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At least 919 records · Page 51Linked to original sources

USGS2020

Ratios of methylmercury to total mercury in predator and primary consumer insects from Adirondack streams in New York State

Mercury (Hg) is a global pollutant that affects aquatic biota in otherwise pristine settings such as the Adirondack region of New York State. Bioaccumulation of Hg is especially problematic in sensitive landscapes, where inorganic mercury from atmospheric deposition is readily converted, via natural processes, to methylmercury (MeHg), the toxic form that is taken up and biomagnified in aquatic food webs. There is great interest in monitoring MeHg in aquatic biota across these sensitive regions to evaluate responses to changes in Hg emissions. Aquatic insects, such as dragonfly larvae, have great potential as MeHg “biosentinels,” but currently are not widely used for this purpose. An important practical consideration in the use of aquatic insects for MeHg biomonitoring is whether total mercury (THg) is a suitable surrogate for MeHg, which is much more technically challenging and expensive to analyze than is THg. The objective of this project was to assess the suitability of THg as a surrogate for MeHg in stream-dwelling insects. Specifically, existing data on immature aquatic insects from nine Adirondack streams were used to characterize MeHg to THg ratios (i.e., MeHg%), and variation in these ratios (e.g., among sites, seasons, taxa) in predator and primary consumer insects, examine how well THg in different groups tracks measured stream water MeHg (i.e., filtered MeHg; FMeHg), and explore the influence of trophic position (indicated by nitrogen stable isotopes; δ 15 N) on the observed MeHg% patterns. Three broad insect feeding groups were included in this analysis: predators, shredders, and scrapers. Predators had the highest MeHg% (median 94%), and MeHg% did not differ significantly among any of the taxa considered: stoneflies, damselflies, and three families of dragonflies (darners, common skimmers, and clubtails). Darners and common skimmers, the most numerous and abundant predators, were combined for further analyses. Site medians for these “selected dragonflies” were all at least 90% (summer-fall collections) and MeHg% did not differ significantly among sites. The correlation between FMeHg and THg in selected dragonflies was nearly as strong as that of FMeHg and dragonfly MeHg. In contrast, median MeHg% in shredders (northern caddisflies) and scrapers (flathead mayflies), which are both primary consumers, was lower overall (medians 52% and 35%, respectively), more variable, and less-well representative of FMeHg than predators. Stable isotope results indicate that variation in feeding position is an important influence on some of the MeHg% patterns observed in this study. This study’s findings suggest that THg is likely to be a suitable surrogate for MeHg in predatory aquatic insects from Adirondack streams, but do not support the use of THg in primary consumers for regional MeHg monitoring.

New York↗

USGS2021

Status of Cisco in Lake Superior in 2017

This report describes the status of fish species and their habitat in Lake Superior during the reporting period of 2012-2016 in response to achievement of fish community objectives (FCOs) established by fishery managers for the lake. The overarching goal for the FCOs continued to be met as the fish community remained diverse, self-regulating, dominated by indigenous species, and able to support sustainable fisheries, although further rehabilitation of certain fish is required. The Lake Superior Lakewide Action and Management Plan classified all habitat indicators for Lake Superior as good. Primary production and zooplankton abundance were stable during the reporting period and unchanged from the two previous reporting periods, indicating the lower food web is healthy. Abundance of the invertebrates Mysis diluviana and Diporeia spp. were stable during the reporting period, and Diporeia spp. density exceeded target levels defined in the Great Lakes Water Quality Agreement. Lake Whitefish (Coregonus clupeaformis) abundance was lower than during the previous reporting period but was within the FCO target. Abundance of lean, siscowet, and humper forms of Lake Trout (Salvelinus namaycush) remained stable at levels seen in previous reporting periods. The FCO for non-indigenous salmonids was met as Chinook Salmon (Oncorhynchus tshawytscha), Coho Salmon (O. kisutch), and steelhead/Rainbow Trout (O. mykiss) were being sustained by natural reproduction, and their abundance remained stable or increased from previous reporting periods. The FCO for Walleye (Sander vitreus) was not met, although populations showed signs of improvement since the previous reporting period. The fish community in littoral areas and embayments continued to be diverse and composed mostly of indigenous species. No new invasive species were found in Lake Superior during the reporting period. Degraded embayment and tributary habitats continued to prevent achievement of the FCOs for Brook Trout (S. fontinalis) and Lake Sturgeon (Acipenser fulvescens). Barriers created for hydroelectric generation either blocked Lake Sturgeon from historically important spawning grounds or reduced stream flows necessary for its reproduction. In tributaries without man-made barriers, Lake Sturgeon was relatively abundant and appeared healthy. Attainment of the FCOs for Brook Trout and Lake Sturgeon will be challenging and can only be attained through development of large-scale management actions like those implemented for Lake Trout rehabilitation and Sea Lamprey (Petromyzon marinus) control. Sea Lamprey-control expenditures doubled in 2016 from past levels and should result in suppression of the population closer to its FCO after 2016. The prey-fish FCO appears to have been met, but biomass of nearly all prey-fish species declined from that reported for the previous reporting period and has been on a downward trajectory since 2000. Predation by Lake Trout is probably to blame for the declining biomass of prey fish. Poor recruitment by Cisco (C. artedi) over the last 15 years is exacerbating the declines in prey-fish biomass because Lake Trout must compensate for the loss of Cisco by consuming other, less-abundant prey fish.

