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USGS2009

An introduction to standardized sampling

It was probably one of the oddest riots in the history of the United States. In Erie, Pennsylvania during 1853. federal marshals were called to restore order during bloody uprisings. A mob of women, equipped with sledgehammers, was tearing up railroad rack to protest standardization of track width (Nesmith 1985). All across the United States, standardization of rail gauges was talking place to improve transportation across the country,but many people did not want consistency. Jobs moving freight from, a train running on one gauge of track to a train running on another gauge were plentiful at this time, and standardization would mean these jobs would disappear. Fortunately, for us today, the riots were quelled and standardization of railroad tack gauges went ahead. The magnificent transportation system of North America was aided by the standardization of rails, contributing to robust economies. Standardization of industrial processes, languages, measurements, and data collection methods has been essential for world progress (Figure 1.1). Today , we are often unaware of the degree of standardization of the most basic elements of our society--from bolts and nuts where thread sizes are standard to computer components that can be used interchangeably to the standard sizes of photos we carry in our wallets or purses. Data collection and presentation are standardized in many disciplines, including medicine, meteorology, geology, and water chemistry. For example, our cholesterol, body temperature, and blood pressure are measured by standard medical tests and compared to averages calculated from the results of the same standard tests for many other people to determine if individuals are higher, lower, or average compared to the population in general. If these diagnostic tests were not standardized, it is unlikely that we would be able to evaluate eve the most basic data about our health. In fact, if standardization was not used in countless other facets of our society our lives would be much more difficult. For data collection purposes, standardization means to collect data in one way so comparisons can be easily made. Although routine data collection has been standardized in many other disciplines, data from freshwater fish sampling across North America have not. Previously, most data collection has been standardized only at local, state, and provincial levels (Bonar and Hubert 2002). Several years ago, when one of the authors (Bonar) was a biologist for a state agency, he was asked to compile as much data as he could about the state's warmwater fish communities to provide information to managers developing fishing regulations. These data had been collected by many biologists over time using different methods, including rotenone, electrofishing, gill netting, and hook-and-line sampling. Data were written carefully on detailed data sheets or in scribbled notes in a biologists's notebook. As you can imagine, these data were a nightmare to compile. However, they were even worse to interpret. How could length-frequency distributions be compared among lakes if the methods used to catch the fish were dissimilar with differing efficiencies in sampling fish of various species and lengths? How could catch per unit effort (CPUE), a common index of population density, be compared when samples were collected one year using fyke nets and the next year by electrofishing? Ultimately, how could one compare if fish population were high, low, or average in growth, body condition, or abundance if there was no compilation of distributions of standard data to facilitate comparison? Months were spent trying to interpret these data, and finally a body of comparable data gathered by similar methods was assimilated. However, much of the nonstandard data had to be discarded--data that had taken thousands of hours to collect but were essentially useless. If all data jhad been collected and recorded in a standard manner, whoch would have required very little extra work, all of these hours of survey effort would not have gone to naught and isights regardimng the fisheries would have been imporived by a larger number of samples.

Book chapter↗

USGS2009

Length frequency, condition, growth, and catch per effort indices for common North American fishes

One of the greatest advantages to using standard sampling is the ability of compare sample data to those data collected from an array of other populations over a wide geographic area using similar techniques. A biologist can then ascertain if the sampling data are within an expected range or are higher or lower than expected when compared to other populations.. When biologists collect data using different biased, unvalidated methods, it is often impossible to compare data among populations and evaluate the results. Standard sampling allows comparisons of data among sampling periods and locations. Until now, summaries of freshwater fisheries data collected in a standard manner across North America have not been available. Length at age, length-weight relationships, and other types of detailed summary data are available in Carlander (1696-1977). However, a variety of sampling methods were used to collect these data, allowing successful comparisons among length at age and length-weight data but making it difficult or impossible to compare size distribution and catch per unit effort (CPUE) data among populations. This chapter provides North American and ecoregion (area that contains a geographically distinct assemblage of natural communities and share similar environmental conditions) averages and distributions of several commonly used sampling techniques described in this book. Biologists using the standardized sampling techniques described in this book will be able to compare their data sets to the summaries provided in the tables that follow to determine if the data from their sampled populations of fish are average, below average, or above average for a given index in their ecoregion or across North America.

