SEARCH · USGS Science

Results for “Lipids”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

USGS2014

Energy demands for maintenance, growth, pregnancy, and lactation of female Pacific walruses ( Odobenus rosmarus divergens )

Decreases in sea ice have altered habitat use and activity patterns of female Pacific walruses Odobenus rosmarus divergens and could affect their energetic demands, reproductive success, and population status. However, a lack of physiological data from walruses has hampered efforts to develop the bioenergetics models required for fully understanding potential population-level impacts. We analyzed long-term longitudinal data sets of caloric consumption and body mass from nine female Pacific walruses housed at six aquaria using a hierarchical Bayesian approach to quantify relative energetic demands for maintenance, growth, pregnancy, and lactation. By examining body mass fluctuations in response to food consumption, the model explicitly uncoupled caloric demand from caloric intake. This is important for pinnipeds because they sequester and deplete large quantities of lipids throughout their lifetimes. Model outputs were scaled to account for activity levels typical of free-ranging Pacific walruses, averaging 83% of the time active in water and 17% of the time hauled-out resting. Estimated caloric requirements ranged from 26,900 kcal d−1 for 2-yr-olds to 93,370 kcal d−1 for simultaneously lactating and pregnant walruses. Daily consumption requirements were higher for pregnancy than lactation, reflecting energetic demands of increasing body size and lipid deposition during pregnancy. Although walruses forage during lactation, fat sequestered during pregnancy sustained 27% of caloric requirements during the first month of lactation, suggesting that walruses use a mixed strategy of capital and income breeding. Ultimately, this model will aid in our understanding of the energetic and population consequences of sea ice loss.

Physiological and Biochemical Zoology↗

USGS2000

Effects of water conditions on clutch size, egg volume, and hatchling mass of mallards and gadwalls in the Prairie Pothole Region

We examined the relationship between local water conditions (measured as the percent of total area of basins covered by water) and clutch size, egg volume, and hatchling mass of Mallards ( Anas platyrhynchos ) and Gadwalls ( A. strepera ) on four study sites in the Prairie Pothole Region of North Dakota and Minnesota, 1988–1994. We also examined the relationship between pond density and clutch size of Mallards and Gadwalls, using data collected at another North Dakota site, 1966–1981. For Mallards, we found no relationships to be significant. For Gadwalls, clutch size increased with percent basin area wet and pond density; hatchling mass marginally increased with percent basin area wet. These species differences may reflect, in part, that Mallards acquire lipid reserves used to produce early clutches before they reach the breeding grounds, whereas Gadwalls acquire lipid reserves locally; thus Gadwall clutches are more likely to be influenced by local food resources.

Minnesota, North Dakota↗

USGS1957

The nutrition of salmonid fishes. I. Chemical and histological studies of wild and domestic fish

Salmonids reared under artificial conditions show marked consistent differences in body composition in comparison with wild salmonids. Protein and mineral levels are lower and lipid values are higher in hatchery fish than in wild fish. As the period of artificial rearing is increased, these differences become more extreme. In hatchery fish, there is generally more microscopically visible fat in the liver and viscera than in these organs in wild fish although extremes are seen in both groups. In young hatchery fish and in wild fish, there is no correlation between fat deposition in the liver and in the pancreas, but in older hatchery fish, both of these organs are fatty and there is a simultaneous increase in total body lipid. In wild fish, ceroid deposition is greater, suggesting that the fatty acids are more highly unsaturated. There is little difference in disease incidence between the two groups, but parasitism is more pronounced in wild fish. The significant variables between wild and artificially produced fish appear to be limited to diet and environment. From the factors discussed above, diet alone is probably the most important single factor in producing the changes observed in body composition.

Alaska, British Columbia, California, Oregon, Wash↗

USGS2014

Habitat coupling in a large lake system: delivery of an energy subsidy by an offshore planktivore to the nearshore zone of Lake Superior

