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USGS2020

Fish growth rates and lake sulphate explain variation in mercury levels in ninespine stickleback (Pungitius pungitius) on the Arctic Coastal Plain of Alaska

Mercury concentrations in freshwater food webs are governed by complex biogeochemical and ecological interactions that spatially vary and are often mediated by climate. The Arctic Coastal Plain of Alaska (ACP) is a heterogeneous, lake-rich landscape where variability in mercury accumulation is poorly understood. Earlier research indicated that the level of catchment influence on lakes varied spatially on the ACP, and affected mercury accumulation in lake sediments. This work sought to determine drivers of spatial variation in mercury accumulation in lake food webs on the ACP. Three lakes that were a priori identified as “high catchment influence” (Reindeer Camp region) and three lakes that were a priori identified as “low catchment influence” (Atqasuk region) were sampled, and variability in water chemistry, food web ecology, and mercury accumulation was investigated. Among-lake differences in ninespine stickleback ( Pungitius pungitius ) length-adjusted methylmercury concentrations were significantly explained by sulphate concentration in lake water, a tracer of catchment runoff input. This effect was mediated by fish growth, which had no pattern between regions. Together, lake water sulphate concentration and fish age-at-size (proxy for growth) accounted for nearly all of the among-lake variability in length-adjusted methylmercury concentrations in stickleback (R 2 adj = 0.94, p < 0.01). The percentage of total mercury as methylmercury (a proxy for net Hg methylation) was higher in sediments of more autochthonous, “low catchment influence” lakes ( p < 0.05), and in the periphyton of more allochthonous, “high catchment influence” lakes (p < 0.05). The results indicate that dominant sources of primary production (littoral macrophyte/biofilm vs. pelagic phytoplankton) and food web structure (detrital vs. grazing) are regulated by catchment characteristics on the ACP, and that this ultimately influences the amount of methylmercury in the aquatic food web. These results have important implications for predicting future mercury concentrations in fish in lakes where fish growth rates and catchment inputs may change in response to a changing climate.

Alaska↗

USGS2017

Mercury bioaccumulation in estuarine fishes: Novel insights from sulfur stable isotopes

Estuaries are transitional habitats characterized by complex biogeochemical and ecological gradients that result in substantial variation in fish total mercury concentrations (THg). We leveraged these gradients and used carbon (δ 13 C), nitrogen (δ 15 N), and sulfur (δ 34 S) stable isotopes to examine the ecological and biogeochemical processes underlying THg bioaccumulation in fishes from the San Francisco Bay Estuary. We employed a tiered approach that first examined processes influencing variation in fish THg among wetlands, and subsequently examined the roles of habitat and within-wetland processes in generating larger-scale patterns in fish THg. We found that δ 34 S, an indicator of sulfate reduction and habitat specific-foraging, was correlated with fish THg at all three spatial scales. Over the observed ranges of δ 34 S, THg concentrations in fish increased by up to 860% within wetlands, 560% among wetlands, and 291% within specific impounded wetland habitats. In contrast, δ 13 C and δ 15 N were not correlated with THg among wetlands and were only important in low salinity impounded wetlands, possibly reflecting more diverse food webs in this habitat. Together, our results highlight the key roles of sulfur biogeochemistry and ecology in influencing estuarine fish THg, as well as the importance of fish ecology and habitat in modulating the relationships between biogeochemical processes and Hg bioaccumulation.

California↗

USGS2012

Absence of fractionation of mercury isotopes during trophic transfer of methylmercury to freshwater fish in captivity

We performed two controlled experiments to determine the amount of mass-dependent and mass-independent fractionation (MDF and MIF) of methylmercury (MeHg) during trophic transfer into fish. In experiment 1, juvenile yellow perch ( Perca flavescens ) were raised in captivity on commercial food pellets and then their diet was either maintained on unamended food pellets (0.1 μg/g MeHg) or was switched to food pellets with 1.0 μg/g or 4.0 μg/g of added MeHg, for a period of 2 months. The difference in δ 202 Hg (MDF) and Δ 199 Hg (MIF) between fish tissues and food pellets with added MeHg was within the analytical uncertainty (δ 202 Hg, 0.07 ‰; Δ 199 Hg, 0.06 ‰), indicating no isotope fractionation. In experiment 2, lake trout ( Salvelinus namaycush ) were raised in captivity on food pellets and then shifted to a diet of bloater ( Coregonus hoyi ) for 6 months. The δ 202 Hg and Δ 199 Hg of the lake trout equaled the isotopic composition of the bloater after 6 months, reflecting reequilibration of the Hg isotopic composition of the fish to new food sources and a lack of isotope fractionation during trophic transfer. We suggest that the stable Hg isotope ratios in fish can be used to trace environmental sources of Hg in aquatic ecosystems.

