Correlations Among Sediment Toxicity End-Points 



All except two of the end-points (R. abronius and A. abdita avoidance) are presented in 

 Table 18 such that a high value indicates non-toxicity (e.g., percent survival, percent 

 normal). Therefore, the results of these correlation analyses should be interpreted carefully 

 with regard to the sign (positive or inverse correlations) for these end-points. Three patterns 

 in toxicity responses among the end-points were apparent, based upon the Spearman rank 

 correlation analysis. First, results for the three end-points of M. edulis survival and normal 

 development and R. abronius survival were relatively highly correlated with each other and 

 not very highly correlated with any others. Second, results for the three end-points of A. 

 abdita survival and avoidance and S. purpuratus echinochrome content were relatively highly 

 correlated with each other. The pattern of response with the S. purpuratus percent normal 

 development end-point contradicted that of A. abdita survival and S. purpuratus echinochrome 

 content. Third, the results for the end-points of D. gyrociliatus egg production and R. abronius 

 avoidance were weakly correlated with each other, indicating patterns that contradicted 

 each other. Neither was highly correlated with the results of any of the other end-points. 

 The correlations were strongest among the end-points in the first group and progressively 

 weaker in the second and third groups. 



Although the toxicity data were not normally distributed, a parametric Principal 

 Components Analysis among the bioassay end-points was performed in an exploratory mode to 

 determine if there were any patterns in correspondence among the tests. Three factors were 

 identified that explained 44.8 percent, 36.3 percent, and 18.9 percent of the total variability, 

 respectively. The first factor suggested that the M. edulis percent normal and percent 

 survival end-points and the R. abronius survival end-point had very similar patterns in toxic 

 responses among the 15 samples. The second factor indicated that A. abdita survival and 

 avoidance and S. purpuratus percent normal and echinochrome content had similar patterns in 

 response. The third factor accounted for little of the total variability and contained the D. 

 gyrociliatus reproduction data. 



Correlations Between Toxicity and Chemical Results 



Results of a Spearman rank analysis of correlations between toxicity test end-points and 

 selected sedimentological variables, chemicals, or chemical classes are listed in Table 19. 

 Trace metal data were normalized to percent fines and organic chemical data were 

 normalized to TOC content. With a total of 190 correlations, the experimental level of 

 significance became 0.05/190 = 0.0003 by the Bonferroni method. None of the correlations 

 were significant at a = 0.0003. Therefore, the results for each toxicity end-point are treated 

 qualitatively. Most of the end-points in Table 19 are presented such that a high value 

 indicates non-toxicity (e.g., % normal, % survival), however, high values for the end-points 

 of avoidance, micronuclei, cytological abnormalities and anaphase aberrations denote 

 toxicity. Therefore, the correlations must be interpreted cautiously with regard to the sign 

 (i.e., positive or negative correlations) for these latter end-points. Some of the end-points 

 that were relatively highly correlated with each other (Table 18) also indicated similar 

 patterns in their correlations with some of the same physical/chemical parameters. First, 

 the toxicity end-points of percent normal development and percent survival of M. edulis, 

 percent survival of R. abronius, and percent normal development of S. purpuratus indicated a 

 similar pattern: they were most strongly inversely correlated with sedimentological 

 factor(s) such as percent silt, percent clay, percent fines, and/or TOC content. The M. edulis 

 end-points also were inversely correlated relatively highly with mercury concentration, 

 whereas the R. abronius survival data were not very highly correlated with any of the 

 chemical variables. Percent normal S. purpuratus data were also relatively highly 

 positively correlated with the concentrations of DDE, other pesticides, zinc, and PCBs. 

 Second, low percent survival and high incidences of avoidance of sediments by A. abdita and 

 low echinochrome content of S. purpuratus also indicated a similar pattern: they were 

 relatively highly correlated with increasing concentrations of DDE, other pesticides, and 

 PCBs. The correlations between A. abdita survival and these chemicals were particularly 

 high. Third, egg production in D. gyrociliatus was most inversely correlated with PAHs, 



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