1. We hypothesised that the autumn spawning migration of Lake Superior cisco ( Coregonus artedi ) provides a resource subsidy, in the form of energy-rich cisco eggs, from the offshore pelagic to the nearshore benthic community over winter, when alternate prey production is likely to be low. 2. We tested this hypothesis using fish and macroinvertebrate surveys, fish population demographics, diet and stable isotope analyses, and bioenergetics modelling. 3. The benthic, congeneric lake whitefish ( C. clupeaformis ) was a clear beneficiary of cisco spawning. Cisco eggs represented 16% of lake whitefish annual consumption in terms of biomass, but 34% of energy (because of their high energy density: >10 kJ g wet mass −1 ). Stable isotope analyses were consistent with these results and suggest that other nearshore fish species may also rely on cisco eggs. 4. The lipid content of lake whitefish liver almost doubled from 26 to 49% between November and March, while that of muscle increased from 14 to 26% over the same period, suggesting lake whitefish were building, rather than depleting, lipid reserves during winter. 5. In the other Laurentian Great Lakes, where cisco populations remain very low and rehabilitation efforts are underway, the offshore-to-nearshore ecological link apparent in Lake Superior has been replaced by non-native planktivorous species. These non-native species spawn in spring have smaller eggs and shorter incubation periods. The rehabilitation of cisco in these systems should reinstate the onshore subsidy as it has in Lake Superior.

Wisconsin↗

USGS2004

Oxidative stress in juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum)

Juvenile chinook salmon, Oncorhynchus tshawytscha (Walbaum), were held in 8-11??C freshwater, starved for 3 days and subjected to a low-water stressor to determine the relationship between the general stress response and oxidative stress. Lipid peroxidation (LPO) levels (lipid hydroperoxides) were measured in kidney, liver and brain samples taken at the beginning of the experiment (0-h unstressed controls) and at 6, 24 and 48 h after application of a continuous low-water stressor. Tissue samples were also taken at 48 h from fish that had not been exposed to the stressor (48-h unstressed controls). Exposure to the low-water stressor affected LPO in kidney and brain tissues. In kidney, LPO decreased 6 h after imposition of the stressor; similar but less pronounced decreases also occurred in the liver and brain. At 48 h, LPO increased (in comparison with 6-h stressed tissues) in the kidney and brain. In comparison with 48-h unstressed controls, LPO levels were higher in the kidney and brain of stressed fish. Although preliminary, results suggest that stress can cause oxidative tissue damage in juvenile chinook salmon. Measures of oxidative stress have shown similar responses to stress in mammals; however, further research is needed to determine the extent of the stress-oxidative stress relationship and the underlying physiological mechanisms in fish.

Aquaculture Research↗

USGS2013

Remote biopsy darting and marking of polar bears

Remote biopsy darting of polar bears ( Ursus maritimus ) is less invasive and time intensive than physical capture and is therefore useful when capture is challenging or unsafe. We worked with two manufacturers to develop a combination biopsy and marking dart for use on polar bears. We had an 80% success rate of collecting a tissue sample with a single biopsy dart and collected tissue samples from 143 polar bears on land, in water, and on sea ice. Dye marks ensured that 96% of the bears were not resampled during the same sampling period, and we recovered 96% of the darts fired. Biopsy heads with 5 mm diameters collected an average of 0.12 g of fur, tissue, and subcutaneous adipose tissue, while biopsy heads with 7 mm diameters collected an average of 0.32 g. Tissue samples were 99.3% successful (142 of 143 samples) in providing a genetic and sex identification of individuals. We had a 64% success rate collecting adipose tissue and we successfully examined fatty acid signatures in all adipose samples. Adipose lipid content values were lower compared to values from immobilized or harvested polar bears, indicating that our method was not suitable for quantifying adipose lipid content.

Marine Mammal Science↗

USGS2010

Influence of fish oils in production catfish feeds on selected disease resistance factors

Healthy channel calfish, Ictalurus punctatus (mean weight: 62.5g), were fed two production feeds that were identical except for the lipid portion, which was either catfish oil or menhaden oil. Fish were held at 18 or 28°C and fed the experimental feeds for four monlhs. A subsample of fish from each of the four treatments was then used to measure scrum antibody titers to Edwardsiella ictaluri , macrophage phagocytic index, phagocytic capacity, and production of intracellular and extracellular superoxide anion. The remaining fish were vaccinated with an E. icraluri bacterin, held for 18-24 days, and the assays were repeated. Fatty acid profiles of the diets indicated catfish oil had a higher percentage of monounsaturated fatty acids and slightly higher n-6 fatty acids. The menhaden oil diet had a higher percentage of the n-3 fatty acids. At 28°C, weight gain and feed conversion were slightly higher in calfish fed the feed containing menhaden oil. Weight gains and feed conversion were similar in fish maintained on the two feeds at 18°C. At the lower temperature, fish fed the diet containing menhaden oil appeared to have enhanced disease resistance factors, particularly phagocytic capacity. However, at 28°C, fish fed the diet containing catfish oil had enhanced phagocytic ability and intracellular superoxide production. Antibody titers were not sigmficantly (P > 0.05) affected by dietary lipid in this study. Vaccination amplified phagocytic ability in both diets at both temperatures and intensified the production of superoxide anion at 28°C.

