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At least 469 records · Page 26Linked to original sources
USGS2016

Adult nest attendance and diet of nestling Resplendent Quetzals (Pharomachrus mocinno) in the Talamanca Mountains of southern Cosa Rica

Resplendent Quetzals ( Pharomachrus mocinno ) inhabit mid to high elevation forests from southern Mexico to Panama. Lipid rich fruits from the Lauraceae family have been found to account for a large proportion of adult diet across their annual life cycle. To better understand the relationship between quetzals and Lauraceae during the breeding season, we studied food deliveries to nestlings in the Talamanca Mountains at San Gerardo de Dota, Costa Rica in the Rio Savegre watershed. Our study had four primary objectives: 1) determine parental contribution of males and females feeding nestling quetzals, 2) determine type of food delivered to nestling quetzals, 3) determine if deliveries of fruit items were related to their abundance and/or nutritional content and 4) determine if Lauraceae fruits made up a large proportion of nestling diets based on the high preference quetzals have displayed for fruits from this plant family. Hourly delivery rates were similar for the male and female (1.24 ± 0.68 and 1.44 ± 0.84). During the first 6 days, the largest proportion of the diet was animal prey; primarily lizards and beetles. After day 6, fruit rapidly became the dominant food item delivered to nestlings until fledging. The dominant number of fruits delivered to nestling quetzals were fruits from the Lauraceae family and included Ocotea holdrigeiana , Necatandra cufodontisii , and Aiouea costaricensis . All three had some of the highest protein and lipid content of all fruits delivered to nestlings. O. holdrigeiana had the highest protein and lipid content of all fruits delivered, had the lowest relative abundance, and was delivered more frequently than all other fruits. Conservation strategies for this species should take into account not just increasing available habitat, but also increasing habitat quality by focusing on species composition to provide abundant food plants for the Resplendent Quetzal to forage.

Ornitologia Neotropical↗
USGS2009

Food supplies of stream-dwelling salmonids

Much is known about the importance of the physical characteristics of salmonid habitat in Alaska and the Pacific Northwest, with far less known about the food sources and trophic processes within these habitats, and the role they play in regulating salmonid productivity. Freshwater food webs supporting salmonids in Alaska rely heavily on nutrient, detritus and prey subsidies from both marine and terrestrial ecosystems. Adult salmon provide a massive input of marine biomass to riverine ecosystems each year when they spawn, die, and decompose, and are a critical food source for young salmon in late summer and fall; riparian forests provide terrestrial invertebrates to streams, which at times comprise over half of the food ingested by stream-resident salmonids; and up-slope, fishless headwater streams are a year-round source of invertebrates and detritus for fish downstream. The quantity of these food resources vary widely depending on source, season, and spatial position within a watershed. Terrestrial invertebrate inputs from riparian habitats are generally the most abundant food source in summer. Juvenile salmonids in streams consume roughly equal amounts of freshwater and terrestrially-derived invertebrates during most of the growing season, but ingest substantial amounts of marine resources (salmon eggs and decomposing salmon tissue) when these food items are present. Quantity, quality, and timing of food resources all appear to be important driving forces in aquatic food web dynamics, community nutrition, and salmonid growth and survival in riverine ecosystems.

Conference Paper↗
USGS1937

Disease relationship of domestic stock and wildlife

From the time that western civilization established itself on the North American continent until very recent years, little thought was given to the diseases, or other forms of loss, in game. In the process of bringing civilization and the incidental domestic arts and trades to the United States it appears to have been the policy to establish domestic farm stock on the land just as abundantly as the carrying capacity of land would tolerate. And judged by the low quality of many of our present farm animals, it is evident that in many cases the land was, and is now, overstocked and undermanaged. In traveling over this country one is impressed by the lack of uniformity, imperfect physical development, and poor state of nutrition of much of the domestic livestock. It would appear that the wild animals unhampered by fencing and other restraint such as controlled mating, feed selection, and enforced habitat in contaminated or polluted environment, have a better chance for perfect growth and complete development to a size and proportion normal for those species. While all of the factors mentioned produce a definitely deleterious result on the welfare of animal life, that of contaminated or polluted environment is by no means the least. The stunting action of disease on the growth of the young is too well known to admit of controversy. The impairment of function of vital organs due to minute cellular changes resulting from sub-acute or chronic infections prevents normal growth. Through centuries of enforced survival in densely congested pastures, pens, and stables, a certain degree of acquired resistance to many diseases has been built up in farm stock. If it were not so, very few barnyard animals would ever survive the conditions generally seen in our agricultural districts. Manure heaps, quantities of partly spoiled feed, and decaying masses of vegetation and refuse have come to be regarded as a natural part of the barnyard scene.

