English abstract
Seagrass beds are unique ecosystems which are rich in biodiversity and serve as nursery and feeding grounds for benthic invertebrates, as well as small fishes, In such ecosystems, seagrasses are the backbone of the system due to the many habitat niches they offer and their extremely high primary production on which the higher trophic level depend. The trophic network of the intertidal seagrass beds of Barr Al Hikman marine system was studied using stable isotope (315N & SPC) signatures of the primary producers, two sources of organic matter. water particulate organic matter (wPOM) and sedimentary particulate organic matter (SPOM), and the fauna. The aim of this study was to estimate the main trophic pathways and functional links between organisms of the benthic ecosystem, and the main organic source which supports the system. Water particulate organic matter (WPOM) was the most depleted food source for 8C signatures (- 15.67 * 2.21 %), but it was not the main contributor to the diet of the fauna. Seagrasses had most enriched $13C (range - 7.56 +0.44 to - 7.39 + 0.41 %), while SPOM and benthic diatoms had intermediate di signatures (range - 10.85 $ 1.32 to - 10.74 $ 2.31%). Seven faunal species, accounting for 33.3% and six faunal species accounting for 28.6% of the 21-species analysed predominantly utilized SPOM and seagrasses in their diet respectively. Benthic diatoms could be the main constituent of SPOM, which is supported by the relatively close N and C mean values of sPOM and benthic diatoms. Seagrass detritus was also a major constituent of the organic pool (SPOM) of Barr Al Hikman marine intertidal area based on C/N ratios and SIMMR analysis. The maximum trophic level of Barr Al Hikman intertidal area was 4.3. The study showed that the primary consumers of Barr Al Hikman intertidal ecosystem depend more on seagrasses rather than benthic diatoms. This study shows that seagrasses is consumed by a larger number of fauna species and is important for a substantial portion of the food web in the tropical seagrass
meadows in Barr Al Hikman area
