Miguel A. Mora

Contaminants in fishes from Great Lakes-influenced sections and above dams of three Michigan rivers. II: Implications for health of mink

Populations of mink (Mustela vison) have declined in many areas of the world. Such declines have been linked to exposures to synthetic, halogenated hydrocarbons. In the Great Lakes region, mink are fewer in areas along the shore of the Great Lakes and their tributaries where mink have access to fish from the Great Lakes. Recently, there has been discussion of the relative merits of passage of fishes around hydroelectric dams on rivers in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on mink, which could consume such fishes from above or below dams on the rivers. Concentrations of organochlorine insecticides, polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachloridibenzo-p-dioxin equivalents (TCDD-EQ), and total mercury were measured in composite samples of fishes from above or below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Concentrations of organochlorine insecticides, PCBs, and TCDD-EQ were all greater in fishes from below the dams than those from above. Concentrations of neither organochlorine insecticides nor mercury in fishes are currently a risk to mink above or below the dams. All of the species of fishes collected from downstream of the dams contained concentrations of PCBs and TCDD-EQ, which represent a hazard to mink. The hazard index for PCBs was less than one for the average of all species from the upstream reaches of the Manistee and Au Sable Rivers, but not the Muskegon. The hazard index (concentration in fish/NOAEC) was greater than 1 for all of the species collected from below the dams, in all three rivers. The greatest hazard index was observed for carp (Cyprinus carpio) downstream on the Muskegon River. Because the concentrations of PCBs used in the hazard assessment were corrected for relative toxic potencies, the hazard ratios based on PCBs should be similar to those based on TCDD-EQ. This was found to be true. Thus, either total PCBs or TCDD-EQ could be used as the critical toxicant in the hazard assessment. However, if uncorrected concentrations of PCBs, expressed as Aroclors®, were used in the hazard assessment, the toxicity of the weathered mixture would have been underestimated by approximately five-fold, and, in that instance, TCDD-EQ would be the critical contaminant for the hazard assessment. The average maximum allowable percentage of fish from above the dams, which would result in no observable adverse effects of TCDD-EQ, was 70%. Based on the average TCDD-EQ concentrations in the fishes, an average of 8.6% of the diet could be made up of fishes from below dams on the rivers. The most restrictive daily allowable intakes were for carp on the Muskegon and steelhead trout (Onchorhyncus mykiss) on the Manistee Rivers. Only 2.7% of the diet could be made up of these two species from influenced portion of the Au Sable River, they would be exposed to 390 μg PCBs and 8.55 ng of TCDD-EQ per day, respectively (Giesy et al. 1994b). Thus, it would take 15.1 or 77 days for mink to receive their total annual dose of PCBs or TCDD-EQ, respectively. At least for chinook salmon, the critical contaminant for the purposes of hazard assessment would be total concentrations of PCBs. Consuming chinook salmon for as little as 2 weeks would deliver the annual allowable dose of PCBs to mink.

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (Empidonax traillii extimus) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats (Icteria virens) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2-35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest MEAN=1505 microg/g dw, n=3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers (Dendroica petechia) and song sparrows (Melospiza melodia). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell should not be ignored.

Polychlorinated biphenyls and chlorinated insecticides in plasma of Caspian terns: Relationships with age, productivity, and colony site tenacity in the great lakes

Chlorinated hydrocarbons such as polychlorinated biphenyls (PCBs) and chlorinated insecticides have often been detected in Great Lakes fish-eating birds at concentrations that are correlated with greater than expected embryo mortality and reduced reproductive success. Blood from 111 known-age, adult Caspian terns (Sterna caspia) nesting in several regions of the upper Great Lakes was collected in 1990 to examine bioavailability of PCBs, to compare concentrations of PCBs among nesting locations, and to determine relationships between concentrations of PCBs and age, productivity, and colony site tenacity. PCBs, DDE, dieldrin, and trans-nonachlor were detected in all the samples. Concentrations of PCBs were, on average, 10, 100, and 250 times greater than those of DDE, dieldrin, and trans-nonachlor, respectively. Concentrations of PCBs were not correlated with age, and were greater in Caspian terns from Saginaw and Green Bays than in Caspian terns from the North Channel and Georgian Bay. Concentrations of PCBs and DDE were significantly correlated with one-another and their accumulation patterns were the most similar among all the chemicals studied. Patterns of organochlorines as determined by cluster analysis were most similar for the nearest nesting locations. The bioaccumulation of PCBs in Great Lakes Caspian terns appeared to be seasonal and did not vary with adult age. A significant negative correlation was observed between mean concentrations of PCBs by region and percent terns returning to natal region. Those populations which were likely to be affected by PCBs were those nesting in Green Bay and Saginaw Bay.

