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USGS2022

Integrating distance sampling survey data with population indices to separate trends in abundance and temporary immigration

Managers rely on accurate estimators of wildlife abundance and trends for management decisions. Despite the focus of contemporary wildlife science on developing methods to improve inference from wildlife surveys, legacy datasets often rely on index counts that lack information about the detection process. Data integration can be a useful tool for combining index counts with data collected under more rigorous designs (i.e., designs that account for the detection process), but care is required when datasets represent different population processes or are mismatched in space and time. This can be particularly problematic in cases where animals aggregate in response to a spatially or temporally limited resource because individuals may temporarily immigrate from outside the study area and be included in the abundance index. Abundance indices based on brown bear ( Ursus arctos ) feeding aggregations within coastal meadows in early summer in Lake Clark National Park and Preserve, Alaska, USA, are one such example. These indices reflect the target population (brown bears residing within the park) and temporary immigrants (i.e., bears drawn from outside the park boundary). To properly account for the effects of temporary immigration, we integrated the index data with abundance data collected via park-wide distance sampling surveys, the latter of which properly addressed the detection process. By assuming that the distance data provide inference on abundance and the index counts represent some combination of abundance and temporary immigration processes, we were able to decompose the relative contribution of each to overall trend. We estimated that the density of brown bears within our study area was 38–54 adults/1,000 km 2 during 2003–2019 and that abundance increased at a rate of approximately 1.4%/year. The contribution of temporary immigrants to overall trend in the index was low, so we created 3 hypothetical scenarios to more fully demonstrate how the integrated approach could be useful in situations where the composite trend in meadow counts may obscure trends in abundance (e.g., opposing trends in abundance and temporary immigration). Our work represents a conceptual advance supporting the integration of legacy index data with more rigorous data streams and is broadly applicable in cases where trends in index values may represent a mixture of population processes.

Alaska↗

USGS2022

Status and trends of the Lake Huron prey fish community, 1976-2019

The USGS Great Lakes Science Center has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October of each year and an acoustics-midwater trawl survey, which began in 2004 and is conducted in September-October. Both surveys were completed in their entirety in 2019. Prey fish biomass in Lake Huron in 2019 was dominated by two species, Bloater ( Coregonus hoyi ) and Rainbow Smelt ( Osmerus mordax ). In the main basin, prey fish biomass remained below levels observed prior to community-wide declines that began in the early to mid 1990s. Bloater was the most abundant prey fish species in the main basin, whereas Rainbow Smelt was the most abundant prey species in the North Channel and in Georgian Bay. Both surveys suggested that Bloater biomass is increasing in the main basin. Low biomass of invasive species like Alewife ( Alosa pseudoharengus ) and Rainbow Smelt is consistent with fish community objectives focused on restoration of native fish communities. Abundance of invasive Round Goby (Neogobius melanostomus) in 2019 was low relative to 2018. Biomass of the native Cisco ( Coregonus artedi ) continued to increase in the North Channel and Georgian Bay. Biomass of slimy sculpin ( Cottus cognatus ) and Deepwater Sculpin ( Myoxocephalus thompsoni ) in 2019 was down from 2018 but within the range observed over the past decade. Reduced lake productivity, predation by a recovering piscivore community, and shifts in food web dynamics that favor fish production in nearshore environments may prevent prey fish biomass in offshore areas from returning to levels observed prior to the early 1990’s. However, increased biomass of Bloater and Cisco suggests that lake conditions may favor recovery of native coregonids.

