Biomonitoring of environmental status and trends (BEST) program: environmental contaminants, health indicators, and reproductive biomarkers in fish from the Mobile, Apalachicola-Chattahoochee-Flint, Savannah, and Pee Dee River basins
Hinck, J.E., V.S. Blazer, N.D. Denslow, K.R. Echols, R.W. Gale, T.W. May, R. Claunch, C.Wieser, P.J. Anderson, J.J. Coyle, T.S. Gross, and D.E. Tillitt
Largemouth bass (Micropterus salmoides) and common carp (Cyprinus carpio) were collected from 13 sites in 4 river basins in the southeastern United States to document spatial trends in accumulative contaminants, health indicators, and reproductive biomarkers. Organochlorine residues, 2,3,7,8- tetrachlorodibenzo-p-dioxin-like activity (TCDD-EQ), and elemental contaminants were measured in composite samples of whole fish, grouped by species and gender, from each site. Fish were field-examined for external and internal anomalies, selected organs were weighed to compute somatic indices, and tissue and fluid samples were preserved for fish health and reproductive biomarker analyses.
Mercury concentrations in bass samples from all sites exceeded toxicity thresholds for mammals [>0.1 micrograms per gram wet weight (μg/g ww)], fish (>0.2 μg/g ww), and birds (>0.3 μg/g ww) and were greatest (>0.5 μg/g ww) in samples from the Alabama River at Eureka Landing, Alabama; the Mobile River at Bucks, Alabama; the Apalachicola River at Blountstown, Florida; the Savannah River at Sylvania, Georgia; and the Pee Dee River at Bucksport, South Carolina. Selenium concentrations were relatively high (>0.75 μg/g ww) in fish from the Tombigbee River at Lavaca, Alabama; the Mobile River at Bucks; and the Chattahoochee River at Omaha, Georgia compared to those from other sites. Concentrations of 2,2-bis (p-chlorophenyl)- 1,1-dichloroethylene (p,p’-DDE) were high in fish from the Chattahoochee River at Omaha and the Mobile River near Bucks, which was near a 2,2-bis (p-chlorophenyl)-1,1- dichloroethylene (DDT) formulating facility that historically discharged into the lower Mobile River.
Toxaphene concentrations in fish from the Flint River near Albany, Georgia (60-100 nanograms per gram (ng/g) ww) may pose a risk to fish. Concentrations of other formerly used (total chlordanes, dieldrin, endrin, aldrin, mirex, and hexachlorobenzene) and currently used (pentachlorobenzene, pentachloroanisole, dacthal, endosulfan, γ-HCH, and methoxychlor) organochlorine residues generally were low or did not exceed toxicity thresholds. Total polychlorinated biphenyls concentrations in samples from the Coosa River at Childersburg, Alabama; the Apalachicola River at Omaha; the Apalachicola River at Blountstown; and the Pee Dee River at Bucksport were >480 ng/g ww and may be a risk to piscivorous wildlife. Dioxin-like activity as measured by TCDD-EQ was greatest [>10 picograms per gram (pg/g)] in male fish from the Coosa River at Childersburg and the Mobile River at Bucks. Hepatic ethoxyresorufin O-deethylase activity generally was greatest in carp from the Mobile River Basin [means >10 picomols per minute per milligram of protein (pmol/min/mg)] and in bass from the Tombigbee River at Lavaca and Pee Dee River at Pee Dee, South Carolina (means >65 pmol/min/mg). Altered biomarkers were noted in fish from all basins.
The field necropsy and histopathological examination determined that fish from the Mobile River Basin generally were in poorer health than those from the other basins. In bass, health assessment index scores were correlated with mercury and p,p’-DDE concentrations. High health assessment index scores in Mobile River Basin fish were widespread and caused primarily by parasitic infestations, which were most severe in fish from the Tombigbee River at Lavaca and the Alabama River at Eureka Landing. Tumors were present in few fish (n = 5; 0.01%). Ovarian tumors of the same origin (smooth muscle) were present in two older carp from the Chattahoochee River near Omaha, Georgia and may be contaminant related. Reproductive biomarkers including gonadosomatic index, vitellogenin concentrations, and steroid hormone concentrations were anomalous in fish from various sites but were not consistently related to any particular chemical contaminant. Intersex gonads were identified in 47 male bass (42%) representing 12 sites and may indicate exposure to endocrine disrupting compounds. The incidence of intersex male bass was greatest in the Pee Dee River Basin and least severe in the Mobile River Basin. Male bass and carp with low concentrations of vitellogenin were common in all basins. Comparatively high vitellogenin concentrations [>0.35 milligram per milliliter (mg/mL)] in male fish from the Coosa River at Childersburg, the Savannah River at Sylvania, and the Pee Dee River at Rockingham and Bucksport indicate exposure to estrogenic or anti-androgenic chemicals.
Chemical contaminants, health indicators, and reproductive biomarker responses in fish from the Colorado River and its tributaries
Hinck, J.E., V.S. Blazer, N.D. Denslow, K.R. Echols, T.S. Gross, T.W. May, P.J. Anderson, J.J. Coyle, and D.E. Tillitt
E. Humpback Chub Early Life History in and around the Little Colorado River
Variation in availability of insect larvae and other food resources may play an important role in determining patterns of juvenile humpback chub growth and survival in the Little Colorado River (LCR). To understand whether differences in the quantity or quality of food resources are an important driver underlying differences in humpback chub growth or movement among habitats, it is necessary to place estimates of juvenile humpback chub growth and survival in the context of the LCR and mainstem food webs as a whole. A food web context is critical because humpback chub are one of several species of fish (i.e., flannelmouth sucker and bluehead sucker) that rely heavily on the LCR for spawning and rearing. Several investigators have documented low invertebrate abundance and biomass in the LCR that provides spawning and nursery habitat for humpback chub and other fish. Food quality could also affect humpback chub growth in the LCR. Quality could be related to the nutritional quality of the organic matter and invertebrates eaten by chub and/or to concentrations of metals and other toxins in their food. Our goal is to develop “metal webs” for the LCR and parts of the mainstem Colorado River in Grand Canyon. We are developing quantitative food webs to measure metal flux (mercury, selenium, and other trace metals) in the Colorado and Little Colorado rivers in Grand Canyon. These studies will identify key pathways of metal exposure to important fish species, such as the endangered humpback chub, and quantify fluxes of contaminants to riparian food webs via the mechanism of aquatic insect emergence.