50 



(H2, 23, 26, and 27), with a range of 2.2 mg-1' at H2 to 4.5 mg-l' at Station 27. 

 Consequently, if the 1996 monitoring cruise at CLIS was conducted between mid- August 

 and mid-September, benthic conditions similar to those experienced during the 1995 survey 

 would have been observed once again (Morris 1997). 



In the past, annual monitoring surveys at the Long Island Sound disposal sites were 

 performed in mid-summer (late July-August), allowing six or more weeks between the end 

 of the disposal season (31 May) and any benthic community assessment operations. In 

 addition, the summer months provide warmer bottom water temperamres (17 to 21° C), 

 which increase the metabolic rates and bioturbation activity of the benthic infaunal 

 populations. 



Prior DAMOS experience has also determined that intensive recruitment of 

 opportunistic, pioneering polychaetes (Stage I individuals) occurs 1-2 weeks after the 

 completion of disposal activity (Germano et al. 1994). Therefore, it is recommended that 

 future survey operations at CLIS requiring the assessment of benthic infaunal 

 recolonization be scheduled for the period between 21 June through 15 July or after the 

 end of September. Monitoring surveys conducted within this time frame should provide 

 adequate recruitment time on the surface of a new dredged material deposit, as well as 

 avoid confounding the monitoring interpretation with the effects of summer hypoxia in the 

 region. 



4.2 Benthic Habitat Conditions 



As the most recent bottom feature within the disposal site, the CLIS 95 mound 

 displayed evidence of rapid benthic recolonization, with Stage I and Stage III activity 

 discovered at every station, and deep RPD depths over most of the mound surface. 

 Capping operations over the CLIS 95 mound were completed on 4 March 1996 (Julian Day 

 63). According to the 1996 CTDEP data set, benthic recovery over the surface of this 

 sediment deposit progressed for approximately five months (8 July 1996) before bottom 

 water DO concentrations approached 5.0 mg-l' (Figure 4-2). 



The REMOTS® assessment for the center of CLIS 94 indicates modest improvement 

 over the one-year-old disposal mound, relative to the September 1995 survey. OSI values 

 increased slightly at two of five stations (CTR and lOOE); increased by three points at one 

 station (lOOW); and decreased slightly at the remaining two stations (lOON and lOOS). 

 Although the OSI values at lOON and lOOS are suggesting a gradual decline in benthic 

 conditions, they are comparable to the 1996 CLIS reference area data and remain relatively 

 high for a recent dredged material deposit. 



Monitoring Cruise at the Central Long Island Sound Disposal Site, July 1996 



