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At least 397 records · Page 22Linked to original sources
USGS2005

Nitrogen controls on ecosystem carbon sequestration: a model implementation and application to Saskatchewan, Canada

A plant–soil nitrogen (N) cycling model was developed and incorporated into the Integrated BIosphere Simulator (IBIS) of Foley et al. [Foley, J.A., Prentice, I.C., Ramankutty, N., Levis, S., Pollard, D., Sitch, S., Haxeltine, A., 1996. An integrated biosphere model of land surface process, terrestrial carbon balance and vegetation dynamics. Global Biogeochem. Cycles 10, 603–628]. In the N-model, soil mineral N regulates ecosystem carbon (C) fluxes and ecosystem C:N ratios. Net primary productivity (NPP) is controlled by feedbacks from both leaf C:N and soil mineral N. Leaf C:N determines the foliar and canopy photosynthesis rates, while soil mineral N determines the N availability for plant growth and the efficiency of biomass construction. Nitrogen controls on the decomposition of soil organic matter (SOM) are implemented through N immobilization and mineralization separately. The model allows greater SOM mineralization at lower mineral N, and conversely, allows greater N immobilization at higher mineral N. The model's seasonal and inter-annual behaviours are demonstrated. A regional simulation for Saskatchewan, Canada, was performed for the period 1851–2000 at a 10 km × 10 km resolution. Simulated NPP was compared with high-resolution (1 km × 1 km) NPP estimated from remote sensing data using the boreal ecosystem productivity simulator (BEPS) [Liu, J., Chen, J.M., Cihlar, J., Park, W.M., 1997. A process-based boreal ecosystem productivity simulator using remote sensing inputs. Remote Sens. Environ. 44, 81–87]. The agreement between IBIS and BEPS, particularly in NPP spatial variation, was considerably improved when the N controls were introduced into IBIS.

Ecological Modelling↗
USGS2009

Modelling predation by transient leopard seals for an ecosystem-based management of Southern Ocean fisheries

Correctly quantifying the impacts of rare apex marine predators is essential to ecosystem-based approaches to fisheries management, where harvesting must be sustainable for targeted species and their dependent predators. This requires modelling the uncertainty in such processes as predator life history, seasonal abundance and movement, size-based predation, energetic requirements, and prey vulnerability. We combined these uncertainties to evaluate the predatory impact of transient leopard seals on a community of mesopredators (seals and penguins) and their prey at South Georgia, and assess the implications for an ecosystem-based management. The mesopredators are highly dependent on Antarctic krill and icefish, which are targeted by regional fisheries. We used a state-space formulation to combine (1) a mark-recapture open-population model and individual identification data to assess seasonally variable leopard seal arrival and departure dates, numbers, and residency times; (2) a size-based bioenergetic model; and (3) a size-based prey choice model from a diet analysis. Our models indicated that prey choice and consumption reflected seasonal changes in leopard seal population size and structure, size-selective predation and prey vulnerability. A population of 104 (90-125) leopard seals, of which 64% were juveniles, consumed less than 2% of the Antarctic fur seal pup production of the area (50% of total ingested energy, IE), but ca. 12-16% of the local gentoo penguin population (20% IE). Antarctic krill (28% IE) were the only observed food of leopard seal pups and supplemented the diet of older individuals. Direct impacts on krill and fish were negligible, but the "escapement" due to leopard seal predation on fur seal pups and penguins could be significant for the mackerel icefish fishery at South Georgia. These results suggest that: (1) rare apex predators like leopard seals may control, and may depend on, populations of mesopredators dependent on prey species targeted by fisheries; and (2) predatory impacts and community control may vary throughout the predator's geographic range, and differ across ecosystems and management areas, depending on the seasonal abundance of the prey and the predator's dispersal movements. This understanding is important to integrate the predator needs as natural mortality of its prey in models to set prey catch limits for fisheries. Reliable estimates of the variability of these needs are essential for a precautionary interpretation in the context of an ecosystem-based management. ?? 2009 Elsevier B.V.

