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Results for “Subterranean Biology”

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9 recordsLinked to original sources
USGS2021

Refining sampling protocols for cavefishes and cave crayfishes to account for environmental variation

Subterranean habitats support a diverse array of organisms and represent imperative habitats in many conservation strategies; however, subterranean habitats are one of the most difficult environments to study. Accounting for variable sampling detection is necessary to properly evaluate conservation options for rare species such as karst and other groundwater organisms. New sampling methods, such as environmental DNA, show promise to improve stygobiont detection; however, sources of sampling bias are poorly understood. Therefore, our objective was to determine factors affecting detection probability of both visual and environmental DNA (eDNA) surveys for cavefishes and cave crayfishes. We sampled 40 sites across the Ozark Highlands ecoregion in Arkansas, Missouri, and Oklahoma, USA using visual and eDNA surveys. We used occupancy modeling to estimate the detection probability of the two taxa using both survey methods under varying environmental conditions. Overall, eDNA sampling resulted in higher detection probability for cavefishes when compared to visual surveys, whereas visual surveys typically had higher detection probability for cave crayfishes. Greater water volume at the time of sampling was related to lower detection using visual surveys for both taxa, but there was no relationship between eDNA detection and water volume. Detection probability of both cavefishes and crayfishes was higher using visual surveys when sampling units were classified by coarse rather than fine substrate, whereas detection of cave crayfishes surveyed using eDNA was higher in coarse substrate environments. Detection of cavefishes and cave crayfishes was higher via eDNA sampling when water was flowing, but similar sampling conditions resulted in lower detection using visual surveys. Our results indicate detection should be considered when sampling stygobionts even if using traditional visual surveys. Environmental DNA is a useful tool; however, the limitations we identified indicate eDNA for these taxa currently are not adequate to replace traditional surveys in subterranean environments.

Arkansas, Missouri, Oklahoma↗
USGS1991

Freshwater molluscs as indicators of bioavailability and toxicity of metals in surface-water systems

During the past several decades, studies from a variety of locations have demonstrated widespread occurrence of metals in surface waters at concentrations significantly higher than background levels. Elevated concentrations are not limited to certain water types or polluted areas; they appear in all types of systems and in all geographic areas. It is clear that metals enter the aquatic systems from diverse sources, both point and nonpoint, and they can be readily transported from one system to another. Transport routes include atmospheric, terrestrial, subterranean, aquatic, and biological pathways (Elder 1988; Salomons and Forstner 1984).

Book chapter↗
USGS2010

Biological pathways of exposure and ecotoxicity values for uranium and associated radionuclides: Chapter D in Hydrological, geological, and biological site characterization of breccia pipe uranium deposits in Northern Arizona

This chapter compiles available chemical and radiation toxicity information for plants and animals from the scientific literature on naturally occurring uranium and associated radionuclides. Specifically, chemical and radiation hazards associated with radionuclides in the uranium decay series including uranium, thallium, thorium, bismuth, radium, radon, protactinium, polonium, actinium, and francium were the focus of the literature compilation. In addition, exposure pathways and a food web specific to the segregation areas were developed. Major biological exposure pathways considered were ingestion, inhalation, absorption, and bioaccumulation, and biota categories included microbes, invertebrates, plants, fishes, amphibians, reptiles, birds, and mammals. These data were developed for incorporation into a risk assessment to be conducted as part of an environmental impact statement for the Bureau of Land Management, which would identify representative plants and animals and their relative sensitivities to exposure of uranium and associated radionuclides. This chapter provides pertinent information to aid in the development of such an ecological risk assessment but does not estimate or derive guidance thresholds for radionuclides associated with uranium. Previous studies have not attempted to quantify the risks to biota caused directly by the chemical or radiation releases at uranium mining sites, although some information is available for uranium mill tailings and uranium mine closure activities. Research into the biological impacts of uranium exposure is strongly biased towards human health and exposure related to enriched or depleted uranium associated with the nuclear energy industry rather than naturally occurring uranium associated with uranium mining. Nevertheless, studies have reported that uranium and other radionuclides can affect the survival, growth, and reproduction of plants and animals. Exposure to chemical and radiation hazards is influenced by a plant’s or an animal’s life history and surrounding environment. Various species of plants, invertebrates, fishes, amphibians, reptiles, birds, and mammals found in the segregation areas that are considered species of concern by State and Federal agencies were included in the development of the site-specific food web. The utilization of subterranean habitats (burrows in uranium-rich areas, burrows in waste rock piles or reclaimed mining areas, mine tunnels) in the seasonally variable but consistently hot, arid environment is of particular concern in the segregation areas. Certain species of reptiles, amphibians, birds, and mammals in the segregation areas spend significant amounts of time in burrows where they can inhale or ingest uranium and other radionuclides through digging, eating, preening, and hibernating. Herbivores may also be exposed though the ingestion of radionuclides that have been aerially deposited on vegetation. Measured tissues concentrations of uranium and other radionuclides are not available for any species of concern in the segregation areas. The sensitivity of these animals to uranium exposure is unknown based on the existing scientific literature, and species-specific uranium presumptive effects levels were only available for two endangered fish species known to inhabit the segregation areas. Overall, the chemical toxicity data available for biological receptors of concern were limited, although chemical and radiation toxicity guidance values are available from several sources. However, caution should be used when directly applying these values to northern Arizona given the unique habitat and life history strategies of biological receptors in the segregation areas and the fact that some guidance values are based on models rather than empirical (laboratory or field) data. No chemical toxicity information based on empirical data is available for reptiles, birds, or wild mammals; therefore, the risks associated with uranium and other radionuclides are unknown for these biota.

