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STUDIES OF THE NIANTIC RIVER, CONNECTICUT WITH SPECIAL REFERENCE TO THE BAY SCALLOP, AEQUIPECTEN IRRADIANS 1
Author(s) -
Marshall Nelson
Publication year - 1960
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1960.5.1.0086
Subject(s) - bay , estuary , oceanography , freshwater inflow , scallop , fishery , plankton , environmental science , argopecten irradians , zostera marina , ecology , seagrass , geology , biology , ecosystem
The Niantic River is a shallow estuary with a tidal prism equal to half the mean low water volume of the basin, and with a twelve‐hour freshwater inflow of less than 3% of the tidal prism. The tidal waters mix offshore with the waters of eastern Long Island Sound, rich in plankton and nutrients. The estuary functions as an ecological concentrating system as the dense and varied populations of grazers consuming the food of these tidal waters benefit from the resources of offshore mixing in addition to the production endemic to the estuary. The disappearance of the eelgrass, Zostera marina, with the epidemic of the early 1930's permitted better circulation near the river bottom. Apparently this was advantageous to the bay scallop, which thereafter became the predominant sessile grazer with a production calculated at 2.2g C/m 2 /yr. Anchorage previously offered by eelgrass for the early setting stages of scallops was subsequently available through the abundance of small branching algae. The brief life history of a bay scallop is outlined on its shell as the surface laid down in each successive year appears rougher or more “weathered” than that formed the year before. By following this differentiation of shell surface, annual rings were determined with more certainty than in earlier studies. Though the time of year when the differentiation of shell surface commences may vary with populations and even with year classes, it is probably due to a common cause, seasonal change in growth rate being most likely. The life history interpreted from shells from Indian middens was essentially the same as observed for living scallops. The scallops of the Niantic River spawn from mid‐June through July. The young of a given year reach maturity and are the chief brood stock of the succeeding spawning season. Mortality rates for all sizes are high during all seasons and few individuals survive to the time of second spawning. The estuaries in which the bay scallop occurs have the following hydrographic features: the ratio of tidal volume to river flow is high, thus the salinity remains high; the basin is relatively shallow, with a resulting high ratio of tidal volume to the volume at low water; the circulation is such as to retain the planktonic scallop larvae in sufficient numbers for reseeding and to provide an adequate supply of planktonic food, perhaps in part supplied by offshore waters.