Ecological Modelling↗
USGS2019

Development and implementation of an empirical habitat change model and decision support tool for estuarine ecosystems

Widespread land use change in coastal ecosystems has led to a decline in the amount of habitat available for fish and wildlife, lower production of ecosystem goods and services, and loss of recreational and aesthetic value. This has prompted global efforts to restore the natural hydrologic regimes of developed shorelines, especially resource-rich estuaries, but the resilience of these restored ecosystems in the face of accelerated sea-level rise (SLR) remains uncertain. We implemented a Mo nitoring-based S imulation of A ccretion i n C oastal E s tuaries (MOSAICS) in R statistical software to address uncertainty in the resilience of modified estuarine habitats, using the Nisqually River Delta in the Pacific Northwest USA as a case study. MOSAICS is a spatially explicit model with a numerical foundation that uses empirical monitoring datasets to forecast habitat change in response to rising tidal levels. Because it accounts for the crucial ecomorphodynamic feedbacks between tidal inundation, vegetative growth, and sediment accretion, MOSAICS can be used to determine whether alternative management scenarios, such as enhanced sediment inputs, will bolster estuarine resilience to SLR. Under moderate SLR (0.62 m), the model predicted that a two-fold increase in mean daily suspended sediment during the rainy season was sufficient to maintain Nisqually’s emergent marshes through 2100, but under high SLR (1.35 m) MOSAICS indicated that greater sediment additions would be necessary to prevent submergence. A comparison between a restored marsh with subsided and high-elevation areas and a relict marsh demonstrated that the subsided restoration area was highly susceptible to SLR. Findings from the MOSAICS model highlight the importance of a site’s initial elevation, capacity for producing above and belowground biomass, and suspended sediment availability when considering management actions in estuaries and other coastal ecosystems.

Washington↗
USGS2013

An integrated multi-criteria scenario evaluation web tool for participatory land-use planning in urbanized areas: The Ecosystem Portfolio Model

Land-use land-cover change is one of the most important and direct drivers of changes in ecosystem functions and services. Given the complexity of the decision-making, there is a need for Internet-based decision support systems with scenario evaluation capabilities to help planners, resource managers and communities visualize, compare and consider trade-offs among the many values at stake in land use planning. This article presents details on an Ecosystem Portfolio Model (EPM) prototype that integrates ecological, socio-economic information and associated values of relevance to decision-makers and stakeholders. The EPM uses a multi-criteria scenario evaluation framework, Geographic Information Systems (GIS) analysis and spatially-explicit land-use/land-cover change-sensitive models to characterize changes in important land-cover related ecosystem values related to ecosystem services and functions, land parcel prices, and community quality-of-life (QoL) metrics. Parameters in the underlying models can be modified through the interface, allowing users in a facilitated group setting to explore simultaneously issues of scientific uncertainty and divergence in the preferences of stakeholders. One application of the South Florida EPM prototype reported in this article shows the modeled changes (which are significant) in aggregate ecological value, landscape patterns and fragmentation, biodiversity potential and ecological restoration potential for current land uses compared to the 2050 land-use scenario. Ongoing refinements to EPM, and future work especially in regard to modifiable sea level rise scenarios are also discussed.

Environmental Modelling and Software↗
USGS2022

Invasion of annual grasses following wildfire corresponds to maladaptive habitat selection by a sagebrush ecosystem indicator species