Lake Superior↗

USGS2021

State of Lake Superior ecosystem in 2017

Lake Superior↗

USGS2021

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

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

Alaska↗

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↗

USGS2022

Status and trends of the Lake Huron prey fish community, 1976-2020

The USGS Great Lakes Science Center (GLSC) 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 and an acoustics-midwater trawl survey conducted in September-October. In 2020, USGS-GLSC vessels were not permitted to cross into Canada due to the COVID-19 pandemic, so prey fish surveys sampled only sites in U.S. (Michigan) waters of Lake Huron. This prevented USGS from providing information about the current status and trends of prey fish communities in Georgian Bay and the North Channel. Prey fish biomass in U.S. waters of Lake Huron in 2020 remained below levels observed prior to community-wide declines that began in the early to mid-1990s. Fish community biomass was dominated by two species, Bloater (Coregonus hoyi) and Rainbow Smelt (Osmerus mordax). While both surveys found Bloater biomass in the main basin had declined from levels observed in 2019, Bloater still comprised over three-quarters of prey fish biomass in Lake Huron in 2020. Biomass and abundance for other prey fish species were within the range observed over the past five years. Current 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. 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, the dominance of Bloater in bottom trawl catches and acoustic surveys suggests that current lake conditions are conducive to the recovery of some native species.

Lake Huron↗

USGS2021

Long-term epilimnetic temperature trends in Lake Mendota and Trout Lake, Wisconsin

Warming of lake surface waters has become a concern to limnologists and water managers because a ir temperatures, which directly affect near - surface water temperatures, are projected to increase in Wisconsin (WICCI 2011) as well as globally (IPCC 2018). This projected increase is in addition to the changes in air temperatures that have already occurred in recent decade s (WICCI 2011, NOAA 2017) . The deleterious effects of increased temperatures in lake surface waters have been extensively reviewed ( e.g., Blenckner 2005, Keller 2007, Adrian et al. 2009, George 2010 ) . Briefly , t he exceedance of thermal preferences or tolerances of aquatic biota can cause altered food webs and loss of biodiversity in lakes ( De Stasio et al. 199 6 , Chu et al. 2005, Graham and Harrod 2009, Woodward et al. 2010, Comte et al. 2013 ) . W armer surface water temperature s can result in stronger and longer thermal stratification in deep lakes ( Robertson and Ragotzkie 1990, Hondzo and Stefan 1993, Livingstone 2003, Butcher et al. 2015 ) . This process in turn can cause the duration and extent of hypolimnetic anoxia to increase, thus reducing hypolimnetic refugia needed for cold - and cool - water fish ( De Stasio et al. 1996 , Magnuson et al. 1997, Jeppesen et al. 2012 , Missaghi et al. 2017) . Longer duration of hypolimnetic anoxia can enhance eutrophic ation because of more internal loading of phosphorus from bottom sediments ( Blenckner et al. 2002, North et al. 2014 ) . Of parti cular concern, w armer water temperatures favor the growth of toxic cyanobacteria in eutrophic systems ( Paerl and Huisman 2008, Wagner and Adrian 2009, Kosten et al. 2012 ) . Another effect of warmer lake surface temperature s is increased evaporation that can result in lower water levels ( Spence et al. 2013, Gronewold and Stow 2014 ) .

