Fish use of intertidal mangrove creeks at Qeshm Island, Iran

Habitat use by fish in intertidal mangrove creeks is relatively unstudied in the Persian Gulf. We investigated the role of temporal variations and creek elevation in shaping fish community structure in intertidal mangrove creeks in the Strait of Hormuz, Qeshm Island, Iran (western Indian Ocean). Block net sampling was carried out to examine the influence of 3 types of temporal dynamics on patterns of fish diversity and biomass. Tides, diel day/night variations, and season all proved important for fish dynamics. The fish assemblage of 29 species was dominated by Mugilidae, which constituted 62% of biomass and 41% by abundance. Although the most abundant species occurred in all creeks and months, the number of species, community biomass and abundanceof individuals wewre significantly influenced by tide and day/night cycles, with highest values during nighttime spring tides and lowest values during daytime neap tides. Gut content studies showed that fish accessing marsh surfaces on nighttime spring tides generally had 75-100% full guts, indicating trophic use of mangrove areas. The findings from this meso-tidal arid area generally agree with previous studies of mangrove creeks from wetter tropical sites, but there were some exceptions. Notably, fish community abundance and biomass in February winter conditions were highest during nighttime neap tide conditions, instead of during nighttime spring tide conditions. This neap tide maximum was associated with a relatively greater dominance of resident fish species during winter, but may also indicate some temperature-related differences in fish use of mangroves that are at the northernmost regional limit of their distributions at Qeshm Island.