Proceedings - Teaching and Learning Centre - Simon Fraser ...

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Fraser River Action Plan 3rd Research Workshop Short exposure durations were used because of the episodic nature of storm run off. All experiments used either dechlorinated Vancouver tap water or sea water from Burrard Inlet. Water temperatures were 8-12 o C for fish studies and 18-22 o C for invertebrate studies. Results The toxicity database collected to date for DDAC and IPBC are summarized in Tables 1, 2 and 3. 1. For DDAC (Table 1), the most sensitive fish species (and life stage) tested so far has been the juvenile white sturgeon (24-h LC50 was between 1 and 10 ppb for fry). 2. For DDAC, the most sensitive invertebrate species (and life stage) tested so far has been Mysidopsis bahia (48-h LC50 = 106 ppb). 3. The fish and invertebrate species that were selected as most relevant to the lower Fraser River (i.e., starry flounder and Neomysis mercedis), were the species tested that were least sensitive to DDAC. The 96-h LC50 value for juvenile starry flounder was four times higher than that for juvenile rainbow trout and around 1,000 times higher than that for juvenile white sturgeon. The 48-h LC50 value for Neomysis mercedis was 10 times higher than that for Mysidopsis bahia. 4. Non-lethal tests with juvenile rainbow trout and starry flounder revealed no major sublethal physiological effects to DDAC at concentrations 50% less than the LC50 concentration (Table 3). A 21day life cycle test with Dapnia magna resulted in a NOEC of 37 ppb, which was also around half of the 48-h LC50 value. We suspect that the toxicity curve for DDAC is fairly steep and results in a thresholdtype lethality within an order of magnitude of the LC50 value. 5. Coho embryos were less sensitive to both DDAC and IPBC than the emergent alevins and fry (Tables 1 and 2). 6. The fish species and life stages tested so far appeared to be more sensitive to IPBC than to DDAC. The LC50 values were generally two or three times lower with IPBC. An exception to this was the coho embryos which were more sensitive to DDAC. 7. The invertebrate species tested so far appeared to be more resistant to IPBC than to DDAC. The LC50 values were generally two or three times higher with IPBC. 8. To date, the information we collected have been qualitatively consistent with existing data (e.g., the relative toxicity of vertebrates vs. invertebrates to the two chemicals). 9. Quantitatively, we found differences in some of the LC50 values we derived. With the important exception of the data on juvenile sturgeon, most of our LC50 values have been within an order of magnitude of those reported in the BC MOELP documents on DDAC and IPBC. 10. Unless there are synergistic actions of IPBC and DDAC, we predict that IPBC will not have a major influence on the overall toxicity of certain anti-sapstain mixtures even though test fish species were more sensitive to IPBC, because IPBC is a small fraction of anti-sapstain mixtures compared with DDAC, and because IPBC appears to have a different mechanism of toxic action to DDAC. Conclusions Data collection has not been completed and so recommendations are tentative at this stage. 1. We have concerns about the use of starry flounder and Neomysis mercedis as relevant test species for the lower Fraser River ecosystem. Likely, they are not the most sensitive components of the vertebrate and invertebrate communities. In addition, we had initial difficulties obtaining and rearing Neomysis, and the collection sites may have pre-exposed the animals to the test chemicals. 2. The effects of salinity on the toxicity of DDAC were small, but we still need information on the possible role of the Fraser River sediments in modulating the toxicity of anti-sapstain chemicals. Page 116
Fraser River Action Plan 3rd Research Workshop 3. The relevance of testing with larval sturgeon vs. other larval species needs to be established. It is not known whether or not juvenile sturgeon are exposed to these toxicants. Furthermore, we do not know if the sensitivity of the larval white sturgeon is similar to other species with a short (around one week) egg developmental stage. There are certainly substantial differences compared with coho salmon which have a much longer (more than four weeks) egg development stage. 4. Even with the above concerns and uncertainties, we suspect that the present regulatory level for DDAC will not protect sensitive invertebrate and fish species from the lethal effects of DDAC if stormwater concentrations approach 700 ppb. Our data are consistent with the idea that short-term (24- to 96-h) exposures to 700 ppb DDAC would result in a significant damage zone. Predictions on the extent of the damage zone will need information on the temporal and spatial characteristics of relevant stormwater discharge and dilution. Page 117
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PROCEEDINGS 3rd RESEARCH WORKSHOP F
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TABLE OF CONTENTS Participants ....
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Development of a Citizen’s Monito
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Fraser River Action Plan 3rd Resear
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SESSION 1 PULP MILL EFFLUENT ISSUES
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SESSION 5 BIOLOGICAL INDICATORS
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SESSION 6 ESTUARY ISSUES
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Fraser River Action Plan The Use of
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Fraser River Action Plan Concluding
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