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At least 73 records · Page 4Linked to original sources
USGS2003

Experimental mycobacteriosis in striped bass Morone saxatilis

Striped bass Morone saxatilis were infected intraperitoneally with approximately 10 5 Mycobacterium marinum, M. shottsii sp. nov., or M. gordonae. Infected fish were maintained in a flow-through freshwater system at 18 to 21°C, and were examined histologically and bacteriologically at 2, 4, 6, 8, 17, 26, 36 and 45 wk post-infection (p.i.). M. marinum caused acute peritonitis, followed by extensive granuloma development in the mesenteries, spleen and anterior kidney. Granulomas in these tissues underwent a temporal progression of distinct morphological stages, culminating in well-circumscribed lesions surrounded by normal or healing tissue. Mycobacteria were cultured in high numbers from splenic tissue at all times p.i. Standard Ziehl-Neelsen staining, however, did not demonstrate acid-fast rods in most early inflammatory foci and granulomas. Large numbers of acid-fast rods were present in granulomas beginning at 8 wk p.i. Between 26 and 45 wk p.i., reactivation of disease was observed in some fish, with disintegration of granulomas, renewed inflammation, and elevated splenic bacterial densities approaching 10 9 colony-forming units g -1 . Infection with M. shottsii or M. gordonae did not produce severe pathology. Mild peritonitis was followed by granuloma formation in the mesenteries, but, with 1 exception, granulomas were not observed in the spleen or anterior kidney. M. shottsii and M. gordonae both established persistent infections in the spleen, but were present at densities at least 2 orders of magnitude less than M. marinum at all time points observed. Granulomas in the mesenteries of M. shottsii- and M. gordonae-infected fish resolved over time, and no reactivation of disease was observed.

Diseases of Aquatic Organisms↗
USGS1997

Effect of parasites on resistance to oxygen starvation in the ruff (sic) (Gymnocephalus cernuus)

Ruffe (Gymnocephalus cernuus) occur widely in Eurasia. This species was accidentally introduced into Lake Superior and rapidly occupied the western part of the lake. Ruffe had a strong impact on populations of commercially important fish species and on commercial fishing. Our studies show that ruffe from Lake Superior are strongly infested by parasites specific to North America. These parasites cause severe pathology in ruffe because this host is less adapted to them.

Russian Journal of Ecology↗
USGS2014

Gross and microscopic pathology of lesions in Pocillopora spp. from the subtropical eastern Pacific

Coral reefs are threatened by a variety of factors including diseases that have caused significant damage in some regions such as in the Caribbean. At present, no data are available on coral diseases in the Mexican Pacific where Pocillopora spp. is a dominant component of coral communities. Here, we describe gross and microscopic morphology of lesions found in pocilloporids at four sites in the Mexican Pacific. Corals were identified and their lesions photographed and quantified in the field. Tissue samples were collected from healthy and affected colonies for histopathology. We recorded seven species of pocilloporids at the study sites with Isla Isabel being the location with the highest coral diversity ( H ′ = 1.27). Lesions were present in 42% of the colonies and included discoloration (32%), predation-induced tissue loss (30%), unexplained tissue loss (3%) and overgrowth by sponges or algae (35%). The most affected species, P . damicornis (50%), was also one of the most common in the region. No species was more prone to a particular lesion, but there was a significant association between location and the presence of lesions. Northern Islas Marietas (61%) and Isla Isabel (41%) had the highest prevalence of lesions, followed by Manzanillo (37%) and Bahías de Huatulco (23%). Histological changes included atrophy of the surface body wall with depletion of zooxanthellae (91%) in corals with discoloration (bleaching). Ablation of tissue from mesoglea (18%) was also observed. Colonies with unexplained tissue loss showed atrophy and thinning of the epidermis (89%), characterized by cuboidal instead of pseudocolumnar cells normally found in healthy pseudocolumnar ciliated epithelium. Bacterial aggregates between the mesoglea and gastrodermis (11%) were very conspicuous in healthy and diseased corals. Lesions produced by fish bites and gastropods were associated with tissue atrophy (40%) and, in some cases, algal overgrowth near the lesion (20%). No infectious agents associated with cell pathology were detected microscopically. Bleaching and overgrowth by algae and sponges, as well as unexplained tissue loss, are common in Pocillopora . These lesions and anatomical changes warrant further study since their incidence is potentially indicative of reef degradation.

