ECOLOGY OF BUZZARDS BAY: An Estuanne Profile 



55 



4.1.2. Flora and Aquatic 



Primary Productivity 



The aquatic flora of Buzzards Bay reflects the 

 diversity of physical environments discussed previ- 

 ously (Table 1.1). The water column supports phy- 

 toplankton communities having a range of produc- 

 tivity from the nutrient-enriched embayments with 

 chlorophyll-^ concentrations over 1 mg/m ; to the 

 open waters near the mouth of the bay at 1 -2 mg/m 3 

 (Roman and Tenore 1978; Howes and Taylor 

 1 99 1 ). Areas of the bay bottom above the photo- 

 synthetic compensation depth and intertidal flats 

 support a variety of benthic floral types with di- 

 verse species assemblages. These floral types in- 

 clude macroalgae, particularly in the areas of hard 

 substrate (e.g.. rocky shores of the.Elizabeth Is- 

 lands) and in the shallow waters and intertidal ar- 

 eas; periphyton. which colonize the surface layers 

 of sandy and muddy bottoms and intertidal flats: 

 and subtidal (eelgrass) and intertidal (salt marsh) 

 rooted macrophyte communities with associated 

 periphytic and epiphytic associations (e.g.. on 

 eelgrass). 



Because secondary production and habitat qual- 

 ity within Buzzards Bay depend directly on the 

 amount and distribution of organic matter produced 

 by phototrophs, it is useful to compare the relative 

 amounts of organic matter produced by the differ- 

 ent floral types. Although Buzzards Bay has been 

 studied for more than a century, a quantitative bay- 

 wide assessment of each of the floral assemblages 

 is not available. However, enough data exist to make 

 relative comparisons (Table 4.5). 



Phytoplankton production has been determined 

 in moderately detailed annual studies on the west- 

 em (Symada 1 990) and eastern (Roman and Tenore 

 1978) shores. It is likely that at least some of the 

 three-fold higher carbon fixation along the western 

 shore (360 g C nr 2 year "' ) versus eastern shore 

 ( 1 06 g C nr 2 year "') results from the greater nutri- 

 ent enrichment from loading in the New Bedford- 

 Fairhaven area. Estimates of eelgrass and salt marsh 

 production should be fairly accurate because of the 

 availability of mapping studies (Hankin et al. 1 985; 

 Costa 1 988a) and site-specific productivity esti- 

 mates ( Valiela and Teal 1 979; Costa 1 988b). Tidal 

 export from salt marshes is also included in studies 



Table 4.5. Annual primary production of the aquatic resources of Buzzards Bay (adapted 

 from Costa 1988b). 



"t = metric ton = 10 6 g 



"Area from Signell 1 987 Production from Camp. Dresser and McKee, Inc 1 990 (360 g C m 2 year 1 , Western Shore) and Roman 

 and Tenore 1978 (106 g C m 2 year '. Eastern Shore) 

 c Area currently colonized as mapped by Costa 1988a 

 "Area from Hankin et al 1985 Production and export extrapolated from Great Sippewissett Marsh (Valiela and Teal 1979). 