Environmental Science & Technology↗

USGS2018

Describing the distribution and productivity of biota along a nearshore to offshore gradient

The Lake Michigan Lakewide Action and Management Plan (LAMP) proposed adding nutrients (phosphorus) to its “pollutant of concern” list in 2002, given that excessive nutrients were causing impairments in nearshore waters. Since that time, scientists have highlighted the “shunting” of nutrients to the nearshore (Hecky et al. 2004), owing to the ability of invasive dreissenid mussels to capture some portion of allochthonous phosphorus that enters the lake through tributaries. These changes are believed to increase productivity in the nearshore, reflected in increased benthic and pelagic primary production and nuisance Cladophora (Auer et al. 2010). Whether increases in primary productivity lead to concomitant increases for secondary (by zooplankton) and tertiary (by fish) production remains largely untested. Hence, understanding the distribution and abundance of nutrients and biota (e.g., zooplankton, fish) across a nearshore to offshore gradient was identified as a Cooperative Science and Monitoring Initiative (CSMI) priority in 2015. Increased understanding of the Lake Michigan nearshore will also facilitate the development of a Nearshore Strategy by the LAMP, which is called for in the 2012 Great Lakes Water Quality Agreement. Working collaboratively with Environmental Protection Agency (EPA) and National Oceanic and Atmospheric Administration (NOAA), United States Geological Survey (USGS) described the distribution of nutrients and biota across nearshore to offshore transects in 2015 (see Appendix 1). At each transect, we sampled the food web at three sites with differing bottom depths: 18 m, 46 m, and 91-110 m. We purposefully chose transects near tributaries of varying total phosphorus (TP) input (see Figure 1, Dolan and Chapra 2012): three transects that were not associated with any large tributary where total phosphorus would be loaded (Waukegan IL, Frankfort MI, Sturgeon Bay WI), three transects adjacent to tributaries presumed to be relatively low loaders of TP (Pere Marquette MI, Root WI, Muskegon MI), and three transects adjacent to tributaries presumed to be relatively high loaders of TP (St. Joseph MI, Kalamazoo MI, Manitowoc WI). USGS estimated chlorophyll concentrations, zooplankton, Mysis , larval fish, and juvenile and adult fish seasonally (April/May, July, October/November) at eight of these transects (all but Muskegon).

Illinois, Michigan, Wisconsin↗

USGS2021

Examining historical mercury sources in the Saint Louis River estuary: How legacy contamination influences biological mercury levels in Great Lakes coastal regions

Industrial chemical contamination within coastal regions of the Great Lakes can pose serious risks to wetland habitat and offshore fisheries, often resulting in fish consumption advisories that directly affect human and wildlife health. Mercury (Hg) is a contaminant of concern in many of these highly urbanized and industrialized coastal regions, one of which is the Saint Louis River estuary (SLRE), the second largest tributary to Lake Superior. The SLRE has legacy Hg contamination that drives high Hg concentrations within sediments, but it is unclear whether legacy-derived Hg actively cycles within the food web. To understand the relative contributions of legacy versus contemporary Hg sources in coastal zones, Hg, carbon, and nitrogen stable isotope ratios were measured in sediments and food webs of SLRE and the Bad River, an estuarine reference site. Hg stable isotope values revealed that legacy contamination of Hg was widespread and heterogeneously distributed in sediments of SLRE, even in areas lacking industrial Hg sources. Similar isotope values were found in benthic invertebrates, riparian spiders, and prey fish from SLRE, confirming legacy Hg reaches the SLRE food web. Direct comparison of prey fish from SLRE and the Bad River confirmed that Hg isotope differences between the sites were not attributable to fractionation associated with rapid Hg bioaccumulation at estuarine mouths, but due to the presence of industrial Hg within SLRE. The Hg stable isotope values of game fish in both estuaries were dependent on fish migration and diet within the estuaries and extending into Lake Superior. These results indicate that Hg from legacy contamination is actively cycling within the SLRE food web and, through migration, this Hg also extends into Lake Superior via game fish. Understanding sources and the movement of Hg within the estuarine food web better informs restoration strategies for other impaired Great Lakes coastal zones.