Book chapter↗

USGS2009

Warmwater fish in rivers

Large warmwater rivers are complex ecosystems and often contain numerous species and habitats. We loosely define a large river as having a drainage area greater than 50,000 km2 and a stream order great than six. Further, these rivers typically have mean discharges greater than 1,500 m3/s. Channel patterns are highly variable among and within large rivers, generally forming a meandering pattern. Currently, many large rivers are confined by bank stabilization and are characterized by a straight channel because of anthropogenic alterations. Further, most large rivers in North America have altered hydrographs because of main-stem dams or dams within the drainage area. Large rivers that have been modified to reduce meandering and flooding present challenges for deployment and operation of fish sampling gear. Water temperature in large rivers is highly variable across North America and varies longitudinally within a river. For example, the Missouri River originates in the Rocky Mountains and terminates at the confluence with the Mississippi River near St. Louis, Missouri. Thus, mean water temperature in the headwaters is considerably different than the confluence. As a result, we defined warmwater by the dominant fish assemblage found in the river. Most fish species can be categorized into broad categories, such as coldwater, coolwater, or warmwater, based on water temperature in the natural environments where they occur. We define warmwater rivers as rivers that were naturally void of coldwater fishes such as trouts, salmons, and ciscoes. This is appropriate because it disregards zoogeographic boundaries that may limit the inclusion of rivers in the warmwater category. For example, the Colorado River is in a different zoogeographic subdivision than the Ohio River (Moyle and Cech 2000), but both rivers contain warmwater fish assemblages.

Book chapter↗

USGS2019

Back from the brink: Sustainable management of the Lake Erie walleye fishery

This chapter describes management actions implemented after a large-scale population decline of the Walleye Sander vitreus population in Lake Erie, one of the Laurentian Great Lakes in North America. Intensive fishery exploitation during the 1950s combined with declining water quality conditions collapsed the Walleye stock during the early 1960s. The fishery persisted at low levels until 1970 when the fishery was closed (1970–1972) due to elevated mercury concentrations in Walleye tissue. Lake Erie fishery managers at the time recognized the need for a coordinated, multi-agency approach to protect this ecologically, economically, and socially important resource. The harvest ban was lifted in 1973 when mercury levels dropped below advisory levels. In 1976, an interagency management framework was established, which relied on a coordinated, science-based management philosophy consisting of estimating safe harvest levels, performing applied research, and conducting annual population assessments. The population rebounded during the 1980s in response to improving environmental conditions, regulated harvest, and a series of strong recruitment events. Declines in harvest and population size were again observed during the late 1990s and mid-2000s, likely due to variation in natural processes controlling recruitment, and fishery managers enacted harvest practices during this period to promote long-term sustainability. Today, Lake Erie Walleyes support one of the largest self-sustaining freshwater fisheries in North America. Throughout the years, Lake Erie managers have iteratively adopted changes to their population assessment model and altered harvest policies to avoid future fishery and population collapses. More than 40 years later, Lake Erie continues to support commercial and recreational fisheries lake wide. Lessons learned from the stock recovery and subsequent coordinated management for fishery sustainability include the importance of conducting routine population assessments, using science-based research to address key uncertainties, adopting modern stock assessment approaches, incorporating stakeholder input into the quota setting process, and addressing environmental concerns collaboratively at the lake level.

