Disposal Site. In Long Island Sound, this event is thought to be 
initiated by high water temperatures, a stratified water column, 
and high rates of organic loading related to sewage enrichment. 
Ampelisca amphipods seen swimming at the waters surface also 
suggested low oxygen bottom waters. Evidence of reduced sediment 
conditions were still observed during the November 1985 survey. 
Amphipod tubes were seen in various stages of decay. Localized 
organic loading and/or water stratification may have contributed 
to this low oxygen stress on the bottom sediments. By the January 
1986 survey, no evidence of near-bottom hypoxia was detected. This 
type of seasonal event has a significant influence on the infaunal 
successional status of the bottom. The fact that shallow RPD 
depths were observed in the REMOTS® photographs from late July and 
again in November does not necessarily mean that bottom oxygen 
values were low over the entire summer period. Bottom hypoxia in 
Long Island Sound usually develops over the period of July to early 
September. Once the water column is reventilated in September, it 
may take several weeks for infaunal benthos to pump aerated water 
back into the sediment and depress the RPD. The rate of RPD 
depression is approximately 0.2-0.3 mm per day (Germano and Rhoads, 
1984). 
5.0 CONCLUSIONS 
The results from the bathymetric and REMOTS® surveys at 
the most recent disposal point (NL-85) and from the southwest 
reconnaissance grid demonstrated that management controls initiated 
by NED to insure containment of dredged material were largely 
successful. Most dredged material apparently was confined within 
a 600 meter radius of the disposal buoy, and no dredged material 
was detected at the southwest grid of stations located just outside 
the designated site boundaries. Relatively thin layers of dredged 
material were detected just outside the eastern site boundary in 
a very small area of minor concern (Figures 3-31 and 3-38). It is 
recommended in the future that the disposal point be located 
farther away from the boundary to avoid any dredged material 
occurring outside the site. Infaunal recolonization of the 
disposal mounds at the New London Disposal Site was proceeding well 
within the normal time course of successional events; the dominant 
taxon at the majority of stations sampled was the amphipod 
Ampelisca vadorum. Many of the older disposal mounds which had 
not been recently used for disposal had well-developed infaunal 
deposit-feeding communities. Areas within the southeastern 
quadrant of the site were obviously being affected by the 
Sound-wide phenomenon of seasonal hypoxia (the "August effect", 
sensu Rhoads and Germano, 1982); the stressed condition of the 
benthic communities in this affected area most likely was not due 
to the recent disposal activities. 
Comparison of the results of trace metal analyses from 
the top 2 cm sections and 2-10 cm sections of sediment cores 
37 
