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At least 1,369 records · Page 76Linked to original sources

USGS2019

Spatially explicit models of seasonal habitat for greater sage‐grouse at broad spatial scales: Informing areas for management in Nevada and northeastern California

Defining boundaries of species' habitat across broad spatial scales is often necessary for management decisions, and yet challenging for species that demonstrate differential variation in seasonal habitat use. Spatially explicit indices that incorporate temporal shifts in selection can help overcome such challenges, especially for species of high conservation concern. Greater sage‐grouse Centrocercus urophasianus (hereafter, sage‐grouse), a sagebrush obligate species inhabiting the American West, represents an important case study because sage‐grouse exhibit seasonal habitat patterns, populations are declining in most portions of their range and are central to contemporary national land use policies. Here, we modeled spatiotemporal selection patterns for telemetered sage‐grouse across multiple study sites (1,084 sage‐grouse; 30,690 locations) in the Great Basin. We developed broad‐scale spatially explicit habitat indices that elucidated space use patterns (spring, summer/fall, and winter) and accounted for regional climatic variation using previously published hydrographic boundaries. We then evaluated differences in selection/avoidance of each habitat characteristic between seasons and hydrographic regions. Most notably, sage‐grouse consistently selected areas dominated by sagebrush with few or no conifers but varied in type of sagebrush selected by season and region. Spatiotemporal variation was most apparent based on availability of water resources and herbaceous cover, where sage‐grouse strongly selected upland natural springs in xeric regions but selected larger wet meadows in mesic regions. Additionally, during the breeding period in spring, herbaceous cover was selected strongly in the mesic regions. Lastly, we expanded upon an existing joint–index framework by combining seasonal habitat indices with a probabilistic index of sage‐grouse abundance and space use to produce habitat maps useful for sage‐grouse management. These products can serve as conservation planning tools that help predict expected benefits of restoration activities, while highlighting areas most critical to sustaining sage‐grouse populations. Our joint–index framework can be applied to other species that exhibit seasonal shifts in habitat requirements to help better guide conservation actions.

California, Nevada↗

USGS2022

Projected stream fish community risk to climate impacts in the Northeastern and Midwestern United States

Climate change is expected to alter stream fish habitat potentially leading to changes in the composition and distribution of fish communities. In the Northeastern and Midwestern United States we identified the distribution and characteristics of those fish communities most and least at risk of experiencing changes in climate which deviate from the climate they are associated with. We classified stream fish communities based on a suite of climate and environmental variables with multivariate regression trees under both recent and future conditions based on eight climate models. Our findings showed that some areas, such as the majority of the Illinois, Wisconsin, and Iowa), have high levels of risk of change in stream class, while much of Kentucky, West Virginia, Virginia, Pennsylvania, Eastern Ohio, Southern Michigan, and the Atlantic Coast are at relatively low risk. Stream class shifts ranged from over 75% of segments lost (associated with cooler temperatures) to gains of over 40% (associated with warmer temperatures). Common warmwater species such as green sunfish ( Lepomis cyanellus ), bluegill ( Lepomis macrochirus ) and largemouth bass ( Micropterus salmoides ) are expected to have the largest net gains in associated stream classes, while species associated with cooler streams such as Southern redbelly dace ( Chrosomus erythrogaster ), slimy sculpin ( Cottus cognatus ), and Eastern blacknose dace ( Rhinichthys atratulus ) were expected to experience the largest proportional losses. By pairing our climate risk predictions with other stressors such anthropogenic land use, habitat fragmentation, and water quality impairment, we identified opportunities for preservation (low risk due to all threats), restoration (low risk due to climate, high risk due to other stressors), and adaptation (high climate risk with low risk from other stressors). Understanding which communities are at risk due to climate change will aid in developing adaptation strategies to help sustain them in the future.

