Review of the oceanography of Long Island Sound 237 



and BuMPUS (1949), the total displacement volume of zooplankton underlying a square 

 metre of sea surface is equal to the amount found on Georges Bank or in the Gulf of 

 Maine and double the crop in southern New England coastal waters. However, its 

 organic content is very low, and it was suggested that the zooplankton is a starved 

 population, possibly with a low rate of production. The extended disposition of the 

 plankton through a long vertical column in such waters requires the expenditure of a 

 relatively large amount of energy in food capture and theoretically should lead to 

 inefficiency in food conversion, with progressive attenuation of the higher members 

 of the food chain. Quantitative information on the total fish population is lacking, 

 but there is no evidence to indicate that it is a large one. Thus the basic production 

 is roughly of the order of magnitude of that found in the English Channel, but it is 

 largely dissipated at the plankton level. 



It would appear that a high level of plant production is necessary but not sufficient 

 for a thriving fishery. Block Island Sound and Georges Bank are probably superior 

 to the English Channel at all levels of the food chain, but the English Channel appears 

 to produce more marketable fish than Long Island Sound despite the high basic 

 production of the latter. 



Optimum efficiency of conversion seems to be characteristic of coastal and bank 

 waters of moderate depth and salinity of 30"".^ or more. A lesser degree of efficiency 

 is probably to be expected in most deep oceanic waters. Two examples of brackish 

 waters that have been examined, namely Long Island Sound and the Moriches-Great 

 South Bay area, although productive in the basic sense also seem to be relatively 

 inefficient in food chain conversions. The underlying reasons for this are not clearly 

 understood, although some of the symptoms are obvious. There is a large proportion 

 of nannoplankton existing in an environment which, according to Ryther's (1954) 

 experimental studies, favours the dominance of such forms. They are not particularly 

 good food for the large zooplankton which in turn would be the major source of food 

 for larger animals. The brackish environment also apparently favours the dominance 

 of zooplankton species that are inefficient feeders. Thus there exists in the water a 

 relatively large quantity of unutilized phytoplankton and organic detritus. This in 

 itself is a clear symptom of a low rate of turnover, and it probably promotes the 

 dissipation of a rnajor fraction of the energy of the system at low levels by bacteria 

 and microzooplankton. It also tends to produce a bottom sediment of high organic 

 content. The latter generally supports a smaller biomass than a mixed sand and mud 

 bottom and one tha^t is qualitatively less desirable for benthic carnivores. The mud 

 bottoms in Long Island Sound have enomious numbers of nematodes and other 

 microfauna which presumably have a high food requirement and rate of production 

 but are of very limited value as food for groundfish. 



REFERENCES 



Atkins W R G (1928), Seasonal variation in the phosphate and silicate content of sea water 

 d^ng 1926 and 1927 in relation to the phytoplankton crop. J. Mar. B.ol. Assoc. U.K.. n.s.. 15, 



BiiEmw," H. B. (1926), Plankton of the offshore waters of the Gulf of Maine. Bull. U.S. Bur. Fish., 



BTr?,nw H^ B^' LiLLiCK L C. and Sears, M.ary (1940). Phytoplankton and planktonic protozoa of 

 ?he offshore wat^^^^^^^^ the Gulf of Mame. I. Numerical d.stnbut.on. Trans. Anwr. Phd. Soc, 



ClakkI: C^Ame), Dynamics of production in a marine area. Ecol. Monogr., 16 (4). 321-335. 