Lake Huron↗

USGS2012

Status and trends of prey fish populations in Lake Michigan, 2012

The U.S. Geological Survey Great Lakes Science Center has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size and age structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2012. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2012 was estimated at 9 kilotonnes (kt, 1 kt = 1000 metric tonnes), which continues the trend of unusually low alewife biomass since 2004 but represented a 20% increase from the 2011 estimate. The age distribution of alewives larger than 100 mm was dominated (i.e., 84%) by age-2. Record low biomass was observed for several species, including bloater (0.4 kt), rainbow smelt (0.1 kt), deepwater sculpin (1.5 kt), and ninespine stickleback (0.01 kt). Slimy sculpin lake-wide biomass was 0.73 kt in 2012, which was the third consecutive year revealing a decline. Estimated biomass of round goby increased by 79% to 3 kt. Burbot lake-wide biomass (0.5 kt in 2012) has remained below 3 kt since 2001. Numeric density of age-0 yellow perch (i.e., < 100 mm) was only 2 fish per ha, which is indicative of a relatively poor year-class. Lake-wide biomass estimates of dreissenid mussels have continued to increase from 2010, from 12 to 95 kt in 2012. Overall, the total lake-wide prey fish biomass estimate (sum of alewife, bloater, rainbow smelt, deepwater sculpin, slimy sculpin, round goby, and ninespine stickleback) in 2012 was 15 kt, which represented the lowest total biomass of the time series.

Lake Michigan↗

USGS2007

Ultraviolet radiation and bio-optics in Crater Lake, Oregon

Crater Lake, Oregon, is a mid-latitude caldera lake famous for its depth (594 m) and blue color. Recent underwater spectral measurements of solar radiation (300-800 nm) support earlier observations of unusual transparency and extend these to UV-B wavelengths. New data suggest that penetration of solar UVR into Crater Lake has a significant ecological impact. Evidence includes a correlation between water column chlorophyll-a and stratospheric ozone since 1984, the scarcity of organisms in the upper water column, and apparent UV screening pigments in phytoplankton that vary with depth. The lowest UV-B diffuse attenuation coefficients (K d,320) were similar to those reported for the clearest natural waters elsewhere, and were lower than estimates for pure water published in 1981. Optical proxies for UVR attenuation were correlated with chlorophyll-a concentration (0-30 m) during typical dry summer months from 1984 to 2002. Using all proxies and measurements of UV transparency, decadal and longer cycles were apparent but no long-term trend since the first optical measurement in 1896. ?? 2007 Springer Science+Business Media B.V.

Hydrobiologia↗

USGS2003

Arsenic behavior in newly drilled wells

In the present paper, inorganic arsenic species and chemical parameters in groundwater were determined to investigate the factors related to the distribution of arsenic species and their dissolution from rock into groundwater. For the study, groundwater and core samples were taken at different depths of two newly drilled wells in Huron and Lapeer Counties, Michigan. Results show that total arsenic concentrations in the core samples varied, ranging from 0.8 to 70.7 mg/kg. Iron concentration in rock was about 1800 times higher than that of arsenic, and there was no correlation between arsenic and iron occurrences in the rock samples. Arsenic concentrations in groundwater ranged from <1 to 171 ??g/l. The arsenic concentration in groundwater depended on the amount of arsenic in aquifer rocks, and as well decreased with increasing depth. Over 90% of arsenic existed in the form of As(III), implying that the groundwater systems were in the reduced condition. The results such as high ferrous ion, low redox potential and low dissolved oxygen supported the observed arsenic species distribution. There was no noticeable difference in the total arsenic concentration and arsenic species ratio between unfiltered and filtered (0.45 ??m) waters, indicating that the particulate form of arsenic was negligible in the groundwater samples. There were correlations between water sampling depth and chemical parameters, and between arsenic concentration and chemical parameters, however, the trends were not always consistent in both wells. ?? 2003 Elsevier Science Ltd. All rights reserved.

Conference Paper↗

USGS2008

Western Mountain Initiative: predicting ecosystem responses to climate change

Mountain ecosystems of the western United States provide irreplaceable goods and services such as water, timber, biodiversity, and recreational opportunities, but their responses to climatic changes are complex and not well understood. The Western Mountain Initiative (WMI), a collaboration between USGS and U.S. Forest Service scientists, catalyzes assessment and synthesis of the effects of disturbance and climate change across western mountain areas, focusing on national parks and surrounding national forests. The WMI takes an ecosystem approach to science, integrating research across science disciplines at scales ranging from field studies to global trends.

