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Because eelgrass is sensitive to variations in water quality from watershed-level impacts, it is considered an indicator of ecosystem state (Dennison et al. 1993). Whereas once large eelgrass meadows colonized much of the shallow water of Boston Harbor, they are now restricted to a few, small patches (Colarusso et al. in press). Airborne remote sensing, field observations, and GIS technology are being used to find and map eelgrass meadows in nearshore habitats of the Gulf of Maine.

In comparison to other estuarine nursery habitats measured, species richness, macroinvertebrate biornass, and primary production is significantly higher in eelgrass. Its loss and subsequent changes in food web structure (McClelland and Valiela 1998) has not only resulted in foregone predator (benthic fish, lobster, and large shellfish) biomass (Heck et al. 1995), but also lost habitat complexity and diminished sediment stability. It is thought that some recolonization of former eelgrass meadows will occur slowly if nitrogen loading is reduced (Duarte 1995). Protecting eelgrass habitat should be an high priority with respect to conservation of coastal nurseries for Atlantic cod (Gotceitas et al. 1997).

Utilization of Proposed HAPC by American Lobster and other Multispecies Groundfish
The American lobster (Homarus americanus) is New England's largest single-species fishery and its most valuable. The life stage distribution relative to nearshore habitats of coastal lobster populations has been well documented. Densities tend to be at least two orders of magnitude higher on hard bottoms than on sediment habitat. Lobster larvae settle in shallow subtidal or low intertidal cobble/ gravel/ pebble substrates, and like post-settlement cod, are very susceptible to predation. These hard-bottom patches support high densities of one and two-year-olds (<40 mm CL) because of the protection afforded by the interstitial spaces (Wahle and Steneck 1992).

No studies have detected early benthic stages (<10 mm CL) on featureless sediment (Wahle 1993). As lobsters outgrow the early benthic phase, they become increasingly mobile on nearshore sediment habitat. The research trawl catch of sublegal (30-82 mm CL) lobster alongshore at depths 59 m may reach 4,000 lobsters (13 bu) in tow times of less than 20 minutes in MDMF bottom trawl surveys (A. Howe, pers. comm.).

Among other multispecies groundfish, it is well known and corroborated by scientific information that winter flounder spend their first two years of life in very shallow coastal water co-occurring with young cod throughout the northern part of their range. While they are commonly reported occupying unvegetated substrates in Canada and New England, eelgrass meadows also serve as nurseries for winter flounder as well as white hake, Urophycis tenuis (Heck et al. 1989).

Conclusion
Although Atlantic cod adults are depleted in the Gulf of Maine, some recruitment will continue to occur because density-dependent effects will increase juvenile survival rates at low abundance (Myers and Cadigan 1993b). Unfortunately, recruitment at low spawner abundance happens at greatly reduced levels for cod (Myers and Barrowman 1996). Recognizing critical habitat (e.g., nearshore cobble patches and eelgrass beds), and protecting it from anthropogenic impacts by risk-adverse management measures should improve juvenile survivorship.

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