Minnesota, Wisconsin↗

USGS2018

A laboratory-calibrated model of coho salmon growth with utility for ecological analyses

We conducted a meta-analysis of laboratory- and hatchery-based growth data to estimate broadly applicable parameters of mass- and temperature-dependent growth of juvenile coho salmon ( Oncorhynchus kisutch ). Following studies of other salmonid species, we incorporated the Ratkowsky growth model into an allometric model and fit this model to growth observations from eight studies spanning ten different populations. To account for changes in growth patterns with food availability, we reparameterized the Ratkowsky model to scale several of its parameters relative to ration. The resulting model was robust across a wide range of ration allocations and experimental conditions, accounting for 99% of the variation in final body mass. We fit this model to growth data from coho salmon inhabiting tributaries and constructed ponds in the Klamath Basin by estimating habitat-specific indices of food availability. The model produced evidence that constructed ponds provided higher food availability than natural tributaries. Because of their simplicity (only mass and temperature are required as inputs) and robustness, ration-varying Ratkowsky models have utility as an ecological tool for capturing growth in freshwater fish populations.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS2000

Food habits of introduced rodents in high-elevation shrubland of Haleakala National Park, Maui, Hawai'i

Mus musculus and Rattus rattus are ubiquitous consumers in the high-elevation shrubland of Haleakala National Park. Food habits of these two rodent species were determined from stomach samples obtained by snaptrapping along transects located at four different elevations during November 1984 and February, May, and August 1985. Mus musculus fed primarily on fruits, grass seeds, and arthropods. Rattus rattus ate various fruits, dicot leaves, and arthropods. Arthropods, many of which are endemic, were taken frequently by Mus musculus throughout the year at the highest elevation where plant food resources were scarce. Araneida, Lepidoptera (primarily larvae), Coleoptera, and Homoptera were the main arthropod taxa taken. These rodents, particularly Mus musculus , exert strong predation pressure on populations of arthropod species, including locally endemic species on upper Haleakala Volcano.

Hawaii↗

USGS2002

Estuaries as nurseries for the jacks Caranx ignobilis and Caranx melampygus (Carangidae) in Hawaii

Estuaries provide juvenile nursery habitat for many species of fish that inhabit marine environments as adults. In Hawaii, some juvenile Caranx ignobilis and Caranx melampygus occupy estuaries opportunistically before moving to nearshore ocean habitats. This study examined the extent and nature of estuarine habitat available in the lower Hanalei River of Kauai, the relative abundance and distribution of jacks in the estuary, and their diets. Salinity measurements indicated that the upstream extent of saltwater ranged from the mouth to nearly 5 km upriver and was strongly influenced by the variable river discharge. Juvenile jacks between 80 and 310 mm FL were observed on underwater transects over the full range of mixohaline conditions. Hand-operated seine collections produced overall catch rates of ???0.64 fish/haul for each of these species. The two jacks ate much the same spectrum of food items. C. ignobilis was somewhat more piscivorous than C. melampygus, as determined by measures of frequency of predation and number and bulk of prey. Data for length at age, incorporating daily otolith increment counts from these estuarine juveniles and previous counts from non-estuarine specimens, were fitted to a lifetime von Bertalanffy growth model. The results greatly extended the age range of the model and suggested that growth rates were not much different between estuarine and non-estuarine fish. ?? 2002 Elsevier Science Ltd. All rights reserved.