Mexican Pacific↗
USGS2014

Atrazine reduces reproduction in Japanese medaka (Oryzias latipes)

Atrazine is an effective broadleaf herbicide and the second most heavily used herbicide in the United States. Effects along the hypothalamus–pituitary–gonad axis in a number of vertebrate taxa have been demonstrated. Seasonally elevated concentrations of atrazine in surface waters may adversely affect fishes, but only a few studies have examined reproductive effects of this chemical. The present study was designed to evaluate a population endpoint (egg production) in conjunction with histological (reproductive stage, gonad pathology) and biochemical (aromatase activity, sex hormone production) phenotypes associated with atrazine exposure in Japanese medaka. Adult virgin breeding groups of one male and four females were exposed to nominal concentrations of 0, 0.5, 5.0, and 50 μg/L (0, 2.3, 23.2, 231 nM) of atrazine in a flow-through diluter for 14 or 38 days. Total egg production was lower (36–42%) in all atrazine-exposed groups as compared to the controls. The decreases in cumulative egg production of atrazine-treated fish were significant by exposure day 24. Reductions in total egg production in atrazine treatment groups were most attributable to a reduced number of eggs ovulated by females in atrazine-treated tanks. Additionally, males exposed to atrazine had a greater number of abnormal germ cells. There was no effect of atrazine on gonadosomatic index, aromatase protein, or whole body 17 β-estradiol or testosterone. Our results suggest that atrazine reduces egg production through alteration of final maturation of oocytes. The reduced egg production observed in this study was very similar to our previously reported results for fathead minnow. This study provides further information with which to evaluate atrazine's risk to fish populations.

Aquatic Toxicology↗
USGS2020

Low oxygen: A (tough) way of life for Okavango fishes

Botswana’s Okavango Delta is a World Heritage Site and biodiverse wilderness. In 2016–2018, following arrival of the annual flood of rainwater from Angola’s highlands, and using continuous oxygen logging, we documented profound aquatic hypoxia that persisted for 3.5 to 5 months in the river channel. Within these periods, dissolved oxygen rarely exceeded 3 mg/L and dropped below 0.5 mg/L for up to two weeks at a time. Although these dissolved oxygen levels are low enough to qualify parts of the Delta as a dead zone, the region is a biodiversity hotspot, raising the question of how fish survive. In association with the hypoxia, histological samples, collected from native Oreochromis andersonii (threespot tilapia), Coptodon rendalli (redbreast tilapia), and Oreochromis macrochir (greenhead tilapia), exhibited widespread hepatic and splenic inflammation with marked granulocyte infiltration, melanomacrophage aggregates, and ceroid and hemosiderin accumulations. It is likely that direct tissue hypoxia and polycythemia-related iron deposition caused this pathology. We propose that Okavango cichlids respond to extended natural hypoxia by increasing erythrocyte production, but with significant health costs. Our findings highlight seasonal hypoxia as an important recurring stressor, which may limit fishery resilience in the Okavango as concurrent human impacts rise. Moreover, they illustrate how fish might respond to hypoxia elsewhere in the world, where dead zones are becoming more common.

