat suitability based on remote sensing supervised image classification analysis , the following is part of what written about in that chapter Chapter 6Habitat vulnerability for the Nile crocodile (Crocodylus niloticus) - lake Nasser- EgyptINTRODUCTION The major conflict between man and crocodile over living space can only be understood once each of the species living necessities is investigated. The fishermen camps and Bedouin communities along the Lake Nasser shoreline require resources from the Lake system and in acquiring these resources the community members create disturbances to crocodile life activities and nesting activities. To facilitate identify the different areas of human disturbance and their respective intensities, the activities and the timing of these activities in relation to crocodile nesting need to be assessed in lake Nasser.Man and crocodile "The fight for space in Lake Nasser".During the history of man on the earth has exposed the tendency to occupy areas which provide in close proximity resources and open spaces. This occupancy is usually to the damage of some natural resource "generally the fact say that as human populations continue to increase, the living space becomes less and less by time" (Shacks 2006). The inability of man to make use of resources without depleting stocks or disturbing natural processes is a concern for our natural world and the species that inhabit it. The crocodile of the Lake Nasser is just one such species suffering at the hands of human disturbances. Lake Nasser in Egypt is certainly the unsung champion of the environmental ecosystem. This unique water reservoir not only provides a continuous water supply to Egypt but also supports many local communities, fishermen and others as well as a huge diversity of fauna and flora, fishing, grazing, tourism, plant collection, mining and agricultures are just some of the more common activities associated with the surrounding communities along the shoreline. On the other hand, we can identify the resources of this ecosystem that shared with the surrounding wildlife, and the Nile crocodile (Crocodylus niloticus) is one such species forced into sharing its resources. Generally the fishermen activities centered on the human camps in Lake Nasser are having a severe influence on the nesting success of crocodiles as well as crocodiles themselves. Illegal hunting practices each year lead to huge tracts of destroyed natural habitat; illegal trades of hatchling and yearning or skin trades of Nile crocodile also lead to huge destroy of the animal future especially in Egypt if the case still without strong control on lake Nasser. The major conflict in fact in between man and crocodile over living space in Lake Nasser region can only be understood once each of the species living requirements is investigated. The fishermen camps and Bedouin communities along the Lake Nasser shoreline require resources from the Lake system and in acquiring these resources the community members create disturbances to crocodile nesting activities. To facilitate identify the different areas of human disturbance and their respective intensities, the activities and the timing of these activities in relation to crocodile nesting need to be assessed.Furthermore, a great deal has been written about the commercial use of wildlife and the way that this can contribute to country development in, Egypt, and it is often argued that sustainability has less to do with the biology of any species than with the human incentives and institutions which provide the context for its use. A clear example in Africa, it was observed that for over 30 years crocodile ranching programs in southern Africa have sought to calm the severe conflict which often exists between crocodiles and man using the value of the animal’s hide to provide conspicuous economic incentives for conservation of the species (Hutton and Games 1992). After a period of growth and replication in Africa market factors have caused a near collapse of several of these programs while in others they appear to have caused a shift in focus from conservation to production efficiency. We need to say to the Egyptian decision makers whom need to transfer the Nile crocodile from appendix I to appendix II without looking about the different study in Africa, may be a severe caused of shift in focus from conservation will be happen. The nature of the conflict The Nile crocodile, Crocodylus niloticus, is the top predator of fresh water systems throughout lake Nasser- Egypt as well as a large part in Africa. They are strict carnivores and relentless predators throughout their lives as they grow from 30/33 cm in total length until might exceed 6.20 m and over 500/750Kg. Like all true crocodiles, this is a tropical/sub-tropical species, rarely found where mean water temperatures are below 15-20 degrees C (upland areas and the south of the continent). Mainly, this crocodile is most abundant in the lakes in Africa and as well as still/low slow-moving water system of Lake Nasser as well as in rivers of savanna Africa. It is, not surprisingly, largely absent from deserts, but it is also rare in moist forest and extensive swamps where it is replaced by Crocodylus cataphractus and Caiman crocodylus. Its absence from these habitats is strongly linked to those morphological characteristics of rivers and lakes which have a directly influence on nesting behaviour (Hutton and Games 1992). The Nile crocodile favors permanent, still or slow-moving water with high, sunny, sandy banks above flood levels with enough vegetation to provide some shade and shelter. Unfortunately, these locations also favored by people. Much of rural Africa remains without modern infrastructure and western-style economic development. Over vast areas, where rain falls in distinct seasons, if at all, water is a scarce commodity. Waterways are life support systems. They provide water for domestic use and irrigation. They support transport systems and whole livelihoods (fishing, watering of livestock, and irrigation for crops, recreation and so forth). High sandy river banks make good fishing camps and village sites. Not surprisingly, people and crocodiles commonly interact, and have always done so. The nature of this interaction