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At least 91 records · Page 5Linked to original sources
USGS1997

The effects of experimental starter diets with different levels of soybean or menhaden oil on red drum (Sciaenops ocellatus)

Red drum reared from captive-spawned eggs were used in a 2 × 4 factorial experiment comparing eight diets with soybean oil (SBO) or menhaden oil (MHO) added to a basal diet (about 3.4% lipid from practical ingredients) at 1.5, 5.2, 9.0, or 12.7%. Triplicate groups of 20 early juveniles (mean 0.4 g) were stocked in 1000 litre fiberglass tanks supplied with filtered estuarine water (17–26 °C, mean 22 °C; 15–35‰) and hand fed twice a day to apparent satiation for 56 days. The fish (range 0.3–9.4 g) appeared to utilize up to 1.5–5.2% dietary SBO (in 5.4–8.7% total lipid). With 0.67% EPA + DHA (eicosapentaenoic and docosahexaenoic acids) in the basal diet, no EFA-deficiency signs were observed. Dietary MHO was utilized up to 12.7%, but fish fed diets with more than 1.5% SBO had lower growth rates and increased feed conversion ratios (especially with 9.0 and 12.7% SBO). Diets containing 1.5% SBO or MHO produced the leanest fish (70.5–71.6% protein, 13.0–13.1% lipid, of whole body). Diets containing 9.0 and 12.7% MHO produced the fattest fish (64.5–66.0% protein and 19.1–19.9% lipid). Percent liver lipid (wet) was highest for fish fed diets containing 5.2% SBO (41.4%), 9.0% MHO (36.5%), and 12.7% MHO (35.4%), and lowest with 1.5% MHO (24.0%). Considering the good survival, absence of disease, and excellent general health, this fatty liver condition did not appear to have short-term adverse effects. All fish in the study had fatty livers to some degree, and their liver histological features differed from those of wild fish. Liver lipid reserves might confer some survival advantage to fish released for stock enhancement if the reserves are used during their transition from cultured to wild status. However, if the hepatocyte changes we observed are not reversible, long-term detrimental effects on liver function are possible.

Aquaculture↗
USGS2005

Sorption of aromatic organic pollutants to grasses from water

The influence of plant lipids on the equilibrium sorption of three aromatic solutes from water was studied. The plant-water sorption isotherms of benzene, 1,2-dichlorobenzene, and phenanthrene were measured over a large range of solute concentrations using sealed vessels containing water, dried plant material, and solute. The plant materials studied include the shoots of annual rye, tall fescue, red fescue, and spinach as well as the roots of annual rye. Seven out of eight sorption isotherms were linear with no evidence of competitive effects between the solutes. For a given plant type, the sorption coefficient increased with decreasing solute water solubility. For a given solute, sorption increased with increasing plant lipid content. The estimated lipid-water partition coefficients of individual solutes were found to be significantly greater than the corresponding octanol-water partition coefficients. This indicates that plant lipids are a more effective partition solvent than octanol for the studied aromatic compounds. As expected, the solute lipid-water partition coefficients were log-linearly related to the respective water solubilities. For the compounds studied, partitioning into the lipids is believed to be the primary sorption mechanism. ?? 2005 American Chemical Society.