Arizona↗
USGS1999

Stream and aquifer biology of south-central Texas — A literature review, 1973-97

This report summarizes in table format 32 aquatic vertebrate (primarily fish), 54 aquatic invertebrate, and 13 aquatic plant studies available for the area of the South-Central Texas study unit of the U.S. Geological Survey National Water-Quality Assessment. The studies, published mostly during 1973–97, pertain to the Guadalupe, San Antonio, and Nueces River Basins, the San Antonio-Nueces and Nueces-Rio Grande Coastal Basins, and the Edwards aquifer where it underlies the upper parts of the three river basins. The biology of the study-unit streams is determined mostly by the characteristics of the ecoregions they transect—the Edwards Plateau, Texas Blackland Prairies, East Central Texas Plains, Western Gulf Coastal Plain, and Southern Texas Plains. About 20 percent of the previous fish and invertebrate studies and about 75 percent of the aquatic plant surveys have centered on Comal Springs in Comal County and San Marcos Springs in Hays County. Although several important studies are available for the San Antonio region, documentation of aquatic biology for the remainder of the study unit is relatively sparse. The streams in the study unit, particularly in the Edwards Plateau, support three dominant biological groups—fish, aquatic invertebrates, and plants. Potential threats to these organisms include impoundments and flood-control projects, siltation from erosion, ground-water pumping, recreational activities, wastewater discharge, and introduction of non-native species. More than 30 non-native fish, invertebrate, and plant species have been introduced into the region. Of the 19 aquatic species Federally listed as endangered or threatened in Texas, 8 are associated with springs and spring runs in the study unit. All of the endangered species in the study unit are associated with springs and spring runs. A large number of endemic species in the study unit are associated with subterranean aquatic ecosystems, most likely a consequence of the unique proximity of the varied topographic and hydrologic conditions of the area and of the geological development of the Edwards aquifer. Ninety-one endemics, including 44 species found solely underground, are associated with the aquatic ecosystems (including springs) of the Edwards aquifer.

Texas↗
USGS2022

Mechanisms and magnitude of dissolved silica release from a New England salt marsh

Salt marshes are sites of silica (SiO 2 ) cycling and export to adjacent coastal systems, where silica availability can exert an important control over coastal marine primary productivity. Mineral weathering and biologic fixation concentrate silica in these systems; however, the relative contributions of geologic versus biogenic silica dissolution to this export are not known. We collected water samples from the tidal creek of a relatively undisturbed New England (USA) salt marsh over 13 tidal cycles in spring, summer, and fall 2014–2016 to determine patterns of dissolved silica (DSi) concentration in the water entering and leaving the marsh. DSi concentrations in the tidal creek peaked in the summer and were at a minimum in the fall. Additionally, we analyzed DSi concentrations and Ge/Si ratios in marsh porewater and groundwater samples as a tracer of DSi origin. Ge/Si ratios in the porewater, subterranean estuary, and fresh groundwater averaged 6.3 ± 0.31 µmol/mol, which is consistent with production via silicate weathering rather than biogenic silica dissolution. These results highlight a previously unstudied role marsh sediment plays in coastal biogeochemistry by supplying DSi to coastal ecosystems. This marsh exported 1170 mmol DSi m −2 year −1 , 85% of which originated from porewater exchange, with minor contributions from brackish groundwater discharge from the subterranean estuary. Examining these values in the context of the other known DSi inputs indicates that coastal marshes provide ~ 75% of the annual silica inputs into the adjacent estuary, Waquoit Bay.

