Productivity of kelp (Laminaria spp.) near the southern limit in the Northwestern Atlantic Ocean

Annual primary production of kelp Laminaria saccharina was calculated from standing crop, density, tissue carbon content and growth rate measurements at 3 sites in Rhode Island, USA -2 within Narragansett Bay and 1 in Rhode Island Sound.Results indicate similar seasonal growth patterns at all sites within Rhode Island.This pattern paralleled those in more northerly locations with rapid growth in late winter/early spring and minimal growth in summer.There was no reduction in production at the Rhode Island sites, although they are near the southern limit of this species.L. digitata was found at the most exposed sites where it compnsed up to 23 % of the total kelp density.The relative contribution of kelp to the total primary productivity varies according to season.The epiphytic community was most abundant in August and September This study is the first report of 7 species of animals epiphytic on Laminaria spp.Lacuna vincta (Mollusca) was found to be an important grazer on the Laminaria blades especially in winter.