Environmental Science & Technology↗
USGS2019

Condition bias of decoy-harvested light geese during the conservation order

Evidence that decoy harvest techniques primarily remove individuals of poorer body condition is well established in short-lived duck species; however, there is limited support for condition bias in longer-lived waterfowl species, such as geese, where decoy harvest is considered primarily additive because of their high natural survival rates. We evaluated support for the harvest condition bias hypothesis of 2 long-lived waterfowl species, the lesser snow goose ( Anser caerulescens caerulescens ) and Ross's goose ( Anser rossii ). We used proximate analysis to quantify lipid and protein content of lesser snow and Ross's geese collected during the Light Goose Conservation Order (LGCO) in 2015 and 2016 during spring migration in Arkansas, Missouri, Nebraska, and South Dakota, USA. In each state, LGCO participants collected birds using traditional decoy techniques and we collected birds from the general population using jump-shooting tactics. Total body lipid content in both lesser snow and Ross's geese varied with age, region of harvest, and harvest type (decoy or jump-shooting). On average, adult lesser snow and Ross's geese harvested over decoys had 60 g and 41 g, respectively, fewer lipids than conspecifics collected using jump-shooting. We observed lower lipid reserves in decoy-shot geese in all 4 states sampled despite general gains in lipid reserves as migration chronology progressed. Our data support that the harvest condition bias extends to longer-lived waterfowl species and during a life-history event (spring migration) in which harvest is not normally observed. In the case of overabundant light geese, the disproportionate harvest of poorer-conditioned lesser snow and Ross's geese may serve as an additional challenge against any realized effects of harvest to reduce the population, in addition to extremely low harvest rates.

Arkansas, Missouri, Nebraska, South Dakota↗
USGS1996

Organochlorine contaminants in double-crested cormorants from Green Bay, WI: I. Large-scale extraction and isolation from eggs using semi-permeable membrane dialysis

A 41.3-kg sample of double-crested cormorant ( Phalacrocorax auritus ) egg contents was extracted, yielding over 2 L of egg lipid. The double-crested cormorant (DCC) egg extract, after clean-up and concentration, was intended for use in egg injection studies to determine the embryotoxicity of the organic contaminants found within the eggs. Large-scale dialysis was used as a preliminary treatment to separate the extracted contaminants from the co-extracted sample lipids. The lipid was dialyzed in 80×5 cm semi-permeable membrane devices (SPMDs) in 50-ml aliquants. After the removal of 87 g of cholesterol by freeze-fractionation, the remaining lipid carryover (56 g) was removed by 100 routine gel permeation chromatography (GPC) operations. A 41,293-g sample was thus extracted and purified to the extent that it could easily be placed at a volume of 5 ml, the volume calculated to be necessary for the egg injection study. Analyses were performed comparing contaminant concentrations in the final purified extract to those present in the original egg material, in the extract after dialysis and cholesterol removal, and in the excluded materials. Recoveries of organochlorine pesticides through dialysis and cholesterol ranged from 96% to 135%. Total polychlorinated biphenyls in the final extract were 96% of those measured in the original egg material. Analysis of excluded lipid and cholesterol indicated that 92% of the polychlorinated dibenzo-dioxins and-furans were separated into the final extract.

Archives of Environmental Contamination and Toxico↗
USGS2016

Cultivation of a native alga for biomass and biofuel accumulation in coal bed methane production water

Coal bed methane (CBM) production has resulted in thousands of ponds in the Powder River Basin of low-quality water in a water-challenged region. A green alga isolate, PW95, was isolated from a CBM production pond, and analysis of a partial ribosomal gene sequence indicated the isolate belongs to the Chlorococcaceae family. Different combinations of macro- and micronutrients were evaluated for PW95 growth in CBM water compared to a defined medium. A small level of growth was observed in unamended CBM water (0.15 g/l), and biomass increased (2-fold) in amended CBM water or defined growth medium. The highest growth rate was observed in CBM water amended with both N and P, and the unamended CBM water displayed the lowest growth rate. The highest lipid content (27%) was observed in CBM water with nitrate, and a significant level of lipid accumulation was not observed in the defined growth medium. Growth analysis indicated that nitrate deprivation coincided with lipid accumulation in CBM production water, and lipid accumulation did not increase with additional phosphorus limitation. The presented results show that CBM production wastewater can be minimally amended and used for the cultivation of a native, lipid-accumulating alga.

