MARSH CREATION: IMPACT OF PESTICIDES ON THE 

 FAUNA, USE OF INFRARED PHOTOGRAPHY, DITCHING AND DIKING 



Robert J. Reimold 



Coastal Resources Division 

 Georgia Department of Natural Resources 

 1200 Glynn Avenue 

 Brunswick, Georgia 31520 



This paper is about pesticides and 

 fauna. I do not intend to talk about 

 the chemistry of pesticides but simply 

 about how a particular pesticide has 

 affected an estuarine system and what we 

 have done to follow the fate of that 

 pesticide. 



We have studied toxaphene which is 

 used to control boll weevil in cotton in 

 estuaries near Brunswick, Georgia, (near 

 a toxaphene manufacturing plant) and in 

 the Duplin Estuary, a pristine estuary, 

 part of a National Estuarine Sanctuary 

 indicative of the Carol inean Biogeo- 

 graphic Province of estuaries from Cape 

 Hatteras to Cape Canaveral. There are 

 two sources of toxaphene pollution in 

 the estuary: one from a manufacturer in 

 Brunswick and the other from agricultur- 

 al runoff. As part of the U.S. Environ- 

 mental Protection Agency (EPA) estuarine 

 monitoring program for pesticides we 

 have looked at fish, finfish, shellfish, 

 sediment, and marsh plants from South 

 Carolina to the Florida border from 1968 

 to 1976. Except for the early years of 

 that study (1968 to 1971), we never 

 found any measurable quantities (accord- 

 ing to EPA detection limits) of toxa- 

 phene anywhere except very close to the 

 Brunswick, Georgia, manufacturing plant. 

 We have studied the toxaphene manufac- 

 turing operation and how it impacts 

 swimming organisms in the estuarine 

 water column. 



Since our study began, the levels 

 of toxaphene in the manufacturing plant 

 effluent decreased from parts per hun- 

 dred to parts per billion (less than 

 2 ppb). Levels in the past year have 

 decreased to 2 ppb. 



How did this affect the receiving 

 waters of the estuary? We could take 

 organisms that live in the estuary, cat- 

 fish or goldfish as scientists often do, 

 put them in tanks with different concen- 

 trations of toxaphene, and determine 



some water quality standards or lethal 

 concentrations within which the fish 

 could survive. But what does that actu- 

 ally mean in the estuary where the or- 

 ganisms live? 



We decided that one approach would 

 be to look at species diversity. We 

 compared several different diversity 

 indices to see how the numbers fluctuate 

 over the years, looking first at diver- 

 sity measured as an index of species 

 richness or variety. This latter diver- 

 sity is useful for comparing one commu- 

 nity to another. We considered the 

 Shannon-Weaver index which combines the 

 variety and evenness component_s of di- 

 versity. The Shannon-Weaver, H, as we 

 refer to it, is also quite useful be- 

 cause it is independent of sample size. 

 If one does not have as many samples in 

 one area as another, one can still make 

 useful comparisons. Shannon-Weaver, H, 

 is also a reasonable index to use be- 

 cause it has a normal distribution and 

 consequently it can be used for standard 

 significance tests such as a t-test. 



Another index, the index of even- 

 ness (J index), assumes that the even- 

 ness or apportionment of individuals 

 among species is comparable. This even- 

 ness varies inversely with indices that 

 are based solely on dominance. In other 

 words, we are not looking at one great 

 or abundant species, or one small and 

 minor species (in terms of numbers of 

 individuals), but rather in terms of how 

 evenly distributed they are, whether 

 there would only be three of everything 

 or thousands of everything. 



Another index we considered is the 

 number of moves index, (NM) that enables 

 us to rank the diversity index and scale 

 it so that the maximum is one and the 

 minimum is zero. 



We based our analysis of the Duplin 

 Estuary and the Brunswick Estuary on 

 nekton sampled with an otter trawl over 



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