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At least 433 records · Page 24Linked to original sources
USGS1979

Hydrocarbon geochemical analyses of Mid-Atlantic Outer Continental Shelf sediments: an environmental assessment

Concentration levels of hydrocarbon in 122 composite mid-Atlantic shelf surface sediment samples have been examined during the second year (1976-1977) of the Bureau of Land Management environmental assessment program. The objective of this study was to establish baseline concentrations and provide data for the "natural variability" curve for the mid-Atlantic region. Concentration levels ( μ g/g) have been determined for the total lipids recovered by liquid column chromatography, and hexane-soluble fraction (aliphatics) benzene fraction (aromatics) as resolved by gas chromatography for each composite sediment sample. Several geochemical parameter values were also determined among which were: 1) n-alkane odd-even ratio; 2) isoprenoid alkane/ n-alkane ratio; 3) pristine/phytane ratio; 4) pristane/n-C 17 ratio; and 5) phytane/n-C 18 ratio. Summary analyses of the concentrations and geochemical 18 parameters are included in this report. Surface sediments examined from the mid-Atlantic shelf contained very low concentrations of resolved aliphatic hydrocarbons, less than 5.0 μ g/gm sediment, and very low concentrations of resolved aromatic hydrocarbons, usually less than 1.0 μ g/gm sediment. Mass spectral analyses of selected hexane eluates confirmed the presence of a series of normal aliphatic alkanes ranging from to n-C 16 to n-C 31 as well as the isoprenoids pristane and phytane. A series of three hydrocarbon peaks in the n-C 20 to n-C 21 range were tentatively identified as n-C 25 unsaturated, branched homologs, The aromatic fractions contained a number of polynuclear aromatics including phenanthrenes, methylphenanthrenes, fluoranthene and pyrcne, benzofluoranthene, and alkyl benzenes. Data accumulated in the second year of the program, coupled with data from the first year's investigations (Miller et al., 1977), have provided the basis for establishing a preliminary natural. "variability curve" for the hydrocarbon concentration levels and distribution in these selected mid-Atlantic shelf samples. This curve shows the seasonal variability noted in both the aliphatic and aromatic hydrocarbons in these samples.

Mid-Atlantic Outer Continental Shelf↗
USGS1987

Manmade organic compounds in the surface waters of the United States: a review of current understanding

This report reviews the occurrence and distribution of manmade organic compounds in the surface waters of the United States. On the basis of their aqueous solubilities, nonionic organic compounds partition themselves between water, dissolved organic matter, particulate organic matter, and the lipid reservoirs of aquatic organisms. Ionized organic compounds can be absorbed to sediments, thereby reducing their aqueous concentrations. Transformation processes of photolysis, hydrolysis, biodegradation, and volatilization can attenuate organic compounds, and attenuation rate commonly follow a first-order kinetic process. Eight groups of manmade organic compounds are discussed: 1. Polychlorinated biphenyls and organochlorine insecticides, 2. Carbamate and organophosphorus insecticides, 3. Herbicides, 4. Phenols, 5. Halogenated aliphatic and monocyclic aromatic hydrocarbons, 6. Phthalate esters, 7. Polychlorinated dibenzo-p-dioxins, and 8. Polycyclic aromatic hydrocarbons. For each compound group, data pertaining to use, production, and properties are presented and discussed. Processes that influence that the environmental fate of each group, as determined primarily through laboratory studies, are reviewed, and important fate processes are identified. Environmental concentrations of compounds from each group in water, biota, and sediment are given to demonstrate representative values for comparison to concentrations determined during ongoing research. Finally, where sufficient data exist, regional and temporal contamination trends in the United States are discussed.

Open-File Report↗
USGS1995

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chlorinated pesticides in aquatic tissue by capillary-column gas chromatography with electron-capture detection

A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron-capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by dissimilar capillary-column gas chromatography with electron-capture detection. The method reporting limits are 5 micrograms per kilogram (μg/kg) for chlorinated compounds, 50 μg/kg for polychlorinated biphenyls, and 200 μg/kg for toxaphene.

