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Inverwhrales — Uiir Liviiit; Risniirces 



For further information: 



William T. Mason, Jr. 



National Biological Senice 



Southeastern Biological Science 



Center 



7920 N.W. 71st St. 



Gainesville. FL 32653 



conspicuously rate in the 48-km (3()-mi) reach 

 downstream from the Twin Cities. There, a 

 heavy pollutant load caused low dissolved o.\y- 

 gen levels on the liver bottom for much of the 

 year. The mayflies were also rare in the upper 

 reach of Lake Pepin, a large (32-km [20-mi]) 

 natural impoundment farther downstream, 

 where they had been abundant in years past. 

 Apparently Lake Pepin was a settling basin for 

 pollutants and decaying algae caused by over- 

 fertilization from the Twin Cities area. 



A 1986 mayfly survey revealed that recent 

 pollution abatement measures in the Twin Cities 

 created favorable conditions for mayflies to 

 return to densities of the 1950's-60's. The dis- 

 tribution of Hexagenia species reflects the sta- 

 tus of aquatic life inhabiting a large river that 

 was otherwise difficult to monitor effectively or 

 economically by standard chemical testing 

 (Fremling 1989. 1990). 



Management Implications 



As with the Ohio River insects, there is a 

 need to maintain a network of routine monitor- 

 ing stations along the 3,218 km (2,000 mi) of 

 the Mississippi River to learn when atypical 

 emergences of mayflies and other aquatic 

 insects occur. This information will allow pub- 

 lic officials and administrators to pinpoint more 

 intensive and detailed analytical surveys that 

 could determine causes of the emergences. 



Today, the greatest future threat to the bur- 

 rowing mayflies in the Mississippi River lies in 

 accelerated siltation and subsequent filling of the 

 navigation pools. These filled areas are rapidly 

 becoming floodplain forests, a conversion that 

 eliminates them as burrowing mayfly habitat, 

 thereby reducing food stocks for fisheries. 



References 



Bemer. L.. and M.L. Pescador. 1988. The maytlies of Florida. 

 University of Florida Press, Gainesville. 415 pp. 



Fremling. C.R. 1964. Mayfly distribution indicates water qual- 

 ity on the Upper Mississippi River. Science 

 146(3648):1 164-1 166. 



Fremling. C.R. 1968. Documentation of mass emergence of 

 Hexagenia mayflies from the Upper Mississippi River 



Transactions of the American Fisheries Society 97(31:278- 

 281. 



Fremling, C.R. 1970. Mayfly distribution as a water quality 

 nide,\. Water Pollution Control Research Senes 16030 

 DQH 1 1/70. U.S. Environmental Protection Agency, Water 

 Quality Office, Washington. DC. 39 pp. 



Fremling. C.R. 1989. Hexagenia maytlies: biological monitors 

 of water quality in the Upper Mississippi River. Journal of 

 the Minnesota Academy of Science 55(11:139-143. 



Fremling, C.R. 1990. Recurrence of Hexagenia maytlies 

 demonstrates improved water quality in Pool 2 and Lake 

 Pepin. Upper Mississippi River Pages 243-248 in l.C. 

 Campbell, ed. Maytlies and stoneflies. Kluwer Academic 

 Publishers. The Netheriands. 



Hamilton, A.L.. and O.A. Saether 1971. The occurrence of 

 characteristic deformities in the chironomid larvae of sever- 

 al Canadian lakes. Canadian Entomologist 103:363-368. 



Hudson. PL.. D.R. Lenat. B.A. Caldwell, and D. Smith. 1990. 

 Chironomldae of the southeastern United States: a checklist 

 of species and notes on biology, distribution, and habitat. 

 U.S. Fish and Wildlife Service Fish and Wildlife Res. 7. 

 46 pp. 



Lenat, DR. 1993, Using mentum deformities of Chinmonms 

 larvae to evaluate the effects of to.xicity and organic loading 

 in streams. Journal of the North Amencan Benthological 

 Society 12:265-269. 



Mason, W.T., Jr. 1975. Chironomidae (Dipteral as biological 

 indicators of water quality. Pages 40-51 in C.C. King and 

 L.E. Elfner. eds. Organisms and biological communities as 

 indicators of environmental quality. Circular 8. Ohio 

 Biological Survey. Columbus. 



Mason. W.T. Jr. PA. Lewis, and J.B. Anderson. 1971. 

 Macroinvertebrate collections and water quality monitonng 

 in the Ohio River Basm 196.3-1967. Office of Technical 

 Programs. Ohio Basin Region, and Analytical Quality 

 Control Laboratory, U.S. Environmental Protection 

 Agency. Cincinnati. OH. 52 pp. 



Merritt, R.W.. and K.W, Cummins. 1984. Introduction. Pages 

 1-3 in R.W. Merrin and K.W. Cummins, eds. An introduc- 

 tion to the aquatic insects of North Amenca. 2nd ed. 

 Kendall/Hunt Publishing Company, Dubuque, lA. 



Paine, G.W., and A.R. Gaufin. 1956. Aquatic Diptera as indi- 

 cators of pollution in a midwestem stream. The Ohio 

 Journal of Science 56:291-304. 



Patrick. R., and DM. Palavage. 1994. The value of species as 

 indicators of water quality. Proceedings of the Academy of 

 Natural Sciences Philadelphia 145:55-92. 



Pennak, R.W. 1978. Fresh-water invertebrates of the United 

 States. 2nd ed. John Wiley & Sons. Inc. New York. 803 pp. 



Roback. S.S. 1957. The immature tendipedids of the 

 Philadelphia area. Academy of Natural Sciences of 

 Philadelphia Monograph 9. 152 pp. 



van Urk, G.. FC.M. Kerkum. and H. Smit. 1992. Life cycle 

 patterns, density, and frequency of deformities in 

 Chimnumus larvae (Diptera: Chironomidae) over a conta- 

 minated sediment gradient. Canadian Journal of Fisheries 

 and Aquatic Sciences 49:2291-2299. 



Biodiversity 

 Degradation 

 in Illinois 

 Stoneflies 



hy 



Donald W. Webb 



Illinois Natural History 



Survey 



Preliminary analysis of the recent collections 

 of Illinois stoneflies indicates a reduction in 

 the species richness in Illinois, a reduction in 

 the spatial distribution of many species, the 

 dominance of more generalist species more tol- 

 erant to environmental perturbations, and the 

 extirpation of several species. 



These general trends can be expanded for all 

 of the central United States. The reduction in 

 stream flow through the construction of locks 

 and dams and the resulting effect of increased 

 sedimentation have severely affected the habitat 



and niche selection available to species such as 

 stoneflies that require rapidly flowing streams. 

 This situation has been compounded by the ero- 

 sional effects of deforestation and agricultural 

 practices, which are maximizing the amount of 

 land put into cultivation, as well as the 

 increased problems related to nonpoint pollu- 

 tion from agricultural pesticides and fertilizers. 

 To properly delineate these trends, the status of 

 stoneflies and most other groups of aquatic 

 organisms in the central United States needs to 

 be evaluated. 