Montana, Wyoming↗
USGS2021

Untargeted lipidomics for determining cellular and sub-cellular responses in Zebrafish (Danio rerio) liver cells following exposure to complex mixtures in U.S. streams

Surface waters often contain a variety of chemical contaminants potentially capable of producing adverse outcomes in both humans and wildlife due to impacts from industrial, urban, and agricultural activity. Here, we report the results of a zebrafish liver (ZFL) cell-based lipidomics approach to assess the potential ecotoxicological effects of complex contaminant mixtures using water collected from eight impacted streams across the United States mainland and Puerto Rico. We initially characterized the ZFL lipidome using high resolution mass spectrometry, resulting in the annotation of 508 lipid species covering 27 classes. We then identified lipid changes induced by all streamwater samples (nonspecific stress indicators) as well as those unique to water samples taken from specific streams. Subcellular impacts were classified based on organelle-specific lipid changes, including increased lipid saturation (endoplasmic reticulum stress), elevated bis(monoacylglycero)phosphate (lysosomal overload), decreased ubiquinone (mitochondrial dysfunction), and elevated ether lipids (peroxisomal stress). Finally, we demonstrate how these results can uniquely inform environmental monitoring and risk assessments of surface waters.

Environmental Science & Technology↗
USGS2005

Relation of organic contaminant equilibrium sorption and kinetic uptake in plants

Plant uptake is one of the environmental processes that influence contaminant fate. Understanding the magnitude and rate of plant uptake is critical to assessing potential crop contamination and the development of phytoremediation technologies. We determined (1) the partition-dominated equilibrium sorption of lindane (LDN) and hexachlorobenzene (HCB) by roots and shoots of wheat seedlings, (2) the kinetic uptake of LDN and HCB by roots and shoots of wheat seedlings, (3) the kinetic uptake of HCB, tetrachloroethylene (PCE), and trichloroethylene (TCE) by roots and shoots of ryegrass seedlings, and (4) the lipid, carbohydrate, and water contents of the plants. Although the determined sorption and the plant composition together suggest the predominant role of plant lipids for the sorption of LDN and HCB, the predicted partition with lipids of LDN and HCB using the octanol-water partition coefficients is notably lower than the measured sorption, due presumably to underestimation of the plant lipid contents and to the fact that octanol is less effective as a partition medium than plant lipids. The equilibrium sorption or the estimated partition can be viewed as the kinetic uptake limits. The uptakes of LDN, PCE, and TCE from water at fixed concentrations increased with exposure time in approach to steady states. The uptake of HCB did not reach a plateau within the tested time because of its exceptionally high partition coefficient. In all of the cases, the observed uptakes were lower than their respective limits, due presumably to contaminant dissipation in and limited water transpiration by the plants. ?? 2005 American Chemical Society.

Environmental Science & Technology↗
USGS2003

Temporal variation of energy reserves in mayfly nymphs ( Hexagenia spp.) from Lake St. Clair and western Erie

1. We analysed changes in energy reserves (lipid and glycogen) and length–weight relationships of burrowing mayflies ( Hexagenia spp.) in 1997–99 to compare an established population in Lake St Clair with a recovering population in western Lake Erie of the Laurentian Great Lakes. In addition, we measured changes in water temperature and potential food in both water columns and sediments. 2. Although overall mean values of lipid and glycogen levels of Hexagenia nymphs from Lake St Clair and western Lake Erie were not significantly different, there were differences in seasonal patterns between the two lakes. In Lake St Clair, levels were highest in early spring, declined throughout the year, and reached their lowest levels in fall during all 3 years of study. In contrast, levels in western Lake Erie were lower in spring, increased to a maximum in summer, then declined in fall. Seasonal patterns in length–weight relationships were similar to those for lipid and glycogen. 3. Total lipid as a percentage of dry weight did not increase with developmental stage of nymphs until just prior to metamorphosis and emergence from water. However, the major reserve lipid, triacylglycerols, increased systematically with development stage. In the final stage of development, triacylglycerols declined, probably as a result of energy consumption and its conversion to other biochemical components for metamorphosis and reproduction. 4. Indicators of potential food (algal fluorescence in the water column and chlorophyll a and chlorophyll a /phaeophytin ratio in sediments) suggest that Hexagenia in Lake St Clair have a food source that is benthic based, especially in early spring, whereas in western Lake Erie nymphs have a food source that is water column based and settles to the lake bottom during late spring and summer.