Okavango Delta↗
USGS2019

Current state of knowledge on biological effects from contaminants on arctic wildlife and fish

Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of the exposure to organohalogen compounds (OHCs) in Arctic biota, there has been a considerable number of new Arctic effect studies. Here, we provide an update on the state of the knowledge of OHC, and also include mercury, exposure and/or associated effects in key Arctic marine and terrestrial mammal and bird species as well as in fish by reviewing the literature published since the last AMAP assessment in 2010. We aimed at updating the knowledge of how single but also combined health effects are or can be associated to the exposure to single compounds or mixtures of OHCs. We also focussed on assessing both potential individual as well as population health impacts using population-specific exposure data post 2000. We have identified quantifiable effects on vitamin metabolism, immune functioning, thyroid and steroid hormone balances, oxidative stress, tissue pathology, and reproduction. As with the previous assessment, a wealth of documentation is available for biological effects in marine mammals and seabirds, and sentinel species such as the sledge dog and Arctic fox, but information for terrestrial vertebrates and fish remain scarce. While hormones and vitamins are thoroughly studied, oxidative stress, immunotoxic and reproductive effects need further investigation. Depending on the species and population, some OHCs and mercury tissue contaminant burdens post 2000 were observed to be high enough to exceed putative risk threshold levels that have been previously estimated for non-target species or populations outside the Arctic. In this assessment, we made use of risk quotient calculations to summarize the cumulative effects of different OHC classes and mercury for which critical body burdens can be estimated for wildlife across the Arctic. As our ultimate goal is to better predict or estimate the effects of OHCs and mercury in Arctic wildlife at the individual, population and ecosystem level, there remain numerous knowledge gaps on the biological effects of exposure in Arctic biota. These knowledge gaps include the establishment of concentration thresholds for individual compounds as well as for realistic cocktail mixtures that in fact indicate biologically relevant, and not statistically determined, health effects for specific species and subpopulations. Finally, we provide future perspectives on understanding Arctic wildlife health using new in vivo, in vitro, and in silico techniques, and provide case studies on multiple stressors to show that future assessments would benefit from significant efforts to integrate human health, wildlife ecology and retrospective and forecasting aspects into assessing the biological effects of OHC and mercury exposure in Arctic wildlife and fish.

Science of the Total Environment↗
USGS2006

Virus diseases of salmonidae in the western United States. II. Aspects of pathogenesis

During the 10 to 15 years investigators from Europe and eastern United States have reported fish diseases of virus etiology. Rucker et al. in 1953 were the first to report a disease of possible virus origin in fish in the western United States. Since then many workers in the western states have described various epizootics caused by transmissible and filterable agents. The etiology and pathology of epizootics reported to date have been three viral diseases: (1) specific for sockeye salmon (Onchorhynchus nerka), (2) specific for chinook salmon (O. tshawytacha); and (3) isolated from rainbow trout (Salmo gairdneri). brook trout (Salvalinus fontinalis). and cutthroat trout ( Salmo clarkii). The most recent historical, etiological and morphological study of diseases of viral and possible viral origin occurring the West has been reported in detail by Parisot et al. With the exception of two investigations, histopathological accounts have been brief and cursory and, to date, pathogenesos of these viral diseases have not been recorded. This study was undertaken to initiate a series concerning pathogeneses of infectious diseases of salmonids. The two viral diseases covered in this paper are the Oregon sockeye disease (OSD) and Sacramento River chinook disease (SRCD). Some preliminary data on pathology of the corresponding material from the hatchery epizootics will also be described and discussed.

Annals of the New York Academy of Sciences↗
USGS2016

Sensitivity of lake sturgeon ( Acipenser fulvescens ) early life stages to 2,3,7,8-tetrachlorodibenzo- P -dioxin and 3,3′,4,4′,5-pentachlorobiphenyl

