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Abstract The present study aims to determine the presence and diversity of the species composition of macroinvertebrate fauna: Cnidaria, Crustacea, Mollusca and Echinodermata inhabiting the mangrove ecosystem (Avicennia marina) at Nabq and Ras Mohamed Protectorates, South Sinai. Moreover, the distribution, status, overall abundance, seasonal variations, Population Density, Species Richness, zonation, and similarity in faunal composition between the different studied sites are also considered. The specimens of the present work are collected seasonally (summer, autumn, winter and spring) from five mangrove swamps, one from Ras Mohamed protectorate and the other four swamps from Nabq protectorate named Gharqana, Arwashia, El-Manqata and Abu Zubad.The present study showed the following results: 1- Ecological Parameters of Ras Mohamed and Nabq Protectorates: Water temperature fluctuated between 21–23°C in winter and 29.5–33°C in summer. Changes in air temperature followed the same pattern but are slightly higher than water temperature in autumn, winter and spring but lower in summer. Approximately there is slightly a change in the pH values of water in mangrove swamps ranged between 7.5 – 8.3 in summer and winter, respectively. Seasonal changes in the concentration of dissolved oxygen in the studied sites indicate that it ranged between (5.4 – 7.3) mg/L. The minimum value is recorded in summer and the maximum value is recorded in winter. Changes in salinity are observed; it ranged between 39.04 ppt. in winter and to 51.48 ppt. in summer. During the present study, three types of habitats at mangrove ecosystem: rocky, sandy and muddy habitats are accommodated different species of macroinvertebrates. 2- Macro-Invertebrates of Mangrove Ecosystem in Ras Mohamed and Nabq Protectorates, South Sinai: The list of the recorded macro-invertebrate species comprised 122 species belonging to 97 genera, 59 families, 16 orders: Rhizostomeae, Decapoda, Archaeogastropoda, Basommatophora, Cephalaspidea, Heterobranchia, Heterostropha, Littorinimorpha, Mesogastropoda, Neogastropoda, Arcoida, Mytiloida, Pterioida, Veneroida, Chitonida and Ophiurida, six classes: Scyphozoa, Malacostraca, Gastropoda, Bivalvia, Polyplacophora and Ophiuroidea and four phyla: Cnidaria, Crustacea, Mollusca and Echinodermata. Mollusca have the highest number of species, being 108 species (88.6%) belonging to 86 genera and 50 families: 69 species of Gastropoda, 38 species of Bivalvia and one species of Polyplacophora. Crustacea is the second group, it is represented by 11 species (9%) belonging to 9 genera and seven families, of which nine species of Brachyura and two species of Anomura. Phylum Echinodermata comes after Mollusca and Crustacea, it represented by two species (1.6%) belonging to one genus. The lowest number of recorded species is belonging to phylum Cnidaria and represented by one species (0.8%). 3- Occurrence Pattern of Macro-invertebrates in Mangrove Ecosystem of Ras Mohamed and Nabq Protectorates: The number of macro-invertebrate species is different with different mangrove sites. El-Gharqana site in Nabq Protectorate has the highest number of species, (92 species: 75 genera and 51 families). Abu Zubad site is next in order and representing by 67 species (58 genera and 37 families), followed by El-Manqata site (57 species: 50 genera and 35 families) and finally Arwashia site has the lowest number of recorded species, (49 species: 43 genera and 35 families). The number of macro-invertebrates species recorded from Ras Mohamed is 55 species (46 genera and 32 families). The status of the recorded species in such specific habitat is markedly variable from phylum to another. For Cnidaria and Echinodermata, the abundant species constituted 100% at Nabq Protectorate. For Crustacea, the abundant species constituted 72.7%. In contrast, 9.1% and represented by one species is considered common and the other species are rare (18.2%) at Nabq Protectorate. On the Other hand, at Ras Mohamed Protectorate the abundant species constituted 85.7% of the total number of crustaceans and 14.3% represented by one species is considered common. The molluscan species exhibit the same pattern as in case of crustacean species; the number of abundant species is 32 (29.9%). However, the common species represented by 18.7% and (51.4%) considered rare at Nabq Protectorate. Whilst, at Ras Mohamed Protectorate the abundant species constituted 41.7% of the total number of Molluscan species, 18.7% is common species and 39.6% is considered rare species. A total of 29087 specimens of all species are collected from the different sites during the present survey. Out of them 21910 specimens (75.3%) are Mollusca, 6792 specimens (23.3%) are Crustacea, 257 specimens (0.9%) are Cnidaria and 128 specimens (0.5%) are Echinodermata. The macro-invertebrate groups exhibit a marked seasonal variation in their occurrence in the mangrove sites at Ras Mohamed and Nabq Protectorates. During summer, the highest number of species is recorded, being 90 species, of which one species of Cnidaria, 11 species of Crustacea, 76 species of Mollusca and two species of Echinodermata. The number of species is declined during autumn and winter to 88 species (one cnidarian, ten crustaceans and 77 molluscans) for the autumn, and (one cnidarian, nine crustaceans, 76 molluscans and two echinoderms) for the winter. During spring, the lowest number of species is recorded, being 76 species, of which one species of Cnidaria, nine species of Crustacea, 64 species of Mollusca and two species of Echinodermata. The population density (number of individuals/m2) of macro-invertebrate species in different seasons is represented in mangrove sites of Ras Mohamed and Nabq Protectorates. The richness value of macro-invertebrate species in Ras Mohamed Protectorate is minimum in summer and maximum in autumn. On the other hand, at Nabq Protectorate the minimum richness value recorded at Arwashia in winter and maximum value recorded at El- Gharqana in winter. Mangrove communities of the five mangrove sites include faunal assemblage of many species. Some groups exhibit clear zonation in distribution (crabs and molluscs), others are just visitors but the majority is resident in the mangrove. The highest similarity of species is shown between macro-invertebrates of El- Gharqana and Abu Zubad sites, being 69.18 %. Whereas, the lowest similarity is recorded between Arwashia and Abu Zubad, being 48.28%. The other indices varied from 52.48% between El- Gharqana and Arwashia to 66.67 % between Ras Mohamed and El- Gharqana.. |