Open-File Report↗
USGS2023

Effects of lead exposure on birds breeding in the Southeast Missouri Lead Mining District

Lead mining in the Southeast Missouri Lead Mining District began in the 1700s and continued for nearly 300 years; the waste piles associated with smelting, mining, and milling of lead ores have released metal residues that have contaminated soil and water in the region. Previous studies in the district have indicated potential harm to wildlife, including birds, because of elevated lead concentrations associated with mining. Exposure to soil-borne lead was correlated with elevated lead concentrations in tissues, inhibition of δ-aminolevulinic acid dehydratase (δALAD), and renal lesions in birds foraging on ground-dwelling invertebrates at contaminated sites (compared to reference sites) in the Southeast Missouri Lead Mining District. This study assessed reproductive outcomes for songbirds exposed to soil-borne lead in the district, examined the relation between lead concentrations in soils and in tissues of ground-feeding birds and prey species, and compared the results to literature-based toxicity thresholds for lead that are associated with negative effects in birds. Three lead-contaminated sites and three reference sites (with background concentrations of lead and no known mining inputs) were compared in two ways: individually to all other sites or by site type. Additional effects of lead exposure were evaluated by examining concentrations of biomarkers (oxidative stress, lipid peroxidation, and deoxyribonucleic acid damage) in liver tissues, δALAD inhibition, and renal and hepatic microscopic lesions in birds from lead-contaminated and reference sites. Lead concentrations in soil were site-dependent and were also generally heterogeneous within the lead-contaminated sites. Between 17 and 74 percent of all soil samples at contaminated sites had lead concentrations that exceeded a threshold (1,000 milligrams per kilogram [mg/kg] lead in soil) previously associated with adverse physiological effects in birds in the Southeast Missouri Lead Mining District. Lead concentrations in mixed invertebrates from lead-contaminated sites (282 to 2,230 mg/kg dry weight [dw]) indicated that consuming soil-dwelling prey species is a potential exposure pathway for adult birds and their broods. At lead-contaminated sites, lead concentrations in 40.5 percent of blood samples (adults and their broods) were within a subclinical effects range (0.9 to 2.3 mg/kg dw), and 18.7 percent of samples had lead concentrations that exceeded clinical effects criteria (greater than 2.3 mg/kg dw). In contrast, only 2.6 percent of blood samples from reference sites were within the subclinical effects range for lead; all other blood samples from the reference sites had lead concentrations representative of background concentrations (less than 0.9 mg/kg dw). Subclinical and clinical threshold exceedances for lead concentrations in livers and kidneys were similarly more prevalent at the contaminated sites compared to the reference sites. Lead concentrations in blood were positively correlated with lead concentrations in soil, livers, and kidneys. Lead concentrations in blood were negatively correlated with δALAD activity; greater than 50 percent of the birds collected at lead-contaminated sites exhibited injury via greater than 50 percent inhibition of δALAD in blood compared to birds at reference sites. Birds with elevated lead concentrations in tissues also exhibited enhanced oxidative stress. Microscopic lesions in the livers and kidneys of birds had similar rates of occurrence at the contaminated and reference sites, and lesion prevalence could not be directly linked to lead exposure. Reproductive success was monitored at 585 nests, and 3 out of 5 species had reduced nest success associated with elevated lead concentrations in soil; habitat measures did not help explain nest success. Reduced nest success may have resulted from greater nest predation resulting from neurological and behavioral effects of lead exposure. Ultimately, these lines of evidence indicate that bird health and reproduction have been negatively affected by exposure to lead-contaminated soils in the Southeast Missouri Lead Mining District.