Fact Sheet↗

USGS2016

Conservation planning for the Colorado River in Utah

Strategic planning is increasingly recognized as necessary for providing the greatest possible conservation benefits for restoration efforts. Rigorous, science-based resource assessment, combined with acknowledgement of broader basin trends, provides a solid foundation for determining effective projects. It is equally important that methods used to prioritize conservation investments are simple and practical enough that they can be implemented in a timely manner and by a variety of resource managers. With the help of local and regional natural resource professionals, we have developed a broad-scale, spatially-explicit assessment of 146 miles (~20,000 acres) of the Colorado River mainstem in Grand and San Juan Counties, Utah that will function as the basis for a systematic, practical approach to conservation planning and riparian restoration prioritization. For the assessment we have: 1) acquired, modified or created spatial datasets of Colorado River bottomland conditions; 2) synthesized those datasets into habitat suitability models and estimates of natural recovery potential, fire risk and relative cost; 3) investigated and described dominant ecosystem trends and human uses, and; 4) suggested site selection and prioritization approaches. Partner organizations (The Nature Conservancy, National Park Service, Bureau of Land Management and Utah Forestry Fire and State Lands) are using the assessment and datasets to identify and prioritize a suite of restoration actions to increase ecosystem resilience and improve habitat for bottomland species. Primary datasets include maps of bottomland cover types, bottomland extent, maps of areas inundated during high and low flow events, as well as locations of campgrounds, roads, fires, invasive vegetation treatment areas and other features. Assessment of conditions and trends in the project area entailed: 1) assemblage of existing data on geology, changes in stream flow, and predictions of future conditions; 2) identification of fish and wildlife species present and grouping species into Conservation Elements (CEs) based on habitat needs, and: 3) acquisition, review and creation of spatial datasets characterizing vegetation, fluvial geomorphic and human features within the bottomland. Interpretation of aerial imagery and assimilation of pre-existing spatial data were central to our efforts in characterizing resources conditions. Detailed maps of vegetation and channel habitat features in the project area were generated from true color, high resolution (0.3m) imagery flown September 16, 2010. We also mapped channel habitat features at high flow on 1.0-m resolution, publicly available, true color imagery. We obtained additional layers such as land ownership, roads, fire history, non-native vegetation treatment areas, and recreational use features from public sources and project partners. Habitat suitability models were created for groups of terrestrial species by combining spatial datasets with the habitat needs of conservation elements, guided by literature, where available, and extensive use of expert knowledge. Conservation elements for endangered fish species life stages were identified but not modeled. Terrestrial CE’s included: • Riparian Overstory -yellow-billed cuckoo, Bullock’s oriole, black-headed grosbeak, blue grosbeak, warbling vireo, Cooper's hawk, screech owl, saw-whet owl, and bald eagle, (best: tall trees, dense canopy, diverse shrub understory, no tamarisk); • Riparian Understory - southwestern willow flycatcher, common yellowthroat, yellow warbler, yellow-breasted chat, beaver, northern river otter, black-necked garter snake, (best: dense mesic shrubs near still water, no tamarisk); • Bat Feeding - Allen's big-eared bat, Townsend's big-eared bat, fringed myotis, Yuma myotis, big free-tailed bat, spotted bat (best: diverse vegetation, close to still water); • Bat Watering - big free-tailed and spotted bats (best: still water with no tall vegetation); •

Utah↗

USGS2008

L5 TM radiometric recalibration procedure using the internal calibration trends from the NLAPS trending database