Connecticut, Delaware, Illinois, Indiana, Iowa, Ke↗

USGS2021

Demography and loss of genetic diversity in two insular populations of the bobcat (Lynx rufus)

Among felids worldwide, only 6 of 38 species have stable or increasing populations, and most felid species are threatened by anthropogenic influences, especially habitat loss and fragmentation. We documented changes in genetic diversity in an isolated, reintroduced population of bobcats on Cumberland Island (CUIS), Georgia, USA, compared to another bobcat population on Kiawah Island, South Carolina, USA, that was naturally established and experiences limited immigration from the mainland. The CUIS population declined from 32 reintroduced bobcats in 1989 to 10–24 individuals during 2012–2019, and observed heterozygosity declined from 0.742 to 0.634 (SD = 0.240). Observed heterozygosity of bobcats on Kiawah was 0.699 (SD = 0.153). We estimated that one bobcat immigrated to Kiawah Island every 5.3 years. We compared the predictions of a novel population viability analysis ( PVA ) to empirical estimates of abundance and genetic diversity on CUIS and used our PVA to identify management actions that are likely to support long-term viability. Mean heterozygosity from the PVA (0.588, SD = 0.065) was within 1 standard deviation of the empirical estimate. The PVA estimated the population would decline following population restoration due to loss of genetic diversity and inbreeding depression. Translocations of one female every four years would stabilize allele heterozygosity similar to the Kiawah Island population, but even translocations of two females every two years would not restore heterozygosity to founder levels. The PVA predicted no management action would result in a one in five probability of extinction within 50 years of reintroduction, but all translocation strategies nearly eliminated extinction risk through 100 years.

Georgia, South Carolina↗

USGS2012

Comparing modern and presettlement forest dynamics of a subboreal wilderness: Does spruce budworm enhance fire risk?

Insect disturbance is often thought to increase fire risk through enhanced fuel loadings, particularly in coniferous forest ecosystems. Yet insect disturbances also affect successional pathways and landscape structure that interact with fire disturbances (and vice-versa) over longer time scales. We applied a landscape succession and disturbance model (LANDIS-II) to evaluate the relative strength of interactions between spruce budworm ( Choristoneura fumiferana ) outbreaks and fire disturbances in the Boundary Waters Canoe Area (BWCA) in northern Minnesota (USA). Disturbance interactions were evaluated for two different scenarios: presettlement forests and fire regimes vs. contemporary forests and fire regimes. Forest composition under the contemporary scenario trended toward mixtures of deciduous species (primarily Betula papyrifera and Populus spp.) and shade-tolerant conifers ( Picea mariana, Abies balsamea, Thuja occidentalis ), with disturbances dominated by a combination of budworm defoliation and high-severity fires. The presettlement scenario retained comparatively more “big pines” (i.e., Pinus strobus, P. resinosa ) and tamarack ( L. laricina ), and experienced less budworm disturbance and a comparatively less-severe fire regime. Spruce budworm disturbance decreased area burned and fire severity under both scenarios when averaged across the entire 300-year simulations. Contrary to past research, area burned and fire severity during outbreak decades were each similar to that observed in non-outbreak decades. Our analyses suggest budworm disturbances within forests of the BWCA have a comparatively weak effect on long-term forest composition due to a combination of characteristics. These include strict host specificity, fine-scaled patchiness created by defoliation damage, and advance regeneration of its primary host, balsam fir ( A. balsamea ) that allows its host to persist despite repeated disturbances. Understanding the nature of the three-way interaction between budworm, fire, and composition has important ramifications for both fire mitigation strategies and ecosystem restoration initiatives. We conclude that budworm disturbance can partially mitigate long-term future fire risk by periodically reducing live ladder fuel within the mixed forest types of the BWCA but will do little to reverse the compositional trends caused in part by reduced fire rotations.

Minnesota↗

USGS2023

An introduction to the evaluation of restoration for avian species at Caminada Headland and Whiskey Island in Louisiana

Barrier islands are crucial for protecting Louisiana’s coastal communities and ecosystems as they reduce coastal erosion and help safeguard native flora and fauna. Along the Louisiana shoreline, these islands are mostly long and thin, running parallel to the shoreline. The islands typically consist of the following components: 1) a sandy beach facing the Gulf of Mexico; 2) vegetated and non-vegetated dunes; 3) overwash areas; 4) swales; 5) upland shrubs; 6) wetland shrubs, such as black mangrove (Avicennia germinans); 7) backbay marshes; and 8) tidal flats. Dune vegetation and vegetation along the back-barrier help bind and collect sediment, which create and maintain wetlands on the north side of the barrier islands. Barrier islands provide various ecological services including: 1) buffering waves to decrease storm impacts; 2) protecting wetlands that provide suitable reproductive habitat and nursery grounds for fish and shellfish; and 3) providing critical habitat for birds and sea turtles (Barbier 2013).

