86 



diversity values at many stations seems to be caused by high species 

 richness. Naturally, these are the stations with high numbers of 

 species. At other stations, however, evenness appears to be the 

 dominant component of diversity. For example, stations 15, 16, 18, 19, 

 20 and 36 only have moderate to low species richness levels but are 

 among the highest stations in evenness which results in diversity levels 

 of over 3.0 at stations where conventional logic would predict depressed 

 diversity. 



Extremely low diversity is limited to stations with very fine 

 sediments. Not all the fine-grained stations exhibit such low 

 diversity, however, and the explanation for this is analogous to that 

 presented above. 



Like the other biological parameters discussed, informational 

 diversity is positively correlated with bottom depth, at the 95% level, 

 and negatively correlated with mean grain size and organic carbon, both 

 at the 99% level (Figs. 32, 33 and 34). As would be expected, diversity 

 is positively correlated at the 99.9% level with species number, but 

 shows no relationship to density. Additionally, diversity is not 

 significantly correlated with any of the trace metals and is not even 

 consistent in the sign of the correlation coefficient. 



Whereas, we believe all of the biological parameters should be 

 re-evaluated in greater depth once the hydrocarbon data can be factored 

 into the analysis, all of them, except diversity, presently add insight 

 into the existing conditions in Casco Bay and will aid us in providing 

 an integrated overview of the biological functioning and health of the 

 system. Diversity, on the other hand, is not presently useful in this 

 regard. Once all the data are available, diversity should again be 