Freshwater Biology↗
USGS2012

Exploring mechanisms underlying sex-specific differences in mortality of Lake Michigan bloaters

Sex-specific differences in mortality rates have been observed among freshwater and marine fish taxa, and underlying mechanisms can include sex-specific differences in (1) age at maturity, (2) growth rate, or (3) activity or behavior during the spawning period. We used a long-term (1973–2009) Lake Michigan data set to evaluate whether there were sex-specific differences in catch per unit effort, mortality, age at maturity, and length at age in bloaters Coregonus hoyi . Because bloater population biomass varied 200-fold during the years analyzed, we divided the data into three periods: (1) 1973–1982 (low biomass), (2) 1983–1997 (high biomass), and (3) 1998–2009 (low biomass). Mortality was higher for males than for females in periods 2 and 3; the average instantaneous total mortality rate ( Z ) over these two periods was 0.71 for males and 0.57 for females. Length at age was slightly greater (2–6%) for females than for males in different age-classes (3–6 years) during each period. Age at maturity was earlier for males than for females in periods 1 and 2, but the mean difference was only 0.2–0.4 years. To test the hypothesis that somatic lipids declined more in males than in females during spawning (perhaps due to increased activity or reduced feeding), we estimated sex-specific percent somatic lipids for fish sampled in 2005–2006 and 2007–2008. During 2005–2006, somatic lipids declined from prespawning to postspawning for males but were unchanged for females. During 2007–2008, however, somatic lipids were unchanged for males, whereas they increased for females. We found that sex-specific differences in Z occurred in the Lake Michigan bloater population, but our hypotheses that sex-specific differences in maturity and growth could explain this pattern were generally unsupported. Our hypothesis that somatic lipids in males declined during spawning at a faster rate than in females will require additional research to clarify its importance.

Transactions of the American Fisheries Society↗
USGS2011

Relationship between oxidative stress, pathology, and behavioral signs of lead poisoning in mallards

Some of the adverse effects of lead (Pb) may be associated with oxidative damage of lipids, proteins, or DNA. In a previous study a linkage was observed between the susceptibilities of waterfowl species to Pb poisoning with oxidative stress . To investigate this relationship among the individuals of a single species, for 3 wk 4 groups of 72 mallards were fed diets containing high or low levels of vitamin E (20 or 220 Ul/kg) and high or low levels of Pb (0 or 2 g/kg). During the first week of Pb exposure, mallards developed hemolytic anemia, and during the second week, signs of neurological impairment. Histological findings in the Pb-exposed mallards were hemosiderosis, demyelinization of sciatic and brachial nerves, and tumefaction of renal tubular epithelium with the presence of intranuclear inclusion bodies. Lipid peroxidation increased with Pb exposure in blood, liver, bile, and brain, but decreased in nerves. Glutathione (GSH) increased with Pb exposure in liver and bile, and its oxidized/reduced ratio only increased in bile. Pb exposure inhibited GSH peroxidase activity (GPX) in plasma, liver, and brain, and decreased protein thiols (PSH) in blood and liver. Vitamin E resulted in significantly lower lipid peroxidation in nerves of control birds relative to unsupplemented controls, but did not alleviate any sign of lead posioning. Pb-induced pathological changes associated with hepatic and nervous functions were significantly correlated with lower GPX activity and PSH concentrations in these tissues rather than lipid peroxidation. Data suggest that inhibition of antioxidant enzymes and interaction with sulfhydryl groups of proteins may play a more important role in Pb poisoning of waterfowl than lipid peroxidation.

Journal of Toxicology and Environmental Health, Pa↗
USGS2005

A mechanistic link between chick diet and decline in seabirds?