Louisiana↗

USGS2020

Odds ratios and hurdle models: a long-term analysis of parasite infection patterns in endangered young-of-the-year suckers from Upper Klamath Lake, Oregon, USA

We used odds ratios and a hurdle model to analyze parasite co-infections over 25 years on >20,000 young-of-the year of endangered Shortnose and Lost River Suckers. Host ecologies differed as did parasite infections. Shortnose Suckers were more likely to be caught inshore and 3–5 times more likely to have Bolbophorus spp. and Contracaecum sp. infections, and Lost River Suckers were more likely to be caught offshore and approximately three times more likely to have Lernaea cyprinacea infections. An observed peak shift seems likely to be due to a lower host size limit for Bolbophorus spp. (13.6 mm) compared with L. cyprinacea (23.4 mm). The large data set allowed us to generate strong hypotheses: (i) that a major marsh restoration project had unintended consequences that resulted in an increase in infections; (ii) that co-infection with Bolbophorus spp. increased the odds of infection by L. cyprinacea and Contracaecum sp.; (iii) that significant declines in the odds of infection over approximately 25 days were due to parasite-induced host mortality; (iv) that the fish’s small size relative to L. cyprinacea and Contracaecum sp. might be directly lethal; (v) that the absence of L. cyprinacea infections in the early 1990s was associated with good year-class production of the suckers; and (vi) that parasites might increase the odds of vagrancy from the nursery ground.

Oregon↗

USGS2010

Trading off short-term and long-term risk: minimizing the threat of Laysan duck extinction from catastrophes and sea-level rise

Conservation of oceanic island species presents many ecological and logistical challenges. The Northwestern Hawaiian Islands (NWHI) include 300,000 km 2 of ocean waters and 10 groups of sub-tropical islands and atolls of high conservation value. Designated as Papahanaumokuakea Marine National Monument, the islands provide habitat for four endangered species of terrestrial birds. Despite their protected status, many of these species are faced with the ongoing threat of extinction due to stochastic catastrophes such as disease, invasive mammal introductions, tsunamis, and hurricanes. To reduce the risk that a single catastrophe would lead to extinction, managers propose to restore multiple "insurance" populations on islands currently unoccupied by these species to increase their range and overall numbers.

Hawai'i↗

USGS2020

RestoreNet: An emerging restoration network reveals controls on seeding success across dryland ecosystems

Drylands are Earth's largest terrestrial biome and support one‐third of the global population. However, they are also highly vulnerable to land degradation. Despite widespread demand for dryland restoration and rehabilitation, little information is available to help land managers effectively re‐establish native perennial vegetation across drylands. RestoreNet is an emerging dryland restoration network that systematically tests revegetation techniques across environmental gradients. Using the RestoreNet experimental framework, we tested the effectiveness of restoration treatments (i.e. ConMod nurse plant structures, mulch, pits) that increase soil moisture and seed mixes with different climatic niches to achieve revegetation goals. Across sites, seedling recruitment was consistently influenced by treatment and seed mix type. Pit and mulch treatments increased total seedling density, with pits promoting the highest seeded species recruitment while limiting non‐native species establishment. Seeding increased total seedling density regardless of seed mix type, but cooler‐adapted seed mixes promoted greater seeded species density and resulted in lower density of unseeded (non‐native) species relative to warmer‐adapted mixes. Seedling recruitment was also controlled by the temporal and environmental context of restoration with the positive effect of high precipitation greatest in the weeks immediately following seeding. Above‐average precipitation during the study period across most of the sites may partially explain why the highest seeded species recruitment occurred in pit treatments and seed mixes with cooler, wetter niche requirements. Synthesis and applications . Results from the dryland restoration network, RestoreNet help to better understand variation in seeding and restoration treatment success across space and time in drylands. Relationships between restoration practices and environmental conditions in our study suggest the importance of anticipatory restoration strategies that forecast seasonal and sub‐seasonal weather conditions and select plant species with climate niche requirements appropriate for current and future climate conditions. This information is critical to land managers tasked with improving ecosystem conditions across degraded dryland regions.