Conference Paper↗
USGS2019

Energy intake rate influences survival of Black Oystercatcher Haematopus bachmani broods

Black Oystercatchers Haematopus bachmani, a species of conservation concern, depend on marine intertidal prey resources. We examined diet, feeding rates, growth, and survival of Black Oystercatcher broods in southcentral Alaska, 2013-2014. To determine the importance of diet on brood survival, we modeled daily survival rates of broods as a function of energy intake rate and other ecological factors. We hypothesized that broods fed at higher energy intake rates would grow faster and fly earlier, thereby being less vulnerable to predators and having higher rates of survival. Consistent with our prediction, broods with higher energy intake rates had higher rates of growth and daily survival. The best-supported model indicated that brood survival varied by energy intake rate and brood age. To understand how adults meet the increasing nutritional needs of developing chicks, we examined delivery rates and prey type and size as a function of brood age. Delivery rates differed by age, but composition and size classes of prey items did not, indicating that adults respond to the rising energetic needs of broods by increasing parental effort rather than switching prey. These findings demonstrate the importance of diet and provisioning to broods and given the consequences of reduced energy intake on survival, indicate that shifts in intertidal invertebrates as a result of climate change could have significant impacts on Black Oystercatcher populations.

Alaska↗
USGS2021

Monitoring the recovery of seabirds and forage fish following a major ecosystem disruption in Lower Cook Inlet

Following the North Pacific marine heatwave of 2014-2016 and associated extreme die-off of seabirds in the winter of 2015-2016, we repeated historical marine bird and forage fish surveys around two seabird colonies (Gull Island, Chisik Island) in lower Cook Inlet during 2016-2019 in order to document immediate and lingering impacts of the heatwave on resident fish and seabird populations. At sea, we conducted acoustic/trawl surveys for fish in near-colony areas, while simultaneously counting seabirds on survey transects. At colonies, we monitored bird numbers on whole colony censuses and population plot counts and assessed annual reproductive success of Black-legged Kittiwakes ( Rissa tridactyla ) and Common Murres ( Uria aalge ). Our studies suggest that impacts of the heatwave on seabirds and their forage base were severe and extended for several years beyond the heatwave itself. Although fish biomass indices were greatest in 2016-2017, the forage community was largely dominated by juvenile fish with low nutritional value following a collapse of key species of forage fish during the marine heatwave. Lowest fish biomass was observed in 2018, coincident with a marked decline in the at-sea abundance of many seabirds around colonies. By 2019 there were signs of improvement in prey abundance and quality, and significant aggregations of pre-spawning capelin and large sand lance were observed in and around Kachemak Bay. In comparison with historical (1996-1999) bird colony surveys, kittiwake population counts decreased by more than 70% at Chisik Island, and by 8-29% at Gull Island. Similarly, murre counts decreased at Chisik Island by 72% and by more than 20% at Gull Island. Kittiwakes had complete reproductive failure at Chisik Island from 2016-2018, with minimal success in 2019. At Gull Island, kittiwakes also failed in 2016 and 2018 but had unusually high productivity in 2017 and 2019. Murres also had complete reproductive failures at Chisik Island in all four years and at Gull Island during 2016, 2017 and 2018. Murres finally fledged chicks in 2019, albeit at about half the normal rate. Finally, we also observed unusually high levels of predator disturbance (egg predation, flushing adults from plots) and unprecedented numbers of adult birds in poor body condition (“skinny murres”), particularly in 2018. Together, these results indicate that an extreme disruption of marine food webs occurred during and after the heatwave. Given the prolonged reproductive failures, continued monitoring is required to assess continuing impacts and recovery from the 2014-2016 heatwave. For example, murre chicks that would have been produced in 2016 should, after 4-5 years away, start recruiting to the colony in 2021, and thereby replace aged adults that would have died naturally in the past year(s). Without such natal recruitment for at least the next 3-4 years, we should document a continuing decline in bird numbers at the colonies.