The aquatic food web of the Great Lakes has been contaminated with polychlorinated biphenyls (PCBs) since the mid-20th century. Threats of PCB exposures to long-lived species of fish, such as lake sturgeon ( Acipenser fulvescens ), have been uncertain because of a lack of information on the relative sensitivity of the species. The objective of the present study was to evaluate the sensitivity of early–life stage lake sturgeon to 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126) or 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD) exposure. Mortality, growth, morphological and tissue pathologies, swimming performance, and activity levels were used as assessment endpoints. Pericardial and yolk sac edema, tubular heart, yolk sac hemorrhaging, and small size were the most commonly observed pathologies in both TCDD and PCB-126 exposures, beginning as early as 4 d postfertilization, with many of these pathologies occurring in a dose-dependent manner. Median lethal doses for PCB-126 and TCDD in lake sturgeon were 5.4 ng/g egg (95% confidence interval, 3.9–7.4 ng/g egg) and 0.61 ng/g egg (0.47–0.82 ng/g egg), respectively. The resulting relative potency factor for PCB-126 (0.11) was greater than the World Health Organization estimate for fish (toxic equivalency factor = 0.005), suggesting that current risk assessments may underestimate PCB toxicity toward lake sturgeon. Swimming activity and endurance were reduced in lake sturgeon survivors from the median lethal doses at 60 d postfertilization. Threshold and median toxicity values indicate that lake sturgeon, like other Acipenser species, are more sensitive to PCB and TCDD than the other genus of sturgeon, Scaphirhynchus , found in North America. Indeed, lake sturgeon populations in the Great Lakes and elsewhere are susceptible to PCB/TCDD-induced developmental toxicity in embryos and reductions in swimming performance.

Environmental Toxicology and Chemistry↗
USGS2014

Monitoring of wild fish health at selected sites in the Great Lakes Basin: methods and preliminary results

During fall 2010 and spring 2011, a total of 119 brown bullhead ( Ameiurus nebulosus ), 136 white sucker ( Catostomus commersoni ), 73 smallmouth bass ( Micropterus dolomieu ), and 59 largemouth bass ( M. salmoides ) were collected from seven Great Lakes Basin Areas of Concern and one Reference Site. Comprehensive fish health assessments were conducted in order to document potential adverse affects from exposure to complex chemical mixtures. Fish were necropsied on site, blood samples obtained, pieces of liver, spleen, kidney, gill and any abnormalities placed in fixative for histopathology. Liver samples were saved for gene expression analysis and otoliths were removed for aging. A suite of fish health indicators was developed and implemented for site comparisons and to document seasonal effects and species differences in response to environmental conditions. Organism level (grossly visible lesions, condition factor), tissue level (microscopic pathology, organosomatic indices, micronuclei, and other nuclear abnormalities), plasma factors (reproductive steroid hormones, vitellogenin), and molecular (gene expression) indicators were included. This report describes the methods and preliminary results.

Great Lakes Basin↗
USGS2025

Pathology, tissue distribution, and phylogenomic characterization of largemouth bass virus isolated from a wild smallmouth bass (Micropterus dolomieu)

We performed a diagnostic disease investigation on a wild smallmouth bass ( Micropterus dolomieu ) with skin ulcers that was collected from Lake Oahe, South Dakota, following reports from anglers of multiple fish with similar lesions. Gross and histologic lesions of ulcerative dermatitis, myositis, and lymphocytolysis within the spleen and kidneys were consistent with largemouth bass virus (LMBV) infection. LMBV was detected by conventional PCR in samples of a skin ulcer, and the complete genome sequence of the LMBV (99,184 bp) was determined from a virus isolate obtained from a homogenized skin sample. A maximum likelihood (ML) phylogenetic analysis based on the major capsid protein (MCP) gene alignment supported the LMBV isolate (LMBV-SD-2023) as a member of the species Ranavirus micropterus1 , branching within the subclade of LMBV isolates recovered from North American largemouth ( Micropterus salmoides ) and smallmouth bass. This is the first detection of LMBV in wild smallmouth bass from South Dakota. The ultrastructure of the LMBV isolate exhibited the expected icosahedral shape of virions budding from cellular membranes. Viral nucleic acid in infected cells was visualized via in situ hybridization (ISH) within dermal granulomas, localized predominantly at the margin of epithelioid macrophages and central necrosis. Further sampling is needed to determine the geographic distribution, affected populations, and evolutionary relationship between isolates of LMBV.