Wisconsin↗

USGS2022

Dynamic abiotic habitat

The factors affecting an organism can be divided into two general classes, abiotic and biotic. Abiotic factors include features of the physical and chemical environment, such as climate, water movement, and many aspects of water quality. Biotic factors refer to those involving living organisms and their interactions, such as the organisms and processes in a food web. We also distinguish between dynamic and stationary abiotic factors. Stationary abiotic factors are fixed in the environment and include things like landscape features (e.g., bays, channels, and surface elevations) that change relatively slowly over time. Dynamic abiotic factors vary over time and space at various scales ranging from sub-daily (e.g., tidal direction and velocity) to annually (e.g., total water inflow and outflow).

California↗

USGS2023

Status and trends of the Lake Huron prey fish community, 1976-2021

The U.S. Geological Survey 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. Due to weather delays and continued travel restrictions during 2021, there were no bottom trawl samples off the port of Goderich, Ontario and two acoustic transects were cancelled in Georgian Bay. Prey fish biomass in Lake Huron in 2021 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) increased in 2021 relative to 2019-2020. Biomass of the native Cisco (Coregonus artedi) increased in the North Channel in 2021 but remained low in Georgian Bay, possibly as an artifact of reduced sampling. Biomass of Slimy Sculpin (Cottus cognatus) and Deepwater Sculpin (Myoxocephalus thompsoni) in 2021 remained low 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 1990s. However, increased biomass of Bloater and Cisco suggests that lake conditions may favor recovery of native corgonines.

Lake Huron↗

USGS2022

Floodplains and climate change

Floodplains are landscape features that are periodically inundated by water from adjacent rivers (Opperman et al. 2010). Ecologically, functional floodplains are characterized by three primary elements: connectivity, flow regime, and spatial scale. Water quantity flowing over floodplains can vary greatly. Based on a flood’s effects on the floodplain, three flood categories have been defined: floodplain-activation floods, floodplain-maintenance floods, and floodplainresetting floods (Box 1). Several physical parameters determine the types of ecosystems on floodplains and the species they will support; these include temperature, water depth, water velocity, and hydrologic connectivity (Opperman et al. 2010). Natural ecosystems commonly found on floodplains include annual vegetation, forests, seasonal wetlands, and permanent ponds or wetlands (Whipple et al. 2012). Floodplains provide many valuable ecosystem services: attenuation of flood flows which reduces flood risk, filtration of surface water, recreation, fisheries, agriculture, biodiversity, food availability, and groundwater recharge, which contributes to more-sustained and cooler dry-season flows (Opperman et al. 2010). -------------------------------------------------------------------------------------------------------------- Box 1 Floodplain-activation flood A small magnitude flood that occurs relatively frequently and produces characteristic ecological benefits such as food-web productivity and habitat creation for native fish spawning and rearing. Floodplain-maintenance flood A higher magnitude flood that, in addition to providing ecological benefits, results in geomorphic changes including bank erosion and deposition on the floodplain. Floodplain-resetting flood A very high-magnitude flood that occurs rarely and results in extensive geomorphic changes, such as the scouring of floodplain surfaces and changes in channel location due to avulsion. ----------------------------------------------------------------------------

California↗

USGS2022

Biology: Integrating core to essential variables (Bio-ICE) task team report for marine mammals

