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Title:Identification of the water quality factors which prevent fingernail clams from recolonizing the Illinois River—phase III
Author(s):Sparks, Richard E.; Sandusky, Michael J.; Paparo, Anthony A.
Contributor(s):Illinois. Natural History Survey Division; Southern Illinois University at Carbondale‏
Subject(s):Water resources development
Water resources development--Illinois
Aquatic ecology
Suspended solids
Suspended sediment
Keokuk Pool
Mississippi River
Illinois River
Pollutant identification
Geographic Coverage:Illinois (state)
Abstract:The purpose of this research was to determine why fingernail clams have been unable to recolonize a 100-mile reach of the Illinois River where they were abundant prior to a die-off in the 1950's. Fingernail clams are major links in food chains leading from detritus and algae to higher level consumers valued by man, such as fish and water fowl. Three suspected toxicants and sediments from the reach where the die-off occurred were tested on intact fingernail clams (Musculium transversum) and gill preparations isolated from the clams. Concentrations of fluoride, lead and cadmium which caused a 50% reduction in the rate of beating of cilia on isolated clam gills, after 10 minutes of exposure (10-minute EC50), were 0.75, 0.02 and 0.06 mg/l , respectively. Mixtures of cadmium and fluoride were slightly more toxic to clam gills than predicted from results of bioassays with single toxicants. A fluoride concentration of 2.82 mg/l killed intact fingernail clams after eight weeks of exposure, while mortality in lesser concentrations and one higher concentration did not differ significantly from controls maintained in well water to which no fluoride had been added. Hence, the sub-lethal response exhibited by the gills is at least four times more sensitive than the lethal response. Maximum fluoride concentrations reported by the U.S. Geological Survey at two stations in the Illinois River ranged from .6 to .8 mg/l between 1979 and 1981, considerably below the concentrations which affected growth and survival of intact clams during 8-week exposures in our laboratory, but slightly above the level which affected isolated clam gills. A lead bioassay using intact clams was completed, but the results were ambiguous because concentration ranges in separate test chambers overlapped. In addition, insoluble lead precipitates accumulated in the test chambers, and the relative toxicity to clams of the soluble versus the insoluble lead was not determined. Until additional bioassays are completed, it is impossible to determine whether the maximum total lead concentrations of 0.40 mg/l which occurred in the Illinois River between 1979 and 1981 could have contributed to the failure of fingernail clams to recolonize the river. Fingernail clams exposed to sediments from lakes along the Illinois River suffered greater mortality after six weeks of exposure than clams exposed to sediment from the Mississippi River, although the differences were not statistically significant. The same sediments tested on clam gills produced statistically significant changes in ciliary beating rate and particle transport rates on the gills. Sediments from the upstream lakes cause a greater depression in the particle transport rate and ciliary beating rates than sediments from downstream lakes. In addition, sediments from the lake furthest upstream caused a drastic change from the normal metachronal beating pattern to an atypical synchronous pattern. The results with the gill assay suggest that sediments in the Illinois River contain unidentified toxic factors and that sediments in the upper river, closer to the metropolitan areas of Joliet and Chicago, are more toxic than sediments further downstream. These results should be confirmed by additional tests with intact clams, including field tests with caged organisms. Parallel chemical analyses and bioassays of extracts from the sediments should be performed to identify the toxic components.
Issue Date:1983-04
Publisher:University of Illinois at Urbana-Champaign. Water Resources Center
Genre:Report (Grant or Annual)
Sponsor:U.S. Department of the Interior
U.S. Geological Survey
Rights Information:Copyright 1983 held by Richard E. Sparks, Michael J. Sandusky, Anthony A. Paparo
Date Available in IDEALS:2016-04-20

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