in Organism-Sediment Index Values. Table 4-1 compares the WLIS 

 data collected during the present survey with data collected in 

 the October 1985 post-storm survey. There is no difference in 

 mean RPD depths for the WLIS stations, but OSI values in the 

 present survey are significantly higher than those measured after 

 the hurricane. This pattern indicates that the infaunal 

 successional stages of the survey area have improved since 

 October 1985. Table 4-1 also compares the WLIS Reference 

 station, as measured in this survey, with the data collected in 

 October 1985. Notably, mean RPD depths were shallower and OSI 

 values were lower at WLIS Reference station in 198 6 than in the 

 disposal area after the storm. 



The highly "stressed" conditions that presently exist 

 at the WLIS Reference station are not readily explained. Near- 

 surface reduced sediment patches were evident in all the 

 References images; this feature suggests disturbance of the 

 bottom (e.g. , predator foraging or trawling activity) . It is 

 known, also, that severe bottom water hypoxia was widespread 

 throughout western Long Island Sound at the time of the survey. 

 In August 198 6, a REMOTS® survey was conducted in Long Island 

 Sound from New Haven, Connecticut to the Throgs Neck Bridge 

 (SAIC, 1987). This survey, funded by EPA Region I, was conducted 

 to characterize the dissolved oxygen conditions within 1 cm of 

 the sediment surface over the entire area. A YSI digital oxygen 

 meter and the YSI probe were mounted on the REMOTS® camera such 

 that the probe membrane was 1 cm above the sediment-water 

 interface. Five replicate images and dissolved oxygen 

 measurements were made at each of 4 5 stations. One of these 

 stations was located near Station 4-A of this survey (40°59.33N 

 and 73°29.503W). The five replicate dissolved oxygen values 

 were: 1.88, 1.90, 2.40, 1.84, and 1.80 mg/1. These values fall 

 well below the Interstate Sanitation Commission's water quality 

 standard of 5 mg/1. Similarly low values were found in deep water 

 (generally > 15 meters) over the entire surveyed area (from 

 Throgs Neck to New Haven) . This hypoxic event was certainly a 

 major contributing factor to the stressed benthic conditions 

 observed at the WLIS survey area in 1986. This event does not 

 explain why the WLIS Reference station was disturbed relative to 

 the WLIS disposal region (both areas lie below a depth of 15 

 meters) . However, it is apparent that the most severe ecosystem 

 stress affecting the western Long Island Sound benthic 

 environment is not directly related to disposal activities but to 

 Sound-wide bottom hypoxia. Since the initiation of REMOTS® 

 monitoring at the WLIS disposal site (1984) , shallow RPD depths 

 have been observed. This suggests persistent or recurrent 

 hypoxia in the western Sound in recent years. Accurate spatial 

 and temporal mapping of this event and research into the possible 

 causes will become an active area of investigation over the next 

 decade. It will be critical to incorporate the findings of this 

 research into the long-term assessment of the impacts of dredged 

 material disposal in Long Island Sound. 



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