Temporal and spatial variation in infaunal community structure in physically active continental shelf sediments at a long-term ecosystem observatory (LEO-15) off New Jersey, USA

When the LEO-15 (Long-term Ecosystem Observatory at 15-m depth) research area was designated around Beach Haven Ridge (39°27.69′ N, 74°15.81′ W) in the early 1990's several stations were selected to reflect the different physical regimes and habitats present in a highly dynamic shelf environment. This study determined the composition, diversity, and abundance of infaunal communities at three contrasting stations on five dates in 1994-1995. A unique sampling scheme was used where a nested design was combined with targeted sampling by divers of benthic topographic habitat features, namely crests and troughs of sand ripples. The total number of taxa collected was 148. The majority of taxa (80%) were either ubiquitous (67 taxa, 45%) or had an apparent affinity for a single station (52 taxa, 35%). The polychaete Polygordius jouinae was numerically dominant. The three distinctive stations 2-4 km apart, the date of sampling and, somewhat surprisingly, whether or not samples were taken in adjacent crests or troughs, all contributed to the structure of LEO-15 infaunal communities. Together these three stations characterize the sediments and fauna in the LEO-15 research area and form the basis for future studies of short and longer-term changes, and of the processes and mechanisms responsible for the patterns observed.