is varied. In many places crocodiles have, from time to time, provided a source of cash income. In the 1940s and 50s they were hunted for their valuable skins, and reduced to very low levels in many localities. Even where there is no commerce involving wild hides, some communities regard crocodiles as part of nature’s bounty and a much favored element of their diet.Often, of course, this role is reversed. Crocodiles attack man during his work and his recreation. They ravage his livestock and both loot and destroy fishing equipment such as gill nets. Although reliable data are hard to come by, there is little doubt that crocodiles account for more human lives and general misery than any other predator on the continent. As a result of the conflict between man and crocodile we know that it is common for rural farmers and fishermen kill crocodiles whenever the opportunity presents itself and, equally as effective over a long period, routinely to destroy nests. Under these conditions it is inevitable that the animal will slowly and inexorably give way in the face of human expansion. People against crocodiles in lake Nasser Egypt and compared with other country Egypt has tropical/subtropical climatic zones in which altitude plays a significant role. As it gets slightly cooler in the winter, crocodiles, being ectotherms, grow more slowly. Less obviously, cool temperatures also determine the sex and intrinsic growth rate of young animals. Temperature is fundamental to the distribution and population dynamics of crocodiles. Nile crocodiles are therefore most abundant and strongly dynamics in hot low-lying / flat areas which in lake Nasser Egypt, as in much of southern Africa, also happen to be where rainfall is lowest and most erratic. In these areas daily life has always revolved around clean water. For various socio-economic and demographic reasons, human populations are growing particularly rapidly in many of these areas and the result is predictable, most of them are fishermen, other in agriculture lands, other known as Bedouins, other are working in tourism, …….etc. By the way, since the construction of Lake Nasser, from 1964/1966 to 2010 crocodiles were responsible for 4 deaths (av 0.09/yr) I mean for about 44 years (salem 2006/2009); on the other hand, only in the same period 1 attack were reported for human and 10:70 attacks were reported in Lake Nasser for dogs, goats and camels. On the hand, from 1965 until mid-1970 crocodiles were responsible for 37 deaths (av 7.4/yr) in what is now Zimbabwe - more than any other wild animal (Hutton and Games 1992). In the 12 years from 1984 until 1995, 71 attacks were reported in the Zimbabwe national press, (Av 6.9/yr) with 53 deaths (Av 4.8/yr), a ratio of fatal to non-fatal attacks of 1:1.89 (Raadsman and Loveridge 1988) THE RESEARCH QUESTION The future of the population of crocodiles in the Lake Nasser is indistinct and the less number of adults are well understood. Recently it was observed a severe reduction of number of adults' individuals due to the direct threats. This study will be benefit the scientific felid and conservation management communities both nationally and internationally by creation of comprehensive management plans as well as will be superior overall understanding of C. niloticus ecology and status in Lake Nasser, and will put our hands on threats that control the Nile crocodile live in Lake Nasser. Finally the low numbers of breeding length adults and a decrease in nest numbers, combined with the associated human activities occurring in the Lake Nasser., has lead to the question of what human impacts are having on crocodile numbers due to the disturbance associated with their?· Mapping habitats
· Habitat suitability patterns · See the chapter 7 and you will find a detailed information upon nesting ecology.
In chapter 8 the author gives detailed information about the lake Nasser fishery from 1964/1966 to 2010
Chapter 8: DIFFERENT STAGES OF THE DEVELOPMENT OF FISH PRODUCTION OF LAKE NASSERComparative study in between past and presentSee the chapter in media coverage In chapter 9 (the last chapter the author discussed the public awareness in / out lake Nasser in details ( see the chapter for further details ).
Workshop and Capacity Building for upcoming generations, fishermen, stakeholders and others Held in Aswan and Lake Nasser – Egypt On the behalf of community environmental education program of Nile crocodile INTRODUCTION
Workshop participants came from crocs team Prefectures. Different work units were represented, including community and district government leaders, prefecture. Most presentations and group discussions took place in space provided by crocs teams. Some good discussions were also had during meal times. Workshop trainers/facilitators, also community environmental education and different types of awareness for local communities and fishermen in Lake Nasser during the diurnal and nocturnal survey of Nile crocodile in Lake Nasser had been carried out and aimed to arise the public awareness of Lake Nasser fishermen, as well as, works extended to the Bedouins of Wadi Allaqi protected.Our project of Nile crocodile in the part of its community's environmental education more than 750 fishermen, 2000 student in different level of schools furthermore, faculty of science students were shared and take apart of our program of awareness, 3 important workshops carried out to raise the student awareness and to address the issue of Nile crocodile Lake Nasser. The main goals and objectives § To discuss current problems of Nile crocodile in lake Nasser and issues and try to find solutions as well other related problems such as the fisheries and fishery production in lake Nasser- To introduce participants to the laws and regulations surrounding biodiversity protection focusing on the Nile crocodile in the Egypt especially in and out protected areas regions such as Lake Nasser.
- To introduce and train participants on wildlife survey methodology as well to inform all of them by the importance of wildlife especially by the Nile crocodile importance in Lake Nasser , and the main role of Nile crocodile in lake Nasser as the top predators in lake Nasser and how it make the lake Nasser fisheries in check by time.
