In subtidal rocky shore areas, the brown algae, Laminaria and Agarum 

 (collectively known as laminarians) , dominate biomass. These laminarians, or 

 kelp, extend from low-water marks to depths of approximately 30 to 60 feet (10 

 to 20 m). 



Macroalgae require adequate light and suitable stable surfaces for attachment. 

 The large rockweeds and kelp need large stones or rocks for attachment. 

 Unstable surfaces, such as mud, sand, or gravel, are generally devoid of the 

 larger algae and may support only relatively minor quantities of small plants 

 and then only in wave-sheltered areas. The growth of macroalgae also is 

 controlled by water temperature, salinity, and the availability of nutrients. 



The convoluted rocky shore along much of the coast of Maine, including its 

 estuaries, provides large areas of dense beds of plants. Rocky shore seaweed 

 communities provide habitat for numerous marine and estuarine animals. 

 Macroalgae are consumed by grazers, such as sea urchins and fish. The amount 

 of material consumed is unknown but in areas that have periodic high densities 

 of sea urchins, such as the Sheepscot River estuary and Cobscook Bay, large 

 quantities of plant material are consumed. Reestablishment of seriously 

 depleted macroalgal populations may take many years. 



Benthic diatoms . Benthic (bottom-dwelling) diatoms are similar to diatoms 

 living in the water column (see "Phytoplankton" above), but they live on 

 bottom substrata in intertidal and shallow subtidal areas. Their contribution 

 to productivity in the estuarine system is undetermined. Benthic diatoms on 

 an intertidal mudflat in the Bristol Channel (Great Britain) had twice the 

 productivity of the phytoplankton in the ovelying water column on a square 

 meter basis (personal communication from R. M. Warwick, Institute for Marine 

 Environment Research, Plymouth, England; April, 1979). Whether this 

 relationship applies to similar habitats in other regions is not known. 



Benthic diatoms are consumed by invertebrate deposit-feeding and grazing 

 species, such as the common periwinkle and the mud snail. The degree of 

 dependence of such species on this food source is unknown but in localized 

 situations it may be significant. 



Microbial producers . Microbial producers are bacteria and other 

 microorganisms that are suspended in the water column. They may be either 

 photosynthetic (i.e., dependent on light for growth) or nonphotosynthetic 

 (e.g., chemosynthetic) . Although little is known about their role in the food 

 chain or their importance as producers, J. Teal (personal communication; Woods 

 Hole Oceanographic Institute, Woods Hole, MA; May, 1980) points out that these 

 organisms are closely related to the cycling of sulfur and carbon in New 

 England salt marshes. 



Consumers 



Consumers are animals that feed on the products of primary production as well 

 as on each other. The major groups are zooplankton, benthic invertebrates, 

 fish, birds, and marine mammals. 



Zooplankton . Zooplankton is the collective term for the diverse 

 assemblage of animals that float or swim weakly in the water column. The 

 principal components of zooplankton are holoplankton (all the life cycle of 



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