Journal of Applied Aquaculture↗

USGS2025

The importance of method selection when estimating diet composition with quantitative fatty acid signature analysis

Quantitative fatty acid signature analysis (QFASA) is a common method of estimating the composition of prey species in the diets of consumers from polar and temperate ecosystems in which lipids are an important source of energy. A key characteristic of QFASA is that the large number of fatty acids that typically comprise lipids permits the dietary contributions of a correspondingly large number of prey types to be estimated. Several modifications to the original QFASA methods have been suggested in the literature and a significant extension of the original model published in 2017 allows simultaneous estimation of both diet proportions and calibration coefficients, which are metabolic constants in the model whose values must otherwise be estimated in independent feeding experiments. However, comparisons of diet estimates obtained using different estimation options have been limited. QFASA has been used to estimate the diet composition of several polar bear ( Ursus maritimus ) subpopulations, including the Southern Beaufort Sea (SBS) subpopulation. Prior QFASA estimates of SBS polar bear diet composition have most often been obtained using variations of the original QFASA model. We investigated the influence of variations in QFASA analytical methods on diet estimates by re-estimating the diet composition of polar bears from the Alaska portion of the SBS using three different methods and found that differences among the three sets of estimates were substantial. Our results illustrate how important the careful and deliberate selection of QFASA methods can be and we provide some guidance on techniques one might use to evaluate options.

PLoS ONE↗

USGS2008

Nutrient-reserve dynamics during egg production by female Greater Scaup (Aythya marila): Relationships with timing of reproduction

We studied nutrient-reserve dynamics of female Greater Scaup ( Aythya marila ) to quantify intraspecific strategies of nutrient acquisition for egg production, particularly in relation to the seasonal timing of reproduction (i.e., date of initiation of rapid follicle growth [RFG]). We collected female Greater Scaup on the Yukon-Kuskokwim Delta, Alaska, from arrival through clutch formation during the 2002 and 2003 breeding seasons, and we subsequently conducted standard proximate body-composition analysis. Endogenous lipid, protein, and mineral reserve levels did not decline during egg production. This result differs from most other nutrient-reserve studies of waterfowl, suggesting that female Greater Scaup rely on exogenous food resources, rather than endogenous nutrient reserves, to meet the energy and nutrient costs of clutch formation. Furthermore, endogenous nutrient-reserve levels did not decline with date of RFG initiation, which indicates that body condition at initiation of egg production was similar across the nesting season. We found evidence of nutrient-reserve thresholds for initiation of RFG, in that lipid, protein, and mineral reserves were smaller in nonreproductive than in reproductive females. In light of recent conservation concerns over declining North American scaup populations, our data contrast with nutrient-reserve dynamics described for Lesser Scaup ( A. affinis ).

The Auk↗

USGS1984

Determining fat digestibility in trout using a metabolic chamber

Fat digestibilities were determined in rainbow trout utilizing a metabolism chamber. Separate and quantitative fecal extracts were freeze dried and total lipids were extracted. Lipid digestibilities were comparable to those obtained by other methods (85‐91%). This method avoids problems due to leaching and the variable of accelerated passage through the gut encountered in other methods.

Progressive Fish-Culturist↗

USGS1995

Apparent digestibility coefficients of carbohydrates for white sturgeon

Apparent digestibility coefficients (ADCs) were determined for white sturgeons ( Acipenser transmontanus ) fed purified diets containing different carbohydrates. White sturgeons were fed, at a rate of 1.0% body weight!d, diets containing one of nine carbohydrates, and feces were collected by manual stripping following a 2‐week feeding period; chromium sesquioxide (Cr 2 O 3 ) was used as an external indicator. The ADCs of carbohydrates, lipid, and protein were significantly affected ( P < 0.05) by carbohydrate source. The ADCs of carbohydrates ranked as follows: glucose, galactose, and maltose > dextrin > fructose and sucrose > lactose and raw corn starch > cellulose. Inclusion of dietary fructose and lactose significantly reduced lipid digestibility ( P < 0.05). Although protein indigestibility was significantly affected, all ADCs were greater than 92%.