Marine mammals are wide-ranging, relatively long-lived organisms that play a crucial role in maintaining healthy ocean ecosystems. Often referred to as ecosystem engineers and sentinel species in marine ecosystems, these charismatic megafauna feed at a variety of trophic levels, affecting food web dynamics and cycling of chemicals and nutrients in the water column as well as in benthic habitats, both nearshore and in the deep ocean. An understanding of their abundance and distribution is an essential starting point for evaluating their role in ocean ecosystems. Accordingly, marine mammals have been included among key variables to monitor in ocean observing systems, from core variables for the U.S. Integrated Ocean Observing System (IOOS) to an Essential Ocean Variable (EOV) for the Global Ocean Observing System (GOOS). They also contribute to several Essential Biodiversity Variables (EBVs) for the Group on Earth Observations Biodiversity Observation Network (GEO BON). Further, evaluation of the health of marine mammal populations will help deliver societal benefits by contributing to the UN Decade of Ocean Science for Sustainable Development; informing reporting activities such as the World Ocean Assessment; and supporting achievement of Sustainable Development Goal 14, the post-2020 framework for the Convention for Biological Diversity, and a new treaty for conservation and sustainable use of marine biodiversity beyond national jurisdiction. In the U.S., the National Marine Fisheries Service (NMFS) and the U.S. Fish and Wildlife Service (FWS) are required to produce stock assessments for marine mammals under the Marine Mammal Protection Act (MMPA, 16 U.S.C. §1371 et seq.). Stock assessment analyses require accurate, up to-date information on abundance and distribution to inform appropriate management and/or conservation measures. Despite the availability of information on abundance and distribution within the stock assessment reports, availability and accessibility of the underlying data to the broader ocean observing community and contribution to EOVs remain inconsistent.

Report↗

USGS2023

2023 Coastal master plan: ICM-wetlands – Submerged aquatic vegetation (SAV) updates

Submerged aquatic vegetation (SAV) provides critical structural habitat for valuable nekton and wildlife species across coastal ecosystems and can buffer the negative effects of land loss. Landscape change and restoration efforts across coastal Louisiana can impact the occurrence, coverage, and species assemblages of SAV, and changes to these foundational species can have cascading impacts across food webs. To support the 2023 Coastal Master Plan efforts, a unique SAV model was developed to assess coverage and occurrence of SAV across aquatic waterbodies in response to environmental variables evaluated. This effort created a spatial model describing the probability of presence of SAV across the study area in response to changing conditions over the modeled time period. To develop the initial coverage data layer, we used remotely sensed Normalized Difference Vegetation Index (NDVI) and modified Normalized Difference Water Index (mNDWI) data from 2015-2018 to identify areas containing variable vegetation and water spectral reflectance. Key environmental variables evaluated included total suspended sediments (TSS), salinity, and physical exposure. Seasonal estimates for TSS and salinity were used, as research indicates that seasonal environmental variability is a significant driver for SAV establishment. Seasonal salinity was derived from Coast-wide Reference Monitoring Station (CRMS) data, and seasonal TSS was estimated from hyperspectral imagery. Estimates of physical exposure have previously been provided by calculating fetch (the distance across water over which waves can propagate), but this proved to be too computationally intensive to be feasible, and we found distance to land to be a reasonable proxy for exposure. To represent geographic conditions and historical factors influences on SAV establishment and occurrence (e.g., variables too numerous and complex to model) we developed a basin variable that served as a proxy for complex historical, or prior, conditions, determined by the forested, fresh, intermediate, brackish, or saline (FFIBS) score. The final model included spring TSS, spring salinity, distance to land, and the basin prior. The model performed well for the area evaluated, correctly classifying SAV (as present or absent) 89% of the time (Kappa = 580). SAV probability of presence responded as expected to change in these environmental variables, with likelihood of occurrence decreasing in response to increasing spring TSS, spring salinity, and distance to land. However, the model was more accurate at predicting absence (true negative = 0.940) than predicting presence (true positive = 0.626), suggesting that the scale of the model may limit the ability to predict presence. Moreover, the simplicity of the model limited the accuracy in highly dynamic environments, for example near the outflow of diversions or areas of significant changes in salinity or TSS. Through incorporating underwater communities like SAV, this master plan provides a holistic view of coastal change and restoration. To create healthy ecological structure and function in wetland habitats, the submergent communities must be considered alongside the emergent habitats. As the benefits of SAV are increasingly recognized, both here in Louisiana and beyond, SAV restoration and the use of SAV communities in assessing and improving ecological condition are becoming more common.