Alaska↗
USGS2021

Synthesis of data and studies relating to Delta Smelt biology in the San Francisco Estuary, emphasizing water year 2017

In the San Francisco Estuary (SFE), the effects of freshwater flow on the aquatic ecosystem have been studied extensively over the years and remains a contentious management issue. It is especially contentious with regards to the Delta Smelt (Hypomesus transpacificus), a species endemic to the SFE that has been listed as threatened under the Federal Endangered Species Act and endangered by the State of California. Early studies of Delta Smelt distribution within the SFE suggested that Delta Smelt habitat is determined largely by freshwater flow; however, the exact mechanisms and processes producing such benefits remained unclear. In the summer of 2017, the Flow Alteration Management, Analysis, and Synthesis Team (FLOAT-MAST) was established to analyze, synthesize, and summarize the data collected from the various flow-related monitoring and special studies occurring in 2017(see Table Intro 4). This report will focus on the 2017 summer-fall status of Delta Smelt and its habitat following a record wet year. There has been a long-term decline in the abundance of Delta Smelt associated with a decline in other pelagic fishes. Investigators concluded that the decline has likely been caused by the interactive effects of several causes, including changes in both physical and biotic habitats, many of which are tied to amount and timing of freshwater flow. For this report, we formulated a number of basic predictions about the likely effects of high flows in 2017 on Delta Smelt and their habitat (Table 3). We use a qualitative weight of evidence approach to evaluate whether these predictions were supported by available data. Data sources included a variety of long-term monitoring surveys conducted by Interagency Ecological Program (IEP) agencies, as well as model outputs. Delta Smelt population, health, and life history metrics rarely responded as predicted. Water temperature appears to have a stronger effect on Delta Smelt growth rate and some metrics of life history diversity than outflow or X2 position. Other life history diversity attributes varied but did not appear to be driven by outflow or temperature. Health status was difficult to interpret. Low prevalence of lesions and improved nutritional condition during the drought was contradicted by declining overall population levels. Because of the sparse catches of Delta Smelt in the post-POD years, we consider the data insufficient to reach firm conclusions about the predictions concerning range and distribution of Delta Smelt, especially in the fall. The prediction of high survival was not supported. The 2017 Delta Smelt year class began with poor recruitment in spring of 2017 and below average survival for spring to summer and summer to fall. Thus, low production and low survival led to low abundance of all life stages. During the fall to winter period survival improved, yet the resulting adults were low in number. Foraging success of the fish captured, as measured by stomach fullness, was high for juveniles and adults in 2017 relative to recent years associated with the higher densities of common zooplankton prey that occurred in 2017.

California↗
USGS2021

Modeling moose habitat use by age, sex, and season in Vermont, USA using high-resolution lidar and national land cover data

Moose ( Alces alces ) populations have experienced unprecedented declines along the southern periphery of their range, including Vermont, USA. Habitat management may be used to improve the status of the population and health of individuals. To date, however, Vermont wildlife managers have been challenged to effectively use this important tool due to the lack of fine-scale information on moose space use and habitat characteristics. To assess habitat use, we combined more than 40,000 moose locations collected from radio-collared individuals (n = 74), recent land cover data, and high resolution, 3-dimensional lidar ( light detection and ranging ) data to develop Resource Utilization Functions (RUF) by age (mature and young adult), season (dormant and growth), and sex. Each RUF linked home range use to average habitat conditions within 400 m or 1 km of each 30 m 2 pixel within the home range. Across analyses, the top RUF models included both composition (as measured through the National Land Cover Database) and structure (as measured through lidar) variables, and significantly outperformed models that excluded lidar variables. These findings support the notion that lidar is an effective tool for improving the ability of models to estimate patterns of habitat use, especially for larger bodied mammals. Generally speaking, female moose actively used areas with proportionally more regenerating forest (i.e., forage < 3.0 m) and more mature forest (i.e., canopy structure > 6.0 m), while males actively used more high elevation, mixed forest types. Further, moose exhibited important seasonal differences in habitat use that likely reflect temporal changes in energetic and nutritional requirements and behavior across the year. Moose used areas with proportionally more regenerating forest (i.e., forage < 3.0 m) during the growth period and female moose had strong positive associations with lidar-derived canopy structure during the growth (but not the dormant) period. Ultimately, the resultant maps of habitat use provide a means of informing management activities (e.g., the restoration or alteration of habitats to benefit moose) and policies around land use that may contribute to population recovery.

