D. Michael Whittle

Biomagnification of α- and γ-Hexabromocyclododecane Isomers in a Lake Ontario Food Web

The extent of bioaccumulation of hexabromocyclododecane (HBCD) isomers (α, β, and γ) was determined in the Lake Ontario pelagic food web using liquid chromatography tandem mass spectrometry (LC/MS/MS). Concentrations of the α-isomer were consistently higher than that of the γ-isomer. The β-isomer was below method detection limits in all samples. Whole body concentrations (ng/g, wet wt) of α- and γ-HBCD were highest in the top predator lake trout samples ranging from 0.4 to 3.8 ng/g for the α-isomer and 0.1 to 0.8 ng/g for the γ-isomer. For the prey fish species, the trends in α- and γ-HBCD levels were slimy sculpin > smelt > alewife. Mean concentrations of total (Σ) HBCD (sum of α- and γ-isomers) in the macrozooplankter Mysis relicta (0.14 ± 0.02 ng/g wet wt) and in the benthic invertebrate Diporeia hoyi (0.16 ± 0.02 ng/g, wet wt) were similar and approximately twice as high as in plankton (0.06 ± 0.02 ng/g, wet wt). A strong positive linear relationship was found between ΣHBCD concentrations (wet wt) and...

Brominated and chlorinated flame retardants in Lake Ontario, Canada, lake trout (Salvelinus namaycush) between 1979 and 2004 and possible influences of food-web changes.

Concentrations of non-polybrominated diphenyl ether (PBDE) brominated (hexabromocyclododecane [HBCD], 1,2-bis[2,4,6-tribromophenoxy]ethane [BTBPE], and pentabromoethylbenzene [PEB]) and chlorinated (Dechlorane Plus [DP] as well as short- and medium-chain chlorinated paraffins [SCCP and MCCP, respectively]) flame retardants were evaluated in archived Lake Ontario, Canada, lake trout (Salvelinus namaycush) samples collected between 1979 and 2004. Polybrominated diphenyl ethers also were analyzed to provide a point of reference for comparison to previous studies. Concentrations of the dominant PBDE congeners (BDEs 28, 47, 99, 100, 153, and 154) increased significantly from 1979 until the mid-1990s, then either leveled off or decreased significantly between 1998 and 2004, a result that corresponds to those of previous studies. In contrast, BDE 209 increased approximately fourfold between 1998 and 2004. The temporal trends of the non-PBDE flame retardants varied, with sum (sigma) HBCD and DP showing significant overall decreases; BTBPE, sigmaSCCP, and sigmaMCCP showing parabolic trends; and PEB showing no overall change during the study period. Because many of the non-PBDE chemicals may be used as replacements for penta- and octa-BDE mixtures, these results will provide a baseline to evaluate future usage patterns. Possible changes in food-web structure, evaluated through stable nitrogen isotopes (delta15N), may be influencing our interpretations of contaminant trends in lake trout and are hypothesized to be partially responsible for the observed decrease in concentrations of BDEs 28, 47, 99, 100, 153, and 154 between 1998 and 2004. Retrospective analyses evaluating temporal trends in stable isotope values at the base of the food web, however, are recommended to test this hypothesis further.

Temporal and Age-Related Trends in Levels of Polychlorinated Biphenyl Congeners and Organochlorine Contaminants in Lake Ontario Lake Trout (Salvelinus namaycush)

Abstract Concentrations of 21 organochlorine contaminants (OCs) and 61 polychlorinated biphenyl (PCB) congeners were determined in archived samples of whole lake trout ( Salvelinus namaycush ), age 4 years, collected yearly from eastern Lake Ontario between 1977 and 1993. Temporal trend data show decreases in all parameters analyzed in samples collected from 1977 to 1993. OC levels declined between 60 and 90% from 1977 to 1993. Trends of total PCB and PCB congeners concentrations were variable, but overall levels declined 80% between 1977 and 1993, from 9,060 ng/g in 1,977 to 1,720 ng/g in 1993. Reanalyzed total PCB levels vary randomly from the historical total PCB levels, but overall exhibit a much smoother trend. The means of the two sample sets were not significantly different at a probability of 0.05. Lake trout aged from 3 to 9 years old, collected in 1988, were analyzed to determine changes in contaminant concentrations with age. OC levels on average increased three-fold from 3-year-old lake trout up to 9-year-old lake trout. Total PCB levels increased from 2,760 ng/g in 3-year-old lake trout to 8,000 ng/g in 9-year-old lake trout, and PCB congener concentrations showed similar increases over the same age range. Lipid content declined 30% between 1977 and 1993, but lipid normalizing the data did not change the observed trends.

