Environmental Baselines in Long Island Sound, 



1972-73 



R. N. REID, A. B. FRAME, and A. F. DRAXLER' 

 ABSTRACT 



Quasi-synoptic surveys of water column temperature, salinity, nutrients and dissolved oxygen, 

 sediment grain sizes and organic content, and benthic macrofauna were conducted throughout Long 

 Island Sound in July-August 1972 and April and September 1973. Temperatures were fairly uniform 

 both vertically and horizontally except for some vertical stratification in .July-August 1972. .Salinities 

 increased gradually from east to west, while deplh-related differences were minor. Concentrations of 

 all nutrients measured indicated that inputs at (he western end dominated nutrient distributions for 

 the Sound. Dissolved oxygen decreased from east to west and with increasing water temperature. 

 Bottom dissolved oxygen values below 2 mg/liter were recorded at several stations in the western 

 .Sound in summer 1972. .\s a rule, sediments of deep w alers in the central and western Sound consisted 

 of silts and days, whereas sands predominated along the Long Island shoreline and in the eastern 

 basin. Sediment organic matter reached highest values (to lOVt) in the westernmost Sound. Three as- 

 semblages of benthic macrofauna were identified via cluster analyses of 1972 data: a bivalve (especial- 

 ly Mulinia lateralis) dominated group in muddy, deepwater regions; a shallow sandy assemblage in 

 which the bivalves Spisula solidissima, Telltna agilis. and Ensis directus predominated; and a third as- 

 semblage transitional in both sediment characteristics and species composition, but with increased 

 dominance by several polychaete species. The mud-bottom and transitional fauna underwent large 

 decreases in numbers of species and individuals from 1972 to 1973. 



INTRODUCTION 



Long Island Sound (LIS) is a large (145 km long by 17 

 km maximum width) estuary bounded on the north by 

 the states of New York and Connecticut and on the south 

 by Long Island, N.Y. (Fig. 1). LIS is considered a highly 

 impacted estuary (Bowman 1977), having been impor- 

 tant for shipping and waste disposal for several centuries. 

 LIS is also heavily used for recreational boating and 

 swimming, and supports large recreational (Mohr 1976) 

 and small commercial (McHugh 1977) fisheries. 



Several comprehensive studies of the chemical ocean- 

 ography of LIS exist (Riley et al. 1956, 1959, 1967; Hardy 

 1972b). Benthic surveys, however, have been limited to 

 rather circumscribed portions of LIS (e.g., Sanders 1956; 

 Michael 1976; McCall 1977; Serafy et al. 1977; Rhoads et 

 al. 1978). Due to their sessile nature and wide variety of 

 life histories and tolerances, the benthic macrofauna are 

 particularly suited for biological monitoring of change 

 (Wilhm 1967; Reish 1972; Boesch 1974; Swartz 1978). 

 Many are also important as contaminant vectors and as 

 forage for resource species. 



We therefore felt it would be useful to conduct a synop- 

 tic study of the water column chemistry and benthos 

 throughout LIS. This information can serve as a "base- 

 line"' against which to measure future natural fluctua- 

 tions and anthropogenic impacts. 



Our surveys began in the summer of 1972. We sampled 

 sediments, benthic macrofauna, and water column tem- 



' Northeast Fisheries Center Sandy Hook Laboratory, National Marine 

 Fisheries Service, NOAA. Highlands, NJ 07732. 



perature, salinity, dissolved oxygen, and nutrients three 

 times (July-August 1972, April and September 1973), 

 and have since surveyed sediments, bottom waters, and 

 macrofauna in September of 1975 and 1976 and July of 

 1977 and 1978. This report summarizes data from the 

 1972 and 1973 cruises. 



METHODS 



We established a total of 142 stations, the majority 

 located every 3-5 km on north-south transects spaced 8.7 

 km apart (on consecutive 5' longitude lines) for the 

 length of LIS (Fig. 1). Latitude, longitude, and depth of 

 each station are given in Table 1. Water column, sedi- 

 ment, and macrofauna samples were taken at all sta- 

 tions on the summer 1972 cruise. On subsequent surveys 

 we have resampled bottom waters ( + 1 m), sediments, 

 and macrofauna from 40 to 95 of these stations. Addi- 

 tional water column sampling was done on the two 1973 

 cruises. Station locating has been by loran A or C and 

 fathometer, augmented by horizontal sextant, land, and 

 buoy ranges when possible. 



On Cruise 1, temperature and salinity were measured 

 at 5 m depth intervals using a Beckman RS-5 induction 

 salinometer. Temperatures were measured with re- 

 versing thermometers on Cruises 2 and 3, and a Beck- 

 man RS-7B salinometer was used for salinity determi- 

 nations. Samples for water chemistry analysis were 

 taken 1 m from surface and bottom, using Van Dorn 

 water bottles on Cruise 1 and Niskin bottles on Cruises 2 

 and 3. Additional water samples were taken at 25 m 

 depth intervals at 15 deepwater stations along the 



