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At least 649 records · Page 36Linked to original sources
USGS1996

Biology of Amur sleeper ( Perccottus glehni ) in the Delta of the Selenga River, Buryatia, Russia

We determined the fecundity, growth, diet, and density of the Amur sleeper ( Perccottus glehni ) in the Selenga River Delta on Lake Baikal during 1986-1991 to better understand how this invading exotic will affect Baikal's endemic fishes. We also compared the Amur sleeper's diet with that of other fishes living in the delta. The largest Amur sleepers were about 200 mm long and weighed 200 g; the oldest were age 7. All females were mature at age 2. Fecundity ranged from 884 eggs at age 1 to 37,056 eggs at age 7. Highest densities of Amur sleepers were found in oxbow lakes where densities sometimes exceeded 4,000 fish per ha. The bulk of the diet of Amur sleeper age 2 and older was chironomids, fish, and fish eggs. Chironomids were also important in the diet of the commercially valuable Siberian roach ( Rutilus rutilus lacustris ) and Siberian dace ( Leuciscus leuciscus baicalensis ). Thus the Amur sleeper may cause population declines of these important endemic fishes through resource competition and predation on their juvenile life stages. However, Amur sleepers were the species of fish most frequently eaten by Eurasian perch ( Perca fluviatilis ) and northern pike ( Esox lucius ). So, maintaining vigorous populations of these two predators may well be an effective strategy for limiting the size of Amur sleeper populations.

Lake Baikai;Selenga River↗
USGS2003

Oral biology and beak disorders of birds

The beak, or bill, of the bird is a complicated structure. The avian skull is described as having some reptilian features; this includes a quadrate bone that articulates with the articular bone of the lower jaw.

Veterinary Clinics of North America: Exotic Animal↗
USGS2017

Biological effects-based tools for monitoring impacted surface waters in the Great Lakes: a multiagency program in support of the Great Lakes Restoration Initiative

There is increasing demand for the implementation of effects-based monitoring and surveillance (EBMS) approaches in the Great Lakes Basin to complement traditional chemical monitoring. Herein, we describe an ongoing multiagency effort to develop and implement EBMS tools, particularly with regard to monitoring potentially toxic chemicals and assessing Areas of Concern (AOCs), as envisioned by the Great Lakes Restoration Initiative (GLRI). Our strategy includes use of both targeted and open-ended/discovery techniques, as appropriate to the amount of information available, to guide a priori end point and/or assay selection. Specifically, a combination of in vivo and in vitro tools is employed by using both wild and caged fish (in vivo), and a variety of receptor- and cell-based assays (in vitro). We employ a work flow that progressively emphasizes in vitro tools for long-term or high-intensity monitoring because of their greater practicality (e.g., lower cost, labor) and relying on in vivo assays for initial surveillance and verification. Our strategy takes advantage of the strengths of a diversity of tools, balancing the depth, breadth, and specificity of information they provide against their costs, transferability, and practicality. Finally, a series of illustrative scenarios is examined that align EBMS options with management goals to illustrate the adaptability and scaling of EBMS approaches and how they can be used in management decisions.

Great Lakes↗
USGS2023

Biological responses of Pacific herring embryos to crude oil are quantifiable at exposure levels below conventional limits of quantitation for PAHs in water and tissues