Progressive Fish-Culturist↗

USGS1996

First-year growth, recruitment, and maturity of walleyes in western Lake Erie

In some lakes, first-year growth of walleyes Stizostedion vitreum has been identified as an important factor governing recruitment of juveniles to the adult population. We developed a regression model for walleye recruitment in western Lake Erie by considering factors such as first-year growth, size of the spawning stock, the rate at which the lake warmed during the spring, and abundance of gizzard shad Dorosoma cepedianum . Gizzard shad abundance during the fall prior to spring walleye spawning explained over 40% of the variation in walleye recruitment. Gizzard shad are relatively high in lipids and are preferred prey for walleyes in Lake Erie. Therefore, the high degree of correlation between shad abundance and subsequent walleye recruitment supported the contention that mature females needed adequate lipid reserves during the winter to spawn the following spring. According to the regression analysis, spring warming rate and size of the parental stock also influenced walleye recruitment. Our regression model explained 92% of the variation in recruitment of age-2 fish into the Lake Erie walleye population from 1981 to 1993. The regression model is potentially valuable as a management tool because it could be used to forecast walleye recruitment to the fishery 2 years in advance. First-year growth was poorly correlated with recruitment, which may reflect the unusually low incidence of walleye cannibalism in western Lake Erie. In contrast, first-year growth was strongly linked to age at maturity.

Transactions of the American Fisheries Society↗

USGS2003

Characterizing aquatic health using salmonid mortality, physiology, and biomass estimates in streams with elevated concentrations of arsenic, cadmium, copper, lead, and zinc in the Boulder River Watershed, Montana

Abandoned tailings and mine adits are located throughout the Boulder River watershed in Montana. In this watershed, all species of fish are absent from some tributary reaches near mine sources; however, populations of brook trout Salvelinus fontitalis , rainbow trout Oncorhynchus mykiss , and cut-throat trout O. clarki are found further downstream. Multiple methods must be used to investigate the effects of metals released by past mining activity because the effects on aquatic life may range in severity, depending on the proximity of mine sources. Therefore, we used three types of effects—those on fish population levels (as measured by survival), those on biomass and density, and those at the level of the individual (as measured by increases in metallothionein, products of lipid peroxidation, and increases in concentrations of tissue metals)—to assess the aquatic health of the Boulder River watershed. Elevated concentrations of Cd, Cu, and Zn in the water column were associated with increased mortality of trout at sites located near mine waste sources. The hypertrophy (swelling), degeneration (dying), and necrosis of epithelial cells observed in the gills support our conclusion that the cause of death was related to metals in the water column. At a site further downstream (lower Cataract Creek), we observed impaired health of resident trout, as well as effects on biomass and density (measured as decreases in the kilograms of trout per hectare and the number per 300 m) and effects at the individual level, including increases in metallothionein, products of lipid peroxidation, and tissue concentrations of metals.

Transactions of the American Fisheries Society↗

USGS1993

Effects of diet and environmental salinity on the growth, mortality, and tissue structure of juvenile striped bass

Juvenile striped bass Morone saxatilis (approximately 60 d old) were fed either a commercial trout feed or an open-formula salmon feed for 16 weeks and reared in 24°C fresh water or saline water prepared from sodium chloride or synthetic sea salt. Fish that were fed salmon feed were larger, contained higher levels of body lipid, and had livers with uniform glycogen vacuolation. Fish that were fed trout feed were smaller, contained less body lipid, and had necrotic liver tissue. More than 95% of the fish fed the trout feed and reared in water containing sodium chloride at 10‰ salinity died within the first 2 weeks. Mortality of fish fed the salmon feed under the same rearing conditions was 3% in 2 weeks. An osmoregulatory dysfunction from an imbalance of environmental calcium and sodium is suggested as the cause of the mortality. Although no definitive cause was established for the diet-related histological changes in the livers of fish that were fed the trout feed, type and level of dietary essential fatty acids are suspected

Journal of Aquatic Animal Health↗

USGS2000

Observations of health indices used to monitor a tailwater trout fishery

Health of the population of rainbow trout Oncorhynchus mykiss in the San Juan River tailwater was monitored to determine the effects of potential crowding from a reduced winter flow test at Navajo Dam, northwestern New Mexico. A systematic necropsy-based health profile provided a rapid method to detect gross changes in the health of the fish population. The health assessment index (HAI) was calculated to quantify the necropsy system and allow statistical comparisons of data sets. Other suborganismic indices were selected to encompass a range of responses specific to the stress of environmental alterations: physiology assessment using total protein and percent muscle lipids, an immune assessment using serum lysozyme, and a cellular-based evaluation using histology. The HAI values showed no clear trend in fish health, although significant differences occurred among fish samples during the test. Significant declines in condition factors and percent muscle lipids throughout the study suggested a seasonal effect. Total protein and lysozyme levels were variable, showing no discernible patterns. Most histological observations appeared to be incidental during the study. Although there was no clear demonstrable effect of altered flow on fish health, this study revealed the sensitivities of various health indicators, which may help in designing future studies and supporting or interpreting results using these approaches.

