EFFECT OF WATER DEPTH ON FISH DISTRIBUTION AND FEEDING HABITS IN EASTERN HAMMAR MARSH USING HEAT MAP PLOTTING TECHNIQUE

Fish assemblage in the East Hammar marsh was described during November 2020 to October 2021. A total of 46,277 individuals comprises of 43 fish species belong to three origins were collected; 20 of marine fish, 12 native species and 11 of exotic species. Water and fish samples were collected from three stations which characterized as having different depths. Nile tilapia Oreochromis niloticus was the most abundant species which reached (18.47%) in Al- Sallal AL- while was the highest abundant species in AL-Mansory attaining (22.01%), Blue tilapia Oreochromis aureus was the most abundant species in AL-Burka which reached (18.43%). The heatmap showed a difference in fish densities according to the depths where fish diversity increased with depth as well as during flood tides. The subtidal zone characterized by variously feeding habit groups with dense herbivores and large –size piscivores unlike small fish that migrate to intertidal zone and shallow areas for feeding and protection from predators. Alien species were also found in all stations in East Hammar marsh but the highest abundance was in the shallow area. The study revealed the clear effect of water depth on fish abundance and diversity whereas exotic species have a significant negative correlation with the depth (r= -0.2) in contrast to the positive relation with native species (r=0.4), and also fish order according to their patterns of feeding habits.