South Dakota↗
USGS1991

Effects of orally administered steroids on lake trout and Atlantic salmon

Lake trout ( Salvelinus namaycush ) and Atlantic salmon ( Salmo salar ) fed 30 mg β‐estradiol/kg of feed for 100 d from first feeding had liver and kidney pathology similar to but much less severe than that previously reported for rainbow trout ( Oncorhynchus mykiss ). Mortality was not affected. Both lake trout and Atlantic salmon treated with estradiol weighed significantly less than control fish at the end of the treatment period and at 200 d posttreatment. Testosterone‐treated fish of both species weighed less than control fish at the end of the treatment period. By day 200 posttreatment, testosterone‐treated and untreated lake trout weighed the same, but testosterone‐treated Atlantic salmon were heavier than control fish. Estradiol treatment produced an all‐female population of Atlantic salmon but not of lake trout. Testosterone at 5 mg/kg feed increased the ratio of males to females in both species.

Progressive Fish-Culturist↗
USGS2020

Ichthyophonus sp. Infection in Opaleye (Girella nigricans)

Over a 3-year-period, 17 wild-caught opaleye (Girella nigricans) housed in a public display aquarium were found dead without premonitory signs. Grossly, 4 animals had pinpoint brown or black foci on coelomic adipose tissue. Histologically, liver, spleen, heart, and posterior kidney had mesomycetozoan granulomas in all cases; other organs were less commonly infected. Four opaleye had goiter; additional substantial lesions were not identified. Granulomas surrounded melanized debris, leukocytes, and mesomycetozoa represented by folded membranes (collapsed schizont walls), intact schizonts (50- to >200 µm in diameter with a multilaminate membrane), plasmodia (budding from schizonts or free in tissue), or rarely germinal tubes (budding from schizonts). Ichthyophonus was grown from fresh tissues in tissue explant broth cultures of the heart, liver, and/or spleen. Polymerase chain reaction using 18S ribosomal DNA primers amplified a 1730-bp region, and the DNA sequence was most similar to Ichthyophonus hoferi, which is often associated with freshwater aquaculture fish.

Veterinary Pathology↗
USGS2006

The effect of chronic chromium exposure on the health of Chinook salmon (Oncorhynchus tshawytscha)

This study was designed to determine fish health impairment of Chinook salmon ( Oncorhynchus tshawytscha ) exposed to chromium. Juvenile Chinook salmon were exposed to aqueous chromium concentrations (0–266 μg l −1 ) that have been documented in porewater from bottom sediments and in well waters near salmon spawning areas in the Columbia River in the northwestern United States. After Chinook salmon parr were exposed to 24 and 54 μg Cr l −1 for 105 days, neither growth nor survival of parr was affected. On day 105, concentrations were increased from 24 to 120 μg Cr l −1 and from 54 to 266 μg Cr l −1 until the end of the experiment on day 134. Weight of parr was decreased in the 24/120 μg Cr l −1 treatment, and survival was decreased in the 54/266 μg Cr l −1 treatment. Fish health was significantly impaired in both the 24/120 and 54/266 μg Cr l −1 treatments. The kidney is the target organ during chromium exposures through the water column. The kidneys of fish exposed to the greatest concentrations of chromium had gross and microscopic lesions (e.g. necrosis of cells lining kidney tububules) and products of lipid peroxidation were elevated. These changes were associated with elevated concentrations of chromium in the kidney, and reduced growth and survival. Also, variations in DNA in the blood were associated with pathological changes in the kidney and spleen. These changes suggest that chromium accumulates and enters the lipid peroxidation pathway where fatty acid damage and DNA damage (expressed as chromosome changes) occur to cause cell death and tissue damage. While most of the physiological malfunctions occurred following parr exposures to concentrations ≥120 μg Cr l −1 , nuclear DNA damage followed exposures to 24 μg Cr l −1 , which was the smallest concentration tested. The abnormalities measured during this study are particularly important because they are associated with impaired growth and reduced survival at concentrations ≥120 μg Cr l −1 . Therefore, these changes can be used to investigate the health of resident fish in natural waters with high chromium concentrations as well as provide insight into the mechanisms of chromium toxicity.

