CHAPTERS. PRACTICAL PROBLEMS IN MANAGING INTERTIDAL FLATS 



Now that a complete taxonomic and func- 

 tional profile of an intertidal flat has been devel- 

 oped in earlier chapters, this chapter will address 

 some practical problems of current concern in the 

 management of intertidal flat habitats. Because 

 the coastal zone is under such heavy and often 

 competing pressures from various groups of users, 

 decisions must often be made which will not 

 please everyone. Needs for housing, recreation, 

 navigation, and boat harbors are often not com- 

 patible with the maintenance of a pristine, natural 

 estuarine ecosystem. To enable coastal zone plan- 

 ners to make informed decisions in managing es- 

 tuarine systems, information on the ecology of 

 various estuarine habitats must be available in a 

 form that permits the merits of various compet- 

 ing, alternative uses to be weighed. The first five 

 chapters include such needed information on the 

 ecology of one estuarine habitat, the intertidal 

 flat. To conclude this report two very specific 

 problems in the management of intertidal flat 

 habitats will be addressed: (1) what guidelines are 

 needed to regulate the perturbation of this habi- 

 tat; and (2) how valuable is this intertidal flat 

 habitat compared with other habitats in an estu- 

 arine system. The final section of this chapter and 

 of this report will summarize information pre- 

 sented in all previous chapters to provide a con- 

 cise model of the role of intertidal flats in the 

 functioning of estuarine systems. 



6.1 RECOVERY OF INTERTIDAL FLATS 

 FOLLOWING PERTURBATION 



Because of the need to maintain sufficient 

 depth in coastal navigation channels and the ten- 

 dency of such channels to fill in with sediments, 

 frequent dredging is necessary in estuaries. Dis- 

 posal of the dredge spoil always presents a prob- 

 lem. Few studies have ever adequately tested 

 whether the added turbidity resulting from 

 dredging has any detrimental effects on estuarine 

 systems. Because the dredging process obviously 

 disturbs the seabottom in the vicinity of the 

 dredging, as well as in areas where the spoil is 



deposited, some of the data relating to the 

 recovery of benthic communities following 

 perturbation will be reviewed. 



Presumably one need only study the benthic 

 invertebrates in such unvegetated soft sediment 

 systems to obtain an indication of the recovery 

 potential of the intertidal flat community. These 

 benthic invertebrates are the food for the shore- 

 birds and bottom-feeding fishes and crabs. So it 

 seems reasonable that a recovery in the benthic 

 invertebrates would be accompanied by a recov- 

 ery in the higher trophic levels also. 



Some workers have studied the recovery of 

 soft-sediment benthic communities from pertur- 

 bations of various sorts. The recovery following a 

 red tide in Florida (Dauer and Simon 1976, Si- 

 mon and Dauer 1977) and after halting a pulp 

 mill effluent in Sweden (Rosenberg 1976) have 

 provided some data on the repopulation process 

 in marine soft sediments in shallow waters. In an 

 extensive series of field experiments in shallow 

 waters of Long Island Sound, McCall (1977) 

 examined the recolonization of defaunated mud 

 which he placed in sediment trays on the bottom. 

 Dcfaunation (i.e., killing all the macro-, meio-, 

 and microfauna) was accomplished by drying 

 natural sediments from the experimental area and 

 then rinsing them with freshwater. In McCall 's 

 shallow-water site, these defaunated sediments 

 were rapidly recolonized by opportunistic 

 benthic species like the polychaetes Streblospio 

 benedicti and Capitella capitata and the amphi- 

 pod Ampelisca abdita. Opportunistic species are 

 characterized by certain life history features held 

 in common: rapid development, frequent repro- 

 duction, fast growth, high recruitment rates, and 

 high mortality rates (McCall 1977). 



Rhoads et al. (1978) reviewed these benthic 

 recolonization studies and concluded that early 

 colonists of disturbed sediments (the opportunis- 

 tic species) share one important ecological chara- 

 teristic: even though some are suspension feeders 

 and others are surface-deposit feeders, all of the 

 early colonists live at or on the sediment surface. 



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