Ecostructuring of marine nematode communities by submarine groundwater discharge.

Inputs of submarine groundwater discharge (SGD) to the coastal ocean may alter local and regional-scale biology. Here, we report on nematode assemblages along the north shore of Long Island, NY. We test if nematode communities differed between sites impacted by mixed fresh-saline SGD and where SGD is exclusively saline. Diversity of nematodes was low at sites impacted by fresh SGD and communities were dominated by a few opportunistic genera. Moreover, a set of typical freshwater nematode genera restricted to impacted sites was observed. Their presence in the marine coastal zone is exceptional and underlines the structuring role that fresh SGD plays in the local ecosystem. Saline SGD structured nematode assemblages differently compared to sites impacted by fresh SGD. The number of nematode genera was markedly higher at saline SGD sites, with a different community structure. This study highlights the importance to which inputs of fresh SGD may have on local ecosystem diversity in marine coastal environments.