64 



BIOLOGICAL REPORT 31 



Table 4.9. Average gut fullness, percent fish with empty guts, and percent carnivory, herbivory, and detntivory 

 in the diets of resident and nonresident salt marsh fishes. Averages are shown ± SE. Asterisks (**) indicate 

 significance oft-test at 0.01 level of significance (From Werme 1981.) 



NS • not significant 



adspersus), and sand lance {Ammodytes 

 americanus). These species are commonly found 

 in Buzzards Bay and are all nonresidents. Adult eels 

 and young bluefish, terns, egrets, and herons enter 

 the marsh sporadically to feed on the fish in these 

 marshes. 



The migration of young fish hatched or reared in 

 the marsh to estuarine waters as well as the tran- 

 sient feeding of deeper water fish such as bluefish 

 and striped bass on marsh residents provide mecha- 

 nisms whereby the abundant productivity found in 

 these intertidal wetlands is exported to estuarine 

 food webs. These processes represent important 

 components of the role and function of these wet- 

 lands in coastal ecology and provide a strong argu- 

 ment in defense of wetland protection and 

 preservation in the coastal landscape. 



Ribbed mussels (Geukensia demissa, formerly 

 \ fodiolus demissus ) an frequently found in the in- 

 tertidal wetland areas around the bay, generally 



growing abundantly in the peat around marsh 

 grasses, and are most prevalent in the lower eleva- 

 tion areas of creekbanks where tidal inundation is 

 greatest. This mussel is important in the ecology of 

 coastal wetlands. Mussels are active filter feeders, 

 straining all types of particulates out of the water 

 column, ingesting the edible and processing the in- 

 edible into pseudofeces that accumulate around the 

 mussel in areas where tidal currents are not suffi- 

 cient to sweep them away. Average rates of 

 biodeposition in the form of pseudofeces for the 

 ribbed mussel is 549 g/year (Davis 1 985 ). These 

 mussels can actually bury themselves in these 

 pseudofeces and in some areas must continuously 

 migrate upward over time. This phenomenon re- 

 sults in the marsh acquiring a hummocky appear- 

 ance with the height of the hummocks being limited 

 to the level at which the mussels can still extract 

 enough food from flooding tidal waters to survive 

 (Teal and Teal 1969). In addition, the network of 