From the Landsat program's inception in 1972 to the present, the earth science user community has benefited from a historical record of remotely sensed data. The multispectral data from the Landsat 5 (L5) Thematic Mapper (TM) sensor provide the backbone for this extensive archive. Historically, the radiometric calibration procedure for this imagery used the instrument's response to the Internal Calibrator (IC) on a scene-by-scene basis to determine the gain and offset for each detector. The IC system degraded with time causing radiometric calibration errors up to 20 percent. In May 2003 the National Landsat Archive Production System (NLAPS) was updated to use a gain model rather than the scene acquisition specific IC gains to calibrate TM data processed in the United States. Further modification of the gain model was performed in 2007. L5 TM data that were processed using IC prior to the calibration update do not benefit from the recent calibration revisions. A procedure has been developed to give users the ability to recalibrate their existing Level-1 products. The best recalibration results are obtained if the work order report that was originally included in the standard data product delivery is available. However, many users may not have the original work order report. In such cases, the IC gain look-up table that was generated using the radiometric gain trends recorded in the NLAPS database can be used for recalibration. This paper discusses the procedure to recalibrate L5 TM data when the work order report originally used in processing is not available. A companion paper discusses the generation of the NLAPS IC gain and bias look-up tables required to perform the recalibration.

Conference Paper↗

USGS2012

Expanded stream gauging includes groundwater data and trends

Population growth has increased water scarcity to the point that documenting current amounts of worldwide water resources is now as critical as any data collection in the Earth sciences. As a key element of this data collection, stream gauges yield continuous hydrologic information and document long-term trends, recording high-frequency hydrologic information over decadal to centennial time frames.

Eos, Transactions, American Geophysical Union↗

USGS2009

Status and trends of the Lake Huron deepwater demersal fish ommunity, 2008

The U.S.Geological Survey Great Lakes Science Center has conducted trawl surveys to assess annual changes in the deepwater demersal fish community of Lake Huron since 1973. Since 1992, surveys have been carried out using a 21 m wing trawl towed on-contour at depths ranging from 9 to 110 m on fixed transects. Sample sites include five ports in U.S. waters with less frequent sampling near Goderich, Ontario. The 2008 fall bottom trawl survey was carried out between October 24 and November 20, 2008 and sampled only the three northern U.S. ports at DeTour, Hammond Bay, and Alpena due to mechanical problems with the research vessel and prolonged periods of bad weather. Therefore, all data presented for 2008 are based on samples collected from these ports. Compared to previous years, alewife populations in Lake Huron remain at low levels after collapsing in 2004. Age-0 alewife density and biomass appears to have increased slightly but overall levels remain near the nadir observed in 2004. Density and biomass of adult and juvenile rainbow smelt showed a decrease from 2007 despite record-high abundance of juveniles observed in 2005, suggesting recruitment was low. Numbers of adult and juvenile bloater were low despite recent high year-classes. Abundances for most other prey species were similar to the low levels observed in 2005 - 2007. We captured one wild juvenile lake trout in 2008 representing the fifth consecutive year that wild lake trout were captured in the survey. Based on pairwise graphical comparisons and nonparametric correlation analyses, dynamics of prey abundance at the three northern ports followed lakewide trends since 1992. Density of benthic macroinvertebrates was at an all-time low in 2008 since sampling began in 2001. The decline in abundance was due to decreases in all taxonomic groups and a large reduction in recruitment of quagga mussels. Density of Diporeia at northern ports in 2008 was the lowest observed. Diporeia were found only at 73-m sites of three ports sampled in northern Lake Huron. While no lakewide estimate of prey biomass was calculated due to the limited spatial scope of the 2008 survey, existing data suggest prey biomass remains depressed. Prey available to salmonids during 2009 will likely be small alewives, small rainbow smelt and small bloaters. Predators in Lake Huron will continue to face potential prey shortages.

