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Role of the Coastal and Upper Estuarine Waters Contributing Phytoplankton to the Shoals of the Niantic Estuary
Author(s) -
Marshall Nelson,
Wheeler Bernice M.
Publication year - 1965
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1935005
Subject(s) - estuary , bay , shoal , oceanography , plankton , phytoplankton , benthic zone , population , environmental science , fishery , geology , ecology , biology , nutrient , demography , sociology
Niantic Bay and the estuarine basin of the Niantic River were studied as source areas of phytoplankton transported across the shoals which separate the upper estuarine basin from the coastal waters and which support dense populations of bay scallops and other benthic filter feeders. Surface and bottom stations in the bay and estuarine basin and two stations over the shoals, where tidal excursions alternately transport water from offshore and from the estuary, were sampled at 5—week intervals for 1 year. Dinoflagellates predominated in the basin of the estuary and, to a lesser extent, were significant seaward into the Bay. The diatoms were most abundant in the Bay where they followed population trends characteristic of Long Island Sound and coastal waters. Two species of chrysophyceans were abundant, chiefly restricted to these near—shore waters but showing no indications that either the Bay or the more confined estuarine waters were more favorable. When the Bay was the predominant phytoplankton source area, as judged by the counts and population trends, the plankton of the mixed waters over the shoals was similar to that of the Bay in kind and in numbers. When the basin was the predominant source area, the plankton over the shoals, though similar in kind, commonly dropped to one—tenth the abundance found up—estuary. This drop may relate to the vertical migration of the flagellates into deeper waters which do not flow freely across the shoals. The lower plankton counts over the shoals may also result from the mixing of the waters ebbing from the basin with the relatively large volume of water over the shoals following the high tide. In the basin of the estuary the phytoplankton volume fluctuated around a mean of 6.90 mm 3 /liter. The average for the Bay was 0.23 mm 3 /liter. Over the shoals the average was 0.63 toward the upper estuary and 0.45 toward the Bay. These averages and other data constitute evidence that the upper estuarine area contributes more phytoplankton to the shoals than do the offshore waters.