Vermont↗
USGS1974

Comparison of bacterial and phytoplankton populations under natural and laboratory conditions

Bacteria and blue-green algae were isolated from Oneida Lake, N.Y., and other sources. The blue-green algae Anabaena flos-aquae , Anabaena spiroides , Gloeotrichia echinulata , and Microcystis aeruginosa were grown under laboratory conditions and were separated into unialgal cultures. The bacterial population living in association with the unialgal blue-green algae differed significantly from the bacterial flora of Oneida Lake. Bacillus , Pseudomonas , Aeromonas , and Zoogloea were the most frequently occurring genera of bacteria from the lake, whereas Flavobacterium , Achromobacter , and Pseudomonas were the most common bacteria isolated from laboratory blue-green cultures. Nutritional and physiological characteristics of bacteria isolated in the laboratory were more uniform than those isolated from the lake.

Journal of Research of the U.S. Geological Survey↗
USGS2023

Camera trap distance sampling survey design, Andersen Airforce Base, Guam

Reliable population estimates of animal density is one of the most elementary needs for the control and management of wildlife, particularly for introduced ungulates on oceanic islands. On Guam, Philippine deer (Rusa marianna) and wild pigs (Sus scrofa; wild boar and descendants of domestic pigs) cause agricultural and ecological damage and are hunted for recreational, nutritional, and cultural uses. Most common population estimation methods are based on capture-recapture and related methods that require marking or uniquely identifying individuals. Capturing, marking, and either recapturing or resighting individuals repeatedly is labor intensive and expensive. In many situations marking or individually distinguishing animals is not feasible, necessitating estimating densities and abundance from unmarked animal populations. Motion-triggered camera traps are a relatively low-cost approach that can be used to generate presence/pseudo-absence and indices of relative abundance on multiple species simultaneously. We used distance sampling with camera traps to estimate deer and pig densities from non-independent observations of unmarked animals while accounting for imperfect detection where some present individuals are not detected. We present methods to (1) process the digital imagery data automatically for species detection and species categorization using a machine learning algorithm, (2) automatically estimate distance to detected species using a separate machine learning algorithm, and (3) estimate densities using distance sampling with camera trap methods. We compare accuracy statistics and results of ungulate densities estimated from automated methods to those estimated from manual assessment. We collected 7,695 videos: 381 videos contained deer and 377 contained pigs. The object detection and identification model performed well with overall accuracy above 80% and F1 scores above 0.9. The hazard-rate key detection function was chosen for deer and pigs based on Akaike’s information criterion accounting for overdispersion. Deer density estimates were 0.53 ± 0.20 deer/ha with higher density in the Plateau area than the Tarague area of Guam. Pig density estimates were 0.53 ± 0.32 pigs/ha, also with higher densities in the Plateau area than the Tarague area. Coefficients of variation ranged from 0.38 to 1.15, and greater numbers of camera traps would be required for pigs than deer to achieve desired coefficients of variation. On average, 101.9 ± 82.3 deer and 131.6 ± 118.8 pigs were detected per day. Microsite heterogeneity affected densities where orientation-specific estimates were less precise than estimates made with the full dataset. We developed a camera trap survey design based on standard camera trapping sampling protocols using motion-activated, digital cameras and determined that distance sampling methods using camera traps produce reliable densities of unmarked deer and pigs on Guam. Our camera trap survey design is based on a regularly sized trapping grid that is generalizable and can be expanded to survey other areas of Guam.