Missouri↗
USGS2002

Water quality, selected chemical characteristics, and toxicity of base flow and urban stormwater in the Pearson Creek and Wilsons Creek Basins, Greene County, Missouri, August 1999 to August 2000

The chemistry and toxicity of base flow and urban stormwater were characterized to determine if urban stormwater was degrading the water quality of the Pearson Creek and Wilsons Creek Basins in and near the city of Springfield, Greene County, Missouri. Potentially toxic components of stormwater (nutrients, trace metals, and organic compounds) were identified to help resource managers identify and minimize the sources of toxicants. Nutrient loading to the James River from these two basins (especially the Wilsons Creek Basin) is of some concern because of the potential to degrade downstream water quality. Toxicity related to dissolved trace metal constituents in stormwater does not appear to be a great concern in these two basins. Increased heterotrophic activity, the result of large densities of fecal indicator bacteria introduced into the streams after storm events, could lead to associated dissolved oxygen stress of native biota. Analysis of stormwater samples detected a greater number of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) than were present in base-flow samples. The number and concentrations of pesticides detected in both the base-flow and stormwater samples were similar.Genotoxicity tests were performed to determine the bioavilability of chemical contaminants and determine the potential harmful effects on aquatic biota of Pearson Creek and Wilsons Creek. Genotoxicity was determined from dialysates from both long-term (approximately 30 days) and storm-event (3 to 5 days) semipermeable membrane device (SPMD) samples that were collected in each basin. Toxicity tests of SPMD samples indicated evidence of genotoxins in all SPMD samples. Hepatic activity assessment of one long-term SPMD sample indicated evidence of contaminant uptake in fish. Chemical analyses of the SPMD samples found that relatively few pesticides and pesticide metabolites had been sequestered in the lipid material of the SPMD; however, numerous PAHs and VOCs were detected in both the long-term and the storm-event exposures. It is suspected, based on the compounds detected in the SPMDs and the water samples, that the observed genotoxicity is largely the result of PAHs and VOCs that were probably derived from petroleum inputs or combustion sources. Therefore the water quality and thus the aquatic environments in the Pearson Creek and Wilsons Creek Basins are being degraded by urban derived contaminants.

Missouri↗
USGS1994

Data on natural organic substances in dissolved, colloidal, suspended-silt and -clay, and bed-sediment phases in the Mississippi River and some of its tributaries, 1987-90

The Mississippi River and some of its tributaries were sampled for natural organic substances dissolved in water and in suspended and bed sediments during seven sampling cruises from 1987-90. The sampling cruises were made during different seasons, in the free-flowing reaches of the river from St. Louis, Missouri, to New Orleans, Louisiana. The first three cruises were made during low-water conditions, and the last four cruises during high-water conditions. The purpose for sampling and characterizing natural organic substances in the various phases in the river was to provide an understanding of how these substances facilitate contaminant transport and transformations in the Mississippi River. Significant conclusions of this study were: (1) Natural organic substances appear to stabilize ' certain colloids against aggregation; therefore, these colloids remain in suspension and can act as transport agents that are not affected by sedimentation. Bacteria were found to be a significant fraction of organic colloids. (2) A new class of organic contaminants (polyethylene glycols) derived from nonionic surfactant residues was discovered dissolved with natural organic substances in water. These polyethylene glycols have the potential to affect both organic and inorganic contaminant transport in water. (3) The entire dissolved organic-matter component under varying hydrologic and seasonal conditions was characterized. (4) A method was developed to characterize organic matter in sediment by solid-state, 13C-nuclear magnetic resonance spectrometry. (5) The organic matter in suspended sediments was characterized by a variety of spectral and nonspectral methods. The protein component (significant in trace-metal binding) and lipid component (significant in organic-contaminant binding) were found to be major constituents in natural organic matter in suspended sediment. (6) Pools are reservoirs acting as traps of sedimentary organic matter of allochthonous origin and export material of autochthonous nitrogen. (7) A major portion of the mass of organic colloids in transport consisted of bacterial cells.