Arizona↗

USGS2010

Design of Cycle 3 of the National Water-Quality Assessment Program, 2013-2022: Part 1: Framework of Water-Quality Issues and Potential Approaches

In 1991, the U.S. Congress established the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program to develop long-term, nationally consistent information on the quality of the Nation's streams and groundwater. Congress recognized the critical need for this information to support scientifically sound management, regulatory, and policy decisions concerning the increasingly stressed water resources of the Nation. The long-term goals of NAWQA are to: (1) assess the status of water-quality conditions in the United States, (2) evaluate long-term trends in water-quality conditions, and (3) link status and trends with an understanding of the natural and human factors that affect water quality. These goals are national in scale, include both surface water and groundwater, and include consideration of water quality in relation to both human uses and aquatic ecosystems. Since 1991, NAWQA assessments and findings have fostered and supported major improvements in the availability and use of unbiased scientific information for decisionmaking, resource management, and planning at all levels of government. These improvements have enabled agencies and stakeholders to cost-effectively address a wide range of water-quality issues related to natural and human influences on the quality of water and potential effects on aquatic ecosystems and human health (http://water.usgs.gov/nawqa/xrel.pdf). NAWQA, like all USGS programs, provides policy relevant information that serves as a scientific basis for decisionmaking related to resource management, protection, and restoration. The information is freely available to all levels of government, nongovernmental organizations, industry, academia, and the public, and is readily accessible on the NAWQA Web site and other diverse formats to serve the needs of the water-resource community at different technical levels. Water-quality conditions in streams and groundwater are described in more than 1,700 publications (available online at http://water.usgs.gov/nawqa/bib/), and are documented by more than 14 million data records representing about 7,600 stream sites, 8,100 wells, and 2,000 water-quality and ecological constituents that are available from the NAWQA data warehouse (http://infotrek.er.usgs.gov/traverse/f?p=NAWQA:HOME:0). The Program promotes collaboration and liaison with government officials, resource managers, industry representatives, and other stakeholders to increase the utility and relevance of NAWQA science to decisionmakers. As part of this effort, NAWQA supports integration of data from other organizations into NAWQA assessments, where appropriate and cost-effective, so that more comprehensive findings are available across geographic and temporal scales.

Open-File Report↗

USGS2004

History and effects of hatchery salmon in the Pacific

There has been a long history of production of hatchery salmon along the Pacific coast - from California’s first efforts in the 1870s using eggs from chinook and rainbow trout to the recent large-scale production hatcheries for pink salmon in Japan and the Russian Far East. The rationale for this production has also varied from replacement of fish lost in commercial ocean harvests to mitigation and restoration of salmon in areas where extensive habitat alteration has reduced salmonid viability and abundance. Over the years, we have become very successful in producing a certain type of product from salmon hatcheries, but until recently we seldom questioned the impacts the production and release of hatchery fish may have on freshwater and marine aquatic ecosystems and on the sustainability of sympatric wild salmon populations. This paper addresses the history of hatcheries around the Pacific Rim and considers potential negative implications of hatchery-produced salmon through discussions of biological impacts and biodiversity, ecological impacts and competitive displacement, fish and ecosystem health, and genetic impacts of hatchery fish as threats to wild populations of Pacific salmon.