Contaminants in fishes from great lakes-influenced sections and above dams of three Michigan Rivers. I: Concentrations of organo chlorine insecticides, polychlorinated biphenyls, dioxin equivalents, and mercury

Fishes of the Great Lakes contain hazardous chemicals such as synthetic halogenated hydrocarbons and metals. These fish can move from the lakes into the Great Lakes tributaries of Michigan. In doing so, they transport concentrationsof contaminants which may represent a risk to wildlife. Concentrations of mercury (Hg), total polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQ), total DDT complex, aldrin, endrin, dieldrin, heptachlor, heptachlor epoxide, lindane, hexachlorobenzene, cis-chlordane, oxychlordane, endosulfan-I, methoxychlor, trans-chlordane, and trans-nonachlor were determined in composite samples of fishes from above and below Michigan hydroelectric dams, which separate the fishes which have access to the Great Lakes from fishes that do not. Mean concentrations of total PCBs, TCDD-EQ, DDT, and most of the other pesticides were greater in composite samples of six species of fishes from below than above the dams on the Au Sable, Manistee, and Muskegon Rivers. Concentrations of mercury, were the same or greater above the dams than below. However, this difference was statistically significant only on the Au Sable. Mercury concentrations ranged from less than 0.05 mg/kg to 0.73 mg Hg/kg, ww. Total concentrations of PCBs ranged from 0.02 to 1.7 mg/kg, ww. Concentrations of 2,3,7,8-tetrachlordibenzo-p-dioxin equivalents varied among fishes and locations. The concentrations of TCDD-EQ ranged from 2.4 to 71 μg/kg, ww, with concentrations in carp being the greatest. Concentrations of TCDD-EQ were greater than the concentrations which would be expected to occur, due solely to the presence of polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and technical mixtures of PCBs.

Organochlorines and trace elements in four colonial waterbird species nesting in the lower Laguna Madre, Texas.

Eggs from four aquatic bird species nesting on the National Audubon Sanctuary Islands of the lower Laguna Madre were collected during 1993 and 1994 to determine concentrations of organochlorine compounds and trace metals and to evaluate their possible detrimental effects on birds nesting in this aquatic ecosystem. The only chlorinated hydrocarbons found above detection limits were p,p′-DDE (DDE), p,p′-DDT (DDT), HCB, HCH, chlordane, and polychlorinated biphenyls (PCBs). Median DDE and PCB levels in eggs of four species were below 1 μg/g ww. Concentrations of DDE were much greater (6–70 fold) than the concentrations of other chlorinated pesticides which were present at or near detection limits. One egg from a snowy egret contained 9.65 μg/g DDE, 0.056 μg/g DDD, and 1.75 μg/g DDT. Ten heavy metals and trace elements (Hg, Se, B, Cr, Cu, Fe, Mg, Mn, Sr, and Zn) were detected in 90% of the samples but at levels that were not of concern. In 1993–1994, concentrations of DDE in eggs of aquatic birds of the lower Laguna Madre were much lower than levels detected in this area during the late 1970s and early 1980s. Concentrations of DDE, PCBs, and trace metals in eggs detected in this study could not be associated with deformities or other detrimental effects on birds.

Seasonal and geographical variation of organochlorine residues in birds from northwest Mexico.

Eight species of birds (129 individuals) were collected from three agricultural areas with long histories of pesticide use in northwestern Mexico. Plucked carcasses were analyzed for organochlorine (OC) pesticides and polychlorobiphenyls (PCBs). DDE was found in all of the samples and at higher levels than other OCs. Mean (geometric) DDE concentrations varied from 0.04 (μg/g) ppm in mourning doves (Zenaida macroura) to 5.05 ppm in double-crested cormorants (Phalacrocorax auritus). Hexachlorocyclohexane (HCH) was detected in 95% of the samples, but at lower levels than DDE. Hexachlorobenzene (HCB) residues were detected more frequently in birds from Mexicali (62%, p < 0.05) than in those from Yaqui and Culiacan. HCH and HCB concentrations were significantly higher in birds from Mexicali during the winter than in the summer (p < 0.05), indicating accumulation of these compounds during that period. Other OCs such as DDT, DDD, dieldrin, oxychlordane, heptachlor epoxide, endosulfan, and endrin were found at lower levels and less frequently. PCBs (quantitated as Aroclor® 1260) were found mostly in cattle egrets (Bubulcus ibis) and cormorants at the three locations. Overall, concentrations of OCs were higher for Mexicali than for Yaqui and Culiacan (p < 0.01). In a few cases, DDE levels were above those that might adversely affect birds.

Selenium, boron, and heavy metals in birds from the Mexicali Valley, Baja California, Mexico.