- To enhance the participants’ capacity to conduct wildlife surveys and other conservation work.
Workshops Schedule
Welcome drink and meal
• General introduction• Introduction of all workshop participants• Session on Nile crocodile in Lake Nasser • Session on “Laws and regulations” in Egypt and environment law 4 for 1994 and the modified one No 9 for 2009 as well other laws• Group discussion on several main conservation problem areasSession Contents
• Land cover and land use in Lake Nasser • Nile crocodile distribution in Lake Nasser • National nature reserves in EgyptBiodiversity conservation
• Ecosystem services provided by Nile crocodile • Estimated number Nile crocodile in Lake Nasser based on based on our survey and compared with what published in the newspapers • Main environmental protection measures: • Laws and regulations• Nature reserve management• Working with local people and communities especially fishermen in and out of Lake Nasser • Nile crocodile surveys and monitoring should inform management decisions• Specifically, how to conduct Nile crocodile surveys: • Importance of environmental education and other community-based workKey issues discussed- Human/ Nile crocodile interaction (conflict);
- Illegal hunting;
- Environmental education and communication
- Lack of basic conservation knowledge
- Lack of dialogues between government, local people, and conservation organizations
- Do you observed any crocodiles in your khor/ area Yes/No?
- Is there a crocodile in your area earlier Yes/No?
- And if that how long by meter or which is longer your boat or the crocodile do you have seen? Where have you seen the crocodiles in khors or in the open water in the lake, or where?
- Do you remember? Approximately how many crocodiles have you seen?
- Do you remember also Size of the largest crocodile you have seen?
- Have you observed any crocodile nests in your area? Or crocodile hatchling in your area or your khor?
- What do you do when you see small crocodile/ hatchling?
- Have you seen crocodile eggs? Do fishermen destroy the crocodile nests / eggs?
- How many fishermen have died from crocodile attacks within past ten / fifteen years ago?
- How many survived from crocodile attacks past ten / fifteen years ago?
- How many crocodiles are killed monthly in your area/ your khor?
- Have you seen them on the land of Lake Nasser shoreline and at what time exactly?
- Are crocodiles useful animals?
- What are the uses of crocodiles?
- Record popular beliefs about crocodiles from your area?
- Have you seen other animals feeding on crocodile eggs / hatchlings? Like birds /foxes, jackal….etc in your area?
- How boats may did you used in your camp and motors?
finally try read the above chapters in details in section of media caverages in this web site
end
Chapter 1: A REVIEW OF SCIENTIFIC STUDIES FOCUSING ON CROCODILE CROCODYLUS NILOTICUS) IN AFRICA AND EGYPT…………………………………. | 1 |
Chapter 2: GENERAL CHARACTERISTICS OF LAKE NASSER………………………. | 10 |
Chapter 3: GRADIENT OF LAKE NASSER SHORELINE VEGETATION AND THEIR AND THEIR ROLE FOR NILE CROCODILE HABITATS………………………………. | 24 |
Chapter 4: Nocturnal spotlight count survey methods for the estimation of abundance, distribution and population trend analysis of the Nile crocodile, Crocodylus niloticus, in Lake Nasser- Egypt…………………………………………………………………………. | 32 |
Chapter 4 part 2: Spotlight count, survey routes and sighted crocodile "Nocturnal spotlight count survey methods for the estimation of abundance, distribution and population trend analysis of the Nile crocodile, Crocodylus niloticus, in Lake Nasser- Egypt"…………… | 59 |
Chapter 5: MORPHOMETRIC MEASUREMENT AND FELID ESTIMATION OF THE SIZE OF NILE CROCODILE IN LAKE NASSER- EGYPT………………………………. | 74 |
Chapter 5 part 2: CAPTURE RECAPTURE AND RELEASE TECHNIQUE METHODS………………………………………………………………………………… | 91 |
Chapter 6: Habitat vulnerability for the Nile crocodile (Crocodylus niloticus) - lake Nasser- Egypt…………………………………………………………………………………………. | 97 |
Chapter 7: STUDY OF THE NILE CROCODILE NESTING HABITAT………………….. | 125 |
Chapter 7 part 2: Lake Nasser important khors 3D simulation using Aster satellite images and Landsat ETM+ Habitat vulnerability for the Nile crocodile (Crocodylus niloticus) - lake Nasser Egypt……………………………………………………………………………….. | 144 |
Chapter 8: DIFFERENT STAGES OF THE DEVELOPMENT OF FISH PRODUCTION OF LAKE NASSER "Comparative study in between past and present"……………………... | 157 |
Chapter 9: Workshop and Building Capacity for upcoming generations, fishermen, stakeholders and others Held in Aswan and Lake Nasser – Egypt On the behalf of community environmental education program of Nile crocodile………………………….. -------------------------------------------------------------------------------------------------- | 172 |
الاشتراك في:
الرسائل (Atom)