Speaking for the Salmon↗

USGS2001

Burrowing mayflies ( Hexagenia ) as indicators of ecosystem health

Three State of the Lakes Ecosystem Conferences have been held since 1996 to encourage the development of Great Lakes indicators of ecosystem health for use in reporting on progress in restoring and maintaining the chemical, physical and biological integrity of the Great Lakes ecosystem. Here we report on the development of an indicator based on burrowing mayflies , Hexagenia (Ephemeroptera: Ephemeridae), using production and biomass as the indicator metrics. Burrowing mayflies were selected because they (1) were historically abundant in unpolluted, soft-bottomed mesotrophic habitats throughout the Great Lakes, (2) are intolerant of and were extirpated by pollution in most of those habitats during the 1940s to1950s, (3) have shown the ability to recover in one of those habitats following pollution abatement, (4) are ecologically important as bioturbators of lakebed sediments and as trophic integrators that link detrital energy resources directly to fishes that feed preferentially on them, and (5) have highly visible mating flights, which carry the message directly to an informed public that the source water body is healthy. In addition, their annual production can be estimated from their mean annual biomass by the sizefrequency method. Productivity and biomass can also could be estimated with a 'cohort-direct' method, using the biomass of mature nymphs collected in May or early June from the cohort that is about to emerge as subimagos in late June or early July. Although both the size-frequency and cohort-direct methods provide reliable estimates of productivity and biomass, the latter method greatly reduces sample collection and processing effort and thus makes it feasible to use Hexagenia as an indicator of ecosystem health in surveys requiring the collection of large numbers of samples.

Aquatic Ecosystem Health & Management↗

USGS2025

Healing ogaa (walleye Sander vitreus) waters: Lessons and future directions for inland fisheries rehabilitation

ulturally, economically, and nutritionally valuable inland fisheries face many new challenges on top of chronic disturbances. In the upper midwestern United States, declines in cool- and coldwater fisheries have been observed, including ogaa/walleye Sander vitreus . In response to population declines, agencies have implemented rehabilitation efforts, and the frequency and intensity of efforts have increased recently given declines. Evaluating intervention outcomes is critical for institutional learning and to understand strategy effectiveness, but is difficult to do when multiple interventions are applied concurrently and in the absence of replication or controls. This review documents walleye rehabilitation efforts in the upper Midwest U.S., where a rehabilitation effort was defined as a coordinated effort with the stated intention to restore a self-sustaining population such that it required limited-to-no further intervention. We discuss: (1) strategies used; (2) similarities and differences in metrics of success; (3) factors leading to success; and (4) recommendations that may increase future successful rehabilitation. Strategies included harvest regulation changes, stocking, fish community manipulations, habitat enhancement, and partner discussions. Overall, evaluations of environmental, habitat, and fish community factors causing walleye population declines were not included in most rehabilitation plans before implementation. This review highlights an increased need for ecosystem-based fisheries management principles and cultivating ecological conditions that favor walleye as a potential path for future rehabilitation plans. Lessons drawn from rehabilitation plans are applicable to global inland fisheries to inform the conservation of declining fish populations.

Michigan, Minnesota, Wisconsin↗

USGS2021

A bright spot analysis of inland recreational fisheries in the face of climate change: Learning about adaptation from small successes

Inland recreational fisheries have social, economic, and ecological importance worldwide but these fisheries are increasingly challenged by the diverse effects of climate change. Coupled with other anthropogenic stressors, climate change has contributed to declines in freshwater biodiversity of greater severity than those observed across marine or terrestrial taxa. At a macro level, inland fisheries are experiencing declines. There are, however, a number of success stories, or ‘bright spots,’ in inland recreational fisheries management, where innovative approaches are leading to increases in social and ecological well-being in the face of climate change. Cases such as these are important sources of inspiration and learning about adaptation to climate and environmental change. In this article, we analyze 11 examples of such ‘bright spots’ drawn from multiple jurisdictions around the world from which we extracted lessons that might apply to fisheries management challenges beyond the region and context of each case. Collectively, these bright spots highlight adaptive initiatives that allow for recreational fisheries management to mitigate to stressors associated with current and future climate change. Examples identified include community-based restoration projects, collaborative and adaptive approaches to short-term fisheries closures, transdisciplinary large-scale conservation projects, and conservation-minded efforts by individuals and communities. By highlighting examples of ‘small wins’ within inland recreational fisheries management, this review contributes to the idea that a ‘positive future’ for inland recreational fisheries in the face of climate change is possible and highlights potential strategies to adapt to current and future climate scenarios.

