Midge Larvae as Indicators of
Radioactive Pollution1
LA VERNE L. CURRY, Professor Biology
Central Michigan College
Mount Pleasant,  Michigan
4
It is particularly appropriate that the bottom dwelling organisms of natural
waters be discussed at a conference on industrial wastes. The amount of these
materials entering the natural waters of the United States has drastically increased during the past decade. Further, it is now recognized that these
wastes cannot be discharged into the most convenient lake or stream without
dramatic effects upon the biota. Three factors associated with these materials which directly influence the biota are elevated temperatures, particulate
matter, and excess of nutrient material. In addition, the increase of radioactive wastes occurring in natural waters is now considered a problem worthy
of future research.
The effect of these factors upon the biota is rather well defined in a majority of cases and has been discussed in some detail (1,2). However, in the
past few years considerable attentionhas been given to radioactive wastes from
the standpoint of a pollutant (3,4), natural occurrence (5), and the accumulation of the radionuclides by a variety of aquatic organisms (6-9). The seriousness of this problem has been great enough to have proposed a subdivision
of ecology, that of radiation ecology (10).
To assist scientists endeavoring to solve problems related to pollution the
biologist has endeavored to find an organism, or group of organisms, that
could be used as an indicator of some types of pollution. The use of several
species of midget larvae, or "blood-worms," has appeared in the literature as
possible indicators (11,12). However, a detailed investigation of the family
(Diptera:Tendipedidae) considered only Tendipes riparius (Meigen) and T.
tentans (Fabricius) as possible species indicating pollutional conditions (13).
The study found many species of midge, some tolerant of varying degrees
of pollution, to breed most abundantly in unpolluted water. This conclusion
is also substantiated by a study of a stream in Ohio (14). In this case it was
concluded that a number of ecological factors, other than pollution, were responsible for the variations in the stream biota. It was further concluded that
a large number of midges are positive indicators of an unpolluted habitat.
A comparison of the toxic effects of small amounts of radioactive pollutants with those of the usual industrial and domestic pollution is difficult to
make. This is due, in general, to the nature of the two types of wastes. However , the concentration of certain radionuclides by marine and fresh water
organisms has been recorded (6-9). In addition, studies on White Oak Creek
and the Columbia River indicate that midge larvae are able to concentrate
isotopes from the water (15,16). The research, upon which this report is
based, is a part of an investigation to determine the manner a specific radionuclide is assimilated and further to observe if a particular species can be used
as an indicator of radioactive pollution.
1 Based in part on results obtained through Contract AT (11-1) - 350 with the
Atomic Energy Commission.
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