Guam↗
USGS2020

Changing nitrogen inputs to the northern San Francisco Estuary: Potential ecosystem responses and opportunities for investigation

Anthropogenic activities have resulted in elevated ambient nitrogen (N) and phosphorus (P) concentrations in many regions of the Sacramento-San Joaquin Delta and Suisun Bay (northern San Francisco Estuary, (nSFE). The Sacramento Regional wastewater treatment plant (SRWTP WWTP) currently acts as the largest N point source to the system, discharging 13,000-15,000 kg/d of ammonium-N (NH4) near the nSFE’s northeastern boundary. By end of 2021, SRWTP will complete major upgrades that will reduce its effluent dissolved inorganic nitrogen (DIN) loads by >65% and release the remaining DIN as predominantly nitrate (NO3). This major change in nitrogen inputs provides a unique opportunity to study ecosystem-scale responses to an altered nutrient regime. While, in general, the nSFE has not experienced some classic symptoms of nutrient over-enrichment typical in other estuaries—e.g., large phytoplankton blooms and hypoxia—other concerning nutrient- related impacts have been hypothesized, including: occurrence of harmful algal blooms (HABs) and the production of cyanotoxins; excessive growth of invasive aquatic vegetation; and declines in the abundance and nutritional quality of phytoplankton. These impacts have repercussions for the system’s food web, habitat quality, and the way we manage for transportation, recreation, water conveyance, and drinking water quality. This report develops and applies a framework for i) identifying and examining ecosystem response scenarios to the forthcoming decreased N loads; and ii) identifying opportunities, and constraints or considerations, for investigating those responses, including key data needs or knowledge gaps. Through applying this framework, we identify a set of plausible response scenarios, and evaluate the feasibility of studying or observing those responses along with key study considerations and data and knowledge gaps.

California↗
USGS2023

Birth rates and neonate survival in a parasite rich moose population in Vermont, USA

Moose ( Alces alces ) populations are declining across much of their southern geographic range in North America. In Vermont and other northeastern states, measurable declines are attributed to low calf survival and reduced productivity associated with persistent winter tick ( Dermacentor albipictus ) parasitism. In 2017–2020, we studied 75 radio-collared female moose (38 calves and 37 adults) in Vermont to examine physiological, spatial, and temporal parameters relative to calf survival and adult productivity. Physiological measures included concentration of fecal glucocorticoid metabolites (fGCM) which reflects stress, and urea nitrogen:creatinine ratios in urine (UN:C) which proxy nutritional state. The pregnancy rate at capture across years was 0.67 (95% CI = 0.50 – 0.80), and was negatively related to presence of lungworm ( Dictyocaulus spp.). The birth rate calculated as the average number of offspring delivered per adult female was <1.0 overall (2017–2020, LCI = 0.22, UCI = 0.86), similar across years, but increased with age. Logistic exposure models indicated that daily calf survival to 60 d increased as Julian birth date and days since birth increased (log odds = 0.0819, SE = 0.0215). The per capita independence rate, or rate that adult females add independent calves to the population, was negatively related to UN:C ratios and positively with fGCM. Further, this rate was related to autumnal habitat use of adult females; it was greater in home ranges characterized by large amounts of mature (canopy) evergreen forests and wetland habitats, and small amounts of mixed forests and elevation than in ranges with abundant levels of mixed forest at high elevation. We conclude that winter ticks can negatively affect moose fecundity, and efforts to reduce host (moose) density through harvest or parasite (host) abundance through habitat manipulation may improve productivity and recruitment in local moose populations.