New Mexico↗

USGS2005

Effectiveness of egg immersion in aqueous solutions of thiamine and thiamine analogs for reducing early mortality syndrome

Protocols used for therapeutic thiamine treatments in salmonine early mortality syndrome (EMS) were investigated in lake trout Salvelinus namaycush and coho salmon Oncorhynchus kisutch to assess their efficacy. At least 500 mg of thiamine HCl/L added to egg baths was required to produce a sustained elevation of thiamine content in lake trout eggs. Thiamine uptake from egg baths was not influenced by a pH ranging from 5.5 to 7.5 or by a water hardness between 2 and 200 mg CaCO3/L. There was poorer thiamine uptake when initial thiamine levels were low, suggesting that current treatment regimes may not be as effective when thiamine levels are severely depressed and that higher treatment doses are necessary. Exposure of eggs to the more lipid-soluble thiamine analog allithiamine (1,000 mg/L) during water hardening increased egg thiamine levels by 1.5-2.5 nmol/g and was completely effective at reversing EMS. Another more lipid-soluble thiamine analog, benfotiamine (100 mg/L), reduced EMS but did not produce detectable increases in egg thiamine content. Although benfotiamine may be more effective than thiamine at mitigating EMS, it is more expensive than thiamine HCl or allithiamine. In addition, there still needs to be a more thorough examination of dose-response relationships. We conclude that allithiamine is an alternative to the use of thiamine in egg baths as a therapeutic treatment for salmonid EMS. ?? Copyright by the American Fisheries Society 2005.

Journal of Aquatic Animal Health↗

USGS2005

Thiamine content and thiaminase activity of ten freshwater stocks and one marine stock of alewives

Alewives Alosa pseudoharengus contain thiaminase activity that has been implicated in the development of a thiamine deficiency and associated effects in salmonines of the Great Lakes basin. Little is known about the factors that regulate thiaminase activity in alewives. We sampled alewives of uniform size (60-120 mm) during the summer of 1998 from the Gulf of St. Lawrence, seven of New York's Finger Lakes, one inland lake in Ontario, and two Great Lakes to assess possible relationships among thiamine, lipid content, fish abundance, lake morphometry, lake productivity, freshwater residency, and thiaminase activity. Thiaminase activity varied significantly among the 11 locations but was unrelated to thiamine concentration, which did not vary significantly. Alewife thiaminase activity in the Finger Lakes was negatively related to lipid content and positively related to measures of lake size (e.g., area, volume, and maximum depth). Activity in the one marine stock sampled in the Gulf of St. Lawrence was comparable to the highest values observed in the 10 freshwater stocks examined. Variation in alewife thiaminase activity has the potential to affect the extent of a thiamine deficiency associated with salmonines who feed on alewives as well as the viability of their offspring.

Big Rideau Lake, Finger Lakes, Gulf of St. Lawrenc↗

USGS2000

Effects of water conditions on clutch size, egg volume, and hatchling mass of mallards and gadwalls in the Prairie Pothole Region

We examined the relationship between local water conditions (measured as the percent of total area of basins that was covered by water) and clutch size, egg volume, and hatchling mass of Mallards (Anas platyrhynchos) and Gadwalls (A. strepera) on four study sites in the Prairie Pothole Region of North Dakota and Minnesota, 1988-1994. We also examined the relationship between pond density and clutch size of Mallards and Gadwalls, using data collected at another North Dakota site, 1966-1981. For Mallards, we found no relationships to be significant. For Gadwalls, clutch size increased with percent basin area wet and pond density; hatchling mass marginally increased with percent basin area wet. These species differences may reflect, in part, that Mallards acquire lipid reserves used to produce early clutches before they reach the breeding grounds, whereas Gadwalls acquire lipid reserves locally; thus Gadwall clutches are more likely to be influenced by local food resources.

Condor↗