Bioaccumulation of Toxaphene Congeners in the Lake Superior Food Web

The bioaccumulation and biotransformation of toxaphene was examined in the food webs of Lake Superior and Siskiwit Lake (Isle Royale) using congener specific analysis as well as stable isotope ratios of carbon and nitrogen to characterize food webs. Toxaphene concentrations (calculated using technical toxaphene) in lake trout (Salvelinus namaycush) from the western basin of Lake Superior (N = 95) averaged (±SD) 889 ± 896 ng/g wet wt and 60 ± 34 ng/g wet wt in Siskiwit Lake. Major congeners in lake trout were B8-789 (P38), B8-2226 (P44), B9-1679 (P50), and B9-1025 (P62). Toxaphene concentrations were found to vary seasonally, especially in lower food web organisms in Lake Superior and to a lesser extent in Siskiwit Lake. Toxaphene concentrations declined significantly in lake herring (Coregonus artedii), rainbow smelt (Omerus mordax), and slimy sculpin (Cottus cognatus) as well as in zooplankton (> 102 μm) and Mysis (Mysis relicta) between May and October. The seasonal variation may reflect seasonal shifts in the species abundance within the zooplankton community. Trophic magnification factors (TMF) derived from regressions of toxaphene congener concentrations versus δ15N were > 1 for most octa- and nonachlorobornanes in Lake Superior except B8-1413 (P26) and B9-715. Log bioaccumulation factors (BAFs) for toxaphene congeners in lake trout (ng/g lipid/ng/L dissolved) ranged from 4.54 to 9.7 and were significantly correlated with log octanol-water partition coefficients. TMFs observed for total toxaphene and congener B9-1679 in Lake Superior were similar to those in Arctic lakes, as well as to previous studies in the Great Lakes, which suggests that the bioaccumulation behavior of toxaphene is similar in pelagic food webs of large, cold water systems. However, toxaphene concentrations were lower in lake trout from Siskiwit Lake and lakes in northwestern Ontario than in Lake Superior possibly because of shorter food chains and greater reliance on zooplankton or other pelagic invertebrates.

Effects of maternally transferred organochlorine contaminants on early life survival in a freshwater fish

Laboratory research has shown that female fish can pass toxic organochlorines (OCs) from their bodies to their eggs, killing their offspring if sufficient quantities are transferred. We conducted a controlled incubation study using gametes from a wild, OC-contaminated walleye (Sander vitreus) population (Bay of Quinte, Lake Ontario, Canada) in order to assess among-female variation in offspring early life survival in relation to ova concentrations of planar OCs (polychlorinated dibenzo-p-dioxins and furans and planar polychlorinated biphenyls) and a suite of other maternal and ova characteristics. Equal volumes of ova from each female were fertilized, pooled, and incubated together as an experimental cohort. Relative survival of each females offspring was estimated as the proportion of surviving larvae (at approximately 5 d posthatch) that she contributed to the cohort as determined by microsatellite DNA parentage assignment. Total planar OC concentration (expressed as toxic equivalency of 2,3,7,8-tetrachlorodibenzo-p-dioxin) of ova was positively related to maternal age and size and to ova lipid content. However, early life survival did not decline with increasing ova planar OC concentrations. Similarly, we observed no significant relationships between early life survival and ova thiamine content, ova fatty acid composition, or maternal age or size. Early life survival was more strongly correlated with date of spawn collection, thyroid hormone status of the ova, and ovum size. Maternally transferred planar OCs do not appear to negatively influence female reproductive success in this walleye population.

Spatial Distribution of Mercury and Organochlorine Contaminants in Great Lakes Sea Lamprey (Petromyzon marinus)

Adult sea lamprey (Petromyzon marinus) were collected during their spawning migration in streams entering each of the Great Lakes, except Lake Michigan. Skinless muscle tissue samples were analyzed for a range of organochlorine contaminants including p,p’-DDE, total PCB, toxaphene, and mercury. Concentrations of p,p’-DDE and PCBs were above the detection limit of 0.002 μg/g in all samples. Levels of total toxaphene in some individuals from Lake Superior were above recent Health Canada consumption advisory limits of 0.2 μg/g for fish. PCBs and ΣDDT concentrations in some lamprey tissue samples from the Lake Ontario basin exceeded limits for unrestricted human consumption. Mercury concentrations were highest in lamprey from the Lake Superior basin. Mercury levels were above the 0.5 μg/g Canada Health Protection Guideline for consumption in 75% of all the lamprey muscle tissue samples analyzed. Comparison of organic contaminant levels for lamprey muscle tissue samples and whole lake trout (Salvelinus namaycush) collected from the same lakes showed patterns of contaminant accumulation that were similar within each lake for both species. Mercury concentrations were up to 10 times higher in lamprey muscle tissue samples than whole lake trout sampled from the same lake. Lamprey display a differential ability to accumulate mercury versus organochlorines. By understanding these relationships for different classes of contaminants, it may be possible to utilize lamprey as a future alternate to lake trout as an indicator species to track spatial and temporal contaminant trends in the Great Lakes.

Use of a simulation model to reconstruct PCB concentrations in prey of Lake Ontario Lake Trout.

Although the alewife (Alosa pseudoharengus) has been the principal prey fish of adult lake trout (Salvelinus namaycush) in Lake Ontario, a lakewide survey of PCB concentration in Lake Ontario alewife was not attempted until 1986. We applied an individual-based model to the 1986 population of Lake Ontario lake trout to (a) estimate the PCB concentration in alewife prior to 1986 and (b) determine the amount of variability in PCB concentrations of lake trout prey. Modeling results indicated that the PCB concentration in adult alewife during 1979-1985 was on the average almost four times greater than the adult alewife PCB concentration observed in 1986. This result suggested that PCB concentration in lake trout prey may fluctuate widely from year to year, perhaps in response to changes in age structure and growth of prey fishes. Secondly, modeling results suggested that spatial variability in the PCB concentrations of lake trout prey was probably greater in Lake Ontario than in Lake Michigan.