A climatic regime shift during the mid-1970s in the North Pacific resulted in decreased availability of lipidrich fish to seabirds and was followed by a dramatic decline in number of kittiwakes breeding on the Pribilof Islands. Although production of chicks in the mid-1970s was adequate to sustain kittiwake populations in the early 1980s, the disappearance of birds from breeding colonies apparently exceeded recruitment. No mechanism has been proposed to explain why recruitment would differ among fledglings fed lipid-rich or lipid-poor fish during development. Here we show that diets low in lipids induce nutritional stress and impair cognitive abilities in young red-legged kittiwakes, Rissa brevirostris. Specifically, growth retardation, increased secretion of stress hormones and inferior ability to associate food distribution with visual cues were observed in individuals fed lipid-poor diets. We conclude that lipid-poor diets during development affect the quality of young seabirds, which is likely to result in their increased mortality and low recruitment. ?? 2005 The Royal Society.

Proceedings of the Royal Society B: Biological Sci↗
USGS2003

Interacting effects of water temperature and swimming activity on body composition and mortality of fasted juvenile rainbow trout

Abstract: We assessed changes in proximate body composition, wet mass, and the occurrence of mortality among sedentary and actively swimming (15 cm/s) juvenile rainbow trout (Oncorhynchus mykiss) (120-142 mm total length) that were held at 4.0, 7.5, or 15.0 ??C and fasted for 140 days. Warmer water temperatures and swimming activity accentuated declines in lipid mass, but they did not similarly affect lean mass and wet mass. Swimming fish conserved lean mass independent of water temperature. Because lean mass exceeded lipid mass, wet mass was not affected substantially by decreases in lipid mass. Consequently, wet mass did not accurately reflect the effects that water temperature and swimming activity had on mortality of fasted rainbow trout. Rather, lipid mass was more accurate in predicting death from starvation. Juvenile rainbow trout survived long periods without food, and fish that died of starvation appeared to have similar body composition. It appears that the ability of fish to endure periods without food depends on the degree to which lipid mass and lean mass can be utilized as energy sources.

Canadian Journal of Zoology↗
USGS2000

Physiological status of naturally reared juvenile spring chinook salmon in the Yakima River: Seasonal dynamics and changes associated with smolting

Two year-classes of juvenile spring chinook salmon Oncorhynchus tshawytscha from the Yakima River, Washington, were sampled from July (3-4 months postemergence) through May (yearling smolt out-migration). Physiological characters measured included liver glycogen, body lipid, gill Na+-K+ ATPase, plasma thyroxine (T4), and plasma insulin-like growth factor-I (IGF-I). Distinct physiological changes were found that corresponded to season. Summer and fall were characterized by relatively high body lipid and condition factor. Winter was characterized by decreases in body lipid, condition factor, and plasma hormones. An increase in condition factor and body lipid was found in February and March. Finally, April and May were characterized by dramatic changes characteristic of smolting, including increased gill Na+-K+ ATPase activity, plasma T4, and IGF-I and decreased condition factor, body lipid, and liver glycogen. These results create a physiological template for juvenile spring chinook salmon in the drainage that provides a baseline for comparison with other years, populations, and life history types. In addition, this baseline provides a standard for controlled laboratory experiments and a target for fish culturists who rear juvenile spring chinook salmon for release from conservation hatcheries. The implications of these results for juvenile chinook salmon ecology and life history are discussed.

