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Biomedical subjects

S E Belanger

Publications and source records attributed to S E Belanger.

7 recordsLinked to original sources
PubMed1999

The effect of the oil dispersant Omni-Clean on the toxicity of fuel oil no. 2 in two bioassays with the sheepshead minnow Cyprinodon variegatus.

Bioassays (7-day early life stage and 96 h acute bioassays) were conducted with the sheepshead minnow, Cyprinodon variegatus, to determine the toxicity of the dispersant Omni-Clean by itself and in combination with fuel oil no. 2. Performance characteristics of both bioassay types were also compared. Bioassays used oil by itself, dispersant by itself, and oil and dispersant in various ratios. Omni-Clean was less toxic than many other dispersants, and had a relatively small effect on individual biomass. Toxicities of the oil/dispersant combinations were generally higher than expected from the toxicities of the oil and dispersant by themselves, indicating a more-than-additive effect on toxicity. The comparison of performance characteristics between the 7-day and the 96-hour bioassays showed that the early life stage test is generally more sensitive, and has the added advantage of an additional and sensitive endpoint (fish biomass).

Animals↗
PubMed1997

Literature review and analysis of biological complexity in model stream ecosystems: influence of size and experimental design.

A meta-analysis of more than 150 model stream ecosystem studies employed in hazard assessment was conducted to assess the effect of model ecosystem size on biological complexity and experimental design. Test system length was highly correlated to duration of colonization and chemical exposure period; however, size was generally unrelated to taxa richness, diversity, abundance, or biomass for algal, protozoan, and invertebrate assemblages. Fish were usually caged and not free-roaming, even in the relatively large (> 10 m) systems. Experimental designs, especially in recent years, have been less concerned with pseudoreplication, resulting in studies emphasizing numerous treatments with few or no replicates. Test systems have evolved that emphasize flow through exposures, use of natural source waters, and regression-style experimental designs. These factors collectively reduce problems historically associated with pseudoreplication. Larger model ecosystems (> 6 m) are advantageous for increasing the ability to sample more intensively through time and space without imposing sampling artifacts. Fish (caged and free-roaming) are also more often used in larger systems. Several model ecosystem studies that were compared with natural field-based communities demonstrated a high degree of correspondence for biological complexity attributes. Well-designed model stream ecosystems have a high degree of biological complexity and reasonable levels of variability for ecologically relevant endpoints. The use of small application factors (approximately equal to 1) is applicable to ecotoxicological results from these studies for risk assessment.

Animals↗
PubMed1997

Stream periphytic biodegradation of the anionic surfactant C12-alkyl sulfate at environmentally relevant concentrations.

The effects of continuous exposure to C12-alkyl sulfate on a periphytic microbial community were determined in an 8-week stream mesocosm study. C12-alkyl sulfate concentrations ranged from environmentally relevant (< 10-20 micrograms/liter) to unrealistically high concentrations (> 1500 micrograms/liter). Endpoints evaluated included turnover rates, bacterial cell density, heterotrophic mixed amino acid uptake, and fatty acid profile evaluations. Predosed periphyton demonstrated a mean turnover rate for C12-alkyl sulfate of 0.08/hr. During the 8-week dosing period, a significant increase in mean turnover rates was observed in streams dosed with > or = 61 micrograms C12-alkyl sulfate/liter, despite a 10 degrees C drop in stream temperature. A significant correlation between turnover rate and C12-alkyl sulfate concentration was also observed. While bacterial cell density increased during the study, it was determined that the biodegradation acclimation to C12-alkyl sulfate was not biomass-specific. Likewise, bacterial activity generally increased over the study, but it did not correlate with either biodegradation or bacterial cell density. Lastly, phospholipid fatty acid profiles indicate that a shift in the microbial community occurred in the high-dose stream as opposed to the control stream. This study demonstrates that C12-alkyl sulfate is rapidly degraded and induces a biodegradative acclimation response at environmentally relevant concentrations.

Amino Acids↗
PubMed1997

Seasonal temperature declines do not decrease periphytic surfactant biodegradation or increase algal species sensitivity.