Vermont↗
USGS2005

Diseases of amphibian eggs and embryos

Amphibians generally are prolific egg producers. In tropical and semi-tropical regions, deposition of eggs may occur year-round or may coincide with rainy seasons, while in temperate regions, deposition of eggs usually occurs immediately after emergence from hibernation. Numbers of eggs produced by each species may vary from a few dozen to thousands. Accordingly, some eggs may be infertile and wastage of embryos is to be expected. Fertility, viability and decomposition of eggs and embryos must be considered before it is assumed that diseases are present. An important consideration in the evaluation of egg masses is the fact that some will contain infertile and non-viable eggs. These infertile and nonviable eggs will undergo decomposition and they may appear similar to eggs that are infected by a pathogen. Evaluation of egg masses and embryos for the presence of disease may require repeated observations in a given breeding season as well as continued monitoring of egg masses during their growth and development and over successive breeding seasons. Amphibian eggs rarely are subjected to a comprehensive health (diagnostic) examination; hence, there is scant literature on the diseases of this life stage. Indeed, the eggs of some North American amphibians have yet to be described. Much basic physiology and normal biomedical baseline data on amphibian eggs is lacking. For example, it is known that the aquatic eggs of some species of shrimp quickly are coated by a protective and commensal bacterium that effectively impedes invasion of the eggs by other environmental organisms and potential pathogens. In the absence of this bacterium, shrimp eggs are rapidly killed by other bacteria and fungi (Green, 2001). The possibility that amphibian eggs also have important symbiotic or commensal bacteria needs to be investigated. Furthermore, the quantity and types of chemicals in the normal gelatinous capsules of amphibian eggs have scarcely been examined. Abnormalities of the female oviduct, either due to infectious disease, nutritional status, hormonal imbalances, or sublethal intoxications, could affect the quality of secreted gelatinous capsules on eggs, thus rendering an egg mass susceptible to other stressors. Diseases of amphibian eggs and embryos presented in this chapter are Lucke frog herpesvirus Ranavirus (iridovirus) infection Bacteria Watermold infection (saprolegniasis) Algae Microsporidia

Book chapter↗
USGS2014

Screening native botanicals for bioactivity: an interdisciplinary approach

Objective: Plant-based therapies have been used in medicine throughout recorded history. Information about the therapeutic properties of plants often can be found in local cultures as folk medicine is communicated from one generation to the next. The aim of this study was to identify native Louisiana plants from Creole folk medicine as a potential source of therapeutic compounds for the treatment of insulin resistance, type 2 diabetes, and related disorders. Methods: We used an interdisciplinary approach combining expertise in disciplines ranging from cultural anthropology and botany to biochemistry and endocrinology to screen native southwest Louisiana plants. Translation of accounts of Creole folk medicine yielded a list of plants with documented use in treating a variety of conditions, including inflammation. These plants were collected, vouchered, and catalogued before extraction of soluble components. Extracts were analyzed for bioactivity in regulating inflammatory responses in macrophages or fatty acid&ndash;induced insulin resistance in C2C12 skeletal muscle cells. Results: Several extracts altered gene expression of inflammatory markers in macrophages. Multiplex analysis of kinase activation in insulin-signaling pathways in skeletal muscle also identified a subset of extracts that alter insulin-stimulated protein kinase B phosphorylation in the presence of fatty-acid&ndash;induced insulin resistance. Conclusion: An interdisciplinary approach to screening botanical sources of therapeutic agents can be successfully applied to identify native plants used in folk medicine as potential sources of therapeutic agents in treating insulin resistance in skeletal muscle or inflammatory processes associated with obesity-related insulin resistance.

Louisiana↗
USGS2007

Construction and testing of a simple and economical soil greenhouse gas automatic sampler

Quantification of soil greenhouse gas emissions requires considerable sampling to account for spatial and/or temporal variation. With manual sampling, additional personnel are often not available to sample multiple sites within a narrow time interval. The objectives were to construct an automatic gas sampler and to compare the accuracy and precision of automatic versus manual sampling. The automatic sampler was tested with carbon dioxide (CO2) fluxes that mimicked the range of CO2 fluxes during a typical corn-growing season in eastern Nebraska. Gas samples were drawn from the chamber at 0, 5, and 10 min manually and with the automatic sampler. The three samples drawn with the automatic sampler were transferred to pre-vacuumed vials after 1 h; thus the samples in syringe barrels stayed connected with the increasing CO2 concentration in the chamber. The automatic sampler sustains accuracy and precision in greenhouse gas sampling while improving time efficiency and reducing labor stress. Copyright ?? Taylor & Francis Group, LLC.