Estuarine, Coastal and Shelf Science↗

USGS2022

Ungulate migrations of the western United States, volume 2

Migration is widespread across taxonomic groups and increasingly recognized as fundamental to maintaining abundant wildlife populations and communities. Many ungulate herds migrate across the western United States to access food and avoid harsh environmental conditions. With the advent of global positioning system (GPS) collars, researchers can describe and map the year-round movements of ungulates at both large and small spatial scales. The migrations can traverse landscapes that are a mix of different jurisdictional ownership and management. Today, the landscapes migrating herds traverse are increasingly threatened by fencing, high-traffic roads, oil and gas development, and other types of permanent development. Through the use of GPS collars, a model of science-based conservation emerged in which migration corridors, stopovers, and winter ranges can be mapped in detail, thereby allowing threats and conservation opportunities to be identified and remedied. In 2018, the U.S. Geological Survey (USGS) assembled a Corridor Mapping Team (CMT) to work collaboratively with western states to map migrations of Odocoileus hemionus (mule deer), Cervus canadensis (elk), and Antilocapra americana (pronghorn). Led by the USGS Wyoming Cooperative Fish and Wildlife Research Unit, the team consists of Federal scientists, university researchers, and biologists and analysts from participating State and Tribal agencies. The first set of maps described a total of 42 migrations across 5 western states and was published in 2020 as the first volume of this report series. This second volume describes an additional 65 migrations mapped within 9 western states and select Tribal lands. As the western United States continues to grow, this report series and the associated map files released by the USGS will allow for migration maps to be used for conservation planning by a wide array of State and Federal stakeholders to reduce barriers to migration caused by fences, roads, and other development.

western United States↗

USGS2014

Mycotoxins: diffuse and point source contributions of natural contaminants of emerging concern to streams

To determine the prevalence of mycotoxins in streams, 116 water samples from 32 streams and three wastewater treatment plant effluents were collected in 2010 providing the broadest investigation on the spatial and temporal occurrence of mycotoxins in streams conducted in the United States to date. Out of the 33 target mycotoxins measured, nine were detected at least once during this study. The detections of mycotoxins were nearly ubiquitous during this study even though the basin size spanned four orders of magnitude. At least one mycotoxin was detected in 94% of the 116 samples collected. Deoxynivalenol was the most frequently detected mycotoxin (77%), followed by nivalenol (59%), beauvericin (43%), zearalenone (26%), β-zearalenol (20%), 3-acetyl-deoxynivalenol (16%), α-zearalenol (10%), diacetoxyscirpenol (5%), and verrucarin A (1%). In addition, one or more of the three known estrogenic compounds (i.e. zearalenone, α-zearalenol, and β-zearalenol) were detected in 43% of the samples, with maximum concentrations substantially higher than observed in previous research. While concentrations were generally low (i.e. < 50 ng/L) during this study, concentrations exceeding 1000 ng/L were measured during spring snowmelt conditions in agricultural settings and in wastewater treatment plant effluent. Results of this study suggest that both diffuse (e.g. release from infected plants and manure applications from exposed livestock) and point (e.g. wastewater treatment plants and food processing plants) sources are important environmental pathways for mycotoxin transport to streams. The ecotoxicological impacts from the long-term, low-level exposures to mycotoxins alone or in combination with complex chemical mixtures are unknown

Science of the Total Environment↗

USGS2016

Vulnerability and adaptation to climate-related fire impacts in rural and urban interior Alaska

This paper explores whether fundamental differences exist between urban and rural vulnerability to climate-induced changes in the fire regime of interior Alaska. We further examine how communities and fire managers have responded to these changes and what additional adaptations could be put in place. We engage a variety of social science methods, including demographic analysis, semi-structured interviews, surveys, workshops and observations of public meetings. This work is part of an interdisciplinary study of feedback and interactions between climate, vegetation, fire and human components of the Boreal forest social–ecological system of interior Alaska. We have learned that although urban and rural communities in interior Alaska face similar increased exposure to wildfire as a result of climate change, important differences exist in their sensitivity to these biophysical, climate-induced changes. In particular, reliance on wild foods, delayed suppression response, financial resources and institutional connections vary between urban and rural communities. These differences depend largely on social, economic and institutional factors, and are not necessarily related to biophysical climate impacts per se. Fire management and suppression action motivated by political, economic or other pressures can serve as unintentional or indirect adaptation to climate change. However, this indirect response alone may not sufficiently reduce vulnerability to a changing fire regime. More deliberate and strategic responses may be required, given the magnitude of the expected climate change and the likelihood of an intensification of the fire regime in interior Alaska.

