Observations on Ichthyoplankton Community Structure, Abundance, and Diversity in a Temperate North American Estuary, Webhannet River, Wells National Estuarine Research Reserve, Wells, Maine, USA

Understanding larval fish population dynamics is important to determining recruitment availability, dispersal distances, as well as observing changes in species distribution and abundance. Most larval fish studies in the Gulf of Maine sample sub-tidal and pelagic habitats, and have poor temporal replication. This study examines the community structure, diversity, and abundance of larval fishes in the Webhannet River Estuary in Wells, ME, USA. Ichthyoplanton were sampled on incoming high tides 2-6 times monthly from July 2008 to December 2013 at a single sampling station and fixed depth of 1 m. A total of 3,037 individuals were collected over the study period representing 23 species of fish, more than any other comparable study in the Gulf of Maine. The three dominant species by number were Tautogolabrus adsperus (Cunner), Ammodytes americanus (Sand Lance), and Enchelyopus cimbrius (four-bearded rockling), respectively. Abundances peak in the fall which corresponds with the major plankton blooms in the Gulf of Maine, however diversity (Shannon Wiener) was highest during the spring. The occurrence of Centropristis striata (Black Sea Bass) larva in 2013, coupled with increasing water temperatures in the Gulf of Maine, may be a sign of range expansions of more southerly species into the Gulf.