Meeting Abstract
Compared to finfish aquaculture, shellfish aquaculture is predicted to have less impact on benthic communities because organic enrichment and biodeposition rates are typically lower, but impacts are likely to vary with species cultured, site characteristics, and farming methods. Oyster aquaculture is a growing industry in Maine and little is known about its impacts on the benthos. We surveyed benthic biodiversity under and adjacent to suspended oyster cages at three farms on different rivers in Maine during 2015 and 2016. We collected sediment using ponar grabs, sieved it (0.5 mm mesh) and preserved all retained material for later identification. Approximately 6000 individual invertebrates were sorted and identified to the lowest taxonomic level possible (i.e., species, genus or family). Annelids and molluscs were the most abundant fauna at all three farms. Taxonomic similarity (percentage similarity) of fauna collected under and adjacent to oyster cages differed by farm, ranging from ~43% to 79%. At two farms, Capitellid polychaetes and Oligochaetes were most abundant under cages (dominance index=0.3-0.4), while Veneriid bivalves, Nereidid and Spionid polychaetes were most abundant in samples taken adjacent to cages at the same farms (dominance index=0.2-0.4). Streblospio benedicti (Spionidae) was the most abundant taxon at the third farm, regardless of sample location in the farm (dominance index ~0.8). Sediment organic content was slightly enriched under cages at only one site (12% vs. 10% organic carbon). Our data suggest that the oyster farms are having relative minor impacts on the benthic community at these sites. This material is based on work supported by the National Science Foundation under Grant No. 1355457.