Pacific herring ( Clupea pallasii ), a cornerstone of marine food webs, generally spawn on marine macroalgae in shallow nearshore areas that are disproportionately at risk from oil spills. Herring embryos are also highly susceptible to toxicity from chemicals leaching from oil stranded in intertidal and subtidal zones. The water-soluble components of crude oil trigger an adverse outcome pathway that involves disruption of the physiological functions of cardiomyocytes in the embryonic herring heart. In previous studies, impaired ionoregulation (calcium and potassium cycling) in response to specific polycyclic aromatic hydrocarbons (PAHs) corresponds to lethal embryolarval heart failure or subtle chamber malformations at the high and low ends of the PAH exposure range, respectively. Sublethal cardiotoxicity, which involves an abnormal outgrowth (ballooning) of the cardiac ventricular chamber soon after hatching, subsequently compromises juvenile heart structure and function, leading to pathological hypertrophy of the ventricle and reduced individual fitness, measured as cardiorespiratory performance. Previous studies have not established a threshold for these sublethal and delayed-in-time effects, even with total (∑)PAH exposures as low as 29 ng/g of wet weight (tissue dose). Here, we extend these earlier findings showing that (1) cyp1a gene expression provides an oil exposure metric that is more sensitive than typical quantitation of PAHs via GC–MS and (2) heart morphometrics in herring embryos provide a similarly sensitive measure of toxic response. Early life stage injury to herring (impaired heart development) thus occurs below the quantitation limits for PAHs in both water and embryonic tissues as a conventional basis for assessing oil-induced losses to coastal marine ecosystems.

Environmental Science and Technology↗
USGS2001

How are climate and marine biological outbreaks functionally linked?

Since the mid-1970s, large-scale episodic events such as disease epidemics, mass mortalities, harmful algal blooms and other population explosions have been occurring in marine environments at an historically unprecedented rate. The variety of organisms involved (host, pathogens and other opportunists) and the absolute number of episodes have also increased during this period. Are these changes coincidental? Between 1972 and 1976, a global climate regime shift took place, and it is manifest most clearly by a change in strength of the North Pacific and North Atlantic pressure systems. Consequences of this regime shift are: (1) prolonged drought conditions in the Sahel region of Africa; (2) increased dust supply to the global atmosphere, by a factor of approximately four; (3) increased easterly trade winds across the Atlantic; (4) increased eolian transport of dust to the Atlantic and Caribbean basins; and (5) increased deposition of iron-rich eolian dust to typically iron-poor marine regions. On the basis of well-documented climate and dust observations and the widely accepted increase in marine outbreak rates, this paper proposes that the increased iron supply has altered the micronutrient factors limiting growth of opportunistic organisms and virulence of pathogenic microbes, particularly in macronutrient-rich coastal systems.

Hydrobiologia↗
USGS2010

Biological communities in San Francisco Bay track large‐scale climate forcing over the North Pacific

Long‐term observations show that fish and plankton populations in the ocean fluctuate in synchrony with large‐scale climate patterns, but similar evidence is lacking for estuaries because of shorter observational records. Marine fish and invertebrates have been sampled in San Francisco Bay since 1980 and exhibit large, unexplained population changes including record‐high abundances of common species after 1999. Our analysis shows that populations of demersal fish, crabs and shrimp covary with the Pacific Decadal Oscillation (PDO) and North Pacific Gyre Oscillation (NPGO), both of which reversed signs in 1999. A time series model forced by the atmospheric driver of NPGO accounts for two‐thirds of the variability in the first principal component of species abundances, and generalized linear models forced by PDO and NPGO account for most of the annual variability of individual species. We infer that synchronous shifts in climate patterns and community variability in San Francisco Bay are related to changes in oceanic wind forcing that modify coastal currents, upwelling intensity, surface temperature, and their influence on recruitment of marine species that utilize estuaries as nursery habitat. Ecological forecasts of estuarine responses to climate change must therefore consider how altered patterns of atmospheric forcing across ocean basins influence coastal oceanography as well as watershed hydrology.

California↗
USGS2020

Adjusting the lens of invasion biology to focus on the impacts of climate-driven range shifts

As Earth’s climate rapidly changes, species range shifts are considered key to species persistence. However, some range-shifting species will alter community structure and ecosystem processes. By adapting existing invasion risk assessment frameworks, we can identify characteristics shared with high-impact introductions and thus predict potential impacts. There are fundamental differences between introduced and range-shifting species, primarily shared evolutionary histories between range shifters and their new community. Nevertheless, impacts can occur via analogous mechanisms, such as wide dispersal, community disturbance and low biotic resistance. As ranges shift in response to climate change, we have an opportunity to develop plans to facilitate advantageous movements and limit those that are problematic.