Book chapter↗

USGS2024

Warmwater fish in rivers

In addition to the gears described in the previous version, this edition includes an updated water body definition that is inclusive of Mexico and Canada as well as standard methods for the use of cast nets in warmwater rivers. There were organizational changes in the trawling and hoop-net sections to make them consistent with the format for this edition, but the methods themselves have not been changed and no standardized gears (e.g., small-mesh and large-mesh trawls are still both present) have been removed. The diversity of warmwater rivers of North America owes to the mosaic of precipitation and geology spanning the continent from the arid systems of the Sonoran Desert to the humid forests of the Appalachian Mountains. The types of rivers discussed in this chapter are highly variable in size from headwaters to mouth but will include parts of rivers that are nonwadeable and larger. Here, we use this flexible definition because we found that regardless of how we classified a river as a whole, whether through basin area, discharge, or stream order, there is sufficient diversity across North America such that major rivers of some regions would be left out. We, therefore, chose to use site-level characterization because characteristics like target fish species and communities and habitat characteristics like water depth, velocity, and channel geomorphology drive or constrain our decisions in the field about what sampling gear to use rather than overall river or river basin characteristics.

Book chapter↗

USGS2022

Evolution and taxonomy of the Paleogene calcareous nannofossil genus Hornibrookina

The genus Hornibrookina consists of enigmatic calcareous nannofossils that first appeared shortly after the K-Pg mass extinction. Due to their relative paucity in most published sections, specimens of this genus have not been previously studied in detail and their paleobiogeographic preferences and evolutionary history have been poorly understood. Biostratigraphic and morphometric analyses of Hornibrookina specimens from outcrops and cores from the Atlantic Ocean, the North Sea, the Southern Ocean, the Indian Ocean, North America, South America, Africa, and New Zealand resulted in a comprehensive and detailed documentation of this group of calcareous nannofossils. Biostratigraphic ranges for each species are refined and a hypothetical evolutionary lineage for this genus is proposed. Two new species (Hornibrookina gracila and Hornibrookina indistincta), two new combinations (Hornibrookina elegans and Hornibrookina australis arca) and one new subspecies (Hornibrookina australis australis) are described. Morphometric analyses prove that Hornibrookina edwardsii and Hornibrookina teuriensis are distinctly different species with biostratigraphically useful ranges. Hornibrookina apellanizii is shown to be invalid.

Micropaleontology↗

USGS2024

Abundance of Long-billed Curlews on military lands in the Columbia Basin

Long-billed Curlews ( Numenius americanus ) are declining throughout North America, and the loss of grassland breeding habitat is one of the primary threats to the species. Intermountain West, in particular, has been identified as the most important region in North America for breeding curlews. Nevertheless, the density and abundance of Long-billed Curlews in this region is not well understood. Lands managed for military training can provide habitat for wildlife species of conservation concern, and increasingly these lands are becoming relevant to sustaining biodiversity. We conducted point count surveys of Long-billed Curlews on Department of Defense lands in the Columbia Basin near Boardman, Oregon, USA during two consecutive breeding seasons. We used multinomial-Poisson mixture models to estimate detection probability and density of curlews and to investigate environmental correlates of those metrics. Mean detection probability at a distance of 400 m was 0.45 and 0.61 in 2015 and 2016, respectively. In 2015, the clarity of skies increased detection probability, but in 2016, none of the variables we measured influenced detection probability. Mean predicted density was 3.3 (95% confidence interval: 2.4–4.7) and 1.8 (1.2–2.7) curlews/km² in 2015 and 2016, respectively. In both years, curlew density was higher in lower-elevation or topographically smoother areas. Estimated abundance of curlews in the study area was 639 (456–912) and 350 (237–520) birds in 2015 and 2016, respectively. The number of curlews appeared to fluctuate across the two years of our study, a demographic trend that may have been influenced by a wildfire in our study area in June 2015. The results of our study indicate that federal grasslands, including areas where military operations are conducted, can provide conservation benefit to breeding Long-billed Curlews.