Washington↗
USGS2004

Patterns of variation in clutch sizes in a guild of temperate-nesting dabbling ducks

Clutch sizes of temperate-nesting dabbling ducks vary widely within and between years. Biologists have long been interested in why such patterns exist but have had difficulty separating intrinsic effects from environmental influences. In an attempt to gain greater insight into the roles of intrinsic and environmental influences on clutch sizes of dabbling ducks, we compared clutch-size patterns of mallard, northern pintail, gadwall, northern shoveler, and blue-winged teal in North Dakota and South Dakota over a 3-year period. The study was conducted during 1993-1995 when wetland habitat conditions were exceptionally consistent within time intervals but varied widely from the onset to the end of the study. We found that clutch sizes of gadwall and blue-winged teal were significantly smaller at the onset of nesting in 1993, when water conditions remained relatively poor following a 5-year drought (1988-1992), and pintail clutch sizes were larger late in the breeding season in 1993 after wetland conditions became exceptionally productive following heavy rains in late May and June. These findings were associated with gadwall and teal relying primarily on nutrients acquired on the breeding grounds to produce early clutches, and pintails using an exceptionally high proportion of their body lipids to produce early clutches, making this species highly dependent on abundant local sources of lipids for clutches produced later. Mallard, pintail, and shoveler rely largely on endogenous lipids carried to the breeding grounds to produce early clutches, and at least in the years of study, clutch sizes exhibited minimal variation at the onset of nesting. Our findings, when examined in context with existing information, suggest that interspecific variation in clutch sizes results from innate differences in several traits -- including body size, diet, timing of lipid acquisition, and nesting-- that affect the amount of lipid available for egg production. Annual differences in clutch sizes of all five species were not significant when effects of annual variation in nest initiation dates was accounted for, reflecting the key role of environmental influences on intraspecific variation among years.

The Auk↗
USGS2008

Thiamine and fatty acid content of Lake Michigan Chinook salmon

Nutritional status of Lake Michigan Chinook salmon (Oncorhynchus tshawytscha) is inadequately documented. An investigation was conducted to determine muscle and liver thiamine content and whole body fatty acid composition in small, medium and large Chinook salmon. Muscle and liver thiamine concentrations were highest in small salmon, and tended to decrease with increasing fish size. Muscle thiamine was higher in fall than spring in large salmon. The high percentage of Chinook salmon (24-32% in fall and 58-71% in spring) with muscle thiamine concentration below 500 pmol/g, which has been associated with loss of equilibrium and death in other Great Lake salmonines, suggest that Chinook appear to rely less on thiamine than other Great Lakes species for which such low concentrations would be associated with thiamine deficiency (Brown et al. 2005b). A positive correlation was observed between liver total thiamine and percent liver lipids (r = 0.53, P < 0.0001, n = 119). In medium and large salmon, liver lipids were observed to be low in fish with less than 4,000 pmol/g liver total thiamine. In individuals with greater than 4,000 pmol/g liver thiamine, liver lipid increased with thiamine concentration. Individual fatty acids declined between fall and spring. Essential omega-3 fatty acids appear to be conserved as lipid content declined. Arachidonic acid (C20:4n6), an essential omega-6 fatty acid was not different between fall and spring, although the sum of omega-6 (Sw6) fatty acids declined over winter. Elevated concentrations of saturated fatty acids (sum) were observed in whole body tissue lipid. In summary, thiamine, a dietary essential vitamin, and individual fatty acids were found to vary in Lake Michigan Chinook salmon by fish size and season of the year.

Journal of Great Lakes Research↗
USGS2020

Winter carry-over effects on spring body condition driven by agricultural subsidies to Lesser Snow Geese (Anser caersulscens caerulescens)

