Responses of a macrobenthic community to seasonal freshwater flow in a wet-dry tropical estuary

Wet-dry tropical estuaries are extreme environments driven by wet season rainfall and runoff events. The biota associated with these systems highly adapted to large fluctuations in salinity. There few examples globally where water extraction for human needs has not yet had a major impact on freshwater flow volumes seasonal variability systems. Therefore, this study examined the importance of seasonally variable intertidal macrobenthic (>0.5 mm mesh size) abundance species composition pristine, wet-dry estuary nearshore environment. focus was mud- sandflats macrobenthos known be an important food source endangered migratory shorebirds fisheries region. Macrobenthos flats were sampled four occasions spanning late-dry, late-flood, early-dry periods across years. Across all sites, total significantly lowest during late-flood period, when salinity low, highest late-dry season, under hypersaline conditions. In muddy estuarine flats, dominant group polychaetes. contrast, sandy bivalves dominated early-dry. However, salinities at their lowest, experienced almost complete loss bivalves. Although short-term negative effects some species, it is clear that recruitment back into begun once tide re-established differences flood response between polychaetes likely reflects life history strategies, burrowing swimming behaviour providing ability seek refuges low periods. Macrobenthic also correlated benthic chlorophyll concentrations, reflecting both primary secondary production impacted flow. This suggests abundance, dominance changes pristine system, demonstrating role inputs.