Oregon↗

USGS2026

Status of round goby invasion fronts in New York and Quebec: Implications for Lake Champlain

Invasive round goby Neogobius melanostomus have advanced eastward through the state of New York and provinces of Ontario and Quebec over the past two decades and are approaching Lake Champlain, one of the largest lakes in North America. This manuscript describes international efforts to monitor round goby populations during 2021–2025 on (a) the southern approach to Lake Champlain via the Hudson River and Champlain Canal, and (b) the northern approach to Lake Champlain via the Saint Lawrence River and Richelieu River. Monitoring utilized environmental DNA (eDNA), backpack electrofishing, beach seining, benthic trawling, and viral hemorrhagic septicemia virus (VHSV) testing. In the Champlain Canal, round goby were captured as far north as the downstream side of the C1 dam (97 kilometers [km] from Lake Champlain) while eDNA detections occurred as far north as the upstream side of the C2 dam (90 km from Lake Champlain). In the Richelieu River, round goby were captured as far south as Saint-Marc-sur-Richelieu (82 km from Lake Champlain) while the southern-most eDNA detections occurred near the Canadian side of the international border (4 km from Lake Champlain). Water temperature influenced habitat usage of round goby in the Champlain Canal, with catch rates in near-shore areas declining at < 10 °C. All VHSV test results were non-detections at the mouth of the Richelieu River, while one positive and two inconclusive results occurred along the Champlain Canal. Together, these data have informed multiple mitigation measures and have implications for management of aquatic invasive species across North America.

BioRxiv↗

USGS2006

Persistence of Pasteurella multocida in wetlands following avian cholera outbreaks

Avian cholera, caused by Pasteurella multocida, affects waterbirds across North America and occurs worldwide among various avian species. Once an epizootic begins, contamination of the wetland environment likely facilitates the transmission of P. multocida to susceptible birds. To evaluate the ability of P. multocida serotype-1, the most common serotype associated with avian cholera in waterfowl in western and central North America, to persist in wetlands and to identify environmental factors associated with its persistence, we collected water and sediment samples from 23 wetlands during winters and springs of 1996a??99. These samples were collected during avian cholera outbreaks and for up to 13 wk following initial sampling. We recovered P. multocida from six wetlands that were sampled following the initial outbreaks, but no P. multocida was isolated later than 7 wk after the initial outbreak sampling. We found no significant relationship between the probability of recovery of P. multocida during resampling and the abundance of the bacterium recovered during initial sampling, the substrate from which isolates were collected, isolate virulence, or water quality conditions previously suggested to be related to the abundance or survival of P. multocida. Our results indicate that wetlands are unlikely to serve as a long-term reservoir for P. multocida because the bacterium does not persist in wetlands for long time periods following avian cholera outbreaks.

Journal of Wildlife Diseases↗

USGS2013

Genomic analysis of avian influenza viruses from waterfowl in Western Alaska, USA

The Yukon-Kuskokwim Delta (Y-K Delta) in western Alaska is an immense and important breeding ground for waterfowl. Migratory birds from the Pacific Americas, Central Pacific, and East Asian-Australasian flyways converge in this region, providing opportunities for intermixing of North American- and Eurasian-origin hosts and infectious agents, such as avian influenza virus (AIV). We characterized the genomes of 90 low pathogenic (LP) AIV isolates from 11 species of waterfowl sampled on the Y-K Delta between 2006 and 2009 as part of an interagency surveillance program for the detection of the H5N1 highly pathogenic (HP) strain of AIV. We found evidence for subtype and genetic differences between viruses from swans and geese, dabbling ducks, and sea ducks. At least one gene segment in 39% of all isolates was Eurasian in origin. Target species (those ranked as having a relatively high potential to introduce HP H5N1 AIV to North America) were no more likely than nontarget species to carry viruses with genes of Eurasian origin. These findings provide evidence that the frequency at which viral gene segments of Eurasian origin are detected does not result from a strong species effect, but rather we suspect it is linked to the geographic location of the Y-K Delta in western Alaska where flyways from different continents overlap. This study provides support for retaining the Y-K Delta as a high priority region for the surveillance of Asian avian pathogens such as HP H5N1 AIV.