Mississippi River↗
USGS1997

Occurrence and Distribution of Organochlorine Compounds in Biological Tissue and Bed Sediment From Streams in the Trinity River Basin, Texas, 1992-93

This report describes the occurrence and distribution of organochlorine compounds in biological tissue and bed sediment from the Trinity River Basin study area of the National Water-Quality Assessment Program. Concentrations of organochlorine pesticides, polychlorinated biphenyls (PCBs), and other organochlorine compounds were determined in biological tissue and surficial bed sediment from 16 stream sites in the Trinity River Basin of east-central Texas. Asiatic clams (Corbicula fluminea) were collected at 10 sites, and fish, including blue catfish (Ictalurus furcatus), common carp (Cyprinus carpio), bluegill (Lepomis cyanellus), and yellow bullhead (Ameiurus natalis) were collected at all mainstem and two tributary sites. Thirty of the 36 compounds analyzed in biological tissue or surficial bed sediment were detected in one or both media. Overall, more organochlorine compounds were detected in bed sediment than in biological tissue; however, various chlordane isomers, DDT metabolites, and PCBs were detected more frequently in tissue than in sediment. The chlordane isomers and PCBs that were detected more frequently in biological tissue also were detected more frequently at urban sites than at agricultural sites. Organochlorine compound concentrations generally were highest in fish tissue from Trinity River mainstem sites. Fish tissue from the mainstem sites contained a higher percentage of lipids than did fish- and clam-tissue samples from the tributary sites.

Water-Resources Investigations Report↗
USGS1997

Organochlorine compounds in fish tissue and bed sediment in the upper Snake River basin, Idaho and western Wyoming, 1992-94

Fish-tissue and bed-sediment samples were collected from 20 sites in the upper Snake River Basin in Idaho and western Wyoming as part of the National Water-Quality Assessment Program to determine the occurrence and distribution of organochlorine compounds. During 1992-94, 41 samples were analyzed for 28 different organochlorine compounds in whole-fish tissue and 32 compounds in bed sediment. Sites sampled were third- through seventh-order streams that represented three environmental settings: reference conditions, agricultural land use, and mixed (agricultural and urban) land use. Fourteen organochlorine compounds were detected in fish tissue and nine in bed sediment. All compounds detected in bed sediment also were detected in fish tissue. Fish-tissue and bed- sediment samples from agricultural and mixed land-use sites contained one or more organochlorine compounds. The most frequently detected compound at all sites was p,p'DDE, which was present in 80 percent of the fish-tissue and 30 percent of the bed-sediment samples. A maximum of three compounds were detected, all in fish-tissue samples from reference (forest and rangeland) sites. The highest number of compounds was detected in fish-tissue (nine) and bed-sediment (eight) samples from mixed land-use sites. No clear relation was apparent between the occurrence of external anomalies and fish-tissue contaminant concentrations or land use. The distribution of organochlorine compounds in the basin was related to land use. Total DDT was detected at sites in all land uses; total PCB was detected at only agricultural and mixed land-use sites. Total chlordane was detected in fish- tissue samples from primarily mixed land-use sites; samples from six of the eight sites contained detectable concentrations. Median concentrations of p,p'DDE in fish-tissue samples from mixed land- use sites were significantly higher (p<0.05) than from reference and agricultural sites. Significant positive relations between percent agricultural land and concentrations of total DDT (r 2 = 0.41) and lipid-normalized total DDT (r 2 =0.48) were observed. Concentrations of p,p'DDE, total PCB, total DDT, and toxaphene in fish-tissue samples from three mixed land-use sites equaled or exceeded national guidelines established for protection of fish-eating wildlife: Portneuf River at Pocatello, total PCB; Rock Creek at Twin Falls, p,p'DDE, total DDT, and toxaphene; and Snake River near Buhl, p,p'DDE and total DDT. Concentrations of total DDT and p,p'DDE in 32 and 34 percent of fish-tissue samples, respectively, analyzed during this study exceeded the 1980-81 U.S. Fish and Wildlife Service/National Contaminant Biomonitoring Program (USFWS/NCBP) geometric mean concentrations. Concentrations of total PCB in samples from the Portneuf River at Pocatello and concentrations of toxaphene in samples from Rock Creek at Twin Falls also exceeded the USFWS/NCBP geometric mean concentrations. Comparisons of 1970-84 USFWS/NCBP concentrations of total DDT and total PCB in fish-tissue samples from the Snake River near Hagerman with concentrations measured during this study indicated a decreasing trend. Concentrations of p,p'DDE in all sediment samples from Rock Creek at Twin Falls exceeded the Canadian Probable Effect Level guideline. Total PCB was detected in sediment from only one site, Portneuf River at Pocatello, which was also the only site where concentrations of total PCB in fish tissue were elevated. Because organochlorine compounds are lipophilic and tend to bioaccumulate in tissue, fish are a better indicator of organochlorine contaminant occurrence and distribution than are bed sediment or water in the upper Snake River Basin. Some of the highest concentrations of organochlorine contaminants in tissue and sediment in the basin were detected at sites receiving irrigation- return flows. Results of this study support the importance of controlling sediment erosion on irrigated land to reduce the quantity of contaminants entering streams that receive irrigation-return flows.

