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At least 469 records · Page 26Linked to original sources
USGS2022

Watershed-scale risk to aquatic organisms from complex chemical mixtures in the Shenandoah River

River waters contain complex chemical mixtures derived from natural and anthropogenic sources. Aquatic organisms are exposed to the entire chemical composition of the water, resulting in potential effects at the organismal through ecosystem level. This study applied a holistic approach to assess landscape, hydrological, chemical, and biological variables. On-site mobile laboratory experiments were conducted to evaluate biological effects of exposure to chemical mixtures in the Shenandoah River Watershed. A suite of 534 inorganic and organic constituents were analyzed, of which 273 were detected. A watershed-scale accumulated wastewater model was developed to predict environmental concentrations of chemicals derived from wastewater treatment plants (WWTPs) to assess potential aquatic organism exposure for all stream reaches in the watershed. Measured and modeled concentrations generally were within a factor of 2. Ecotoxicological effects from exposure to individual components of the chemical mixture were evaluated using risk quotients (RQs) based on measured or predicted environmental concentrations and no effect concentrations or chronic toxicity threshold values. Seventy-two percent of the compounds had RQ values <0.1, indicating limited risk from individual chemicals. However, when individual RQs were aggregated into a risk index, most stream reaches receiving WWTP effluent posed potential risk to aquatic organisms from exposure to complex chemical mixtures.

Virginia↗
USGS2005

Geophysical monitoring of a field-scale biostimulation pilot project

The USGS conducted a geophysical investigation in support of a U.S. Naval Facilities Engineering Command, Southern Division field‐scale biostimulation pilot project at Anoka County Riverfront Park (ACP), downgradient of the Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota. The goal of the pilot project is to evaluate subsurface injection of vegetable oil emulsion (VOE) to stimulate microbial degradation of chlorinated hydrocarbons. To monitor the emplacement and movement of the VOE and changes in water chemistry resulting from VOE dissolution and/or enhanced biological activity, the USGS acquired cross‐hole radar zero‐offset profiles, traveltime tomograms, and borehole geophysical logs during five site visits over 1.5 years. Analysis of pre‐ and postinjection data sets using petrophysical models developed to estimate VOE saturation and changes in total dissolved solids provides insights into the spatial and temporal distribution of VOE and ground water with altered chemistry. Radar slowness‐difference tomograms and zero‐offset slowness profiles indicate that the VOE remained close to the injection wells, whereas radar attenuation profiles and electromagnetic induction logs indicate that bulk electrical conductivity increased downgradient of the injection zone, diagnostic of changing water chemistry. Geophysical logs indicate that some screened intervals were located above or below zones of elevated dissolved solids; hence, the geophysical data provide a broader context for interpretation of water samples and evaluation of the biostimulation effort. Our results include (1) demonstration of field and data analysis methods for geophysical monitoring of VOE biostimulation and (2) site‐specific insights into the spatial and temporal distributions of VOE at the ACP.

Minnesota↗
USGS1994

Physical, chemical, and biological data for detailed study of irrigation drainage in the Klamath Basin, California and Oregon, 1990-92

Physical, chemical, and biological data were collected between 1990 and 1992 as part of a detailed study by the U.S. Department of Interior of the effects of irrigation drainage on aquatic resources in the Klamath Basin of California and Oregon. Most of the sites for data collection were in and around the upper and lower sump of Tule Lake, in the Tule Lake National Wildlife Refuge, and along major drains in Lower Klamath National Wildlife Refuge. The physical and chemical data consist of particle-size determinations and concentrations of carbon, mercury, arsenic, chlorophenoxy acid, and organochlorine, organophosphate, and carbamate pesticides in bottom sediment; and concentrations of organophosphate, carbamate, and pyrethroid pesticides, major and trace inorganic constituents, nitrogen, phosphorus, and organic carbon in water. Continuous dissolved oxygen, pH, specific conduc- tance, and temperature data from selected sites in 1991 and 1992 are presented in graphical form to summarize the diel water-quality conditions. The biological data consists of concentrations of inorganic constituents and organochlorine pesticides in tissue, invertebrate and fish population surveys, fish health surveys, frog call surveys, egg shell thickness of avian eggs, and in situ and static toxicity bioassay data collected in 1991 and 1992 using aquatic bacteria, plants, invertebrates, fish, and bird species as test organisms.