Trace elements in irrigation drainwater in some areas of the southwestern United States have been detected at concentrations that are associated with reproductive, teratogenic and behavioral anomalies in birds. For example, increased bird mortalities were linked with high concentrations of selenium (Se) at the Kesterson Reservoir in California (Ohlendorf et aL 1986a). Agricultural ecosystems in northwestern Mexico resemble closely those of central and southern California because they are also intensively irrigated and there is concern that elevated concentrations of trace elements in these areas could also result in detrimental effects on resident and migratory birds and other wildlife. The Mexicali Valley is located in northeastern Baja California, south of the Imperial Valley in California. Approximately 70% of the cultivated land in Mexicali (182,000 hectares) is irrigated by gravity flow with water from the Colorado River (Secretaria de Agricultura y Recursos Hidraulicos 1984), and elevated concentrations of trace elements in agricultural drainwaters might be expected. Runoff is discharged directly to canals and to the Hardy River. The Hardy River also receives brine waste with potentially high concentrations of arsenic (As) and boron (B) from a geothermal energy plant located at Cerro Prieto in the middle of the agricultural valley, approximately 30 km south of the city of Mexicali (Comisi6n Federal de Electricidad 1987). There are no studies that evaluate the environmental hazards and concentrations of trace elements in wildlife of the Mexicali Valley, except for some data on fish and clams. Concentrations of mercury (Hg) in fish and clams from irrigation canals and drainages of the Mexicali Valley were measured to evaluate the extent of Hg contamination by the Cerro

Environmental contaminants in prey and tissues of the peregrine falcon in the Big Bend Region, Texas, USA

Peregrine falcons (Falco peregrinus) have been recorded nesting in Big Bend National Park, Texas, USA and other areas of the Chihuahuan Desert since the early 1900s. From 1993 to 1996, peregrine falcon productivity rates were very low and coincided with periods of low rainfall. However, low productivity also was suspected to be caused by environmental contaminants. To evaluate potential impacts of contaminants on peregrine falcon populations, likely avian and bat prey species were collected during 1994 and 1997 breeding seasons in selected regions of western Texas, primarily in Big Bend National Park. Tissues of three peregrine falcons found injured or dead and feathers of one live fledgling also were analyzed. Overall, mean concentrations of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], a metabolite of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], were low in all prey species except for northern rough-winged swallows (Stelgidopteryx serripennis, mean = 5.1 microg/g ww). Concentrations of mercury and selenium were elevated in some species, up to 2.5 microg/g dw, and 15 microg/g dw, respectively, which upon consumption could seriously affect reproduction of top predators. DDE levels near 5 microg/g ww were detected in carcass of one peregrine falcon found dead but the cause of death was unknown. Mercury, selenium, and DDE to some extent, may be contributing to low reproductive rates of peregrine falcons in the Big Bend region.

A comparative assessment of contaminants in fish from four resacas of the Texas, USA–Tamaulipas, Mexico border region

A recent survey of contaminant information for the Lower Rio Grande Valley (LRGV), Texas, has shown that little is known about contaminants and their impacts on biota of resacas (oxbows) along the US-Mexico border. In 1996, fish were collected from four resacas in the Texas-Tamaulipas border region to assess contaminant loadings and their impacts on fish and birds. Tissue residue concentrations in fish were analyzed and also compared to two histopathological bioindicators of unhealthy environmental conditions. Of the organochlorine insecticides measured, DDE was the most common and was present at relatively high concentrations (10 microg/g w/w) at some sites. DDE concentrations were nearly 20 times greater in fish from resacas in Texas than from resacas in Tamaulipas, although the limited sample sizes obtained precluded statistical comparisons. DDE concentrations in fish from the two Texas resacas were also greater than those reported in fish from nearby areas during the 1980s and 1990s. Most trace element concentrations were similar among resacas from Texas and Tamaulipas. Arsenic, however, was two to six times greater in fish from a downtown resaca in Matamoros than in fish from other resacas in Tamaulipas and Texas. The bioindicators, pigment accumulation, and macrophage aggregates (MAs), in general, reflected the contamination indicated by the tissue residues for each site. Overall, it appears that some resacas of the US-Mexico border region are contaminant sinks and could pose potential health or reproductive problems for fish and wildlife, and humans that consume fish from those sites.

Concentrations of Dissolved and Particulate Polychlorinated Biphenyls in Water from the Saginaw River, Michigan

The Saginaw River receives water from a major drainage basin in the east-central portion of the lower peninsula of Michigan. Historically the river has been contaminated with polychlorinated biphenyls (PCBs) from several sources. The present study was conducted to determine the concentrations of PCBs in both the dissolved and particulate phases of water in the lower Saginaw River, as well as the relative contribution of PCBs from the lower portion of the river relative to more upstream locations. Water samples were collected in 1990–1991, during a range of discharge conditions. Suspended particulates were collected from water onto glass-fiber filters by use of a “Penta-plate” filtration apparatus. Filtered water was subsequently passed through XAD-2 macroreticular resin to collect the “dissolved” PCBs. Concentrations of PCBs in both phases were determined by congener specific gas chromatography with electron capture detection. Total concentrations of PCBs ranged from 11 to 31 ng/L. The concentrations of PCBs in the dissolved phase ranged from 1.9 to 16 ng/L. The ratio of total PCBs bound to suspended particulates, relative to dissolved PCBs, was 2:1 and remained fairly constant for discharges less than approximately 400 M3/sec. The loading of total PCBs to Saginaw Bay was estimated to be 225 kg/yr, of which approximately 60% was found to be contributed by the lower 8 km of the Saginaw River.