zone habitats have been formulated (e.g., 

 Kennedy 1980) although no generally 

 accepted method presently exists. 



Unlike salt marshes that are recog- 

 nized for their potential for exporting 

 the primary production of grasses to 

 adjacent marine habitats, tidal flats 

 function as sites for the conversion of 

 plant production into animal biomass. The 

 most tangible evidence of the value of New 

 England tidal flats to human consumers is 

 the shellfish and baitworm fisheries. All 

 New England coastal states exploit tidal 

 flat shellfish populations. The extent of 

 these fisheries varies widely between 

 states and harvestable catch is largely 

 dependent upon habitat quality. In south- 

 ern New England, urbanization of the 

 coastal zone and associated pollution has 

 resulted in the closure of many tidal 

 flats to shellfishing. In Connecticut 

 only a few hundred pounds of shellfish are 

 harvested annually and virtually all of 

 the common tidal flat shellfish (e.g., Mj^ 

 arenaria and Mercenaria mercenaria ) sold 

 commercially are imported from outside the 

 State. In northern New England, where 

 coastal urbanization is not as extensive, 

 tidal flat shellfish and baitworm fisher- 

 ies are extremely important industries. 

 In Maine soft-shell clam (Mya^ arenaria ) 

 and baitworm (N ereis virens and Glycera 

 dibranchiata ) fisheries rank third and 

 fourth in economic value after the exten- 

 sive lobster and (now diminished) shrimp 

 fisheries. While soft-shell clams and 

 baitworms are not restricted to tidal flat 

 habitats, their abundance is greatest in 

 these areas and destruction or degradation 

 of these habitats would eliminate the 

 fisheries. Other species of economically 

 valuable invertebrates (e.g., crabs) are 

 also found on New England tidal flats. 

 Crabs do not depend entirely on flats, but 

 use them as important feeding sites. 



The value of tidal flats to coastal 

 fish populations is more difficult to 

 assess. Most fish frequenting flats are 

 juveniles and are known to consume tidal 

 flat food items (especially benthic inver- 

 tebrates). Relatively little is known 

 about the degree of dependence of juve- 

 nile fish on flats and about the contribu- 

 tion of these populations to commercial 



catches. Probably demersal fishes (e.g., 

 winter flounder) rely most heavily on 

 tidal flats for feeding, but to what 

 extent remains conjecture. Tyler (1971b) 

 has suggested that the destruction of 

 tidal flats in the Bay of Fundy would 

 reduce the winter flounder populations. 

 Shallow water coastal habitats provide 

 juvenile fish a refuge from their preda- 

 tors in addition to serving as sheltered 

 feeding areas. 



Many species of shorebirds rely heav- 

 ily (and some species exclusively) upon 

 tidal flats for feeding and resting sites. 

 Without productive benthic invertebrate 

 populations on flats some bird species 

 would probably suffer population declines. 

 A recent study (Goss-Custard 1977) that 

 has addressed the importance of tidal 

 flats to shorebird populations, however, 

 has failed to define the degree to which 

 the birds are limited by tidal flat habi- 

 tat availability. Other groups of birds 

 (e.g., gulls, terns, waterfowl), while not 

 as dependent on tidal flats for feeding 

 sites, are commonly present and are known 

 to consume benthic invertebrates. 



One of the major difficulties in 

 attempting to assign specific values to 

 tidal flat habitats centers on the lack of 

 information about the magnitude of their 

 primary and secondary productivity and 

 about how much of that production is chan- 

 neled to higher trophic levels within the 

 coastal food web. Examination of the 

 sources and amounts 9f organic materials 

 entering the flats from other systems, the 

 rates at which these organics are utili- 

 zed, and the amounts passed to different 

 trophic levels requires detailed informa- 

 tion about energy flow, life history char- 

 acteristics of resident and transient 

 organisms, as well as insight into abiotic 

 and biotic processes affecting tidal flat 

 populations. This lack of knowledge, of 

 course, does not diminish the importance 

 of tidal flats to the coastal zone. More 

 information about ecological processes and 

 interrelationships on tidal flats is 

 required before planners, managers, and 

 legislators will be able to develop a com- 

 prehensive and rational basis for the pre- 

 servation, utilization, and management of 

 tidal flats. 



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