Idaho;Wyoming↗
USGS1998

Water-quality assessment of the Upper Mississippi River Basin, Minnesota and Wisconsin: Polychlorinated biphenyls in common carp and walleye fillets, 1975-95

Spatial and temporal distribution of polychlorinated biphenyls (PCBs) in common carp ( Cyprinus carpio ) and walleye ( Stizostedion vitreum ) fillets from rivers in the Upper Mississippi River Basin upstream of the outlet of Lake Pepin are summarized. PCB concentrations in common carp and walleye fillets collected from rivers in the UMIS during 1975-95 by the Minnesota Fish Contaminant Monitoring Program (MFCMP) and the Wisconsin Department of Natural Resources (WDNR) were analyzed. PCBs in fish tissue are of concern because PCBs are potentially toxic, teratogenic, and are linked to poor fetal development and endocrine disruption in fish and other animals including humans, that consume fish. This summary was part of an analysis of historical data for the Upper Mississippi River (UMIS) study unit of the National Water-Quality Assessment (NAWQA) Program. The UMIS study unit is a 47,000 square-mile basin that includes the drainage of the Mississippi River upstream of the outlet of Lake Pepin and encompasses the Twin Cities metropolitan area. PCB concentrations for individual samples at all sites ranged from 0.07 to 33.0 milligrams per kilograms (mg/kg) for common carp and from 0.07 to 9.8 mg/kg for walleye during 1975-95. During 1975-79 and 1980-87, 10 and 4 percent of walleye samples and 45 and 36 percent of common carp samples, respectively, exceeded the U.S. Food and Drug Administration guideline of 2 mg/kg PCB in fish tissue. PCB concentrations in individual common carp and walleye samples were below 2 mg/kg after 1987. Median PCB concentrations at individual sites and within stream segments were generally greatest in common carp and walleye from Mississippi River segments in the TCMA during 1975-79 and 1980-87. There was a significant difference among lipid-normalized PCB (LNPCB) concentrations in common carp, considering all stream segments combined, during all three time periods (1975-79, 1980-87, and 1988-95). LNPCB concentrations in common carp and walleye at those stream segments upstream or outside the TCMA were generally lower than those in UMR segments within the TCMA. The spatial distribution of PCB and LNPCB concentrations in common carp and walleye correspond with historical point- and non point-source PCB inputs in the densely populated TCMA, and concentrations in fish were greater in areas that historically had elevated PCB concentrations in bed sediment. Median PCB concentrations in common carp and walleye at individual sites were greatest during 1975-79 and 1980-87, and least during 1988-95 at most sites. Most of the river segments exhibited over 80 percent decline in median PCB concentrations in common carp and walleye between the 1975-79 and 1988-95 time periods. The results from these temporal analyses were similar to those of other studies in the United States and in Minnesota and Wisconsin that reported a significant downward trend in PCB concentrations in fish. Although, PCB concentrations have decreased during 1975-95, low concentrations of PCBs still remain in the aquatic environment despite the fact that PCBs were banned nearly 20 years ago.

