Spatial and diurnal distribution of invertebrate and fish fauna of a Zostera marina bed and nearby unvegetated sediments in Damariscotta River, Maine(USA)

Fish, epibenthos and macroinfauna were collected in a Zostera marina bed an d nearby unvegetated sediments in the estuary of the Damariscotta River, on the mid-coast of Maine. Samples of epibenthic fauna and fish were collecte d at low tides both during day and night, and samples of infauna;st low tid es during the day. The mean density of Zostera shoots in the study area was 335 m(-2). Abundance and species number of fish were greater at night than during the day and greater in eelgrass beds (Z. marina) than in unvegetate d habitats. Daytime fish collections were dominated by Atlantic silversides (Medinia medinia), while juvenile winter flounder (Pseudopleuronectes amer icanus) dominated night collections. Also Zostera-associated epifaunal abun dances and number of species were significantly higher at night than during the day. Mysis stenolepis, Idotea balthica and Littorina obtusata were dom inant species in the epifauna samples. Of the total of 37 invertebrate spec ies encountered, only five occurred both in the infaunal and epifaunal samp les. Nineteen different taxa were collected from the benthic core samples. The most abundant invertebrate infaunal taxa were sipunculids, the polychae te Nereis virens, and oligochaetes. Infaunal invertebrate abundances and sp ecies diversity were significantly higher in eelgrass beds than in unvegeta ted sediments. The abundance and number of species of benthic invertebrates were also positively correlated to seagrass biomass. Community diversity v alues (H') were relatively low but fit well in the general pattern of decre asing diversity towards northern latitudes. (C) 1999 Elsevier Science B.V. All rights reserved.