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Review of the oceanography of Long Island Sound
Riley, G.A. (1955). Review of the oceanography of Long Island Sound, in: Papers in Marine Biology and Oceanography. Dedicated to Henry Bryant Bigelow, By His Former Students and Associates on the occasion of The Twenty-fifth Anniversary of the Founding of The Woods Hole Oceanographic Institution 1955. Deep-Sea Research (1953), 3(Supplement): pp. 224-238
In: (1955). Papers in Marine Biology and Oceanography. Dedicated to Henry Bryant Bigelow, By His Former Students and Associates on the occasion of The Twenty-fifth Anniversary of the Founding of The Woods Hole Oceanographic Institution 1955. Deep-Sea Research (1953), 3(Supplement). Pergamon Press: London & New York. 498 pp., more
In: Deep-Sea Research (1953). Pergamon: Oxford; New York. ISSN 0146-6291; e-ISSN 1878-2485, more
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    Marine

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  • Riley, G.A.

Abstract
    Long Island Sound is a shallow, semi-enclosed body of slightly brackish (23-31 ‰) water with an area of about 900 nautical square miles. Moderate tidal currents permit a small seasonal thermocline and slight vertical gradients in salinity, oxygen and nutrient salts. The major feature of non-tidal circulation is a two-layered transport system in which a freshened surface layer moves eastward out of the Sound and is replaced by a more saline inflow along the bottom. The latter contains more nutrients than the outflowing surface water, so that the transport system tends to accumulate and conserve nutrients. Freshwater drainage also makes a significant contribution of nitrate. Phytoplankton concentrations are large, but the species composition is relatively limited. A large diatom flowering occurs in late winter, following an early winter minimum, with only minor fluctuations the rest of the year. There is sufficient mixing to prevent a large accumulation of nutrients in the bottom water, so that there is neither pronounced poverty in summer nor a big autumn flowering following destruction of the thermocline. Major limiting factors are the amount of effective light in autumn and winter and the nitrogen supply in spring and summer. Variations in light and temperature from one year to the next affect the winter species composition and the time of the flowering. Diatoms are largely replaced in summer by naked flagellates and other nannoplankton. During one summer when nitrate concentrations were higher than usual, diatoms were abundant and there was also an unusually large zooplankton crop. A causal connection is indicated but not well established. The zooplankton consists of large numbers of small animals. Relatively few species are present. The dominants are two species of the copepod Acartia which alternate seasonally. Descriptive and experimental studies suggest that seasonal replacement is primarily a temperature-controlled competition rather than a direct, lethal temperature effect. Experiments show that the Acartias have high respiratory rates and low grazing rates compared with most other copepods that have been examined and possibly are able to achieve dominance only in waters sufficiently brackish to exclude more efficient oceanic species. Preliminary studies of bottom fauna indicate a relatively large biomass, again consisting of large numbers of small animals. Fish eggs and larvae are abundant, and the Sound may be an important spawning and nursery ground. However, commercial fishery statistics show no indications of a large population of mature fish. Total phytoplankton production is about the same as in the open coastal and bank waters off New England. Most of this production is utilized in the support of small animals which do not provide an adequate food supply for the efficient production of large carnivores.

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