Diversity and seasonal succession of resident and migratory macrobenthic fauna of saltmarsh restoration site at Sonadia Island, Cox’s Bazar, Bangladesh

The present research was carried out to assess the diversity and seasonal succession of resident and migratory fauna in the saltmarsh restoration site at Sonadia Island, Cox’s Bazar, Bangladesh. Two experimental plots (100 × 100 m ²) viz., saltmarsh restoration site (RS) and impacted site (IS) were selected in the study area for collecting resident and migratory fauna in different seasons using stratified random sampling technique. A total of 118 resident fauna of different groups were recorded from RS in different seasons whereas the total number of 54 species/taxa were recorded from the IS of saltmarsh habitat in Sonadia Island. Recorded species/taxa of RS were comprised of 8 phyla, 10 classes and 65 families where Gastropoda were consisted of 33 species, Bivalvia were 78 species, 15 species of Polychaeta, Hoplonemertea were 3 species, Holothuroidea and Pilidiophora were consisted of 2 species and also some other class: Chromadorea, Sipunculidae of 1 species. The position of Glycera sp. in the family Glyceridae of Polychaeta recorded from RS was ranked first due to their highest abundance (207 indiv./m²). Species diversity of RS were varied from 5.98 to 6.47 in different seasons. Other resident fauna of IS were under 3 phyla, 5 classes and 35 families. The phylum Mollusca contributed the highest number of species under the families Potamididae, Veneridae, Naticidae, Turritellidae, Trochidae, Arcidae and Nerillidae. Among them, Potamididae and Veneridae were the most dominant families. Migratory faunae of different finfish and shellfish (31 species) were identified from RS and IS under 11 orders and 22 families of 2 phyla during this study. Chordata and Arthropoda were the most dominant group, consisting of Chelon labrosus, Liza vaigiensis, Pomadasys argyreus, Eleutheronema tetradactylum, Platycephalus indica etc., which were also important in the saltmarsh area. Species diversity (H′ log2) of the migratory faunae were 4.34-4.58 in different seasons. From the above-mentioned result, it is indicated that the protected as well as the restored saltmarsh vegetation favors to inhabit a large number of resident fauna of diverse group, the findings of which would be very much helpful for the conservation and management of marine biodiversity to a greater extent.