Nature Climate Change↗
USGS2024

Hair mercury isotopes, a noninvasive biomarker for dietary methylmercury exposure and biological uptake

Background . Fish and rice are the main dietary sources of methylmercury (MeHg); however, rice does not contain the same beneficial nutrients as fish, and these differences can impact the observed health effects of MeHg. Hence, it is important to validate a biomarker, which can distinguish among dietary MeHg sources. Methods . Mercury (Hg) stable isotopes were analyzed in hair samples from peripartum mothers in China ( n = 265). Associations between mass dependent fractionation (MDF) ( δ 202 Hg) and mass independent fractionation (MIF) ( Δ 199 Hg) (dependent variables) and dietary MeHg intake (independent variable) were investigated using multivariable regression models. Results . In adjusted models, hair Δ 199 Hg was positively correlated with serum omega-3 fatty acids (a biomarker for fish consumption) and negatively correlated with maternal rice MeHg intake, indicating MIF recorded in hair can be used to distinguish MeHg intake predominantly from fish versus rice. Conversely, in adjusted models, hair δ 202 Hg was not correlated with measures of dietary measures of MeHg intake. Instead, hair δ 202 Hg was strongly, negatively correlated with hair Hg, which explained 27–29% of the variability in hair δ 202 Hg. Conclusions . Our results indicated that hair Δ 199 Hg can be used to distinguish MeHg intake from fish versus rice. Results also suggested that lighter isotopes were preferentially accumulated in hair, potentially reflecting Hg binding to thiols ( i.e. , cysteine); however, more research is needed to elucidate this hypothesis. Broader impacts include 1) validation of a non-invasive biomarker to distinguish MeHg intake from rice versus fish, and 2) the potential to use Hg isotopes to investigate Hg binding in tissues.

Environmental Science: Processes & Impacts↗
USGS2003

Atlantic coast feeding habits of striped bass: A synthesis supporting a coast-wide understanding of trophic biology

The recent increase in the Atlantic coast population of striped bass, Morone saxatilis (Walbaum), prompted managers to re-evaluate their predatory impact. Published and unpublished diet data for striped bass on the Atlantic Coast of North America were examined for geographical, ontogenetic and seasonal patterns in the diet and to assess diet for this species. Diets of young-of-the-year (YOY) striped bass were similar across the Upper Atlantic (UPATL), Chesapeake and Delaware Bays (CBDEL) and North Carolina (NCARO) areas of the Atlantic coast where either fish or mysid shrimp dominate the diet. For age one and older striped bass, cluster analysis partitioned diets based on predominance of either Atlantic menhaden, Brevoortia tyrannus (Latrobe), characteristic of striped bass from the CBDEL and NCARO regions, or non-menhaden fishes or invertebrates, characteristic of fish from the UPATL, in the diet. The predominance of invertebrates in the diets of striped bass in the UPATL region can be attributed to the absence of several important species groups in Northern waters, particularly sciaenid fishes, and to the sporadic occurrences of Atlantic menhaden to UPATL waters. In all regions, across most seasons and in most size classes of striped bass, the clupeiod fishes; menhaden, anchovies (Anchoa spp.) and river herrings (Alosa spp,) and Atlantic herring, Clupea harengus L., dominated the diets of striped bass above the first year of life.

Fisheries Management and Ecology↗
USGS2018

Voyageurs National Park: Water-level regulation and effects on water quality and aquatic biology

Following dam installations in the remote Rainy Lake Basin during the early 1900s, water - level fluctuations were considered extreme (1914–1949) compared to more natural conditions. In 1949, the International Joint Commission (IJC), which sets rules governing dam operation on waters shared by the United States and Canada, established the first rule curves to regulate water levels on these waterbodies. However, rule curves established prior to 2000 were determined to be detrimental to the ecosystem. Therefore, the IJC implemented an order in 2000 to change rule curves and to restore a more natural water regime. After 2000, measured chlorophyll- a concentrations in the two most eutrophic water bodies decreased whereas concentrations in oligotrophic lakes did not show significant water - quality differences. Fish mercury data were inconclusive, due to the variation in water levels and fish mercury concentrations, but can be used by the IJC as part of a long term data set.