Open-File Report↗
USGS2002

Level I water-quality inventory and monitoring, Richmond National Battlefield Park, Virginia

The U.S. Geological Survey conducted a Level I Water-Quality Inventory and Monitoring (WAQIM) data-collection effort for Richmond National Battlefield Park (Richmond NBP) from August 2001 through April 2002. The primary objective of the WAQIM program was to provide the National Park Service (NPS) and Richmond NBP with at least a nominal inventory of its natural resources and to provide those data in a data-management system consistent with park management needs. Water-quality inventory data (physical, chemical, and biological) were collected from "key" water bodies within the boundaries of Richmond NBP. The key water bodies are those waters within park boundaries that are essential to the central cultural, historical or natural resources management themes of the parks or provide habitats to threatened or endangered plants and animals. Data were collected during the fall, winter, spring, and summer over a range of hydrologic conditions. Because of the drought conditions that persisted during the study period, variations in flow between seasons were less pronounced than during normal hydrologic conditions.

Virginia↗
USGS2012

Warming and increased precipitation frequency on the Colorado Plateau: Implications for biological soil crusts and soil processes

Aims Changes in temperature and precipitation are expected to influence ecosystem processes worldwide. Despite their globally large extent, few studies to date have examined the effects of climate change in desert ecosystems, where biological soil crusts are key nutrient cycling components. The goal of this work was to assess how increased temperature and frequency of summertime precipitation affect the contributions of crust organisms to soil processes. Methods With a combination of experimental 2°C warming and altered summer precipitation frequency applied over 2 years, we measured soil nutrient cycling and the structure and function of crust communities. Results We saw no change in crust cover, composition, or other measures of crust function in response to 2°C warming and no effects on any measure of soil chemistry. In contrast, crust cover and function responded to increased frequency of summer precipitation, shifting from moss to cyanobacteria-dominated crusts; however, in the short timeframe we measured, there was no accompanying change in soil chemistry. Total bacterial and fungal biomass was also reduced in watered plots, while the activity of two enzymes increased, indicating a functional change in the microbial community. Conclusions Taken together, our results highlight the limited effects of warming alone on biological soil crust communities and soil chemistry, but demonstrate the substantially larger effects of altered summertime precipitation.

Plant and Soil↗
USGS1995

Differing Eocene floral histories in southeastern North America and Western Europe: Influence of paleogeography

Pollen data show that in southeastern North America, the Eocene angiosperm flora attained its maximum relative diversity some 8 m.y. after the late early Eocene to earliest middle Eocene climatic maximum. Increasing diversity resulted in part from the flora's position on a large continent which allowed easy migration. In western Europe, the floral diversity began decreasing even before the climatic maximum. Paleogeography played large roles in this diversity decrease. In western Europe, terrestrial floras were on islands and peninsulas in the sea, so that the floras underwent increasing isolation and partial local extermination. Temperate plants generally did not migrate to western Europe, because of a lack of nearby uplands, lack of northern terrestrial source areas for these plants, and presence of the Turgai Straights barrier. The Eocene climate of western Europe cooled at least partly because of decreasing contact with the warm Tethys Seaway.