Minnesota, Wisconsin↗
USGS1998

Correlation between plasma component levels of cultured fish and resistance to bacterial infection

Mortalities of yellowtail Seriola quinqueradiata artificially infected with Lactococcus garvieae and of rainbow trout Oncorhynchus mykiss artificially infected with Vibrio anguillarum were compared with the levels of plasma components measured prior to challenge. The levels of plasma total cholesterol, free cholesterol and phospholipid of fish surviving infection were significantly higher in both yellowtail and rainbow trout than those of fish which died during the challenge test. Mortality of yellowtail with plasma total cholesterol levels lower than 250 mg/100 ml was significantly higher than that of fish which had cholesterol levels higher than 275 mg/100 ml (p < 0.05). Rainbow trout whose cholesterol was lower than 520 mg/100 ml suffered a significantly higher mortality due to vibriosis than fish having cholesterol levels higher than 560 mg/100 ml (p < 0.005). These results indicate that low levels of plasma lipid components may be an indicator of lowered disease resistance in cultured fish.

Fish Pathology↗
USGS2008

Evaluation of morphological indices and total body electrical conductivity to assess body composition in big brown bats

Bat researchers have used both morphological indices and total body electric conductivity (TOBEC) as proxies for body condition in a variety of studies, but have typically not validated these indices against direct measurement of body composition. We quantified body composition (total carcass lipids) to determine if morphological indices were useful predictors of body condition in big brown bats (Eptesicus fuscus). We also evaluated body composition indirectly by TOBEC using EM-SCAN?? technology. The most important predictors of body composition in multiple regression analysis were body mass-to-forearm ratio (partial r2 = 0.82, P < 0.001) followed by TOBEC measurement (partial r2 = 0.08, P < 0.001) and to a minor extent head length (partial r2 = 0.02, P < 0.05). Morphological condition indices alone may be adequate for some studies because of lower cost and effort. Marking bats with passive integrated transponder (PIT) tags affected TOBEC measurements. ?? Museum and Institute of Zoology PAS.

Acta Chiropterologica↗
USGS2017

Diet composition and provisioning rates of nestlings determine reproductive success in a subtropical seabird

Understanding how both quality and quantity of prey affect the population dynamics of marine predators is a crucial step toward predicting the effects of environmental perturbations on population-level processes. The Junk Food Hypothesis, which posits that energetic content of prey species may influence reproductive capacity of marine top predators regardless of prey availability, has been proposed as a mechanism by which changes in prey populations could affect predator populations in high latitude systems; however, support for this hypothesis has been inconsistent across studies, and further data are needed to elucidate variation in the relative importance of prey quantity and quality, both among predator species and across ecological systems. We tested the relative importance of prey quantity and quality to nestling survival in the eastern brown pelican Pelecanus occidentalis carolinensis across 9 breeding colonies in the northern Gulf of Mexico that varied in underlying availability of a key prey resource, the Gulf menhaden Brevoortia patronus . Both feeding frequency and meal mass were significantly correlated to energy provisioning rates and nestling survival, while energy density of meals had little effect on either metric. Compared to previous results from cold-water systems, we found lower and less variable energy densities (4.4 kJ g -1 , vs. 5.2 to 6.5 kJ g -1 in other studies) and lipid content (9% dry mass, vs. 16 to 23% in other studies) of common prey items. While Gulf menhaden was the most common prey species at all colonies, the proportion of menhaden fed to nestlings varied and was not strongly correlated to fledging success. We conclude that quantity rather than quality of prey, particularly small schooling fish, is the main driver of brown pelican reproductive success in this system, and that environmental perturbations affecting biomass, distribution, and abundance of forage fish could substantially affect brown pelican reproductive success.

Gulf of Mexico↗
USGS2019

Extreme reduction in nutritional value of a key forage fish during the Pacific marine heatwave of 2014–2016

Pacific sand lance Ammodytes personatus are a key forage fish in the North Pacific for many species of salmon, groundfish, seabirds, and marine mammals and have historically been important to predators in relatively warm years. However, extreme declines in the nutritional value of sand lance in Prince William Sound, Alaska, USA, during 2012-2016 indicate that energy transfer from lower trophic levels to predators via sand lance may have been disrupted during the North Pacific marine heatwave in 2015 and 2016. Nutritional value (length, energy density, and whole-body energy) was measured in age-0 and age-1 sand lance collected during July in cool (2012-2013) and increasingly warm (2014-2016) years. The value of age-0 fish was relatively stable, with only minor differences among years for length and whole-body energy. By contrast, the value of age-1 fish significantly declined in 2015, and by 2016 they were 38% shorter and 13% lower in energy density compared to cooler years. This contributed to significant declines in whole-body energy of 44% in 2015 and 89% in 2016 compared to cooler years (2012-2014). The 2015 sand lance cohort experienced little growth or lipid accumulation from July 2015 at age-0 to July 2016 at age-1. This effective disruption of energy flow through pelagic food webs probably contributed to population declines and/or breeding failures observed among several predators in the Gulf of Alaska and suggests that tipping points were reached during the heatwave.