Alaska↗

USGS2015

Influence of ecological factors on prevalence of meningeal worm ( Parelaphostrongylus tenuis infection in South Dakota, USA

The meningeal worm ( Parelaphostrongylus tenuis ) is a nematode parasite that commonly infects white-tailed deer ( Odocoileus virginianus ; WTD) throughout the deciduous forest biome and deciduous-coniferous ecotone of eastern and central North America; the species is not known to occur west of the grassland biome of central North America. We used county-specific prevalence data to evaluate potential effects of landscape and climatologic factors on the spatial distribution of meningeal worm infection in South Dakota, US. Probability of infection increased 4-fold between eastern and western South Dakota and 1.3-fold for each 1-cm increase in summer precipitation. Sixty-three percent of WTD had only a single worm in the cranium. Expansion of meningeal worm infection across western South Dakota may be inherently low due to the combined effects of arid climate and potential attributes of the Missouri River that limit regional movements by infected WTD. Use of landscape genetic analyses to identify potential relationships between landscape features and population genetic structure of infected deer and parasites may contribute to a greater understanding of regional heterogeneity in meningeal worm infection rates across South Dakota, particularly in counties adjacent to the Missouri River. Future research evaluating heterogeneity in prevalence and intensity of infection between fawn and yearling deer, and the potential role of yearling male deer as dispersal agents of meningeal worms across the Missouri River, also is warranted.

South Dakota↗

USGS2016

Survey for West Nile virus antibodies in wild ducks, 2004-06, USA

Detection of West Nile virus (WNV) in ducks has been reported in North America in isolated cases of mortality in wild waterbirds and following outbreaks in farmed ducks. Although the virus has been noted as an apparent incidental finding in several species of ducks, little is known about the prevalence of exposure or the outcome of infection with WNV in wild ducks in North America. From 2004–06, we collected sera from 1,406 wild-caught American Wigeon ( Anas americana ), Mallard ( Anas platyrhynchos ), and Northern Pintail ( Anas acuta ) ducks at national wildlife refuges (NWRs) in North Dakota and Wood Ducks ( Aix sponsa ) at NWRs in South Carolina and Tennessee. We measured the prevalence of previous exposure to WNV in these ducks by measuring WNV antibodies and evaluated variation in exposure among species, age, and year. Additionally, we evaluated the performance of a commercial antibody to wild bird immunoglobulin in duck species that varied in their phylogenetic relatedness to the bird species the antibody was directed against. As determined by a screening immunoassay and a confirmatory plaque reduction neutralization assay, the prevalence of WNV antibody was 10%. In light of experimental studies that show ducks to be relatively resistant to mortality caused by WNV, the antibody prevalence we detected suggests that wild ducks may be less-frequently exposed to WNV than expected for birds inhabiting wetlands where they may acquire infection from mosquitoes.

North Dakota, South Carolina, Tennessee↗

USGS2016

Susceptibility and antibody response of Vesper Sparrows ( Pooecetes gramineus ) to West Nile virus: A potential amplification host in sagebrush-grassland habitat

West Nile virus (WNV) spread to the US western plains states in 2003, when a significant mortality event attributed to WNV occurred in Greater Sage-grouse ( Centrocercus urophasianus ). The role of avian species inhabiting sagebrush in the amplification of WNV in arid and semiarid regions of the North America is unknown. We conducted an experimental WNV challenge study in Vesper Sparrows ( Pooecetes gramineus ), a species common to sagebrush and grassland habitats found throughout much of North America. We found Vesper Sparrows to be moderately susceptible to WNV, developing viremia considered sufficient to transmit WNV to feeding mosquitoes, but the majority of birds were capable of surviving infection and developing a humoral immune response to the WNV nonstructural 1 and envelope proteins. Despite clearance of viremia, after 6 mo, WNV was detected molecularly in three birds and cultured from one bird. Surviving Vesper Sparrows were resistant to reinfection 6 mo after the initial challenge. Vesper sparrows could play a role in the amplification of WNV in sagebrush habitat and other areas of their range, but rapid clearance of WNV may limit their importance as competent amplification hosts of WNV.