Lake Huron↗

USGS2015

Status and trends of prey fish populations in Lake Michigan, 2014

The U.S. Geological Survey Great Lakes Science Center has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size and age structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2014. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2014 was estimated at 1.6 kilotonnes (kt, 1 kt = 1000 metric tonnes), which was a record low and only 16% of the average biomass estimated since 2005. Moreover, the age distribution of alewives remained truncated with no alewife exceeding an age of 5. Record low biomass was also observed for nearly every other prey fish species: bloater (0.3 kt), rainbow smelt (0.02 kt), slimy sculpin (0.09 kt), deepwater sculpin (1.0 kt) and ninespine stickleback (0.004 kt). Round goby was the only prey fish species to avoid a record-low biomass estimate (2.04 kt); the 2014 estimate was 58% of the average lakewide biomass observed since 2006 when round gobies became relatively abundant in our catches. Burbot lake-wide biomass (0.5 kt in 2014) has remained below 3 kt since 2001. No age-0 yellow perch (i.e., < 100 mm) were captured during the survey, which is indicative of a poor year-class. Lake-wide biomass estimate of dreissenid mussels in 2014 was 23.9 kt, not different from 2013 (23.2 kt). Overall, the total lake-wide prey fish biomass estimate (sum of alewife, bloater, rainbow smelt, deepwater sculpin, slimy sculpin, round goby, and ninespine stickleback) in 2014 was only 5.1 kt, compared to the previous record-low prey fish biomass of 15.2 kt in 2012. In 2014, alewives and round gobies constituted 71% of this total, following a trend of dominance by these species since 2012.

Lake Michigan↗

USGS2023

Long-term trends of local bird populations based on monitoring schemes: Are they suitable for justifying management measures?

Local biodiversity monitoring is important to assess the effects of global change, but also to evaluate the performance of landscape and wildlife protection, since large-scale assessments may buffer local fluctuations, rare species tend to be underrepresented, and management actions are usually implemented on local scales. We estimated population trends of 58 bird species using open-population N-mixture models based on count data in two localities in southeastern Spain, which have been collected according to a citizen science monitoring program (SACRE, Monitoring Common Breeding Birds in Spain) over 21 and 15 years, respectively. We performed different abundance models for each species and study area, accounting for imperfect detection of individuals in replicated counts. After selecting the best models for each species and study area, empirical Bayes methods were used for estimating abundances, which allowed us to calculate population growth rates ( λ ) and finally population trends. We also compared the two local population trends and related them with national and European trends, and species functional traits (phenological status, dietary, and habitat specialization characteristics). Our results showed increasing trends for most species, but a weak correlation between populations of the same species from both study areas. In general, local population trends were consistent with the trends observed at national and continental scales, although contrasting patterns exist for several species, mainly with increasing local trends and decreasing Spanish and European trends. Moreover, we found no evidence of a relationship between population trends and species traits. We conclude that using open-population N-mixture models is an appropriate method to estimate population trends, and that citizen science-based monitoring schemes can be a source of data for such analyses. This modeling approach can help managers to assess the effectiveness of their actions at the local level in the context of global change.