Reviews in Fish Biology and Fisheries↗

USGS2025

Pit tag application in native freshwater mussels: Case studies across small, medium, and large rivers

Since their first use in the mid-1980s, external passive integrated transponder (PIT) tags have facilitated innovative investigations into multiple biological traits of animals. For native freshwater mussels, PIT tags are frequently used in capture-mark-recapture applications because they allow repeated, noninvasive sampling, are easy to apply, have high retention rates, and have negligible short-term effects on growth and survival. Because of these traits, resource managers and scientists are using PIT-tagged animals to estimate survival and movement of mussels associated with restoration efforts. However, consistency is limited in how PIT tags are affixed, monitored, and reported. Thus, our objectives were to (1) share our collective experiences in PIT tagging mussels across three case studies in small, medium, and large rivers and (2) propose guidelines for tagging and reporting data from PIT tag studies with native freshwater mussels to facilitate comparisons across future studies. The number of studies that have marked mussels with PIT tags has increased over the past 10 years. The ability to detect mussels using PIT tags has substantially advanced research in three areas of mussel ecology: (1) estimating vital rates (e.g., growth and survival), (2) tracking movements and behaviors of captively propagated, wild, and translocated individuals, and (3) improving our understanding of life history traits, such as reproductive timing. Each case study offers insights on tagging methods, tag loss, tag retention, and monitoring frequency across multiple species that range in conservation status from common to rare. We conclude with best-practice guidelines for placing PIT tags on freshwater mussels and a list of variables that could be reported in future studies to facilitate cross-system comparisons.

Freshwater Mollusk Biology and Conservation↗

USGS2011

Effects of conservation practices on wetland ecosystem services in the Mississippi Alluvial Valley

Restoration of wetland ecosystems is an important priority for many state and federal agencies, as well as nongovernmental conservation organizations. The historic conversion of wetlands in the Mississippi Alluvial Valley (MAV) has resulted in large‐scale implementation of a variety of conservation practices designed to restore and enhance wetland ecosystem services. As a consequence, the effectiveness of multiple approaches in achieving desired conservation goals varies depending on site conditions, practices employed, and specific ecosystem services. We reviewed government agency programs and the scientific literature to evaluate the effects of conservation practices on wetlands in the MAV. There were 68 different conservation practices applied to a combined total of 1.27 million ha in the MAV between 2000 and 2006. These practices fell into two categories: Wetland Conservation Practices and Upland Conservation Practices. Sixteen different practices accounted for nearly 92% of the total area, and only three of these are directly related to wetlands: Wetland Wildlife Habitat Management, Wetland Restoration, and Riparian Forest Buffer. All three of these practices involve reforestation, primarily planting hard‐mast species such as Quercus sp. and Carya sp. These plantings are likely to develop into even‐aged stands of low tree diversity with little structural heterogeneity, which will impact future wildlife habitat. Since hydrology is a critical driver of wetland processes, the ability of a given conservation practice to restore wetland hydrology is a key determinant of how well it can restore ecosystem services. However, there is little to no follow‐up monitoring of projects, so it is difficult to know how much variability exists for any given practice or the efficacy of specific practices. Conservation practices that only plant trees without reconnecting the wetland to the hydrologic and nutrient fluxes in the watershed may restore some wildlife habitat but will do little for regulating services such as nitrogen retention. While conservation practices have overall beneficial effects on many ecosystem services in the MAV, the most effective are those with a direct link between the actions associated with a given practice and controls over ecosystem processes and services.