Louisiana↗

USGS2023

Nearshore ecosystems in the Gulf of Alaska

Nearshore ecosystem monitoring in western Prince William Sound, Kenai Fjords National Park, Kachemak Bay, and Katmai National Park and Preserve has been conducted as a single Nearshore Component of the Gulf Watch Alaska program over the past five years (2017-2021). This program builds on the previous five years and continues, in many cases, decades of preceding research and monitoring. During the 2017-2021 period of Gulf Watch Alaska, we successfully collected data on more than 200 nearshore metrics across all regions. These metrics were explicitly selected because of their value as trophically-connected features that offer insights into causes of changes through bottom-up and top-down forces within the nearshore food web. During these past 5 years, this study design has been applied to documenting and understanding several perturbations, including the Pacific Marine Heatwave and loss of sea stars due to sea star wasting. Continued monitoring will allow for a better understanding of change in nearshore ecosystems across the Gulf of Alaska and the status of spill injured resources, including greater perspective on oil spill effects and recovery relative to other types of perturbations. This information will be critical for anticipating and responding to ongoing and future changes in the region, as well as providing data for understanding global-scale variation in marine environments.

Alaska↗

USGS2020

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

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

California↗

USGS2023

Gap analysis: A proposed methodology to describe and map historical and contemporary populations and habitats

This is a methodology paper that describes an approach for modeling and mapping historical and contemporary spawning areas for coregonine fishes in the Laurentian Great Lakes. Coregonines are a family of native whitefishes and ciscoes that are now greatly reduced or extirpated, but once served important roles for both the food web and society. This method can illustrate where habitats once existed and where they are today - critical information for restoration and conservation actions.

Great Lakes↗

USGS2025

Photographic guide to the leaf litter arthropod community of the lowland wet forest ecosystem of the Island of Hawaiʻi

Leaf litter arthropods are important components of the food web in forests, and their presence and diversity can provide information on forest health. There has been very little documentation of the leaf litter arthropods in Hawaiian forest ecosystems. This technical report is a photographic guide to some common arthropods collected from forest leaf litter at the Liko Nā Pilina Hybrid Ecosystems Project study site, a lowland wet forest in Hilo, Island of Hawaiʻi, USA. Leaf litter samples were collected from plots of invaded and experimental restoration communities using two complementary methods (litterbags and quadrats), and arthropods were extracted using Berlese funnels. The field site contained many morphospecies that were rare and locally distributed across plots, and only a few that were very common and widely distributed. The majority of the morphospecies identified were mites. This photoguide is designed to help identify arthropods found in plant litter in Hawaiian lowland forests and it may assist with research and education efforts concerned with the diversity, ecology, or conservation of litter arthropods across the Hawaiian archipelago and other Pacific islands.

Hawaii↗

USGS2017

Can we save large carnivores without losing large carnivore science?

Large carnivores are depicted to shape entire ecosystems through top-down processes. Studies describing these processes are often used to support interventionist wildlife management practices, including carnivore reintroduction or lethal control programs. Unfortunately, there is an increasing tendency to ignore, disregard or devalue fundamental principles of the scientific method when communicating the reliability of current evidence for the ecological roles that large carnivores may play, eroding public confidence in large carnivore science and scientists. Here, we discuss six interrelated issues that currently undermine the reliability of the available literature on the ecological roles of large carnivores: (1) the overall paucity of available data, (2) reliability of carnivore population sampling techniques, (3) general disregard for alternative hypotheses to top-down forcing, (4) lack of applied science studies, (5) frequent use of logical fallacies, and (6) generalisation of results from relatively pristine systems to those substantially altered by humans. We first describe how widespread these issues are, and given this, show, for example, that evidence for the roles of wolves ( Canis lupus ) and dingoes ( Canis lupus dingo ) in initiating trophic cascades is not as strong as is often claimed. Managers and policy makers should exercise caution when relying on this literature to inform wildlife management decisions. We emphasise the value of manipulative experiments and discuss the role of scientific knowledge in the decision-making process. We hope that the issues we raise here prompt deeper consideration of actual evidence, leading towards an improvement in both the rigour and communication of large carnivore science.

Food Webs↗

USGS2017

Large carnivore science: non-experimental studies are useful, but experiments are better

We recently described the following six interrelated issues that justify questioning some of the discourse about the reliability of the literature on the ecological roles of large carnivores (Allen et al. In press): 1. The overall paucity of available data, 2. The reliability of carnivore population sampling techniques, 3. The general disregard for alternative hypotheses to top-down forcing, 4. The lack of applied science studies, 5. The frequent use of logical fallacies, 6. The generalisation of results from relatively pristine systems to those substantially altered by humans.

Food Webs↗