A 



CADDISFLY LARVA 



B 



BEETLE LARVA 



BEETLE LARVA 



BLACKFLY STONEFLY 

 LARVA LARVA 





MAYFLY LARVA 



WATER FLEA 



D 



MIDGE FLY 

 LARVA 



OLIGOCHAETE 



Figure 53. Common invertebrates of southeastern rivers: (A) snag fauna of a Coastal 

 Plain blackwater river, (B) blackwater river drift fauna, (C) Coastal Plain alluvial 

 river drift fauna, (D) bottom sand fauna of a Coastal Plain blackwater river. Black- 

 water river data from Satilla River, GA (Benke et al. 1979); alluvial river data from 

 Altamaha River, GA (Gardner et al. 1975). (Modified from Wharton et al. 1981.) 



1975), especially where some follow normal 

 metabolic mineral pathways in organisms 

 (50Sr as Ca, is^^j gg K). Radioactive ele- 

 ments adsorb on algae and particulate 

 matter, but their assimilation by aquatic 

 fauna is strongly reduced (from 90% to 

 10%) by adsorption to inorganic clays 

 ingested with the food. 



Unlike the bioaccumulation of pesti- 

 cides, studies suggest that highest con- 

 centrations of radionuclides typically 

 occur at lower trophic levels; algae may 

 concentrate ^^'^Cs 25,000 times while fish 

 may do so only 1000 times (Nelson et al. 

 1972). On the other hand, large hatches 

 of emerging insects such as chironomids 

 carry only small quantities of radionu- 

 clides from the system (Nelson et al. 

 1972) while deer, who graze herbs, shrubs, 

 and mushrooms, may acquire considerable 

 amounts of radionuclides. 



Stomach analyses of various verte- 

 brates (Figure 49) have yielded data on 

 food preferences. The use of the huge 

 acorn crop and other foods has been 

 reviewed (Wharton et al. 1981). Tight 

 coupling of dietary needs and floodplain 

 hydrology is suogested by Fredrickson 

 (1979) and Drobney (1977). They found 

 that a high protein intake essential to 

 wood duck egg production is gained from 

 aquatic and terrestrial macroinvertebrates 

 at the edge of high water as it advances 

 or recedes through Zones III, IV, and V. 



Unsupported opinions about the value 

 of an animal species in food webs can be 

 highly misleading in floodplains. For 

 example, the largely cryptozoic and 

 fossorial salamanders appear to be an 

 insignificant component of possible food 

 webs, yet they are very efficient convert- 

 ers of energy into biom.ass and are prob- 



99 