Numerous wildlife species within semi-arid shrubland ecosystems across western North America are experiencing substantial habitat loss and fragmentation. These changes in habitat are often attributed to a diverse suite of factors including prolonged and increasingly severe droughts, conifer expansion, anthropogenic development, domestic and feral livestock grazing, and invasion of exotic annual grasses, which promotes increased wildfire frequency and severity. Greater sage-grouse ( Centrocercus urophasianus ; hereafter, sage-grouse) are considered an indicator of sagebrush ecosystem health and have experienced widespread population decline associated with habitat loss and degradation, as well as changes in predator communities. Our objectives were to model and map sage-grouse habitat selection and survival during the important brood-rearing life stage in relation to landscape-scale environmental predictors. Furthermore, we sought to understand impacts of wildfire and annual grass invasion on brood habitat, as these accelerated disturbance regimes are a primary cause of habitat loss within the Great Basin region of the USA. We used a hierarchical Bayesian modeling framework to estimate resource selection functions and survival for early and late brood-rearing stages of sage-grouse in relation to a broad suite of habitat characteristics evaluated at multiple spatial scales within the Great Basin from 2009 to 2019. Sage-grouse selected for greater perennial grass cover, higher relative elevations, and areas closer to springs and wet meadows during both early and late brood-rearing. Terrain characteristics, including heat load and aspect, were important in survival models, as was variation in shrub height. We also found strong evidence for higher survival for both early and late broods within previously burned areas, but survival within burned areas decreased as annual grass cover (i.e. cheatgrass , Bromus tectorum ) increased. This interaction effect demonstrates how invasion of annual grasses into burned areas, which has become prevalent in Great Basin sagebrush ecosystems, can lead to maladaptive habitat selection by brood-rearing greater sage-grouse. Understanding these complex relationships aids wildlife conservation and habitat management as wildfire and annual grass cycles continue to accelerate across western ecosystems.

California, Nevada↗
USGS2018

A method to quantify and value floodplain sediment and nutrient retention ecosystem services

Floodplains provide critical ecosystem services to local and downstream communities by retaining floodwaters, sediments, and nutrients. The dynamic nature of floodplains is such that these areas can both accumulate sediment and nutrients through deposition, and export material downstream through erosion. Therefore, estimating floodplain sediment and nutrient retention should consider the net flux of both depositional and erosive processes. An ecosystem services framework was used to quantify and value the sediment and nutrient ecosystem service provided by floodplains in the Difficult Run watershed, a small (151 km 2 ) suburban watershed located in the Piedmont of Virginia (USA). A sediment balance was developed for Difficult Run and two nested watersheds. The balance included upland sediment delivery to streams, stream bank flux, floodplain flux, and stream load. Upland sediment delivery was estimated using geospatial datasets and a modified Revised Universal Soil Loss Equation. Predictive models were developed to extrapolate field measurements of the flux of sediment, sediment-bound nitrogen (N), and sediment-bound phosphorus (P) from stream banks and floodplains to 3232 delineated stream segments in the study area. A replacement cost approach was used to estimate the economic value of the sediment and nutrient retention ecosystem service based on estimated net stream bank and floodplain flux of sediment-bound N for all streams in the study area. Results indicated the net fluvial fluxes of sediment, sediment-bound N, and sediment-bound P were −10,439 Mg yr −1 (net export), 57,300 kg-N yr −1 (net trapping), and 98 kg-P yr −1 (net trapping), respectively. For sediment, floodplain retention was offset by substantial losses from stream bank erosion, particularly in headwater catchments, resulting in a net export of sediment. Nutrient retention in the floodplain exceeded that lost through stream bank erosion resulting in net retention of nutrients (TN and TP). Using a conservative cost estimate of \$12.69 (USD) per kilogram of nitrogen, derived from wastewater treatment costs, the estimated annual value for sediment and nutrient retention on Difficult Run floodplains was \$727,226 ± 194,220 USD/yr. Values and differences in floodplain nitrogen retention among stream reaches can be used to target areas for floodplain conservation and stream restoration. The methods presented are scalable and transferable to other areas if appropriate datasets are available for validation.

