FEEDING ECOLOGY

Dugong feeding ecology along the Egyptian Red Sea

This study focused on the popular habitats of dugongs in Marsa Alam and Wadi El-Gemal National Park (WGNP) in the Red Sea off southern Egypt in 2016 and 2017. 

We assessed the abundance of seagrass species, dimensions of feeding trails, grazing rate compared to its relative accessibility, and frequency of feeding trails and estimated the existing dugong population via different trail widths.

DUGONG GRAZING EFFECT

The grazing effect of Dugong on seagrass: a field experiment at Wadi El Gemal National Park, Egypt.

The grazing effect by dugong on seagrass was experimentally observed for one year in 2016 at the Shams Alam site within Wadi El-Gemal National Park.

Two levels of grazing intensity (low grazing and high grazing) were performed to understand the competition and recovery between the seagrass species and compared to a control area with no grazing.

SHARK PHOTO ID

Photo-identification of the oceanic whitetip shark (Carcharhinus longimanus) at Elphinstone Reef, Egypt, Red Sea.

A photo identification project on the oceanic whitetip shark by SCUBA diving was carried out from Jun 28, 2016, to Jan 5, 2019.

The shape and the white apex of the first dorsal fin were used as main features to identify 105 oceanic whitetip sharks at Elphinstone Reef. Eight individuals were males and 97 were females (male-to-female ratio of 1:13.125).

DUGONG QUESTIONNAIR SURVEY

Assessing dugong distribution and overlapping threats along the northwestern Red Sea, Egypt

A total of 207 interviews were completed from August 2015 to May 2016 in seven regions along the Egyptian Red Sea coast.  From 1980 to 2016 Dugong was sighted at 95 locations,  Seagrass distribution, and fishing areas were overlaid on GIS maps to highlight the overlaps between dugong distribution, and anthropogenic threats, and to identify potential conservation hotspots.

The minimum population size was estimated to be between 73 and 97 individuals in the north-western Red Sea, Egypt.

NEW RECORD

Evidence of the occurrence of a large dugong in the Red Sea, Egypt

Three feeding trails of a large dugong with a width of 30 cm were recorded at 11 m depth at Marsa Hermez off the Egyptian Red Sea coast on the 23rd of January 2019.

The present results indicate the demonstration of the presence of a large female dugong in the Red Sea and the presence of female dugongs with calves in key habitats.

DOLPHIN TOURISM IMPACTS

Effects of swim-with-dolphin tourism on the behaviour of spinner dolphins, at Samadai Reef in the Egyptian Red Sea

Behaviour of the spinner dolphins was monitored both on days when tourist boats were present and on days when they were absent using Marcov chain modelling.

Tourist activities affect the transition probabilities between dolphin activity states from resting to milling, or travelling, from milling to travelling or avoiding, and from travelling to avoiding.

DUGONG STATUS

Status of Red Sea Dugongs

Research on dugongs in the Red Sea began with largely anatomical and physiological work on dugongs that were accidentally killed or purposely netted.

Currently, largely due to observations of live dugongs in the wild and to data that can be collected underwater during SCUBA diving, snorkeling, and stranded carcasses.

DUGONG PHOTO ID

Photo identification of dugongs in Marsa Alam and Wadi El-Gemal National Park, Egypt

Using underwater photo identification, an ID catalog was prepared for the dugongs with records of their occurrence among sites, in the Red Sea, Egypt.

A total of 30 dugongs were recorded at the southern Egyptian Red Sea coast between December 2015 and October 2017, 16 at Marsa Alam and 14 at Wadi El-Gemal National Park.

STRANDED DUGONG CALF

Stranding of a neonatal dugong calf in Wadi El-Gemal National Park: Implications for dugong conservation in Egypt

A male dugong calf of 120cm long was observed in Wadi El-Gemal National Park on September 29th, 2015. It was released back to the sea but was found dead on October 4th, 2015. Photo ID confirmed the individual. The time budget of behavioural activities was recorded before and after stranding.

After stranding, the calf surfaced to breathe, rest more, and travel less. It died 12 days after the first observation on September 22nd. All possible measurements were taken.

DUGONG FEEDING TRAILS

Analysis of Feeding Trails Provides Evidence of the Number of Dugongs Excavating Seagrass at Key Habitats Seasonally in the Egyptian Red Sea.

The aims of the work were: 1. Estimate the temporal and spatial variation of seagrass abundance. 2. Identify the temporal and spatial variation of the feeding trails. 3. Examine a relationship between the dugong muzzle width and total body length using laser photogrammetry technique. 4. Create predictive modeling maps for suitable dugong habitats and calving. 5. Raise awareness of dive guides, snorkeling guides, and local communities. 6. Preparing the first management plan for dugong conservation in Egypt.

RED SEA DUGONGS

A global assessment of dugong status and
conservation needs

The following Important Marine Mammal Areas of relevance to dugongs have been declared in the Red Sea: the ‘Northern Red Sea Islands’ and the ‘Southern Egyptian Red Sea Bays, Offshore Reefs and Islands’ in Egypt; and the ‘Farasan Archipelago’ in Saudi Arabia.

Dugongs have likely declined in the Red Sea in recent decades due to human-caused mortalities relating to past hunting pressure and current incidental bycatch and habitat loss.

Contemporary data on abundance for the entire region could enable an IUCN subregional assessment of the status of the dugong in the Red Sea.

PROF. HAMED GOHAR

The Red Sea Dugong

Gohar (1957) recorded 16 dugongs within 70 km between Hurghada and Ras Gemsha over 14 years. He obtained his specimens using specially made fishing nets.

Gohar (1957) recorded 10 females, six males, and no calves. He studied the anatomy of the dugong. He reported that in males, the distance between the anal and genital opening is approximately 1/7th the total length of the animal while in females the distance between the vulvar and the anal clefts was between 2.5 to 3.5 cm.

DOLPHIN PHOTO ID

Estimation of the abundance of the spinner dolphin Stenella longirostris using photo identification technique in Samadai Reef, Red Sea, Egypt

Dolphins were photographed for individual identification purposes in Samadai Reef, Marsa Alam, Red Sea, between January 2012 and March 2013.

A total of 255 spinner dolphins were identified with a mean identification rate of 45%. A total of 33 individuals (12.9%) were resighted 4 to 8 times, and 131 individuals (51.4%) were sighted only once. Photo identification analysis provided a population size of 567 to 637 dolphins.

SHARK ECOLOGY

Human impact on the presence of sharks at diving sites, Red Sea, Egypt

The study was carried out between June and November 2008 at Elphinstone, Daedalus, Big Brothers Island, Small Brother Island, Zabargad Island, Rocky Island, and Habili Ali.

Eight species of sharks for a total of 292 specimens were recorded: whale shark (1 specimen), pelagic thresher shark (12), silvertip shark (1), gray reef shark (61), silky shark (2), oceanic whitetip shark (123), whitetip reef shark (5), and scalloped hammerhead (87). The frequency of encounters in Elphinstone is considerably lower than in other study sites.

DOLPHIN BEHAVIOUR

Behaviour of Spinner Dolphin at Sha'ab Samadai, Marsa Alam, Red Sea, Egypt

The behaviour of the Spinner Dolphin Stenella longirostris was studied at Sha'ab Samadai, Marsa Alam, Red Sea. The data were collected from October 2005 until September 2006 using surface observations.

Four objectives were studied: arrival and departure time of dolphins, distribution of dolphin movements within the lagoon, aerial behaviours and human effects on dolphin behaviour.