Journal of Ornithology↗

USGS2018

Promoting synergy in the innovative use of environmental data—Workshop summary

From December 2 to 4, 2015, NatureServe and the U.S. Geological Survey organized and hosted a biodiversity and ecological informatics workshop at the U.S. Department of the Interior in Washington, D.C. The workshop objective was to identify user-driven future directions and areas of collaboration in advanced applications of environmental data applied to forecasting and decision making for the sustainability of biodiversity and ecosystem services. Substantial effort to recruit attendees from diverse Federal, State, and private sector organizations successfully attracted participants from 20 Federal agencies and 48 different institutions in the academic, nonprofit, State government, and commercial sectors; the total number of attendees ranged from 100 to 144 during the 3-day workshop. The first one-half of the workshop was divided into 7 plenary sessions and 3 sets of lightning talk sessions organized by sector, providing 48 oral and visual plenary presentations that shared diverse perspectives on biodiversity and ecological informatics, including original biospatial analyses from 6 graduate student map contest winners. The second one-half of the workshop focused on 10 breakout sessions with participant-driven themes from the environmental data sphere and concluded with an address by the Director of the U.S. Fish and Wildlife Service. The workshop was structured to encourage interactivity. About 80–90 percent of attendees provided direct feedback using clicker devices for specific questions related to biodiversity and ecological data uses and needs, and 10 breakout session leaders shared the highlights of their group discussions during the final workshop plenary sessions. Participants were encouraged to use the Twitter hashtag #ShareUrData. Over lunch on day 2 there were 20 simultaneous presentations of tools and apps during a special “Tools Café” session. The 10 participant-defined breakout session topics are listed below: Ecosystem services and ecological indicators Inventory and monitoring Biogeographic map of the Nation Pollinators Invasive species Remote sensing Drivers of agricultural change Citizen science Climate Hydrology and watersheds Numerous common themes that emerged from the workshop include the following: The vital importance of completing foundational environmental datasets that are nationally consistent and are essential to multiple sectors, such as the Soil Survey Geographic database high-resolution soils data, a minimum 5-meter resolution digital elevation model, national hydrographic data, high-resolution land cover data, time series high-resolution spatial climate data from historical to future time steps, and a national wetland inventory. Improved, nationally consistent environmental datasets (integrated with targeted observations) will dramatically advance forecasting capacity and support early warning systems (that is, drought, forest disease); however, multiagency coordination should focus on decision support tools that convey appropriate actions and responses to adapt to, and mitigate, potential negative consequences. Digitizing and providing access to the vast stores of underused historical data that can be leveraged for this purpose is of national importance. Modern computational techniques and the ever-increasing flow of environmental data from ground and remote observations can support improved understanding of environmental change. Success of understanding patterns of change for decision making requires establishing baselines from which change can be measured. The value of digitized historical data is greater than ever before. There is a need to recognize the multifaceted potential of citizen science to engage the public in resource stewardship, to create the next generation of science, technology, engineering, math, and environmental leaders, and to have sufficient field personnel to monitor environmental trends, including early detection of alien invasive species, phenological shifts, shifting distribution and abundance of indicator species, and species inventories. The Federal government has an essential role in creating the infrastructure to dramatically improve mobilization of citizen science (and other) data by fostering the following: creation of data standards, creation of nationally consistent framework datasets, vertical integration of observation data, visualization and dissemination of aggregated datasets, and calculation and communication of derived trends. Current and near future trends in the availability of remotely sensed data (rapid expansion of satellite fleets and drones) is revolutionizing access to near-real-time ecological data. Targeted integration with ground-based observations and instrumentation has an extremely valuable role in validating remotely sensed data, filling data gaps, improving data quality, and fully realizing the potential of the near-real-time monitoring of environmental indicator trends. Integrated management of environmental data at the landscape scale is required even as specific actions on the ground are largely local in nature. The workshop highlighted numerous success stories; however, almost every breakout group pointed out the still-too-fragmented nature of the current data landscape. Management and delivery of the necessary data, tools, and analyses to sustain our Nation’s environmental capital must be a collaborative effort between Federal, State, and local governments, academia, nonprofits, and the commercial sector, even though the responsibilities of each sector are different.

Open-File Report↗

USGS2026

Population trends of dabbling ducks wintering in the alluvial valleys of Arkansas and Mississippi

