(e.g. phytoplankton) , consumers, (e.g., fish), and decomposers (e.g., 

 bacteria). Consumers and decomposers both contribute to the degradation of 

 organic matter, and many consumers feed on organic detritus, all of which 

 falls under heterotrophic nutrition. 



Data on the biota (except fishes) of the coastal zone lakes generally are too 

 sparse to be representative. Data of Cooper (1939 and 1942) on net plankton 

 are not suitable for meaningful comparisons. The most complete biological 

 data on coastal zone lakes are those for Highland, Brewer, Branch, and Green 

 lakes. These lakes were included by Cowing and Scott (1975 to 1977) in their 

 report on 3 years' data from 43 Maine lakes. The authors calculated trophic 

 state indices for these lakes, indicating that Green Lake (region 5) is 

 oligotrophic, Branch (region 5) and Highland (region 1) oligomesotrophic, and 

 Brewer (region 4) mesotrophic. 



The abundance and biomass of organisms in Maine lakes have been correlated to 

 the lakes' trophic status by Cowing and Scott (1975 to 1977) and Davis and 

 coworkers (1978a). The annual mean phytoplankton density in Maine lakes 

 ranges from about 100 cells/ml to at least 30,000 cells/ml, and annual mean 

 phytoplankton biomass (as total volumes of cells) ranges from about 20,000 to 

 >2 million ym^/ml (Davis et al. 1978a). Summer phytoplankton in relatively 

 oligotrophic lakes (e.g.. Green and Branch) are dominated by small flagellates 

 and diatoms, whereas relatively eutrophic Brewer Lake is dominated by blue- 

 green algae Aphanizomenon flos-aquae and Gomphosphaeria aponina . Elsewhere in 

 the coastal zone the blue-green algae genus Anabaena has been found to 

 predominate the summer plankton of relatively eutrophic lakes (e.g., Togus and 

 Pleasant Ponds in region 2; Cobbossee Watershed District 1977a and 1977b). 

 Outside the coastal zone, small blue-green algae ( Merismopedia tenuissima ) , 

 several diatoms (especially Tabellaria spp.) and small unicellular flagellates 

 dominated the summer phytoplankton in relatively oligotrophic lakes. Under 

 eutrophic conditions the summer phytoplankton was dominated by Anabaena spp., 

 Oscillatoria spp., and Gomphosphaeria spp. In addition to these the taxa 

 Anacystis , Asterionella , Cyclotella , Chromulina , and Ochromonas occur commonly 

 in Maine lakes (Davis et al. 1978a). 



Genera of macrophytes that occur commonly in Maine lakes include: (1) 



emergents, Scirpus , Eleocharis, Typha, Pontederia , and Sparganium ; (2) the 



floating-leaved plants, Nuphar, Brasenia, Nymphaea, and Valisneria ; and (3) 



the submerged plants, Eriocaulon , Potamogeton , Myriophyllum , Utricularia , and 

 Osoetes (Cowing and Scott 1975, 1976, and 1977). A complete list of aquatic 



vascular plant species that occur in Maine coastal counties encompassed in the 

 characterization area is given in appendix A of chapter 8. 



The abundance and biomass of the benthos in March is also related to the 

 trophic status of Maine lakes. Phaenopsectra ( Tribelos ) spp. and Micropsectra 

 spp. were found in the relatively oligotrophic lakes and Chironomus plumosus 

 in the relatively eutrophic lakes (Cowing and Scott 1975 to 1977; and Davis et 

 al. 1978a). Ericaulon septangulare is a common macrophyte of the relatively 

 oligotrophic lakes. 



Based on plankton biomass calculations coastal zone lakes (mean 9.2 cnr /m^ ; 

 min-max 1.8 to 39.3 cm /m ) are more productive in summer than Maine lakes as 

 a whole (mean 4.8 cm^ /m^ ; min-max 0.7 to 10.9 cm^ /m^ ; Cooper 1939, 1942; 

 Fuller and Cooper 1946; Davis et al. 1978a). These data also suggest that 



7-23 



10-80 