Virginia↗
USGS2019

Valuation of the flood attenuation ecosystem service in Difficult Run, VA, USA

Floodplains and riparian wetlands provide several ecosystem services that directly benefit people. We present a methodology for valuing the flood attenuation ecosystem service in Difficult Run, a suburban watershed with extensive natural floodplains in northern Virginia. High-resolution lidar-derived data were combined with GIS modeling techniques to produce estimates of flood inundation. We combined the modeled estimates with parcel-level property and primary economic data using a baseline and a counterfactual scenario to estimate the magnitude of flood attenuation and the associated value of the ecosystem service. Our framework brings new models and data to look at floodplains and an alternative land surface scenario in a way that has not previously been done. Annualized avoided property losses totaled $42,184 in the baseline scenario and $115,596 in the counterfactual scenario for the combined 200-, 100-, 50-, 20-, 10-, and 5-year flood events. We estimate the total annualized value of the flood attenuation ecosystem service in Difficult Run is $73,412, which is $77 per hectare of floodplain area and is consistent with similar valuation studies of floodplains. The framework presented here is not specific to the study area and could be deployed at larger spatial areas in other locations. Our methods may better inform land use decision making on the impacts of development in and surrounding floodplain areas.

Virginia↗
USGS2019

Seasonal patterns in hydrochemical mixing in three Great Lakes rivermouth ecosystems

Rivermouth ecosystems in the Laurentian Great Lakes represent complex hydrologic mixing zones where lake and river water combine to form biologically productive areas that are functionally similar to marine estuaries. As urban, industrial, shipping, and recreational centers, rivermouths are the focus of human interactions with the Great Lakes and, likewise, may represent critical habitat for larval fish and other biota. The hydrology and related geomorphology in these deltaic systems form the basis for ecosystem processes and wetland habitat structure but are poorly understood. To this end, a multidisciplinary team of scientists examined hydrogeomorphic structure and lake-tributary mixing in rivermouths using water chemistry, stable isotopes, and current profiling over a five-month period. Results showed that the maximum depth of the rivermouth ecosystem influenced mixing, with temperature-related, density-dependent wedging and layering that isolated lake water below river water occurring in deeper systems. The inherent size of the rivermouth ecosystem, local geomorphology, and human modifications such as shoreline armoring and dredging influenced mixing by altering the propensity for density differences to occur. The improved scientific understanding and framework for characterizing hydrogeomorphic processes in Great Lakes rivermouths across a disturbance gradient is useful for conservation, management, restoration, and protection of critical habitats needed by native species.

Michigan, Wisconsin↗
USGS2014

Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins

The ocean’s continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO 2 -induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO 2 -induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services including primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins.

Journal of Marine Systems↗
USGS2019

A multidisciplinary coastal vulnerability assessment for local government focused on ecosystems, Santa Barbara area, California

Incorporating coastal ecosystems in climate adaptation planning is needed to maintain the well-being of both natural and human systems. Our vulnerability study uses a multidisciplinary approach to evaluate climate change vulnerability of an urbanized coastal community that could serve as a model approach for communities worldwide, particularly in similar Mediterranean climates. We synthesize projected changes in climate, coastal erosion and flooding, watershed runoff and impacts to two important coastal ecosystems, sandy beaches and coastal salt marshes. Using downscaled climate models along with other regional models, we find that temperature, extreme heat events, and sea level are expected to increase in the future, along with more intense rainfall events, despite a negligible change in annual rainfall. Consequently, more droughts are expected but the magnitude of larger flood events will increase. Associated with the continuing rise of mean sea level, extreme coastal water levels will occur with increasingly greater magnitudes and frequency. Severe flooding will occur for both natural (wetlands, beaches) and built environments (airport, harbor, freeway, and residential areas). Adaptation actions can reduce the impact of rising sea level, which will cause losses of sandy beach zones and salt marsh habitats that support the highest biodiversity in these ecosystems, including regionally rare and endangered species, with substantial impacts occurring by 2050. Providing for inland transgression of coastal habitats, effective sediment management, reduced beach grooming and removal of shoreline armoring are adaptations that would help maintain coastal ecosystems and the beneficial services they provide.