Historical Biology↗
USGS2022

Processes and mechanisms of coastal woody-plant mortality

Observations of woody plant mortality in coastal ecosystems are globally widespread, but the overarching processes and underlying mechanisms are poorly understood. This knowledge deficiency, combined with rapidly changing water levels, storm surges, atmospheric CO 2 , and vapor pressure deficit, creates large predictive uncertainty regarding how coastal ecosystems will respond to global change. Here we synthesize the literature on the mechanisms that underlie coastal woody-plant mortality, with the goal of producing a testable hypothesis framework. The key emergent mechanisms underlying mortality include hypoxic, osmotic, and ionic-driven reductions in whole-plant hydraulic conductance and photosynthesis that ultimately drive the coupled processes of hydraulic failure and carbon starvation. The relative importance of these processes in driving mortality, their order of progression, and their degree of coupling depends on the characteristics of the anomalous water exposure, on topographic effects, and on taxa-specific variation in traits and trait acclimation. Greater inundation exposure could accelerate mortality globally; however, the interaction of changing inundation exposure with elevated CO 2 , drought, and rising vapor pressure deficit could influence mortality likelihood. Models of coastal forests that incorporate the frequency and duration of inundation, the role of climatic drivers, and the processes of hydraulic failure and carbon starvation can yield improved estimates of inundation-induced woody-plant mortality.

Global Change Biology↗
USGS1987

Below-ground herbivory in natural communities: a review emphasizing fossorial animals

Roots, bulbs, corms, and other below-ground organs are almost universally present in communities containing vascular plants. A large and taxonomically diverse group of herbivores uses these below-ground plant parts as its sole or primary source of food. Important within this group are plant-parasitic nematodes and several fossorial taxa that affect plants through their soil-disturbing activities as well as by consuming plant tissue. The fossorial taxa are probably best exemplified by fossorial rodents, which are distributed on all continents except Australia. All other fossorial herbivores are insects. The impact of below-groud herbivory on individual plant fitness will depend upon the extent to which, and under what circumstances, the consumption of plant tissue disrupts one or more of the six functions of below-ground plant parts. Below-ground herbivory is probably more often chronic than acute. Indirect evidence suggests that plants have responded evolutionarily to herbivory by enhancing the functional capacities of below-ground organs, thus developing a degree of tolerance, and by producing compounds that serve as feeding deterrents. Many plant species respond to the removal of root tissues by increasing the growth rate of the remaining roots and initiating new roots. Soil movement and mixing by fossorial rodents infleuce the environment of other below-ground herbivores as well as that of plants and plant propagules. The relationships among the various groups of below-ground herbivores, and between below-ground herbivores and plants, are at best poorly known, yet they appear to have major roles in determining the structure and regulating the functioning of natural communities.

The Quarterly Review of Biology↗
USGS2018

Multi-year data from satellite- and ground-based sensors show details and scale matter in assessing climate’s effects on wetland surface water, amphibians, and landscape conditions

Long-term, interdisciplinary studies of relations between climate and ecological conditions on wetland-upland landscapes have been lacking, especially studies integrated across scales meaningful for adaptive resource management. We collected data in situ at individual wetlands, and via satellite for surrounding 4-km 2 landscape blocks, to assess relations between annual weather dynamics, snow duration, phenology, wetland surface-water availability, amphibian presence and calling activity, greenness, and evapotranspiration in four U.S. conservation areas from 2008 to 2012. Amid recent decades of relatively warm growing seasons, 2012 and 2010 were the first and second warmest seasons, respectively, dating back to 1895. Accordingly, we observed the earliest starts of springtime biological activity during those two years. In all years, early-season amphibians first called soon after daily mean air temperatures were ≥ 0°C and snow had mostly melted. Similarly, satellite-based indicators suggested seasonal leaf-out happened soon after snowmelt and temperature thresholds for plant growth had occurred. Daily fluctuations in weather and water levels were related to amphibian calling activity, including decoupling the timing of the onset of calling at the start of season from the onset of calling events later in the season. Within-season variation in temperature and precipitation also was related to vegetation greenness and evapotranspiration, but more at monthly and seasonal scales. Wetland water levels were moderately to strongly associated with precipitation and early or intermittent wetland drying likely reduced amphibian reproduction success in some years, even though Pseudacris crucifer occupied sites at consistently high levels. Notably, satellite-based indicators of landscape water availability did not suggest such consequential, intra-seasonal variability in wetland surface-water availability. Our cross-disciplinary data show how temperature and precipitation interacted to affect key ecological relations and outcomes on our study landscapes. These results demonstrate the value of multi-year studies and the importance of scale for understanding actual climate-related effects in these areas.

