The Red Sea forms a semi–closed basin of the African Rift, which extends about 1920 km from Ras Muhammad at the southern tip of the Sinai Peninsula to the Straits of Bab el Mandab at the entrance to the Gulf of Aden  This great water body is a unique habitats for coral reefs, mangroves and sea grass beds, which provide basic benefits of food, shoreline protection and stabilization, and economic benefits for tourism . Five species of marine turtles have been observed in the Egyptian Red Sea: the green turtle (Chelonia mydas), the hawksbill (Eretmochelys imbricata), the loggerhead (Caretta caretta), the olive–ridley turtle (Lepidochelys olivacea) and the leatherback turtle (Dermochelys coriacea) [ 3, 4]. These five species face habitat deterioration and accidental capture during fishing. Climate change is also having an impact on turtle nesting sites through higher sand temperatures, which affect the sex of hatchlings . About one out of every 1,000 hatchlings that emerge will survive to maturity . The green and hawksbill turtles are more common and have been observed feeding and nesting along the Egyptian Red Sea coast . At present time, these two species are enlisted in the Red List either as critically endangered, hawksbill turtles [7,8] or endangered, green turtles [7, 9]. Little attention has been given to the ecology of these species in the Red Sea in Egypt . Frazier and PERSGA/GEF [11, 12] presented reviews of marine turtles of the Egyptian Red Sea. In the Red Sea, around 450 green turtles are typically observed nesting annually. . However, most of the marine turtle population estimates available in the literature are based on scattered surveys and interviews with fishermen. Frazier and Salas  reported less than 100 nests for the green turtle along the entire Egyptian coast. Recently, [13,12] addressed two major nesting areas for green turtles (Zabargad Island and Wadi El Gimal beach areas) and two valuable offshore areas for the hawksbill (Giftun and Shaker Islands). They also reported scattered nesting events along the coast but at very low–density .
Along the Egyptian coast, green turtle nests are laid from June to August with a peak in July . At the northern Red Sea at Hurghada, Giftun Island is considered a shelter for nesting and breeding for the hawksbill turtle . Giftun was banned from access . However, some restaurants remain there and are accessible to tourists.
Nesting sites along the Egyptian Red Sea coast are exposed to increasing pressure from unsustainable coastal development [4, 12, 13]. The increasing habitat degradation due to irrational land use, and the growing number of tourists and vessels are identified threats to nesting turtles [12, 8, 13]. The characters of sediments have direct effects on the breeding of sea turtles. For instance, the hatching success of Lepidochelys olivacea in Baja California is affected by both distance from the sea and humidity in the nest . First studies on sea turtle behaviour [16, 17, 18] discovered that species from the Cheloniidae Family (loggerhead, green, hawksbill and olive ridley turtles), have an established practice just before the selection of a nesting site, which is to press their heads into the sand, probably to check suitable environmental characteristics of the area such as moisture, temperature or salinity. Land erosion is another factor affecting adversely breeding and hatching success . Furthermore, one of the potential threats deteriorating the life span and survival of marine turtles is pollution . One of the major categories of potential pollutants that have impact upon marine turtles are debris, oil, tar and heavy metal pollution [20, 21].  conducted a field study to determine the concentrations of Cd, Pb, Fe, Cr, Ni, Se, Sb, As and Cu were investigated in the nesting environment of green turtles in Mediterranean Sea near Kazan, Mersin–Turkey.
Marine turtles grow slowly, breed infrequently, undertake long migrations, and utilize many habitats that expose them to human–induced mortality . Recently, Geographic Information Systems (GIS) along with a variety of remote–sensing techniques have revolutionized sea turtle research. Geographic Information Systems (GIS) have become primary tools for analysing data to identify biological and migratory patterns of behavior. GIS allows graphical representation and analysis of geospatial data . GIS information about sea turtle ecology provides a strong foundation for sea turtle conservation. GIS has been useful in furthering our understanding of sea turtle range and habitat use, and has become an important tool in assessing threats to sea turtle populations ). Our knowledge about nesting habitat of sea turtles can be enhanced with satellite observations on environmental conditions .
Other satellite technology has been used to assess the suitability and quality of nesting areas. For example, Global position system (GPS) data was used to detect location of surveyed sites and points [26,27,287] With our improved ability to estimate anthropogenic pressures and activities from advanced sources such as satellite imagery and remote sensing, we are able explore the impact of human-threats on species at various scales .
Materials and Methods
Big Giftun Island as a nesting study site comprises three subsites: Big Giftun site 1, Big Giftun site 2, and Big Giftun site 3 (Turtle Bay), (Fig. 3) the area was visited in reference with last survey years, the three sites were defined with GPS coordinates for old nests observations, sampling, and other equipment were conducted at nesting areas of selected hawksbill turtles (Eretmochelys imbricata) were the survey conducted between mid-April and finished in August, 2015. These species are considered common throughout the region and are known to feed and nest there .