Alaska↗

USGS2006

EMMMA: A web-based system for environmental mercury mapping, modeling, and analysis

Mercury in our environment - in our air, water, soil, and especially our food - poses significant hazards to human health, particularly for developing fetuses and young children. Because of the importance of this issue and the length of time it has been studied, large and complex data sets of mercury concentrations in various media and associated ancillary data have been generated by many Federal, State, Tribal, and local agencies. To facilitate efficient and effective use of these data in managing and mitigating human and wildlife exposure to mercury, the U.S. Geological Survey (USGS) and the National Institute of Environmental Health Sciences have developed a website for visualizing and studying the distribution of mercury in our environment. The Environmental Mercury Mapping, Modeling, and Analysis (EMMMA) website (http://emmma.usgs.gov) provides health and environmental researchers, managers, and other decision-makers the ability to: 1) Interactively view and access a nationwide collection of environmental mercury data (fish tissue, atmospheric emissions and deposition, stream sediments, soils, and coal) and mercuryrelated data (mine locations); 2) Interactively view and access predictions of the National Descriptive Model of Mercury in Fish (NDMMF) at 4,976 sites and 6,829 sampling events (events are unique combinations of site and sampling date) across the United States; and 3) Use interactive mapping and graphing capabilities to visualize spatial and temporal trends and study relationships between mercury and other variables.

Open-File Report↗

USGS1970

Deuterium: Natural variations used as a biological tracer

The suggestion is made that isotope tracing be carried out by monitoring the natural variations in deuterium concentrations. As an example, the natural variations in deuterium concentrations between food and water collected in Illinois and food and water collected in Colorado were used to determine the residence time of water in the blood and urine of rats. We observed not only a 51/2-day turnover time of water in the blood and urine, but also evidence for the influx of water vapor from the atmosphere through the lungs into the blood.

Science↗

USGS2008

Warming of the Indian Ocean threatens eastern and southern African food security but could be mitigated by agricultural development

Since 1980, the number of undernourished people in eastern and southern Africa has more than doubled. Rural development stalled and rural poverty expanded during the 1990s. Population growth remains very high, and declining per-capita agricultural capacity retards progress toward Millennium Development goals. Analyses of in situ station data and satellite observations of precipitation have identified another problematic trend: main growing-season rainfall receipts have diminished by ???15% in food-insecure countries clustered along the western rim of the Indian Ocean. Occurring during the main growing seasons in poor countries dependent on rain-fed agriculture, these declines are societally dangerous. Will they persist or intensify? Tracing moisture deficits upstream to an anthropogenically warming Indian Ocean leads us to conclude that further rainfall declines are likely. We present analyses suggesting that warming in the central Indian Ocean disrupts onshore moisture transports, reducing continental rainfall. Thus, late 20th-century anthropogenic Indian Ocean warming has probably already produced societally dangerous climate change by creating drought and social disruption in some of the world's most fragile food economies. We quantify the potential impacts of the observed precipitation and agricultural capacity trends by modeling 'millions of undernourished people' as a function of rainfall, population, cultivated area, seed, and fertilizer use. Persistence of current tendencies may result in a 50% increase in undernourished people by 2030. On the other hand, modest increases in per-capita agricultural productivity could more than offset the observed precipitation declines. Investing in agricultural development can help mitigate climate change while decreasing rural poverty and vulnerability. ?? 2008 by The National Academy of Sciences of the USA.

Proceedings of the National Academy of Sciences of↗

USGS2007

An evaluation of selenium concentrations in water, sediment, invertebrates, and fish from the Solomon River Basin

The Solomon River Basin is located in north-central Kansas in an area underlain by marine geologic shales. Selenium is an indigenous constituent of these shales and is readily leached into the surrounding groundwater. Portions of the Basin are irrigated primarily through the pumping of selenium-contaminated groundwater from wells onto fields in agricultural production. Water, sediment, macroinvertebrates, and fish were collected from various sites in the Basin in 1998 and analyzed for selenium. Selenium concentrations were analyzed spatially and temporally and compared to reported selenium toxic effect thresholds for specific ecosystem components: water, sediments, food-chain organisms, and wholebody fish. A selenium aquatic hazard assessment for the Basin was determined based on protocol established by Lemly. Throughout the Basin, water, macroinvertebrate, and whole fish samples exceeded levels suspected of causing reproductive impairment in fish. Population structures of several fish species implied that successful reproduction was occurring; however, the influence of immigration of fish from low-selenium habitats could not be discounted. Site-specific fish reproduction studies are needed to determine the true impact of selenium on fishery resources in the Basin. ?? Springer Science+Business Media B.V. 2007.