Minnesota, Wisconsin↗
USGS2007

Coastal Prairie Restoration Information System: Version 1 (Louisiana)

The Coastal Prairie Restoration Information System (CPR) is a Microsoft Access database that allows users to query and view data about Louisiana coastal prairie species. Less than 0.1% of Louisiana's coastal prairie vegetation remains in a relatively undisturbed condition. Encompassing as much as 1 million hectares of land, coastal prairie is a hybrid of coastal wetlands and tall grass prairie. Over 550 plant species have been identified in Louisiana's coastal prairies to date. Efforts to conserve and restore this endangered ecosystem are limited by the ability of workers to identify and access knowledge about this diverse group of plants. In this database, a variety of data are provided for each of 650 coastal prairie species in Louisiana. The database was developed at the U.S. Geological Survey National Wetlands Research Center by Larry Allain, with software development by Myra Silva. Additional funding was provided by the biology department of the University of Louisiana at Lafayette (ULL), the ULL Center for Environmental and Ecological Technology, and the National Science Foundation.

Data Series↗
USGS2021

The transformation of dryland rivers: The future of introduced tamarisk in the U.S.

Tamarix spp. (tamarisk or saltcedar), a shrub-like tree, was intentionally introduced to the U.S. from Asia in the mid-1800s. Tamarisk thrives in today’s human-altered streamside (riparian) habitats and can be found along wetlands, rivers, lakes, and streams across the western U.S. In 2001, a biological control agent, Diorhabda spp. (tamarisk leaf beetle), was released in six states, and has since spread throughout the southwestern U.S. and northern Mexico. Beetle defoliation of tamarisk has altered tamarisk’s water use and effectiveness as erosion control, as well as dynamics of native and nonnative plant and wildlife species. The full effects of the tamarisk leaf beetle on ecosystem function remain unknown. The U.S. Geological Survey collaborates with Tribal, State, Federal agencies, and other institutions to provide current, fact-based information on the effects of tamarisk and the tamarisk leaf beetle on managed resources, and provides sound science for conservation and restoration of riparian habitats in the southwestern U.S.

Fact Sheet↗
USGS2020

Biological assessment of a proposed vegetation management program to benefit tribes in eastern Oklahoma

Tribal communities may benefit from land management activities that enhance their use of resources on tribal lands. The Bureau of Indian Affairs is implementing a 5-year vegetation management program to provide support for projects that develop and use natural and cultural resources and improve opportunities for agricultural activities to benefit 20 Indian Tribes and Nations in the Eastern Oklahoma Region of the Bureau of Indian Affairs. The bureau is working with individual Tribes to identify project objectives and design treatments, which include prescribed burning, timber removal, thinning, and reduction of hazardous fuels. The total action area for the vegetation management program is estimated to be 236,575 acres, representing approximately 1 percent of the region. A biological assessment was prepared, in cooperation with the bureau and U.S. Fish and Wildlife Service, to evaluate the potential effects of the proposed vegetation management program on 22 federally threatened, endangered, and candidate species that may occur within the Eastern Oklahoma Region. The species evaluated included one plant, two insects, one reptile, five fresh-water mussels, four fishes, five birds, and four bats. Because the proposed treatments will be largely restricted to terrestrial systems, it is expected that there will be no adverse effects on the 15 species associated with aquatic habitats, provided that best management practices are followed. The proposed treatments may affect but are unlikely to adversely affect six of the primarily terrestrial species (the Papaipema eryngii [rattlesnake master borer], Picoides borealis [red-cockaded woodpecker], Myotis grisescens [gray bat], Myotis sodalis [Indiana bat], Myotis septentrionalis [northern long-eared bat], and Corynorhinus townsendii ingens [Ozark big-eared bat]), provided that best management practices are followed, including avoidance of critical habitat features. The only species likely to be adversely affected by the proposed treatments is Nicrophorus americanus (American burying beetle) as a consequence of short-term disturbances to soils and vegetation. Most adverse effects of the treatments (such as soil compaction and decreased cover in the forest understory) are expected to be short term (habitat will recover or be restored within 5 years of treatments). Less than 1 percent of the action area is expected to result in long-term adverse effects to the American burying beetle as a result of permanent cover changes that persist for more than 5 years. It is expected that the primary treatments will be largely beneficial to the American burying beetle population in the region by reducing the risk of high-severity fires and expansion of invasive woody shrubs, such as Juniperus virginiana (eastern redcedar) within potential beetle habitat and the surrounding landscape. Overall, the proposed management program is expected to provide long-term benefits to American burying beetle habitat across 91 percent of the action area.