Marine Ecology Progress Series↗
USGS2006

Assessing the nutritional stress hypothesis: Relative influence of diet quantity and quality on seabird productivity

Food availability comprises a complex interaction of factors that integrates abundance, taxonomic composition, accessibility, and quality of the prey base. The relationship between food availability and reproductive performance can be assessed via the nutritional stress (NSH) and junk-food (JFH) hypotheses. With respect to reproductive success, NSH posits that a deficiency in any of the aforementioned metrics can have a deleterious effect on a population via poor reproductive success. JFH, a component of NSH, posits specifically that it is a decline in the quality of food (i.e. energy density and lipid content) that leads to poor reproductive success. We assessed each in relation to reproductive success in a piscivorous seabird, the black-legged kittiwake Rissa tridactyla . We measured productivity, taxonomic composition, frequency, size, and quality of meals delivered to nestlings from 1996 to 1999 at 6 colonies in Alaska, USA, 3 each in Prince William Sound and Lower Cook Inlet. Productivity varied widely among colony-years. Pacific herring Clupea pallasi , sand lance Ammodytes hexapterus , and capelin Mallotus villosus comprised ca. 80% of the diet among colony-years, and each was characterized by relatively high energy density. Diet quality for kittiwakes in this region therefore remained uniformly high during this study. Meal delivery rate and meal size were quite variable among colony-years, however, and best explained the variability in productivity. Parent kittiwakes appeared to select prey that were energy dense and that maximized the biomass provisioned to broods. While these results fail to support JFH, they do provide substantial support for NSH.

Marine Ecology Progress Series↗
USGS2014

Evaluation of potential protective factors against metabolic syndrome in bottlenose dolphins:feeding and activity patterns of dolphins in Sarasota Bay, Florida

Free-ranging bottlenose dolphins (Tursiops truncatus) living in Sarasota Bay, Florida appear to have a lower risk of developing insulin resistance and metabolic syndrome compared to a group of dolphins managed under human care. Similar to humans, differences in diet and activity cycles between these groups may explain why Sarasota dolphins have lower insulin, glucose, and lipids. To identify potential protective factors against metabolic syndrome, existing and new data were incorporated to describe feeding and activity patterns of the Sarasota Bay wild dolphin community. Sarasota dolphins eat a wide variety of live fish and spend 10&acirc;&euro;&ldquo;20% of daylight hours foraging and feeding. Feeding occurs throughout the day, with the dolphins eating small proportions of their total daily intake in brief bouts. The natural pattern of wild dolphins is to feed as necessary and possible at any time of the day or night. Wild dolphins rarely eat dead fish or consume large amounts of prey in concentrated time periods. Wild dolphins are active throughout the day and night; they may engage in bouts of each key activity category at any time during daytime. Dive patterns of radio-tagged dolphins varied only slightly with time of day. Travel rates may be slightly lower at night, suggesting a diurnal rhythm, albeit not one involving complete, extended rest. In comparison, the managed dolphins are older; often fed a smaller variety of frozen-thawed fish types; fed fish species not in their natural diet; feedings and engaged activities are often during the day; and they are fed larger but fewer meals. In summary, potential protective factors against metabolic syndrome in dolphins may include young age, activity, and small meals fed throughout the day and night, and specific fish nutrients. These protective factors against insulin resistance and type 2 diabetes are similar to those reported in humans. Further studies may benefit humans and dolphins.