Minnesota↗
USGS2022

Global environmental changes more frequently offset than intensify detrimental effects of biological invasions

Human-induced abiotic global environmental changes (GECs) and the spread of nonnative invasive species are rapidly altering ecosystems. Understanding the relative and interactive effects of invasion and GECs is critical for informing ecosystem adaptation and management, but this information has not been synthesized. We conducted a meta-analysis to investigate effects of invasions, GECs, and their combined influences on native ecosystems. We found 458 cases from 95 published studies that reported individual and combined effects of invasions and a GEC stressor, which was most commonly warming, drought, or nitrogen addition. We calculated standardized effect sizes (Hedges’ d ) for individual and combined treatments and classified interactions as additive (sum of individual treatment effects), antagonistic (smaller than expected), or synergistic (outside the expected range). The ecological effects of GECs varied, with detrimental effects more likely with drought than the other GECs. Invasions were more strongly detrimental, on average, than GECs. Invasion and GEC interactions were mostly antagonistic, but synergistic interactions occurred in >25% of cases and mostly led to more detrimental outcomes for ecosystems. While interactive effects were most often smaller than expected from individual invasion and GEC effects, synergisms were not rare and occurred across ecological responses from the individual to the ecosystem scale. Overall, interactions between invasions and GECs were typically no worse than the effects of invasions alone, highlighting the importance of managing invasions locally as a crucial step toward reducing harm from multiple global changes.

Proceedings of the National Academy of Sciences↗
USGS2011

Biology, status, and management of the yellowstone cutthroat trout

Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri were historically distributed in the Yellowstone River drainage (Montana and Wyoming) and the Snake River drainage (Wyoming, Idaho, Utah, Nevada, and probably Washington). Individual populations evolved distinct life history characteristics in response to the diverse environments in which they were isolated after the last glaciation. Anthropogenic activities have resulted in a substantial decline (42% of the historical range is currently occupied; 28% is occupied by core [genetically unaltered] populations), but the number of extant populations, especially in headwater streams, has precluded listing of this taxon under the Endangered Species Act. Primary threats to persistence of Yellowstone cutthroat trout include (1) invasive species, resulting in hybridization, predation, disease, and interspecific competition; (2) habitat degradation from human activities such as agricultural practices, water diversions, grazing, dam construction, mineral extraction, grazing, timber harvest, and road construction; and (3) climate change, including an escalating risk of drought, wildfire, winter flooding, and rising temperatures. Extirpation of individual populations or assemblages has led to increasing isolation and fragmentation of remaining groups, which in turn raises susceptibility to the demographic influences of disturbance (both human and stochastic) and genetic factors. Primary conservation strategies include (1) preventing risks associated with invasive species by isolating populations of Yellowstone cutthroat trout and (2) connecting occupied habitats (where possible) to preserve metapopulation function and the expression of multiple life histories. Because persistence of isolated populations may be greater in the short term, current management is focused on isolating individual populations and restoring habitats; however, this approach implies that humans will act as dispersal agents if a population is extirpated because of stochastic events.

