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To identify the distribution pattern of macrofaunal assemblages of the Dafeng intertidal flats in response to hydrodynamic and sediment dynamic processes in the northern Jiangsu coast, East China, macrofauna sampling and hydrodynamic observations were carried out simultaneously across the mud flat, mixed mud-sand flat, and silt-sand flat of the intertidal zone in June 2018. Results show that there was a clear zonal distribution pattern of the macrofaunal communities, as is controlled by local hydrological and sedimentary environments. Principal component analysis (PCA) revealed three types of intertidal area in terms of hydrological and surficial sediment parameters. Similarly, three distinct groups of the macrofaunal communities, i.e., mud flat, mix mud-sand, and silt-sand groups, were recognized at similarity level of 24% based on the CLUSTER analysis in similarity profile (SIMPROF) test. Correlation analysis upon best variables stepwise search (BVSTEP) indicated the importance of the hydrodynamics (e.g., water temperature and salinity, tidal duration, flow speed, suspended sediment concentration, and wave height) in the differentiation of macrofaunal communities with different taxonomic classes over the intertidal zone. Therefore, macrofaunal assemblages, similar to hydrology and surficial sediment, have a unique zonation pattern. Small-sized deposit feeders adapt better to low energy environments, thus dominated the upper part of the intertidal flat, whilst the heavy and large-sized filter feeders and deposit feeders were dominant over the middle and lower parts. The hydrodynamic and sediment processes cause biota-niche separation, which affected the biological processes across the intertidal flat. [ABSTRACT FROM AUTHOR]

In 2012, Hurricane Sandy created a new tidal inlet at Fire Island National Seashore (FIIS) in New York, USA, consequently altering environmental conditions within Great South Bay. This event presented a unique opportunity to establish new ecological baselines, assess resulting ecological change, and explore management implications. This study focuses on benthic mapping within the bayside of FIIS using acoustic, grab sample, and imagery data. Biotope (habitat) maps were developed describing relationships between macrofaunal communities and their environment. Additionally, biotopes were prioritized by "ecological value" based on user-defined criteria (presence of seagrass and potential for higher trophic level interactions) to guide management. While there are limited pre-Sandy data for comparison, findings from this study suggest the inlet has been a positive ecological influence on the nearby area. Dense concentrations of mature blue mussels (Mytilus edulis) documented near the inlet are considered ecologically beneficial and represent a post-Sandy distinction in ecosystem structure; M. edulis was last common when the inlet was previously open (early 1800s). The inlet is also likely responsible for seagrass expansion near the inlet but decline in other areas. This study advances the utility of the Coastal and Marine Ecological Classification Standard (CMECS) by including CMECS-defined data in analyses and expanding the definition of "dominance." CMECS played a key role in developing map units, interpreting biotopes, and establishing statistically significant and ecologically meaningful biotic–abiotic relationships. This study also highlights the value and management applications of benthic mapping specific to FIIS and more broadly and advocates for similar studies elsewhere. [ABSTRACT FROM AUTHOR]