Nevada↗

USGS2025

Mortality events in Yuma myotis (Myotis yumanensis) due to white-nose syndrome in Washington, USA

The impacts of white-nose syndrome (WNS) on many bat species in eastern North America have been well documented because of the length of time that the causative agent, Pseudogymnoascus destructans ( Pd ), has been present and the ability to monitor bat hibernacula in that region. However, the disease outcomes for bat species in western North America are less known because of the more recent arrival of Pd and the challenges associated with monitoring hibernating bat populations in parts of the western US. We report on mortality events involving Yuma myotis ( Myotis yumanensis ) bats at two locations in King and Benton counties, Washington, US, that were attributed to WNS during the late winters of 2020–21 and 2024, respectively. All bats that were grossly examined had depleted subcutaneous white adipose tissue, tested positive for the presence of Pd , had histopathologic lesions consistent with WNS, and did not exhibit evidence of other disease processes that may have contributed to death. Mortality was likely higher than what was documented because the locations of the Pd -contaminated hibernacula from which the bats originated were inaccessible or unknown and thus could not be surveyed. These findings indicate that Yuma myotis may be highly susceptible to WNS, and close monitoring is warranted to understand how WNS will affect population trends in this (and other) western bat species.

Washington↗

USGS2022

Positively selected genes in the hoary bat (Lasiurus cinereus) lineage: Prominence of thymus expression, immune and metabolic function, and regions of ancient synteny

Background Bats of the genus Lasiurus occur throughout the Americas and have diversified into at least 20 species among three subgenera. The hoary bat ( Lasiurus cinereus ) is highly migratory and ranges farther across North America than any other wild mammal. Despite the ecological importance of this species as a major insect predator, and the particular susceptibility of lasiurine bats to wind turbine strikes, our understanding of hoary bat ecology, physiology, and behavior remains poor. Methods To better understand adaptive evolution in this lineage, we used whole-genome sequencing to identify protein-coding sequence and explore signatures of positive selection. Gene models were predicted with Maker and compared to seven well-annotated and phylogenetically representative species. Evolutionary rate analysis was performed with PAML. Results Of 9,447 single-copy orthologous groups that met evaluation criteria, 150 genes had a significant excess of nonsynonymous substitutions along the L. cinereus branch ( P < 0.001 after manual review of alignments). Selected genes as a group had biased expression, most strongly in thymus tissue. We identified 23 selected genes with reported immune functions as well as a divergent paralog of Steep1 within suborder Yangochiroptera. Seventeen genes had roles in lipid and glucose metabolic pathways, partially overlapping with 15 mitochondrion-associated genes; these adaptations may reflect the metabolic challenges of hibernation, long-distance migration, and seasonal variation in prey abundance. The genomic distribution of positively selected genes differed significantly from background expectation by discrete Kolmogorov–Smirnov test ( P < 0.001). Remarkably, the top three physical clusters all coincided with islands of conserved synteny predating Mammalia, the largest of which shares synteny with the human cat-eye critical region (CECR) on 22q11. This observation coupled with the expansion of a novel Tbx1 -like gene family may indicate evolutionary innovation during pharyngeal arch development: both the CECR and Tbx1 cause dosage-dependent congenital abnormalities in thymus, heart, and head, and craniodysmorphy is associated with human orthologs of other positively selected genes as well.

PeerJ↗

USGS2018

Distribution and seasonal differences in Pacific Lamprey and Lampetra spp eDNA across 18 Puget Sound watersheds

Lampreys have a worldwide distribution, are functionally important to ecological communities and serve significant roles in many cultures. In Pacific coast drainages of North America, lamprey populations have suffered large declines. However, lamprey population status and trends within many areas of this region are unknown and such information is needed for advancing conservation goals. We developed two quantitative PCR-based, aquatic environmental DNA (eDNA) assays for detection of Pacific Lamprey ( Entosphenus tridentatus ) and Lampetra spp, using locked nucleic acids (LNAs) in the probe design. We used these assays to characterize the spatial distribution of lamprey in 18 watersheds of Puget Sound, Washington, by collecting water samples in spring and fall. Pacific Lamprey and Lampetra spp were each detected in 14 watersheds and co-occurred in 10 watersheds. Lamprey eDNA detection rates were much higher in spring compared to fall. Specifically, the Pacific Lamprey eDNA detection rate was 3.5 times higher in spring and the Lampetra spp eDNA detection rate was 1.5 times higher in spring even though larval lamprey are present in streams year-round. This significant finding highlights the importance of seasonality on eDNA detection. Higher stream discharge in the fall likely contributed to reduced eDNA detection rates, although seasonal life history events may have also contributed. These eDNA assays differentiate Pacific Lamprey and Lampetra spp across much of their range along the west coast of North America. Sequence analysis indicates the Pacific Lamprey assay also targets other Entosphenus spp and indicates the Lampetra spp assay may have limited or no capability of detecting Lampetra in some locations south of the Columbia River Basin. Nevertheless, these assays will serve as a valuable tool for resource managers and have direct application to lamprey conservation efforts, such as mapping species distributions, occupancy modeling, and monitoring translocations and reintroductions.