Massachusetts↗
USGS2019

Microbial assemblages reflect environmental heterogeneity in alpine streams

Alpine streams are dynamic habitats harboring substantial biodiversity across small spatial extents. The diversity of alpine stream biota is largely reflective of environmental heterogeneity stemming from varying hydrological sources. Globally, alpine stream diversity is under threat as meltwater sources recede and stream conditions become increasingly homogeneous. Much attention has been devoted to macroinvertebrate diversity in alpine headwaters, yet to fully understand the breadth of climate change threats, a more thorough accounting of microbial diversity is needed. We characterized microbial diversity (specifically Bacteria and Archaea) of 13 streams in two disjunct Rocky Mountain subranges through 16S rRNA gene sequencing. Our study encompassed the spectrum of alpine stream sources (glaciers, snowfields, subterranean ice, and groundwater) and three microhabitats (ice, biofilms, and streamwater). We observed no difference in regional (γ) diversity between subranges but substantial differences in diversity among (β) stream types and microhabitats. Within‐stream (α) diversity was highest in groundwater‐fed springs, lowest in glacier‐fed streams, and positively correlated with water temperature for both streamwater and biofilm assemblages. We identified an underappreciated alpine stream type—the icy seep—that are fed by subterranean ice, exhibit cold temperatures (summer mean <2°C), moderate bed stability, and relatively high conductivity. Icy seeps will likely be important for combatting biodiversity losses as they contain similar microbial assemblages to streams fed by surface ice yet may be buffered against climate change by insulating debris cover. Our results show that the patterns of microbial diversity support an ominous trend for alpine stream biodiversity; as meltwater sources decline, stream communities will become more diverse locally, but regional diversity will be lost. Icy seeps, however, represent a source of optimism for the future of biodiversity in these imperiled ecosystems.

Montana↗
USGS2010

Unusual subterranean aggregations of the California Giant Salamander, Dicamptodon ensatus

Larval Dicamptodon are one of the most abundant vertebrates in headwater streams in the Pacific Northwest. Their numbers and biomass can exceed those of all other amphibians, and of salmonid fishes. By contrast, metamorphosed Dicamptodon are only found infrequently, usually during formal surveys using pitfall traps, cover boards, or time constrained surveys However, we found two aggregations (23 and 27 individuals) of metamorphosed Dicamptodon ensatus during a culvert removal project at Point Reyes National Seashore, California. Furthermore, we found an additional 23 terrestrial D. ensatus in terrestrial habitat adjacent to the culverts. We did not expect these aggregations because metamorphosed individuals are so rarely encountered, and aggregations are likely to increase competition and predation in a species known to feed regularly on vertebrate prey. Deteriorating culverts might provide an unusually high-quality habitat that leads to aggregations such as we describe. Our observations may provide insight into the natural haunts of D. ensatus—underground burrows or caverns—and if so, then aggregations may be normal, but rarely seen.

Herpetological Conservation and Biology↗
USGS2011

Microhabitat associations of a semi-terrestrial fish, Kryptolebias marmoratus (Poey 1880) in a mosquito-ditched mangrove forest, west-central Florida

Mangrove rivulus ( Kryptolebias marmoratus ) is one of the few species of fish that is semi-terrestrial and able to use exposed intertidal and potentially supratidal habitats for prolonged periods of time. Based on previous work demonstrating frequent use of subterranean crab burrows as well as damp leaf litter and logs, we examined the microhabitat associations of rivulus in a mosquito-ditched mangrove forest on the Gulf coast of Florida near the northern limit of its distribution. We captured 161 rivulus on 20 dates between late April and mid-December 2007 using trench traps. Fish ranged in size from 7 to 35 mm SL. Peak abundance in mid-summer coincided with recruitment of a new year-class. The three study sites occurred within 0.5 km of one another, and experienced similar water temperatures and salinities. Nevertheless, they differed in their degree of tidal inundation, standing stock of leaf litter, and density of entrances to fiddler crab burrows. We consistently observed the highest mean catches of rivulus away from permanent subtidal waters of mosquito ditches, at intermediate relative elevations, and where leaf litter was locally abundant. Density of entrances to crab burrows was apparently unrelated to rivulus distribution or abundance in these forests.

Florida↗
USGS2021

Using expert knowledge to support Endangered Species Act decision‐making for data‐deficient species

Many questions relevant to conservation decision making are characterized by extreme uncertainty due to lack of empirical data and complexity of the underlying ecological processes, leading to a rapid increase in the use of structured protocols to elicit expert knowledge. Published ecological applications often employ a modified Delphi method, where experts provide judgments anonymously and mathematical aggregation techniques are used to combine judgments. The Sheffield Elicitation Framework (SHELF) differs in its behavioral approach to synthesizing individual judgments into a fully specified probability distribution for an unknown quantity. This study demonstrates the remote use of the SHELF protocol for an extinction risk assessment of three subterranean aquatic species petitioned for listing under the US Endangered Species Act. Experts were provided an empirical threat assessment for each known locality using video conferencing and asked for judgments on the probability of population persistence over four generations using online submission forms and R‐shiny apps available through the SHELF package. Despite large uncertainty for all populations, results reveal key differences between species’ risk of extirpation based on spatial variation in dominant threats, local land use and management practices, and microhabitat use. The resulting probability distributions provide decision makers with a full picture of uncertainty that is consistent with the probabilistic nature of risk assessments, and discussions during the behavioral aggregation stage clearly document dominant threats (e.g., development, timber harvest, animal agriculture, and cave visitation) and their interactions with local cave geology and species’ habitat preferences. Our virtual implementation of the SHELF protocol demonstrates the flexibility of this approach for conservation applications operating on budgets and timelines that can limit in‐person meetings of geographically dispersed experts.

Conservation Biology↗