Idaho, Montana, Utah, Wyoming↗
USGS2013

Biological consequences of the coaster brook trout restoration stocking program in Lake Superior tributaries with Pictured Rocks National Lakeshore

The coaster Brook Trout Salvelinus fontinalis is a Lake Superior ecotype representing intraspecific variation that has been impacted by habitat loss and overfishing. Hatchery strains of Brook Trout derived from populations in Lake Superior were stocked into streams within Pictured Rocks National Lakeshore, Michigan, as part of an effort to rehabilitate adfluvial coaster Brook Trout. Wild and hatchery Brook Trout from three streams (Mosquito River, Hurricane River, and Sevenmile Creek) were examined for movement behavior, size, physiology, and reproductive success. Behavior and size of the stocked fish were similar to those of wild fish, and less than 15% of the stocked, tagged Brook Trout emigrated from the river into which they were stocked. There was little evidence of successful reproduction by stocked Brook Trout. Similar to the results of other studies, our findings suggest that the stocking of nonlocal Brook Trout strains where a local population already exists results in limited natural reproduction and should be avoided, particularly if the mechanisms governing the ecotype of interest are poorly understood.

Michigan↗
USGS2001

Biological structure and dynamics of littoral fish assemblages in the eastern Finger Lakes

Fish assemblages from three of the New York Finger Lakes were examined for structure within and between lakes and over time. Species-area relationships indicated that local fish assemblages are the result of recent, lake-specific events that altered the regional species pool. Fish assemblages varied among seasons and those occupying eutrophic waters had different characteristics from those in oligotrophic waters. Bluntnose minnows ( Pimephales notatus ) were a persistent and important component of most assemblages, but abundance of bluegill ( Lepomis macrochirus ) was the most distinguishing feature. Species associations indicated that interactions among the fishes had little influence on assemblage structure. Correlations between community structure and abiotic factors were identified. Ten abiotic variables were strongly associated with the species assemblages, but could not fully explain differences between assemblages. Results indicate that the abundance and diversity of water column feeders was related to productivity of lake habitat. In general, fish populations were smaller in oligotrophic waters and water column feeders were poorly represented in those assemblages. Productivity at various trophic levels was implicated as a major factor determining lake fish assemblage structure.

New York↗
USGS2021

The importance of forests in bumble bee biology and conservation

Declines of many bumble bee species have raised concerns because of their importance as pollinators and potential harbingers of declines among other insect taxa. At present, bumble bee conservation is predominantly focused on midsummer flower restoration in open habitats. However, a growing body of evidence suggests that forests may play an important role in bumble bee life history. Compared with open habitats, forests and woody edges provide food resources during phenologically distinct periods, are often preferred nesting and overwintering habitats, and can offer favorable abiotic conditions in a changing climate. Future research efforts are needed in order to anticipate how ongoing changes in forests, such as overbrowsing by deer, plant invasions, and shifting canopy demographics, affect the suitability of these habitats for bumble bees. Forested habitats are increasingly appreciated in the life cycles of many bumble bees, and they deserve greater attention from those who wish to understand bumble bee populations and aid in their conservation.

BioScience↗
USGS1974

Various fish species as biological control agents for the dark rice field mosquito in Arkansas rice fields

During the summers of 1972–73, 10 fish species were evaluated as predators against larvae of the dark rice field mosquito, Psorophora confinnis (Lynch-Arribalzaga), near Stuttgart, Ark. Stocking rates were 0.02, 0.03, and 0.06 fish/ft 2 . At the lowest stocking rate green sunfish, Lepomis cyanellus Rafinesque, reduced larval numbers by 89.7% and were significantly more effective than adult mosquitofish, Gambusia affinis (Baird and Girard). The white amur, Ctenopharynogodon idella Valenciennes, was intermediate in effectiveness when compared with the above. At 0.03 fish/ft 2 , green sunfish reduced larvae by 99.2% and were significantly more efficient than juvenile mosquitofish, which had little effect on the larval population. At the 0.06 fish/ft 2 rate mosquitofish; white amur; Israeli carp, Cyprinus carpio L.; and hybrids (Israeli carp × goldfish) were significantly more effective than bigmouth buffalo, Ictiobus cyprinellus (Valenciennes); black buffalo, Ictiobus niger (Rafinesque); goldfish, Carassius auratus (L.); or juvenile mosquitofish. Recovery counts of fish indicated that fish survived under natural conditions in Arkansas rice fields.

Arkansas↗