Aquatic Toxicology↗
USGS2003

Safety of Aquaflor (florfenicol, 50% Type A Medicated Article), administered in feed to channel catfish, Ictalurus punctatus

Aquaflor, a feed premix containing the broad spectrum antibacterial agent florfenicol (50% w/w), is being developed for use to control enteric septicemia (ESC) in channel catfish Ictalurus punctatus caused by the gram-negative enterobacterium Edwardsiella ictaluri . The recommended dose of Aquaflor to control ESC is 10 mg/kg body weight (BW)/day for 10 days. The study objective was to determine the safety of Aquaflor administered in feed to channel catfish at doses of 0 (control), 10, 30, and 50 mg/kg BW/day for 20 consecutive days. Parameters evaluated included daily mortality, behavioral (appetite, distribution, flight/fright response), and water chemistry observations, initial and terminal weight measurements, and gross and microscopic pathology. Medicated feed consumption was 67—86% of target with group mean doses of 8.5 mg/kg BW/day, 24.6 mg/kg BW/day, and 34.9 mg/kg BW/day. There were no mortalities or clinically observable changes noted at any of the dose levels tested. Aquaflor-related changes were limited to the food consumption and histopathology data. Although Aquaflor-related decreased feed consumption was noted in the 30 and 50 mg/kg BW/day groups, there were no differences in fish growth among the treatment groups. Aquaflor-related histopathology findings were limited to a histomorphologically evident dose-dependent decrease in hematopoietic/lymphopoietic tissue in the anterior kidneys, posterior kidneys, and spleens of channel catfish.

Toxicologic Pathology↗
USGS2003

Safety of aquaflor (florfenicol, 50% type a medicated article), administered in feed to channel catfish, Ictalurus punctatus

Aquaflor, a feed premix containing the broad spectrum antibacterial agent florfenicol (50% w/w), is being developed for use to control enteric septicemia (ESC) in channel catfish Ictalurus punctatus caused by the gram-negative enterobacterium Edwardsiella ictaluri . The recommended dose of Aquaflor to control ESC is 10 mg/kg body weight (BW)/day for 10 days. The study objective was to determine the safety of Aquaflor administered in feed to channel catfish at doses of 0 (control), 10, 30, and 50 mg/kg BW/day for 20 consecutive days. Parameters evaluated included daily mortality, behavioral (appetite, distribution, flight/fright response), and water chemistry observations, initial and terminal weight measurements, and gross and microscopic pathology. Medicated feed consumption was 67-86% of target with group mean doses of 8.5 mg/kg BW/day, 24.6 mg/kg BW/day, and 34.9 mg/kg BW/day. There were no mortalities or clinically observable changes noted at any of the dose levels tested. Aquaflor-related changes were limited to the food consumption and histopathology data. Although Aquaflor-related decreased feed consumption was noted in the 30 and 50 mg/kg BW/day groups, there were no differences in fish growth among the treatment groups. Aquaflor-related histopathology findings were limited to a histomorphologically evident dose-dependent decrease in hematopoietic/lymphopoietic tissue in the anterior kidneys, posterior kidneys, and spleens of channel catfish.