Environmental Monitoring and Assessment↗

USGS2010

Growth, condition factor, and bioenergetics modeling link warmer stream temperatures below a small dam to reduced performance of juvenile steelhead

We investigated the growth and feeding performance of juvenile steelhead Oncorhynchus mykiss using field measures and bioenergetics modeling. Juvenile steelhead populations were sampled from mid-June through August 2004 at study sites upstream and downstream of Hemlock Dam. The growth and diet of juvenile steelhead were determined for a warm (summer) and subsequent (late summer) transitional period at each study site. Empirical data on the growth and diet of juvenile steelhead and mean daily temperatures were used in a bioenergetics model to estimate the proportion of maximum consumption achieved by juvenile steelhead by site and period. Modeled estimates of feeding performance were better for juvenile steelhead at the upstream compared to the downstream site during both periods. The median condition factor of juvenile steelhead did not change over the summer at the upstream site, but showed a significant decline over time at the downstream site. A negative trend in median condition factor at the downstream site supported bioenergetics modeling results that suggested the warmer stream temperatures had a negative impact on juvenile steelhead. Bioenergetics modeling predicted a lower feeding performance for juvenile steelhead rearing downstream compared to upstream of Hemlock Dam although food availability appeared to be limited at both study sites during the warm period. Warmer water temperatures, greater diel variation, and change in diel pattern likely led to the reduced feeding performance and reduced growth, which could have affected the overall survival of juvenile steelhead downstream of Hemlock Dam. ?? 2010 by the Northwest Scientific Association.

Northwest Science↗

USGS2024

Restoring Pacific Lamprey in the Umpqua River Basin of Oregon: A workshop summary

The Umpqua River Basin in southwestern Oregon (Figure 1) is part of the lands inhabited by the Cow Creek Band of Umpqua Tribe of Indians and an area of active co-management authority. This Basin supports a unique fish fauna, including important populations of Pacific salmon ( Oncorhynchus spp.) and steelhead ( O. mykiss ), and other native fishes that are endemic to the region (Mims et al. 2018). Among these species, the Pacific Lamprey ( Entosphenus tridentatus ) is one of the most unique, representing an ancient lineage of jawless fishes that long predates the evolution of any other species of fish in the basin (Clemens et al. 2017, 2021a). The Pacific Lamprey also represents an important cultural and food resource that features prominently in the indigenous practices of the Cow Creek Band of Umpqua Tribe of Indians. This report provides a select summary of topics related to the conservation of Pacific Lamprey in the Umpqua River Basin. Many of the topics addressed herein were discussed in a workshop co-hosted by the Cow Creek Band of Umpqua Tribe of Indians and the U.S. Geological Survey in April of 2022. This workshop was focused on threats to Pacific Lamprey in fresh waters of the basin. The workshop highlighted science conducted over the past 15 years by local managers and researchers to understand and address these threats and provide new information relevant to the conservation and restoration of Pacific Lamprey. Attendees included staff from the Coquille Indian Tribe, Yakama Nation, Columbia River Inter-Tribal Fish Commission, Partnership for Umpqua Rivers, Rogue River Watershed Council, Curry Watersheds Council, PacifiCorp, Trout Unlimited, Jackson Soil and Water Conservation District, Oregon Department of Fish and Wildlife, Bureau of Land Management, U.S. Fish and Wildlife Service, and U.S. Forest Service. This report provides an overview of this workshop and recent science and provides an overview of potential future efforts that could inform restoration of Pacific Lamprey. This summary is organized into four sections that relate to the main topics of the workshop: 1) The physical habitat template (stream flow, instream wood, sediment, and water temperature), 2) movement barriers and reservoirs, 3) biological invasions, and 4) climate adaptation. These do not represent an exhaustive list of topics related to conservation of Pacific Lamprey in the Umpqua Basin.

Oregon↗

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↗