California↗
USGS2026

Cyanobacteria and aquatic ecosystem dynamics across 28,000 years of environmental changes in subtropical North America

Ecological pressures on aquatic ecosystems have increased over recent centuries due to human activities and climate change. However, contextualizing ecosystem deterioration is often challenging due to limited knowledge of environmental changes over millennial timescales. Subtropical Carolina bays in North Carolina, USA, have remained unglaciated, preserving paleolimnological records that extend back to the last glacial period. Here, we analyzed a sediment core from the ecologically rich Lake Waccamaw spanning more than 28,000 years for aquatic proxies of nutrients, photosynthetic pigments, cyanotoxins, carbon isotopes, and terrestrial proxies of pollen and charcoal. The study explored paleolimnological changes in the aquatic environment connected to land changes and climate during the late Quaternary in the southeastern Atlantic Coastal Plain. Results reveal that while current levels of colonial cyanobacteria are high, past levels of cyanobacteria, other primary producers, and cyanotoxins were higher under natural climate variability. Abrupt ecosystem responses to increasing trophic conditions during Interstadial 3 (27.8–26.4 cal ka BP) and the early Holocene (11.4–7 cal ka BP) were marked by increases in primary producer abundance, deciduous vegetation expansion, and fire activity. Cyanobacteria remained dominant throughout the record, with colonial forms prevailing during the Holocene. Increases in pigment concentrations aligned with Quercus and were primarily driven by hydroclimatic variability and nutrient stoichiometry. Transitions between Pinus and Quercus pollen matched stadials and interstadials in the δ 18 Ο record from the North Greenland Ice Core Project (NGRIP). This study highlights the value of multi-proxy millennial-scale paleolimnological records for understanding aquatic ecosystem responses to climate conditions during the late Pleistocene.

North Carolina↗
USGS2018

Insights from long-term ungrazed and grazed watersheds in a salt desert Colorado Plateau ecosystem

Dryland ecosystems cover over 41% of the earth’s land surface, and living within these important ecosystems are approximately 2 billion people, a large proportion of whom are subsistence agropastoralists. Improper grazing in drylands can negatively impact ecosystem productivity, soil conservation, hydrologic processes, downstream water quantity and quality, and ultimately human health and economic well-being. Concerns regarding the degraded state of western US rangelands in the 1950s resulted in an interagency committee to study the effects of land use on runoff and erosion processes. In 1953, a federal research group established four paired watersheds in western Colorado to study the interaction of grazing by domestic livestock, runoff, and sediment yield. Exclusion of livestock from half of the watersheds dramatically reduced runoff and sediment yield after the first 10 yr—primarily due to changes in ground cover but not vegetation. Here, we report results of repeated soils and vegetation assessments of the experimental watersheds after more than 50 yr of grazing exclusion. Results show that many of the differences in soil conditions between grazed and ungrazed watersheds observed in the 1950s and 1960s were still present in 2004, despite reduced numbers of livestock: few differences in vegetation cover but large differences in biological soil crusts, soil stability, soil compaction, and soil biogeochemistry. There were differences among soil types in response to grazing history, especially soil lichen cover and soil organic matter, nitrogen, and sodium. Comparisons of ground cover measured in 2004 with those measured in 1953, 1966, and 1972 suggest much of the differences between grazed and ungrazed watersheds likely were driven by high sheep numbers during droughts in the 1950s. Persistence of these differences, despite large reductions in stocking rates , suggest the combination of overgrazing and drought may have pushed these salt desert ecosystems into a persistent, degraded ecological state.