Oklahoma↗
USGS2011

Structural and functional effects of herbicides on non-target organisms in aquatic ecosystems with an emphasis on atrazine

Herbicide use has increased dramatically around the world over the past 6 decades (Gianessi and Reigner, 2007). Few herbicides were in use in the 1950s. However, by 2001 approximately 1.14 billion kilograms of herbicides were applied globally for the control of undesireable vegetation in agricultural, silvicultural, lawncare, aquacultural, and irrigation/recreational water management activities (Kiely et al., 2004). Twenty-eight percent of the total mass of herbicides is applied in the United States, with the remaining 72 percent being applied elsewhere around the globe (Kiely et al., 2004). Herbicides represent 36% of global pesticide use, followed by insecticides (25%), fungicides (10%) and other chemical classes (Kiely et al., 2004). Agricultural production accounts for approximately 90% of herbicide use in the U.S. (Kiely et al., 2004). Gianessi and Reigner (2007) indicated that herbicides are routinely used on more than 90% of the area designated for large commercial crops including corn, soybeans, cotton, sugar beets, peanuts, and rice. Increased farm mechanization, technological advancements in production of inexpensive sources of inorganic nitrogen fertilizer (e.g., anhydrous ammonia), and conversion of forest, grassland, and wetland habitats to cropland has led to a tremendous increase in global food production over the past half-century. Herbicides have augmented advances in large-scale agricultural systems and have largely replaced mechanical and hand-weeding control mechanisms (Gianessi and Reigner, 2007). The wide-spread use of herbicides in agriculture has resulted in frequent chemical detections in surface and groundwaters (Gilliom, 2007). The majority of herbicides used are highly water soluble and are therefore prone to runoff from terrestrial environments. In additon, spray drift and atmospheric deposition can contribute to herbicide contamination of aquatic environments. Lastly, selected herbicides are deliberately applied to aquatic environments for controlling nuisance aquatic vegetation. Although aquatic herbicide exposure has been widely documented, these exposures are not necessarily related to adverse non-target ecological effects on natural communities in aquatic environments. This chapter evaluates the potential for effects of herbicides on the structure and function of aquatic envrionments at the population, community, and ecosystem levels of biological organization. In this manuscript I examine several critical aspects of the subject matter area: primary herbicides in use and chemical modes of action; the regulatory process used for registration and risk assessment of herbicides; data regarding non-target risks and the relative sensitivity of aquatic plants, inveretebrates, and fish to herbicides; and emerging areas of science regarding the potential for endocrine-disrupting effects of herbicides on aquatic vertebrates. Much of the focus of this paper is on atrazine due to the extensive database which exists regarding its fate and effects.