Arkansas, Kentucky, Louisiana, Mississippi, Missou↗

USGS1997

Development of an IBI-based assessment of depressional wetlands in Maryland and Delaware

The hydrogeomorphic approach (HGM) of wetland assessment emphasizes functional components of wetlands such as water storage, transformation and cycling of elements, accumulation of sediments, and preservation of habitats. Many of the elements measured in HGM are physical rather than ecological or biological. The HGM approach, therefore, provides information on certain aspects of wetlands and omits other aspects. In contrast, the Index of Biological Integrity (IBI) approach focuses on biological components of wetlands such as species richness, the presence or proportion of certain 'indicator' species, representation of different trophic levels, and measures of wildlife or fish health. Here too, some aspects of a wetland are omitted and others not covered by HGM are included. We contend that these differences in focus add strengths and weaknesses to each method. This paper reviews progress on the development of IBIs for restored depressional wetlands in the Mid-Atlantic States, especially Maryland and Delaware. During our first field season we identified 25 wetlands ranging from 1-10 acres, most of which were restored with federal, state, and private landowner cooperation over hydric soils. Separate IBIs are being created for macrophytes, macroinvertebrates, amphibians, and data on mammal and avian populations are being collected. Simultaneously, chemical and physical data are being collected on water DO, turbidity, temperature, conductivity, nitrates, ammonia, chlorophyll, pH; soil metal levels and texture; and wetland size, configuration, hydrology, drainage area, and surrounding land use.

Book chapter↗

USGS2017

Development of a multimetric index for integrated assessment of salt marsh ecosystem condition

Tools for assessing and communicating salt marsh condition are essential to guide decisions aimed at maintaining or restoring ecosystem integrity and services. Multimetric indices (MMIs) are increasingly used to provide integrated assessments of ecosystem condition. We employed a theory-based approach that considers the multivariate relationship of metrics with human disturbance to construct a salt marsh MMI for five National Parks in the northeastern USA. We quantified the degree of human disturbance for each marsh using the first principal component score from a principal components analysis of physical, chemical, and land use stressors. We then applied a metric selection algorithm to different combinations of about 45 vegetation and nekton metrics (e.g., species abundance, species richness, and ecological and functional classifications) derived from multi-year monitoring data. While MMIs derived from nekton or vegetation metrics alone were strongly correlated with human disturbance ( r values from −0.80 to −0.93), an MMI derived from both vegetation and nekton metrics yielded an exceptionally strong correlation with disturbance ( r = −0.96). Individual MMIs included from one to five metrics. The metric-assembly algorithm yielded parsimonious MMIs that exhibit the greatest possible correlations with disturbance in a way that is objective, efficient, and reproducible.

Estuaries and Coasts↗

USGS2025

Spatial and temporal variation in dissolved organic matter in urban streams in metropolitan Boston, Massachusetts (USA)

Urban riverine systems are heterogeneous, and the substantial variability in impervious cover, riparian cover, wetlands, and wastewater and stormwater infrastructure affect sources and transport of dissolved organic matter (DOM), of which dissolved organic C (DOC) is a substantial component. An understanding of the quantity, bioavailability, and timing of DOM inputs (a key energy source for food webs and a component of nutrient cycling) to streams within cities can help to better evaluate drivers of DOM variability. We sampled 100 stream sites in the greater Boston (Massachusetts, USA) area spanning a range of land cover, riparian vegetation, stream size, housing and infrastructure age, and sociodemographic characteristics. Water samples collected during 4 seasonal synoptic events in 2021 and 2022 were analyzed for DOC concentration and DOM characteristics (using fluorescence excitation–emission matrices and absorbance spectra). Temporally, we observed more-autochthonous DOM and lower DOC concentrations in the summer, possibly due to low precipitation and streamflow disconnecting streams from humic wetland and soil C sources. Consistent with other studies, we observed that more-urbanized streams had DOM that was less humic and more autotrophic. Higher wetland cover was associated with more-humic, higher-molecular-weight DOM and was the strongest predictor of DOM characteristics, suggesting that managers should consider the impacts of development on DOM, stream ecological functions, and CO 2 emissions. Interestingly, except during the very dry summer, sites downstream of combined sewer outfalls showed distinctly higher concentrations of protein-like DOM, suggesting the influence of sewage overflows and highlighting the potential for monitoring wastewater contamination using protein-like DOM. Although sociodemographic variables were not strong predictors of DOM composition, we observed a possible association between lower-income areas with less canopy cover and more-autochthonous DOM and between areas with older housing, more canopy cover, and more-humic DOM. These patterns suggest that equitable repair of wastewater infrastructure and restoration of riparian vegetation is needed.

Massachusetts↗