harvested there since 1957 primarily 

 because of pollution and overfishing 

 (Robadue and Lee 1980). The soft-shell 

 clam fishery in upper Narragansett Bay is 

 apparently experiencing a similar fate. 

 In 1949, approximately 296,600 kg (650,000 

 lb) of clams were harvested while in 1979 

 commercial landings declined to about 

 3,650 kg (8000 lb). Abundant populations 

 of clams have been reported in the upper 

 bay but many areas have been closed to 

 shellfishing because of organic pollution 

 (Robadue and Lee 1980). In Connecticut, 

 approximately 90% of tidal flats are 

 closed to shellfishing because of pollu- 

 tion. Urbanization and its associated 

 impacts on northern New England tidal 

 flats have not yet been as severe. Al- 

 though approximately 20% of Maine's tidal 

 flats are closed annually to soft-shell 

 clamming because of water pollution, over- 

 exploitation of the shellfisheries may 

 pose a greater threat to clam populations 

 than habitat degradation (Doggett and 

 Sykes 1980). 



The effects of changing habitat qual- 

 ity extend to other groups of organisms 

 using tidal flats. Haedrich and Hall 

 (1976) suggested that the degree of sea- 

 sonal change in New England fish communi- 

 ties (see Chapter 4) is a convenient indi- 

 cator of estuarine environmental "health". 

 Environments unaffected by pollution 

 should exhibit high annual diversity of 

 fish species and pronounced seasonal turn- 

 over in species composition. Where unfav- 

 orable habitat change has occurred, the 

 most sensitive species will be eliminated 

 and only those best-adapted to inhospit- 

 able conditions will remain. The net 

 effect upon fish communities, therefore, 

 is an overall reduction in the variety of 

 species that utilize the habitat. 



Other sources of pollution are also 

 responsible for damage to New England 

 tidal flats. One of the more severe and 

 long-lasting impacts is from oil spills. 

 In a well -documented study of a relatively 

 small spill in Wild Harbor, Massachusetts, 

 Sanders et al. (1980) observed an almost 

 complete elimination of benthic organisms 

 at several oiled sites. The effects of 

 oil on the biota were still detectable at 

 this site 5 years after the spill, in part 

 because oil remained in the sediments and 

 did not degrade or disperse. 



Not all responses to environmental 

 degradation are as dramatic as these. 

 Sindermann (1979a), in reviewing pollu- 

 tion-associated diseases in fish, sug- 

 gested that many effects are subtle (e.g., 

 fin rot and fin erosion) and due to 

 chronic exposure of fish to a polluted 

 inshore environment. Since many fish 

 inhabiting inshore waters are juveniles, 

 they may be even more sensitive to these 

 chronic effects than adults. 



The New England region provides a 

 well -documented historical case study of 

 environmental degradation and destruction 

 of tidal flats and their resident organ- 

 isms. These changes in New England should 

 provide an impetus for developing manage- 

 ment criteria for tidal flat habitats. To 

 begin such an undertaking, however, the 

 tidal flat's importance to the coastal 

 zone must be well-understood. 



6.3 THE IMPORTANCE OF NEW ENGLAND TIDAL 

 FLATS 



In the past, legislation protecting 

 marine coastal habitats was based on a 

 series of suppositions regarding the role 

 of these habitats in the overall coastal 

 zone (e.g., Oviatt et al. 1977). The sup- 

 positions focused on a habitat's role as 

 wildlife, fisheries, and storm-control 

 areas in addition to its potential for 

 exporting organic materials to stimulate 

 or enhance production in adjacent marine 

 systems. While much attention has been 

 directed toward identifying the function- 

 ing of specific coastal habitats, it has 

 been more difficult to assign a "value" to 

 individual systems. Early efforts to 

 evaluate habitats converted primary pro- 

 duction values for salt marshes into aver- 

 age dollar value per calorie produced by 

 the marsh (Gosselink et al. 1974). This 

 approach remains subjective because many 

 of the functions or roles of salt marshes 

 lie outside recognized monetary systems 

 and do not have an agreed monetary value 

 (Shabman and Batie 1980). In addition, 

 adequate evaluation of coastal zone habi- 

 tats must include values associated with 

 incremental changes (i.e., with time) in 

 these habitats and not be restricted to 

 the worth of an "average" salt marsh, 

 tidal flat, or estuary. Alternative 

 approaches to value assessment of coastal 



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