Book chapter↗
USGS2012

Tropical forest carbon balance in a warmer world: a critical review spanning microbial- to ecosystem-scale processes

Tropical forests play a major role in regulating global carbon (C) fluxes and stocks, and even small changes to C cycling in this productive biome could dramatically affect atmospheric carbon dioxide (CO 2 ) concentrations. Temperature is expected to increase over all land surfaces in the future, yet we have a surprisingly poor understanding of how tropical forests will respond to this significant climatic change. Here we present a contemporary synthesis of the existing data and what they suggest about how tropical forests will respond to increasing temperatures. Our goals were to: (i) determine whether there is enough evidence to support the conclusion that increased temperature will affect tropical forest C balance; (ii) if there is sufficient evidence, determine what direction this effect will take; and, (iii) establish what steps should to be taken to resolve the uncertainties surrounding tropical forest responses to increasing temperatures. We approach these questions from a mass-balance perspective and therefore focus primarily on the effects of temperature on inputs and outputs of C, spanning microbial- to ecosystem-scale responses. We found that, while there is the strong potential for temperature to affect processes related to C cycling and storage in tropical forests, a notable lack of data combined with the physical, biological and chemical diversity of the forests themselves make it difficult to resolve this issue with certainty. We suggest a variety of experimental approaches that could help elucidate how tropical forests will respond to warming, including large-scale in situ manipulation experiments, longer term field experiments, the incorporation of a range of scales in the investigation of warming effects (both spatial and temporal), as well as the inclusion of a diversity of tropical forest sites. Finally, we highlight areas of tropical forest research where notably few data are available, including temperature effects on: nutrient cycling, heterotrophic versus autotrophic respiration, thermal acclimation versus substrate limitation of plant and microbial communities, below-ground C allocation, species composition (plant and microbial), and the hydraulic architecture of roots. Whether or not tropical forests will become a source or a sink of C in a warmer world remains highly uncertain. Given the importance of these ecosystems to the global C budget, resolving this uncertainty is a primary research priority.

Biological Reviews↗
USGS2020

Insights into mercury source identification and bioaccumulation using stable isotope approaches in the Hannibal Pool of the Ohio River

Mercury contamination in river systems due to historic and current Hg releases is a persistent concern for both wildlife and human health. In larger rivers, like the Ohio River, USA, it is difficult to directly link Hg discharges to bioaccumulation due to the existence of multiple industrial Hg sources as well as the varied dietary and migratory habits of biota. To better understand how industrial effluent influences the cycling and bioaccumulation of Hg within the Ohio River, Hg stable isotope analysis was applied to various nonbiological and biological media. High Hg concentrations in suspended particulate matter suggest this vector was the largest contributor of Hg to the water column, and distinct Hg source signatures were observed in effluent particulates from different industrial processes, such as chlor‐alkali activity (δ 202 Hg = −0.52‰) and coal power plant discharge (δ 202 Hg = −1.39‰). Despite this distinction, average sediments (δ 202 Hg = −1.00 ± 0.23‰) showed intermediate isotopic signatures that suggest the accumulation of a mixed Hg source driven by multiple industrial discharges. Biota in the system were shown to have a conserved range of δ 202 Hg and estimation approaches related these signatures back to particulate matter within Hannibal Pool. Mussels were found to conserve Hg isotopes signatures independently of food web drivers and served as ideal water column indicators of bioaccumulated Hg sources. This study highlights the complexity of Hg cycling within an industrialized river and shows that an isotope tracer approach can provide insight to water column sources of Hg. Integr Environ Assess Manag 2021;17:233−242. Published 2020. This article is a US Government work and is in the public domain in the USA.

Ohio↗
USGS2012

Experimental determination of soil heat storage for the simulation of heat transport in a coastal wetland