Puget Sound↗

USGS2013

New insights into the diets of harbor seals in the Salish Sea revealed by quantitative fatty acid signature analysis

Harbor seals ( Phoca vitulina ) are an abundant predator along the west coast of North America, and there is considerable interest in their diet composition, especially in regard to predation on valued fish stocks. Available information on harbor seal diets, primarily derived from scat analysis, suggests that adult salmon ( Oncorhynchus spp.), Pacific Herring ( Clupea pallasii ), and gadids predominate. Because diet assessments based on scat analysis may be biased, we investigated diet composition through quantitative analysis of fatty acid signatures. Blubber samples from 49 harbor seals captured in western North America from haul-outs within the area of the San Juan Islands and southern Strait of Georgia in the Salish Sea were analyzed for fatty acid composition, along with 269 fish and squid specimens representing 27 potential prey classes. Diet estimates varied spatially, demographically, and among individual harbor seals. Findings confirmed the prevalence of previously identified prey species in harbor seal diets, but other species also contributed significantly. In particular, Black ( Sebastes melanops ) and Yellowtail ( S. flavidus ) Rockfish were estimated to compose up to 50% of some individual seal diets. Specialization and high predation rates on Black and Yellowtail Rockfish by a subset of harbor seals may play a role in the population dynamics of these regional rockfish stocks that is greater than previously realized.

British Columbia, Washington↗

USGS2018

Inland waters

1. The total flux of carbon—which includes gaseous emissions, lateral flux, and burial—from inland waters across the conterminous United States (CONUS) and Alaska is 193 teragrams of carbon (Tg C) per year. The dominant pathway for carbon movement out of inland waters is the emission of carbon dioxide gas across water surfaces of streams, rivers, and lakes (110.1 Tg C per year), a flux not identified in the First State of the Carbon Cycle Report (SOCCR1; CCSP 2007). Second to gaseous emissions are the lateral fluxes of carbon through rivers to coastal environments (59.8 Tg C per year). Total carbon burial in lakes and reservoirs represents the smallest flux for CONUS and Alaska (22.5 Tg C per year) (medium confidence). 2. Based on estimates presented herein, the carbon flux from inland waters is now understood to be four times larger than estimates presented in SOCCR1. The total flux of carbon from inland waters across North America is estimated to be 507 Tg C per year based on a modeling approach that integrates high-resolution U.S. data and continental-scale estimates of water area, discharge, and carbon emissions. This estimate represents a weighted average of 24 grams of carbon per m2 per year of continental area exported and removed through inland waters in North America (low confidence). 3. Future research can address critical knowledge gaps and uncertainties related to inland water carbon fluxes. This chapter, for example, does not include methane emissions, which cannot be calculated as precisely as other carbon fluxes because of significant data gaps. Key to reducing uncertainties in estimated carbon fluxes is increased temporal resolution of carbon concentration and discharge sampling to provide better representations of storms and other extreme events for estimates of total inland water carbon fluxes. Improved spatial resolution of sampling also could potentially highlight anthropogenic influences on the quantity and quality of carbon fluxes in inland waters and provide information for land-use planning and management of water resources. Finally, uncertainties could likely be reduced if the community of scientists working in inland waters establishes and adopts standard measurement techniques and protocols similar to those maintained through collaborative efforts of the International Ocean Carbon Coordination Project and relevant governmental agencies from participating nations.

Book chapter↗

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