an 8-yr period. There was a dramatic 

 change both in the number of species and 

 in the number of individuals over the 

 years. We evaluated biomass, the wet 

 weight of nekton, to get some idea of 

 their size. We have changes in biomass 

 and numbers over the periods sampled. 

 The diversity indices for Terry 

 Creek, the stream into which the toxa- 

 phene effluent was discharged, reveal 

 that in 1968 there were only three dif- 

 ferent kinds of organisms that lived 

 there as opposed to nearly 25 species by 

 1976. We considered the biomass of the 

 same area and noted increases in biomass 

 with time also. 



After the first 3 yr, the number of 

 species remained more constant in the 

 Brunswick Estuary than it did in the 

 natural Duplin estuary. At all the 

 Brunswick sampling stations, there were 

 variations in the biomass although the 

 number of species stayed rather con- 

 stant. 



The index of diversity "D" is based 

 on species richness or variety. "D" in 

 Terry Creek increased, and so did bio- 

 mass between 1968 and 1976. H, the 

 Shannon-Weaver index, independent of 

 sample size has some merits that other 

 indices do not have. In terms of number 

 of individuals, there are not any dif- 

 ferences between diversity indices from 

 1973 to 1976 although between 1968 and 

 1973 there were great differences. 

 The Shannon-Weaver index when com- 

 puted on the basis of biomass reveals no 

 significant differences during the last 

 3 yr of the study. The apparent toxa- 

 phene concentration of the effluent from 

 the manufacturing plant was in parts per 

 hundred in 197C and less than 10 ppb by 

 1976. J 



The evenness index "J" documents 

 the apportionment of individuals among 

 species. We noted this index approach- 

 ing unity, but the change was not as 

 striking as that seen with some of the 

 other indices considered. 



Perhaps some have used otter trawls 

 to sample fish. It is really quite sim- 

 ple to measure and weigh each fish. 

 There are a number of simple computer 

 programs that can be used to compute all 

 previously mentioned diversity indices. 

 After one has taken the trouble to sam- 

 ple the fish, one might want to use that 

 data to compute a species diversity 



index. I caution not to compute only 

 one index because therein are some weak- 

 nesses. I recommend a review of "Funda- 

 mentals of Ecology," (Odum 1971) which 

 contains a chapter summarizing species 

 diversity, the different indices, the 

 requisite, the mathematical equations, 

 and their meaning. 



Several things have come to my 

 attention during this meeting that are 

 important but were not part of the pro- 

 gram. One is the proper uses and inter- 

 pretation of color infrared (IR) photo- 

 graphy. Those who do not use color IR 

 photography in their work probably 

 should consider it. Much information 

 can be gleaned from color infrared pho- 

 tography that is not on the old black 

 and white photography. When I say color 

 IR, I am not talking about the satellite 

 imagery that is made into a color pro- 

 duct on which one can view all of Mary- 

 land or all of Arizona. I am talking 

 about photography on which one can actu- 

 ally see some of the 1-, 4-, or 18-hec- 

 tare sites with which one has to work 

 with every day. What kind of details 

 can one expect to see? 



One might be able to pick out each 

 individual plant and enumerate the total 

 number of plants. The photography is 

 useful for ecological delineation and 

 for economic delineation including legal 

 purposes. Photography can be used to 

 determine where the location of some- 

 thing is on the face of the earth. As 

 an example, color IR photography has 

 been used in wetlands to delineate the 

 boundary of the biological mean high 

 water line. Such delineation, however, 

 did not stand up in court. 



At Sapelo we coupled ground truth 

 measurements (tide gauges) with aerial 

 photography in order to remotely deter- 

 mine the mean high water mark. We then 

 surveyed the marsh to locate the eleva- 

 tion of mean high water and found it 

 fairly closely paralleled the dividing 

 line between the tall and short forms of 

 salt marsh cordgrass ( Spartina alterni- 

 fl ora ) near the mouth of the estuary. 

 We went 1 km further upstream on the 

 same estuary and found mean high water 

 to parallel the break between Spartina 

 al term" flora and Juncus roemerianus . 

 For ecological purposes, that division 

 is approximately where the tide flows 

 and ebbs every day. If one is going to 



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