Salt Desert Colorado Plateau Ecosystem↗
USGS2022

Environmental filtering controls soil biodiversity in wet tropical ecosystems

The environmental factors controlling soil biodiversity along resource gradients remain poorly understood in wet tropical ecosystems. Aboveground biodiversity is expected to be driven by changes in nutrient availability in these ecosystems, however, much less is known about the importance of nutrient availability in driving soil biodiversity. Here, we combined a cross-continental soil survey across tropical regions with a three decades' field experiment adding nitrogen (N) and phosphorus (P) (100 kg N ha −1 y −1 and 100 kg P ha −1 y −1 ) to Hawai'ian tropical forests with contrasting substrate ages (300 and 4,100,000 years) to investigate the influence of nutrient availability to explain the biodiversity of soil bacteria, fungi, protists, invertebrates and key functional genes. We found that soil biodiversity was driven by soil acidification during long-term pedogenesis and across environmental gradients, rather than by nutrient limitations. In fact, our results showed that experimental N additions caused substantial acidification in soils from Hawai'i. These declines in pH were related to large decreases in soil biodiversity from tropical ecosystems in four continents. Moreover, the microbial activity did not change in response to long-term N and P additions. We concluded that environmental filtering drives the biodiversity of multiple soil organisms, and that the acidification effects associated with N additions can further create substantial undesired net negative effects on overall soil biodiversity in naturally tropical acid soils. This knowledge is integral for the understanding and management of soil biodiversity in tropical ecosystems globally.

Hawai'i↗
USGS2024

Mapping development preferences on the perceived value of ecosystem services and land use conflict and compatibility in Greater Kuala Lumpur

Rapid and unplanned development can diminish the social values for ecosystem services associated with urban landscapes. Tropical Global South cities, such as Greater Kuala Lumpur (GKL), Malaysia, that are highly biodiverse, are particularly vulnerable to the fragmentation and loss of natural ecosystems. This study investigates the social values for ecosystem services in GKL, a rapidly urbanising metropolitan area in Southeast Asia and presents the novel application of the SolVES ( Social Values for Ecosystem Services ) tool to an urban area. A public participatory GIS (PPGIS) survey was conducted to assess residents’ development preferences and perceived distribution of social values. The study revealed two groups of respondents, using cluster analysis, each with unique development preferences - a group favouring both green and grey developments and another favouring green development but strongly opposing grey development. The two groups differed statistically in their sociodemographic characteristics, and also how they mapped different social values. Our spatial analysis of their preferences towards future urban expansion in GKL highlighted locations where there is potential for land-use conflict. For example, the favour-balanced-development group tended to value built areas over green spaces. These findings support the need to consider residents’ preferences and socioecological traits through greater public engagement in urban landscape management.

Greater Kuala Lumpur↗
USGS2021

Bayesian change point quantile regression approach to enhance the understanding of shifting phytoplankton-dimethyl sulfide relationships in aquatic ecosystems

Dimethyl sulfide (DMS) serves as an anti-greenhouse gas, plays multiple roles 7 in aquatic ecosystems, and contributes to the global sulfur cycle. The chlorophyll 8 a (CHL, an indicator of phytoplankton biomass)-DMS relationship is critical for 9 estimating DMS emissions from aquatic ecosystems. Importantly, recent research has 10 identified that the CHL-DMS relationship has a breakpoint, where the relationship 11 is positive below a CHL threshold and negative at higher CHL concentrations. 12 Conventionally, mean regression methods are employed to characterize the CHL-DMS 13 relationship. However, these approaches focus on the response of mean conditions 14 and cannot illustrate responses of other parts of the DMS distribution, which could 15 be important in order to obtain a complete view of the CHL-DMS relationship. In 16 this study, for the first time, we proposed a novel Bayesian change point quantile 17 regression (BCPQR) model that integrates and inherits advantages of Bayesian change 18 point models and Bayesian quantile regression models. Our objective was to examine 19 whether or not the BCPQR approach could enhance the understanding of shifting 20 CHL-DMS relationships in aquatic ecosystems. We fitted BCPQR models at five 21 regression quantiles for freshwater lakes and for seas. We found that BCPQR models 22 could provide a relatively complete view on the CHL-DMS relationship. In particular, 23 it quantified the upper boundary of the relationship, representing the limiting effect of 24 CHL on DMS. Based on the results of paired parameter comparisons, we revealed the 25 inequality of regression slopes in BCPQR models for seas, indicating that applying 26 the mean regression method to develop the CHL-DMS relationship in seas might not 27 be appropriate. We also confirmed relationship differences between lakes and seas at 28 multiple regression quantiles. Further, by introducing the concept of DMS emission 29 potential, we found that pH was not likely a key factor leading to the change of the 30 CHL-DMS relationship in lakes. These findings cannot be revealed using piecewise 31 linear regression. We thereby concluded that the BCPQR model does indeed enhance 32 the understanding of shifting CHL-DMS relationships in aquatic ecosystems and is 33 expected to benefit efforts aimed at estimating DMS emissions. Considering that 34 shifting (threshold) relationships are not rare and that the BCPQR model can easily 35 be adapted to different systems, the BCPQR approach is expected to have great 36 potential for generalization in other environmental and ecological studies.