Journal of Plant Nutrition↗
USGS2016

Prolonged stimulation of corticosterone secretion by corticotropin-releasing hormone in rats exhibiting high preference for dietary fat

Through the secretion of corticosterone, the hypothalamo-pituitary-adrenal (HPA) axis is thought to play an important role in the regulation of caloric intake and dietary fat preference. In an earlier study, we demonstrated a positive correlation between urinary corticosterone output and dietary fat preference. Furthermore, dietary fat preference was augmented following chronic but not acute hypercorticosteronemia produced by exogenous corticosterone administration. These observations led us to explore whether the HPA axis of rats exhibiting high preference for fat may have exaggerated sensitivity to corticotropin-releasing hormone (CRH). The results of these studies show a delayed and blunted but more prolonged corticosterone response to CRH in the fat-preferring rats compared with that of the carbohydrate-preferring rats.

Nutritional Neuroscience↗
USGS1971

Visceral granuloma in brook trout (Salvelinus fontinalis)

Brook trout were fed a synthetic diet with suspect diet components added or a meat-meal diet with individual components removed to determine their effect on the incidence of visceral granuloma. Removal or addition of cottonseed meal had the greatest effect on incidence. Gossypol was not the causative agent. The disease is characterized, histologically, by the presence of Langhans-type giant cells and concretions like Schaumann bodies giving an apparent similarity to sarcoidosis in humans. Gross symptoms of the disease are papillary growths of connective tissue on the serosal surface of the stomach, and calcification of the posterior kidney. In severe cases, lesions may be present throughout the visceral mass. Visceral granuloma is similar to nephrocalcinosis in rainbow trout and may be the same disease modified by difference in species response.

Journal of Nutrition↗
USGS1974

Effect of dietary biotin and lipid on growth, stamina, lipid metabolism and biotin-containing enzymes in brook trout (Salvelinus fontinalis)

Simultaneous dietary fat and biotin deficiencies in brook trout suppressed weight gain, feed/gain efficiency, swimming stamina, and total liver lipids. Dietary fat alone reduced body water, increased body fat and ash, reversed the elevating effect of biotin plus fat on liver palmitic and stearic acids, and widened the 16:0 to 16:1, 18:0 to 18:1, 18:2 to 20:4 and 18:3 to 22:5 liver fatty acid ratios. Fat also accentuated the accumulation of liver oleic and linoleic acids caused by biotin deprivation and apparently prevented docosapentaenoic acid biosynthesis in biotin-deprived trout. Fish fed fat with no biotin had the least, and those fed biotin with no fat the most, liver acetyl CoA carboxylase (ACC) and pyruvate carboxylase (PC) activities. Those fed neither supplemental biotin nor fat and those fed both showed equal liver ACC activity.

Journal of Nutrition↗
USGS1976

Vitamin E and selenium interrelations in the diet of Atlantic salmon (Salmo salar): Gross, histological and biochemical deficiency signs

Either simultaneous or separate dietary deficiencies of vitamin E and selenium in Atlantic salmon during first 4 weeks of feeding caused twice the mortality shown in fish fed both supplemental vitamin E (0.5 IU/g dry diet) and selenium (0.1 µg/g). Subsequent dietary repletion with both vitamin E and selenium significantly reduced mortality during the following 2 weeks. Larger salmon (0.9 g initial mean weight), with vitamin E deficiency with or without selenium resulted in the following deficiency signs: extreme anemia, pale gills, anisocytosis, poikilocytosis, elevated plasma protein, exudative diathesis, dermal depigmentation, in vitro ascorbic acid-stimulated peroxidation in hepatic microsomes, yellow-orange liver color, yellow-brown intestinal contents, enlarged gall bladder distended with dark green bile, low vitamin E in carcass and hepatic tissue, muscular dystrophy, increased carcass fat and water, and a response to handling characterized by a transitory fainting with interruption in swimming. A deficiency of dietary selenium suppressed plasma glutathione peroxidase activity. Supplemental selenium with vitamin E significantly increased tocopherol activity in hepatic, but not carcass tissues. Supplements of both vitamin E and selenium were necessary to prevent muscular dystrophy.

Journal of Nutrition↗