Florida↗
USGS2025

Prevalence of pelagic diatoms and harmful algae in tellinid bivalve diets during record low sea ice in the Pacific Arctic determined by DNA metabarcoding

Understanding changes at the base of the marine food web in the rapidly transforming Arctic is essential for predicting and evaluating ecosystem dynamics. The northern Bering Sea experienced record low sea ice in 2018, followed by the second lowest in 2019, highlighting the urgency of the issue for this region. In this study, we investigated the diet of the clam Macoma calcarea in the Pacific Arctic using DNA metabarcoding, employing 18S and rbcL markers to identify dietary components. Our findings revealed a strong dependence on pelagic diatoms, particularly Chaetoceros sp., with a near absence of ice algae in the clam diet. This pattern reflects the lack of lipid-rich ice algal production during these low sea ice events. Additionally, our analysis detected algae capable of producing harmful toxins, notably Alexandrium dinoflagellates, in the clam diet, underscoring the need for increased monitoring due to potential ecosystem and human health risks. This study demonstrates the utility of DNA metabarcoding in unraveling the complex dynamics of Arctic marine food webs and pelagic-benthic coupling, providing a glimpse of future conditions in a rapidly changing environment.

Bering Sea, Chukchi Sea↗
USGS2022

Hepatic gene expression profiling of American kestrels (Falco sparverius) exposed in ovo to three alternative brominated flame retardants

A number of brominated flame retardants (BFRs) have been reported to interfere with the thyroid signaling pathway and cause oxidative stress in birds, yet the underlying shifts in gene expression associated with these effects remain poorly understood. In this study, we measured hepatic transcriptional responses of 31 genes in American kestrel ( Falco sparverius ) hatchlings following in ovo exposure to one of three high-volume alternative BFRs: 1,2-bis(2,4,6-tribromophenoxy) ethane (BTPBE), bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH), or 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB). Hatchling kestrels exhibited shifts in the expression of genes related to oxidative stress ( CYP, GSTA, SOD, and GPX1 ), thyroid hormone metabolism and transport ( DIO1, DIO2 , and TTR ), lipid and protein metabolism (PPAR, HMGCR, FAB1, and LPL), and cytokine-mediated inflammation ( TLR3, IL18, IRF7, STAT3, RACK1, and CEBPB ). Male and female hatchlings differed in which genes were differentially expressed, as well as the direction of the effect (up- vs. downregulation). These results build upon our previous findings of increased oxidative stress and disrupted thyroid signaling pathway in the same hatchlings. Furthermore, our results indicate that inflammatory responses appear to occur in female hatchlings exposed to BTBPE and EHTBB in ovo. Gene expression analysis revealed multiple affected pathways, adding to the growing evidence that sublethal physiological effects are complex and are a concern for birds exposed to BTBPE, EHTBB, or TBPH in ovo.

Biology↗
USGS2015

Methane oxidation and molecular characterization of methanotrophs from a former mercury mine impoundment

The Herman Pit, once a mercury mine, is an impoundment located in an active geothermal area. Its acidic waters are permeated by hundreds of gas seeps. One seep was sampled and found to be composed of mostly CO 2 with some CH 4 present. The &delta; 13 CH 4 value suggested a complex origin for the methane: i.e. , a thermogenic component plus a biological methanogenic portion. The relatively 12 C-enriched CO 2 suggested a reworking of the ebullitive methane by methanotrophic bacteria. Therefore, we tested bottom sediments for their ability to consume methane by conducting aerobic incubations of slurried materials. Methane was removed from the headspace of live slurries, and subsequent additions of methane resulted in faster removal rates. This activity could be transferred to an artificial, acidic medium, indicating the presence of acidophilic or acid-tolerant methanotrophs, the latter reinforced by the observation of maximum activity at pH = 4.5 with incubated slurries. A successful extraction of sterol and hopanoid lipids characteristic of methanotrophs was achieved, and their abundances greatly increased with increased sediment methane consumption. DNA extracted from methane-oxidizing enrichment cultures was amplified and sequenced for pmoA genes that aligned with methanotrophic members of the Gammaproteobacteria . An enrichment culture was established that grew in an acidic (pH 4.5) medium via methane oxidation.

California↗