relationships with latitude, i.e. with values increasing as latitude decreased (p < 0.01). 
Depth had a significant direct influence on diversity (p < 0.001) and a significant inverse 
effect on density (p < 0.01). None of the three benthic variables varied significantly in 
relation to % fines (at p < 0.1), though in general there was a tendency for muddier 
sediments (higher percent fines) to have lower species richness and diversity and 
higher densities than coarser sediments. 
Alternatively, it is possible that for some of these sites the lower values of benthic 
variables reflect symptoms of disturbance induced by other unmeasured stressors. In 
efforts to be consistent with the underlying concepts and protocols of earlier EMAP and 
NCA programs, the indicators in this study included measures of stressors, such as 
chemical contaminants and symptoms of eutrophication, which are often associated 
with adverse biological impacts in shallower estuarine and inland ecosystems. 
However, there may be other sources of human-induced stress in these offshore 
systems that pose greater risks to living resources and which have not been adequately 
captured. One such activity is commercial trawling, which is a major industry in shelf 
waters, including NMSs, and which could have significant adverse effects on bottom 
habitats and benthic organisms (Jones 1992, Jennings and Kaiser 1998, Dayton et al. 
1995, National Research Council 2002, Watling and Norse 1998). Future monitoring 
efforts in these offshore areas should include indicators of such alternative sources of 
disturbance. 
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