Some compounds in sediments may be mutagenic or promutagenic and their effects probably 

 are undetectable with tests of acute mortality. 



Dinophilus gyrociliatus. This species had been used to test the toxicity of dissolved 

 contaminants and effluents. Because of its short life cycle, the species can be used to quickly 

 determine effects upon reproductive success (Carr et al., 1986) 



The survival of D. gyrociliatus was found to be relatively resistant to Endosulfan and 

 pentachlorophenol, but egg production was observed to be sensitive to complex effluents and 

 pentachlorophenol (Carr et al., 1986). In this evaluation, survival also was insensitive 

 However, egg production was sensitive to about one-third of the samples tested. There are 

 no other sediment toxicity data with which to compare the results of these tests. The end- 

 point of egg production is a biologically meaningful indicator of reproductive success. As 

 expected with a test of pore water, the results were not strongly correlated with those from 

 the tests of the solid phase sediments or elutriates. However, they were relatively highly 

 correlated with the concentrations of PAHs in bulk sediments. The medium that is tested, 

 the pore water, is predicted by equilibrium-partitioning theory to be the controlling exposure 

 medium in the toxicity of sediments to infaunal organisms (DiToro, in press). Laboratory 

 toxicity test results are often more highly correlated with TOC-normalized pore water 

 chemical concentrations than with non-TOC-normalized pore water or bulk sediment 

 chemical data (DiToro, in press). However, since the borosilicate filter used in the pore 

 water extraction method may have removed some of the potentially toxic polar compounds, 

 including organic compounds, this test may have underestimated the pore water toxicity. In 

 conclusion, further testing and evaluation of other pore water extraction methods are needed 

 to increase the sensitivity of this promising test. 



Patterns in the Toxicity Data. Three patterns in toxicological response to the samples 

 described above were suggested by the rank correlations among toxicity tests (Table 11) and 

 by correlations with similar chemical or physical variables (Table 12). These patterns were 

 not related to the medium tested (i.e., solid phase, elutriate, pore water), nor to the 

 biological type of end-point. Whereas the toxicity test end-points within each affinity 

 group indicated similar patterns in response, some indicated negative correlations with end- 

 points in other affinity groups. For example, the data from the M. edulis percent normal 

 development end-point and the A. abdita avoidance end-point were positively correlated 

 and, therefore, contradicted each other. Two end-points of the S. purpuratus test, 

 echinochrome content and percent normal development, also contradicted each other. 

 Despite the suggestions derived from the correlations between toxicity and chemical data, 

 the etiological agents for each test are unknown. It is possible that each end-point 

 responded to different physical or chemical properties, including those that were not 

 quantified, in the very complex sediments that were tested. Therefore, until the 

 relationships between these toxicity end-points and specific chemicals are quantified in 

 empirical experimentation, comprehensive assessments of sediment toxicity are best made 

 with multiple end-points. 



Many of the toxicity end-points measured in all samples indicated that samples 1, 2, and 

 3 from Oakland Inner Harbor were among the most toxic samples. As expected, these 

 samples were also the most contaminated since the Oakland Inner Harbor is surrounded by a 

 highly industrialized and urbanized area. However, unexpectedly, several of the end- 

 points (e.g., M. edulis and S. purpuratus abnormal development and R. abronius survival) 

 indicated that samples 13, 14, and 15 collected in Tomales Bay were among the most toxic 

 samples. These unexpected results are not easily explained. The chemical data collected 

 with the toxicity results and chemical analyses of previously collected sediments from the 

 Tomales Bay location suggest that it is not contaminated. Tomales Bay receives no major 

 industrial or municipal wastes and is mostly surrounded by pastures and forests. However, 

 benthos samples collected synoptically with the sediments tested in this evaluation were 

 dominated by relatively hardy polychaetes and molluscs and were nearly devoid of 

 relatively sensitive crustaceans, possibly corroborating the toxicity test results. The model 

 developed by DeWitt et al. (1988) for interpreting the results of measuring R. abronius 

 survival in uncontaminated fine-grained sediments does not account, alone, for the degree of 

 toxicity observed or for the multiplicity of end-points that indicated that these sediments 



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