Water Research↗
USGS1996

The developing framework of marine ecotoxicology: Pollutants as a variable in marine ecosystems?

Marine ecosystems include a subset in which at least some interrelated geochemical, biochemical, physiological, population and community characteristics are changed by pollutants. Moderate contamination is relatively widespread in coastal and estuarine ecosystems, so the subset of ecosystems with at least some processes affected could be relatively large. Pollutant influences have changed and will probably continue to change on time scales of decades. Biological exposures and dose in such ecosystems are species-specific and determined by how the species is exposed to different environmental media and the geochemistry of individual pollutants within those media. Bioaccumulation models offer significant promise for interpreting such exposures. Biological responses to pollutants need to be more directly linked to exposure and dose. At the level of the individual this might be improved by better understanding relationships between tissue concentrations of pollutants and responses to pollutants. Multi-discipline field and laboratory studies combined with advanced understanding of some basic processes have reduced the ambiguities in interpreting a few physiological/organismic responses to pollutants in nature. Recognition of pollutant-induced patterns in population responses could lead to similar advances. A rational framework for ecotoxicology is developing, but its further advance is dependent upon better integration of ecotoxicology with basic marine ecology and biology.

Journal of Experimental Marine Biology and Ecology↗
USGS2003

Information technology challenges of biodiversity and ecosystems informatics

Computer scientists, biologists, and natural resource managers recently met to examine the prospects for advancing computer science and information technology research by focusing on the complex and often-unique challenges found in the biodiversity and ecosystem domain. The workshop and its final report reveal that the biodiversity and ecosystem sciences are fundamentally information sciences and often address problems having distinctive attributes of scale and socio-technical complexity. The paper provides an overview of the emerging field of biodiversity and ecosystem informatics and demonstrates how the demands of biodiversity and ecosystem research can advance our understanding and use of information technologies.

Information Systems↗
USGS2025

Ecosystem drivers of freshwater mercury bioaccumulation are context-dependent: Insights from continental-scale modeling

Significant variation in mercury (Hg) bioaccumulation is observed across the diversity of freshwater ecosystems in North America. While there is support for the major drivers of Hg bioaccumulation, the relative influence of different external factors can vary widely among waterbodies, which makes predicting Hg risk across large spatial scales particularly challenging. We modeled Hg bioaccumulation by coupling Hg concentrations in more than 21,000 dragonflies collected across the United States from 2008 to 2021 with a suite of chemical (e.g., dissolved organic carbon (DOC), pH, sulfate) and landscape (e.g., soil characteristics, land cover) variables representing external drivers of Hg methylation, transport, and uptake. Model predictions explained 85% of the variation in dragonfly Hg concentrations across the United States. Certain predictor variables were more important than others (e.g., DOC, pH, and percent wetland), and they varied among waterbodies. Variation in Hg bioaccumulation was explained by including habitat and ecosystem type in a hierarchical modeling framework, which confirms the context-dependency of external factors in explaining Hg bioaccumulation across disparate freshwater ecosystems. This continent-scale model provides valuable insights into the processes underlying landscape-scale patterns in Hg exposure risk and demonstrates that drivers of Hg methylation and bioaccumulation are habitat- and ecosystem-dependent.

Environmental Science and Technology↗