Anthropogenic changes to landscapes associated with intensive agriculture often have deleterious effects on avian abundance. However, some species like the Lesser Snow Goose ( Anser caerulescens caerulescens ), can benefit from increases in agricultural crops on both wintering and migratory stopover sites. We investigated the influence of winter habitat use on spring body condition in Lesser Snow Goose, a species that has increased in population following expansion into agriculturally based winter habitats. We used stable isotope measurements of four elements (δ 2 H, δ 13 C, δ 15 N, and δ 34 S) to determine likely prior winter habitat use of snow geese collected during spring migration across Arkansas, Missouri, and Nebraska in 2016. We evaluated differences in body size, lipid, and protein reserves from individuals with isotope values that suggested winter habitat use in traditional coastal marsh and non-coastal /agriculture habitat. Inferred winter habitat influenced total body lipid levels in snow geese collected during spring migration. Adult and juvenile individuals inferred to have overwintered in coastal marsh (n = 60) had, on average, 33.4 g (95% Confidence Interval: 0.4 g, 66.4 g) less lipid than counterparts wintering in non-coastal / agricultural habitat (n = 77). Waterfowl foods found in marshes typically have low true metabolizable energy values as a consequence of their high fiber content, which likely increases daily consumption rates. Increased energy expenditure related to greater time spent foraging, paired with lower energetic rewards, may result in lower lipid reserves among geese using coastal marsh habitats compared to birds using agricultural landscapes. Consequently, carry-over effects based on winter habitat use could explain variation in lipid reserves among individuals during spring migration and may ultimately explain differential fitness rates or susceptibility to harvest. Our results have implications for the conservation and management of this species as historic wetland landscapes become more intensively converted and used for agricultural purposes.

Arkansas, Missouri, Nebraska↗
USGS2009

Effects of egg order on organic and inorganic element concentrations and egg characteristics in tree swallows, tachycineta bicolor

The laying order of tree swallow eggs was identified from the Housatonic River, Berkshire County, Massachusetts, USA, and eggs were chemically analyzed individually to document possible effects of laying order on organic contaminant and inorganic element concentrations. Effects of laying order on other parameters such as egg weight, size, and lipid and moisture content also were assessed. Some effects of egg order on total polychlorinated biphenyls (PCBs) were detected, but the effect was not uniform across individual females or between years. In 2004, clutches with higher total PCBs tended to have concentrations decline across egg order, whereas clutches with lower concentrations of PCBs tended to increase across egg order. In contrast, in 2005, there was a tendency for concentrations to increase across egg order. Polychlorinated biphenyl concentrations were highly variable within and among clutches in both years. The directionality of egg order associations (i.e., slopes) for trace elements was element dependent, was positive for Mn and Zn, was negative for B, and had no slope for Cr. Whole egg weight increased across egg order. Percentage lipid was variable within a clutch, with no pattern common across all females. Percentage lipid was also correlated with organic contaminant concentration. In highly contaminated environments, higher lipid content could have the unanticipated corollary of having higher concentrations of lipophilic contaminants such as PCBs. To reduce the effect of high variation within a clutch when assessing contamination exposure, it is recommended that two eggs per clutch be collected and pooled for chemical analysis. We further recommend that, as long as the two eggs are randomly collected, the additional effort needed to identify and collect specific eggs is not warranted.

Massachusetts↗
USGS2006

Nutritional condition of Pacific Black Brant wintering at the extremes of their range

Endogenous stores of energy allow birds to survive periods of severe weather and food shortage during winter. We documented changes in lipid, protein, moisture, and ash in body tissues of adult female Pacific Black Brant (Branta bernicla nigricans) and modeled the energetic costs of wintering. Birds were collected at the extremes of their winter range, in Alaska and Baja California, Mexico. Body lipids decreased over winter for birds in Alaska but increased for those in Baja California. Conversely, body protein increased over winter for Brant in Alaska and remained stable for birds in Baja California. Lipid stores likely fuel migration for Brant wintering in Baja California and ensure winter survival for those in Alaska. Increases in body protein may support earlier reproduction for Brant in Alaska. Predicted energy demands were similar between sites during late winter but avenues of expenditure were different. Birds in Baja California spent more energy on lipid synthesis while those in Alaska incurred higher thermoregulatory costs. Estimated daily intake rates of eelgrass were similar between sites in early winter; however, feeding time was more constrained in Alaska because of high tides and short photoperiods. Despite differences in energetic costs and foraging time, Brant wintering at both sites appeared to be in good condition. We suggest that wintering in Alaska may be more advantageous than long-distance migration if winter survival is similar between sites and constraints on foraging time do not impair body condition. ?? The Cooper Ornithological Society 2006.

Alaska, Baja California↗