the treated areas (Figure 27; Krebs et al. 

 1974). Aldrin was apparently closely 

 bound to sediment particles because the 

 effect was absent as little as 1 m 

 downstream from the treated area (Krebs 

 and Valiela 1977). Judging from its lack 

 of movement in the sediments, aldrin 

 slowly degraded in place just as DDT 

 does in anoxic sediments. Aldrin 

 disappeared from the sludge after its 

 use was banned in 1972; fiddler crab 

 populations returned to pre-aldrin 

 levels within about 1 year (Teal et al. 

 1982). 



Information is also available on the 

 effects and persistence of other organic 

 pollutants, particularly petroleum. In 

 1969, 2,000 barrels of No. 2 fuel oil from 

 the barge Florida were spilled in Wild 

 Harbor at West Falmouth, Massachusetts. 

 In the most heavily affected areas, the 

 oil persisted in sediments for as long as 

 12 years, although over 90% of the area 



HF= 25 g/m 2 /week 



Figure 27. Distribution of fiddler crabs 

 ( Uca pugnax ) in marshes receiving sewage 

 sludge. The duplicate censuses are shown 

 extending back from the creek next to one 

 another for comparison although all were 

 made in the center of the respective plots 

 (the size of the plots is indicated by the 

 dashed line) (from data of Krebs and 

 Valiela 1977). 



recovered within about 6 years. 

 "Recovery" was measured in terms of a lack 

 of either killing Spartina alternif lora or 

 preventing its regrowth (Teal and Howarth 

 1983). Hydrocarbons from the spill 

 reduced population levels of Uca pugnax 

 much as aldrin had (Krebs and Burns 1977). 

 Post-spill levels of more than 100 ug of 

 the lighter hydrocarbons per gram of mud 

 killed both Spartina and fiddler crabs 

 (Burns and Teal 1979; Hampson and Moul 

 1979). 



The persistence of oil in the 

 sediments acted like a predator or trap 

 for the crabs. Resident crabs in 

 contaminated sediments died; in response 

 to their absence, neighboring populations 

 expanded into the contaminated areas and 

 the invading individuals died in turn. 

 Overwintering young crabs were the most 

 sensitive, probably because they were in 

 intimate contact with the contaminated 

 sediments in their burrows (Krebs and 

 Burns 1977). 



There are also studies of the 

 persistence of hydrocarbons contained in 

 the sewage sludge added experimentally to 

 Great Sippewissett Salt Marsh. These 

 hydrocarbons are those that survived both 

 the sewage treatment and sterilization 

 necessary before the sludge is sold. 

 Preliminary studies indicate that there is 

 little buildup of these hydrocarbons in 

 treated marsh sediments or in untreated 

 nearby sediments (J.M. Teal, unpubl. 

 data); this suggests that the hydrocarbons 

 must degrade quite rapidly. 



6. 3. 3. Nutrients 



Marshes have been considered for use 

 in the treatment of sewage. In fact, one 

 of the highest economic values placed on 

 marshes is arrived at considering them in 

 this context (Gosselink et al. 1973). It 

 is, therefore, important to know what the 

 effects of such use would be. The Great 

 Sippewissett Salt Marsh fertilization 

 experiments were designed partly to study 

 these effects and will be used as an 

 example. 



The experiments of Great Sippewissett 

 Salt Marsh measured the marsh's retention 

 of nutrients to evaluate the possible 

 eutrophication of the waters associated 



48 