The effects of seasonally decreasing river water temperature on surfactant biodegradation and algal sensitivity are reviewed from four stream mesocosm studies conducted over a 5-year period. Seasonal temperatures ranged from 28 to 0 degree C over all studies and temperature declines were approximately 9 to 14 degrees C over the course of each individual study. Mesocosm periphyton were naturally colonized on tile substrata with in-flowing river water for a period of 3 to 8 weeks prior to the initiation of sampling. Streams were dosed for 8 to 11 weeks with microgram/L (ppb) quantities of the surfactants C12-alkyl sulfate (C12-AS), C45E2.17S-alkyl ethoxysulfate (AES), C25E6-alkyl ethoxylate (AE) or 0 to 13% final effluent during the sampling period. Mineralization of C12-AS and AE by periphyton in the dosed streams generally increased over the dosing period while mineralization remained approximately constant in the control streams. The results from the AE study occurred with an increase in periphyton heterotrophic respiration. Mineralization of AES increased over the dosing period in streams receiving the highest dose of AES and remained constant in streams receiving lower doses. All studies involving surfactant exposure demonstrated a positive correlation between surfactant concentration and mineralization during periods of seasonal temperature decline. Mineralization of AE by periphyton dosed with final effluent increased slightly over the testing period. Periphytic algal taxonomy and biovolume were evaluated during the AES study. Overall, these tests showed no increases in species sensitivity over the testing period. Taken collectively, these results indicate that there is no correlation between naturally decreasing seasonal temperatures and lower rates of surfactant mineralization or increased species sensitivity by naturally acclimated periphyton.

Biodegradation, Environmental↗
PubMed1986

Effects of chrysotile asbestos on coho salmon and green sunfish: evidence of behavioral and pathological stress.

The effects of chrysotile asbestos on larval coho salmon (Oncorhynchus kisutch) and juvenile green sunfish (Lepomis cyanellus) were investigated at levels approximating those reported in the Great Lakes basin (10(6) fibers/liter). Behavioral stress effects, such as loss of rheotaxic position and balance, were observed in salmon exposed at 3.0 X 10(6) fibers/liter and in sunfish exposed at 1.5 and 3.0 X 10(6) fibers/liter. Coho larvae at 1.5 X 10(6) fibers/liter were significantly more susceptible to an anesthetic stress test, becoming ataxic and losing equilibrium faster than control cohorts (P less than 0.001). Two of 106 larvae exposed at 3.0 X 10(6) fibers/liter developed tumorous swellings and three additional fish developed coelomic distentions. Cytological examination of ventral epidermal tissue revealed cellular histolysis, and evidence by transmission electron microscopy confirmed the presence of asbestos in the salmon larvae. Distortion of the lateral line region in asbestos-treated coho salmon was linked to behavioral and orientational aberrations. Differential mortality was not observed between control and treated groups of either test species.

Animals↗
PubMedDate not supplied

Ecotoxicological testing: small is reliable.

The focus of environmental regulations has changed significantly since the introduction of the bioassay as a standard means of assessing environmental impact. Prominent in this change is an increasing emphasis on protecting the integrity of natural ecosystems, which incorporate community- and system-level properties as well as organismal and population processes. Consequently, support for the use of multispecies testing has widened to include not only ecologists in academia but environmental scientists in the regulatory and industrial sector as well. The reason for this trend is clear: the additional environmental realism gained from tests utilizing communities of organisms allows for greater insight into the potential hazard of chemicals and other forms of human activity to natural ecosystems that cannot be obtained from single species tests alone. Many of the problems cited for multispecies testing early in their evolution as a hazard assessment tool have been refuted or overcome. In particular, the use of natural microbial communities minimizes several shortcomings typically associated with multispecies toxicity testing. This article includes the utility of microcosm and mesocosm tests using aquatic microbial communities as hazard assessment tools in conjunction with accumulating information on their performance in toxicity testing protocols. An increasing body of experimental evidence supports an expansion in the use of these tests for a variety of regulatory and research purposes. A shift in research focus is needed, however, to answer remaining questions and further refine standard protocols for these valuable ecotoxicological tools.

Biological Assay↗