Two physical experiments were developed to better define the thermal interaction of wetland water and the underlying soil layer. This information is important to numerical models of flow and heat transport that have been developed to support biological studies in the South Florida coastal wetland areas. The experimental apparatus consists of two 1.32 m diameter by 0.99 m tall, trailer-mounted, well-insulated tanks filled with soil and water. A peat–sand–soil mixture was used to represent the wetland soil, and artificial plants were used as a surrogate for emergent wetland vegetation based on size and density observed in the field. The tanks are instrumented with thermocouples to measure vertical and horizontal temperature variations and were placed in an outdoor environment subject to solar radiation, wind, and other factors affecting the heat transfer. Instruments also measure solar radiation, relative humidity, and wind speed. Tests indicate that heat transfer through the sides and bottoms of the tanks is negligible, so the experiments represent vertical heat transfer effects only. The temperature fluctuations measured in the vertical profile through the soil and water are used to calibrate a one-dimensional heat-transport model. The model was used to calculate the thermal conductivity of the soil. Additionally, the model was used to calculate the total heat stored in the soil. This information was then used in a lumped parameter model to calculate an effective depth of soil which provides the appropriate heat storage to be combined with the heat storage in the water column. An effective depth, in the model, of 5.1 cm of wetland soil represents the heat storage needed to match the data taken in the tank containing 55.9 cm of peat/sand/soil mix. The artificial low-density laboratory sawgrass reduced the solar energy absorbed by the 35.6 cm of water and 55.9 cm of soil at midday by less than 5%. The maximum heat transfer into the underlying peat–sand–soil mix lags behind maximum solar radiation by approximately 2 h. A slightly longer temperature lag was observed between the maximum solar radiation and maximum water temperature both with and without soil.

Journal of Hydrology↗
USGS2003

Molecular and isotopic tracers used to examine sources of organic matter and its incorporation into the food webs of San Francisco Bay

Multiple indicators (Chl a , C : N ratios, [ &delta; 13 C]POC, and two classes of lipid biomarker compounds- sterols and phospholipid ester-linked fatty acids) were used to evaluate spatial and temporal variations in the origin of particulate organic matter (POM) in the San Francisco Bay (SFB) estuary. Comparisons were made between the northern and southern subestuaries of SFB, as well as along the salinity gradient of northern SFB. Two sample types were collected-seston, which was used to characterize the bulk POM, and tissues of the suspension-feeding bivalve Potamocorbula amurensis -in order to evaluate the assimilable portion of the POM. Samples were collected around biological and physical events (phytoplankton blooms and freshwater inflow) thought to be the primary mechanisms controlling temporal variability in organic matter sources. Seston samples indicate that phytoplankton sources of POM are important throughout the entire SFB system, with additional inputs of organic matter from bacterial and terrestrial vascular plant sources delivered to the northern region. Analysis of biomarker compounds in P. amurensis tissues indicates that phytoplankton supply a large fraction of the assimilable carbon to clams throughout SFB, although isotopic analysis of clam tissues suggests that the origin of this reactive carbon varies spatially and that freshwater algae are an important source of reactive organic matter to clams living in northern SFB.

California↗
USGS2024

A review of the ecology and conservation biology of Sali (Micronesian Starling, Aplonis opaca guami) on Guam

The accidental introduction of the Brown Treesnake (BTS, Boiga irregularis ) to Guam following World War II led to the extinction, extirpation, or severe decline of most of Guam’s native avifauna. One forest bird species that managed to persist is the cavity-nesting Såli (Micronesian Starling, Aplonis opaca guami ), a once-ubiquitous native omnivore whose current Guam distribution is restricted primarily to urbanized areas in the northern half of the island, with a second much smaller population on Cocos Island off southern Guam. Såli on Guam breed year-round and are habitat generalists with large home ranges. Besides arthropods and small vertebrates, they consume fruit from a wide range of native and introduced plant species and are key seed dispersers within the local ecosystem. Såli on Guam suffer extremely high post-fledging mortality due to predation by BTS and cats, leading to a population age structure strongly skewed towards adult birds. Other threats include habitat loss and degradation, extreme weather events, and sea level rise. Key management activities aimed at restoring this species include predator control, while non-native ungulate removal and vegetation management may be undertaken to support broader ecological recovery. This species account on Såli provides a review of the literature on this species, synthesizing information on habitat use, life history, and demographics to provide a biological foundation for future recovery efforts.

Micronesica↗