Population abundances, distributions, and compositions across a diversity of taxa are changing, partly as a consequence of human-induced global modifications. Although linking population fluctuations to anthropogenic-induced alterations can be challenging, it is increasingly clear that long-term monitoring is critical to understanding changing populations. For waterfowl, concerns over recent declines in breeding populations or possible redistribution from using traditional wintering grounds for some species support continued monitoring of regional populations. To further understand population trends on traditional wintering grounds, we examined abundance trends over time within the Mississippi and Arkansas portions of the Mississippi Alluvial Valley, using two sources of data: systematic aerial surveys and citizen science data. We found great annual variability in rates of population change ( r ranging from −1.04 to 0.71) in five species of dabbling ducks. Despite this annual variation, green-winged teal Anas carolinensis , mallards Anas platyrhynchos , northern pintail Anas acuta , and northern shoveler Spatula clypeata showed no significant trends in population size over approximately 15 years in Mississippi and Arkansas, but gadwall Mareca strepera showed a 4% annual increase in the citizen science data for Mississippi. Despite substantial variation in annual abundance, the timing of peak abundance was remarkably consistent from year to year, with peaks typically occurring in January. Our results demonstrate that autumn–winter population numbers of dabbling ducks can be quite variable interannually, but they lack a consistent trend in the Mississippi Alluvial Valley during the past two decades. Going forward, investigation into how citizen science data could be leveraged to increase the precision of trends within this landscape might be of benefit, and sampling efforts could perhaps be added towards the latter portion of the wintering period. As populations continue to adjust in a changing world, maintaining monitoring surveys in regions important to waterfowl is an effective and important means of evaluating trends.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗

USGS2023

Recent and future declines of a historically widespread pollinator linked to climate, land cover, and pesticides

The acute decline in global biodiversity includes not only the loss of rare species, but also the rapid collapse of common species across many different taxa. The loss of pollinating insects is of particular concern because of the ecological and economic values these species provide. The western bumble bee ( Bombus occidentalis ) was once common in western North America, but this species has become increasingly rare through much of its range. To understand potential mechanisms driving these declines, we used Bayesian occupancy models to investigate the effects of climate and land cover from 1998 to 2020, pesticide use from 2008 to 2014, and projected expected occupancy under three future scenarios. Using 14,457 surveys across 2.8 million km 2 in the western United States, we found strong negative relationships between increasing temperature and drought on occupancy and identified neonicotinoids as the pesticides of greatest negative influence across our study region. The mean predicted occupancy declined by 57% from 1998 to 2020, ranging from 15 to 83% declines across 16 ecoregions. Even under the most optimistic scenario, we found continued declines in nearly half of the ecoregions by the 2050s and mean declines of 93% under the most severe scenario across all ecoregions. This assessment underscores the tenuous future of B. occidentalis and demonstrates the scale of stressors likely contributing to rapid loss of related pollinator species throughout the globe. Scaled-up, international species-monitoring schemes and improved integration of data from formal surveys and community science will substantively improve the understanding of stressors and bumble bee population trends.

Proceedings of the National Academy of Sciences↗

USGS2015

Status and trends of prey fish populations in Lake Michigan, 2013

The U.S. Geological Survey Great Lakes Science Center has conducted lake-wide surveys of the fish community in Lake Michigan each fall since 1973 using standard 12-m bottom trawls towed along contour at depths of 9 to 110 m at each of seven index transects. The resulting data on relative abundance, size and age structure, and condition of individual fishes are used to estimate various population parameters that are in turn used by state and tribal agencies in managing Lake Michigan fish stocks. All seven established index transects of the survey were completed in 2013. The survey provides relative abundance and biomass estimates between the 5-m and 114-m depth contours of the lake (herein, lake-wide) for prey fish populations, as well as burbot, yellow perch, and the introduced dreissenid mussels. Lake-wide biomass of alewives in 2013 was estimated at 29 kilotonnes (kt, 1 kt = 1000 metric tonnes), which was more than three times the 2012 estimate. However, the unusually high standard error associated with the 2013 estimate indicated no significant increase in lake-wide biomass between 2012 and 2013. Moreover, the age distribution of alewives remained truncated with no alewife exceeding an age of 5. The population of age-1 and older alewives was dominated (i.e., 88%) by the 2010 and 2012 year-classes. Record low biomass was observed for deepwater sculpin (1.3 kt) and ninespine stickleback (0.004 kt) in 2013, while bloater (1.6 kt) and rainbow smelt (0.2 kt) biomasses remained at low levels. Slimy sculpin lake-wide biomass was 0.32 kt in 2013, marking the fourth consecutive year of a decline. The 2013 biomass of round goby was estimated at 10.9 kt, which represented the peak estimate to date. Burbot lake-wide biomass (0.4 kt in 2013) has remained below 3 kt since 2001. Numeric density of age-0 yellow perch (i.e., < 100 mm) was only 1 fish per ha, which is indicative of a relatively poor year-class. Lake-wide biomass estimate of dreissenid mussels in 2013 was 23.2 kt. Overall, the total lake-wide prey fish biomass estimate (sum of alewife, bloater, rainbow smelt, deepwater sculpin, slimy sculpin, round goby, and ninespine stickleback) in 2013 was 43 kt, with alewives and round gobies constituting 92% of this total.