Toxicologic Pathology↗
USGS2006

Some aspects of pathogenesis of infectious hematopoietic necrosis (IHN)

The histopathogenesis of infectious haematopoietic necrosis (IHN) virus infection was studied by exposing juvenile sockeye salmon ( Oncorhynchus nerka ) to the IHN virus. Fish samples were taken every 24 h for histological examination and for determination of virus concentration. A close correlation was found between histopathological changes and virus concentration. The most significant changes occurred 4 days after exposure. The haematopocitic tissue of the kidney was the most extensively involved but minor degenerative changes were seen in the liver, pancreas, and in the granular cells of the digestive tract. On the 4th day, maximum tissue concentration of virus was reached and the mortality increased. By the 5th day, 90% of the samples showed extensive pathological changes in the kidney, together with variable changes in spleen, liver, pancreas, and gut. Similarities in the histopathogenesis of IHN, Oregon sockeye disease (OSD), Sacramento River chinook disease (SRCD) and viral haemorrhagic septicaemia (VHS), are discussed.

Journal of Fish Biology↗
USGS2003

Pallid sturgeon in the Lower Mississippi Region: Hematology and genome information

This project (Project 1448-43270-2M-002) has been coordinated through the Natchitoches National Fish Hatchery (NNFH) and the U.S. Geological Survey’s National Wetlands Research Center (NWRC). From November 2001 to April 2002, over 280 sturgeon of the genus Scaphirhynchus (including pallid sturgeon, shovelnose, and their hybrids) were sampled from the outflow channel of the Old River Control Structure Complex (ORCC) in Concordia Parish, La. In the overall project, several datasets were collected (see Appendix), including species identification by using microsatellites and morphometric characters, food habits, physical anomalies, information on blood cells, and pathologic evidence of iridovirus – the first indication in the lower Mississippi population of pallid sturgeon. In this study, data on blood cells were obtained from the sturgeon collected monthly from approximately 20 different animals at each sampling time. This report presents preliminary information on differential blood cell identifications in sturgeon, data on comparative genomic DNA content and DNA degradation, and summaries and interpretations of data collected in light of available scientific literature addressing blood parameters of fish and sturgeon, in particular. Results obtained from collection and examination of blood and body fluids are often essential in establishing the health of fish (Blaxhall, 1972; Fange, 1992). Blood cells and sperm cells can be obtained nondestructively from fishes, even from small specimens that weigh less than 100 g (Stoskopf, 1992a). For flow cytometry assays, whereby cells are analyzed individually in a fluid stream, less than 1 :L of blood is needed. Examinations of blood by microscopy and flow cytometry were performed at NWRC in assisting in the efforts directed at recovery of the pallid sturgeon population in the Lower Mississippi River Basin.

Open-File Report↗
USGS2014

Identifying non-point sources of endocrine active compounds and their biological impacts in freshwater lakes

Contaminants of emerging concern, particularly endocrine active compounds (EACs), have been identified as a threat to aquatic wildlife. However, little is known about the impact of EACs on lakes through groundwater from onsite wastewater treatment systems (OWTS). This study aims to identify specific contributions of OWTS to Sullivan Lake, Minnesota, USA. Lake hydrology, water chemistry, caged bluegill sunfish ( Lepomis macrochirus ), and larval fathead minnow ( Pimephales promelas ) exposures were used to assess whether EACs entered the lake through OWTS inflow and the resultant biological impact on fish. Study areas included two OWTS-influenced near-shore sites with native bluegill spawning habitats and two in-lake control sites without nearby EAC sources. Caged bluegill sunfish were analyzed for plasma vitellogenin concentrations, organosomatic indices, and histological pathologies. Surface and porewater was collected from each site and analyzed for EACs. Porewater was also collected for laboratory exposure of larval fathead minnow, before analysis of predator escape performance and gene expression profiles. Chemical analysis showed EACs present at low concentrations at each study site, whereas discrete variations were reported between sites and between summer and fall samplings. Body condition index and liver vacuolization of sunfish were found to differ among study sites as did gene expression in exposed larval fathead minnows. Interestingly, biological exposure data and water chemistry did not match. Therefore, although results highlight the potential impacts of seepage from OWTS, further investigation of mixture effects and life history factor as well as chemical fate is warranted.

Minnesota↗