Effects of pollution on nematode assemblage structure and diversity on beaches of the northern Persian Gulf

This study is the first to present data on local (=beach) and gamma diversity of beach nematode assemblages from the Persian Gulf. We investigated four beaches near the city of Bandar Abbas, Iran. On each beach, we sampled three stations at 50-m intervals, with increasing distance from a local pollution source, mostly domestic sewage. A total of 39 genera from 17 families was recorded. This gamma diversity is low and suggests that the entire area experiences substantial stress. Five genera together comprised 75% of nematode abundance. There were significant differences in abundance as well as genus diversity between locations, but these did not unequivocally correlate with known drivers of benthic assemblage structure like sediment granulometry and hydrodynamics. The location exposed to the strongest local pollution input had the lowest nematode diversity and a very low abundance at the station nearest the pollution source. Distance from local pollution sources also significantly impacted genus diversity, but this pattern was only pronounced in two of the four beaches. Our data demonstrate that local sources of anthropogenic disturbance are a major driver of assemblage diversity and structure in this area, despite an overarching effect of natural (salinity, temperature) and anthropogenic stressors.