Lake Michigan↗

USGS2015

Status and trends of the Lake Huron offshore demersal fish community, 1976-2012

The USGS Great Lakes Science Center has conducted trawl surveys to assess annual changes in the offshore demersal fish community of Lake Huron since 1973. Sample sites include five ports in U.S. waters with less frequent sampling near Goderich, Ontario. The 2012 fall bottom trawl survey was carried out between 20 October – 5 November 2012 and included all U.S. ports as well as Goderich, ON. The 2012 main basin prey fish biomass estimate for Lake Huron was 97 kilotonnes, higher than the estimate in 2011 (63.2 Kt), approximately one third of the maximum estimate in the time series, and nearly 6 times higher than the minimum estimate in 2009. The biomass estimates for adult alewife in 2012 were higher than 2011, but remained much lower than observed before the crash in 2004, and populations were dominated by small fish. Estimated biomass of rainbow smelt also increased and was the highest observed since 2005. Estimated adult bloater biomass in Lake Huron has been increasing in recent years, and the 2012 biomass estimate was the third highest ever observed in the survey. Biomass estimates for trout-perch and ninespine stickleback were higher than in 2011 but still remained low compared to historic estimates. The estimated biomass of deepwater and slimy sculpins increased over 2011, and slimy sculpin in particular seem to be increasing in abundance. The 2012 biomass estimate for round goby was similar to that in 2011 and was the highest observed in the survey. Substantial numbers of wild juvenile lake trout were captured again in 2012, suggesting that natural reproduction by lake trout continues to occur. The 2012 Lake Huron bottom trawl survey results suggest that several species of offshore demersal fish are beginning to increase in abundance.

Michigan↗

USGS2014

Status and trends of the Lake Huron offshore Demersal fish community, 1976-2013

The USGS Great Lakes Science Center has conducted trawl surveys to assess annual changes in the offshore demersal fish community of Lake Huron since 1973. Sample sites include five ports in U.S. waters with less frequent sampling near Goderich, Ontario. The 2013 fall bottom trawl survey was carried out between 25 October – 21 November 2013 and included all U.S. ports as well as Goderich, ON. The 2013 main basin prey fish biomass estimate for Lake Huron was 47 kilotonnes, less than half of the estimate in 2012 (97 Kt), and approximately 13 percent of the maximum estimate in the time series. The biomass etimate for YAO alewife in 2013 was lower than in 2012, remained much lower than levels observed before the crash in 2004, and populations were dominated by small fish. Estimated biomass of rainbow smelt also decreased and was the second lowest observed in the time series. Estimated YAO bloater biomass in Lake Huron was also reduced compared to 2012. YOY alewife, rainbow smelt, and bloater abundance and biomass increased over 2012. Biomass estimates for deepwater and slimy sculpins, trout-perch, ninespine stickleback, and round goby in 2013 were lower than in 2012 and remained low compared to historic estimates. Wild juvenile lake trout were captured again in 2013, suggesting that natural reproduction by lake trout continues to occur.

Report↗