As the field of environmental toxicology progresses, research is revealing effects on species that expand beyond the traditional endpoints of survival, growth, and reproduction as measured in single organism lab studies. Exposure to contaminants can result in adverse effects to endocrine function, olfaction, behavior, and other physiological impairments that may be exacerbated in combination with ecological stressors. Decisions regarding the management of species listed under the Endangered Species Act necessitate an examination of the best available data regarding all the effects of stressors on the conservation of those species, as well as treatment of uncertainty that is inclusive of all potential risks and is commensurate with their protected status. Analysis of potential linkages between sublethal responses of pesticides to higher-order responses in individuals and populations often requires extrapolation of incomplete data sets to provide protection to vulnerable species facing a myriad of potential threats. The adverse outcome pathway model provides a useful framework for the incorporation and use of currently available data, as well as a means to identify vital data gaps to be filled through future research and monitoring.

Eleven male walleyes (Sander vitreus) and 10 female walleyes from the Saginaw Bay (Lake Huron) population were caught during the spawning run at Dow Dam (Midland, Michigan) in the Tittabawassee River during April 1996, and individual whole-fish polychlorinated biphenyl (PCB) determinations were made. Total PCB concentrations averaged 7.95 and 3.17 mg/kg for males and females, respectively. As part of the Natural Resource Damage Assessment remediation process, contaminated sediments from the Saginaw River, the main tributary to Saginaw Bay, were removed during 2000 and 2001. Total PCB concentrations of 10 male and 10 female walleyes caught at Dow Dam during April 2007 averaged 1.58 and 0.55 mg/kg, respectively. Thus, dredging of the Saginaw River appeared to be effective in reducing PCB concentrations of Saginaw Bay adult walleyes, as both males and females decreased in PCB concentration by more than 80% between 1996 and 2007. However, the ratio of male PCB concentration to female PCB concentration did not decline between 1996 and 2007. This persistent gender difference in PCB concentrations was apparently due to a gender difference in habitat utilization coupled with a persistent spatial gradient in prey fish PCB concentrations from the Saginaw River to Lake Huron. Published by Elsevier Inc.

Knowledge of the spawning cycle and factors affecting fecundity of slimy sculpins (Cottus cognatus) are important in understanding the population dynamics of this species in large lake systems, like Lake Ontario. Fecundity and the spawning cycle of slimy sculpins were described from samples of slimy sculpins and their egg masses collected with bottom trawls during four annual surveys, April to October, 1988 to 1994. Incidence of gravid females and collections of their egg masses indicated that spawning by slimy sculpins likely occurred from late April to mid October in Lake Ontario. Protracted spawning by slimy sculpins in Lake Ontario is probably a function of the annual water temperature cycle at various depths. Mean length of gravid females was inversely related to density of slimy sculpins. Fecundity ranged from 55 to 1,157 eggs among fish 55 to 127 mm long, and for similar-sized fish, fecundity was inversely related to density of slimy sculpins. Fecundity was about 50% higher at Olcott, where population indices of slimy sculpins were low, compared with Nine Mile Point where indices were much higher. Somatic weight or total length were both good predictors of fecundity. Lipid content of slimy sculpins was lower in an area of high sculpin abundance than in an area of low sculpin abundance, suggesting that fecundity was a function of density-dependent food availability. In large aquatic ecosystems, samples from more than one area may be necessary to describe fecundity of a sedentary species like slimy sculpin, especially if fish densities vary considerably among geographic areas. Large geographic variations in fecundity may be an indicator of spatial imbalance of a species with its prey. Low fecundity may be a compensatory response of slimy sculpins to low food supplies, thereby limiting population growth.

An individual-based model (IBM) was applied to dieldrin contamination in the lake trout (Salvelinus namaycush) population of Lake Michigan in order to determine if a model structure originally developed for contamination by polychlorinated biphenyls (PCBs) in Lake Michigan lake trout would also apply to dieldrin contamination. Many different congeners constitute PCBs, whereas dieldrin is a single chemical compound. The model accurately accounted for the variation in dieldrin concentrations exhibited within the Lake Michigan lake trout population. The degree of variability included in dieldrin concentrations of the prey fish was similar to that used for modeling total PCBs. These results supported the argument that any heterogeneity in PCB congener distribution in Lake Michigan contributed relatively little to the observed variability in lake trout total PCB concentrations. Furthermore, these results indicate that the IBM has potential to be applicable to a variety of organochlorine contaminants. The IBM should prove useful for risk assessment of contaminants in fish.

The biomagnification of polychlorinated biphenyls (PCB), toxaphene, and the DDT family of metabolites was investigated in the epibenthicMysis relicta (mysid), the benthicPontoporeia hoyi (amphipod), plankton, particulate flux, surficial sediments, andMyoxocephalus thompsoni (deepwater sculpin) in southeastern Lake Michigan. DDE was the most strongly biomagnified compound, increasing 28.7 times in average concentration from plankton to fish. PCB increased 12.9 times in average concentration from plankton to fish while toxaphene increased by an average factor of 4.7. Particle flux was comprised of lower chlorinated PCB homologues (average chlorine number=3.8) than the biota (4.5-5.0) and sediments (4.6), possibly reflecting strong influences from atmospheric deposition and/or Zooplankton egestion. The percent of higher chlorinated PCB homologues (5 and 6 chlorine atoms per PCB molecule) increased from 54–56% of the total PCB in plankton andM. relicta, to 61% inP. hoyi, to 74% in sculpins. Amphipods contained greater concentrations than mysids of PCB, DDT residues, and toxaphene, possibly reflecting differences in habitat (benthic vs epibenthic) and diet (detritus vs plankton). Based on estimates of average areal biomass and contaminant concentration, offshore Lake MichiganP. hoyi populations contain approximately 15.0 times as much toxaphene, 9.5 times as much total DDT, and 12.0 times as much PCB as the offshoreM. relicta populations. Thus, amphipods may represent a greater reservoir than mysids for contaminant storage and subsequent recycling in offshore Lake Michigan.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAtmospheric transport of toxaphene to Lake MichiganClifford P. Rice, Perry J. Samson, and George E. NoguchiCite this: Environ. Sci. Technol. 1986, 20, 11, 1109–1116Publication Date (Print):November 1, 1986Publication History Published online1 May 2002Published inissue 1 November 1986https://doi.org/10.1021/es00153a005RIGHTS & PERMISSIONSArticle Views57Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts