Effects of geothermal effluents on aquatic ecosystems

The use of geothermal energy for electrical generation and a variety of other purposes requires the handling and disposal of large volumes of geothermal fluids. These fluids contain constituents such as dissolved ammonia, hydrogen sulfide gas, and trace elements. Facilities in the United States are not expected to routinely discharge large volumes of toxic geothermal fluids. However, chronic effects on aquatic ecosystems are possible at concentrations where acute toxicity would be neither expected nor observed. Also, some trace elements may accumulate to hazardous levels in ecosystems, even when released at nontoxic concentrations.     

WATER LOSSES ALONG A REACH OF THE PECOS RIVER IN NEW MEXICO1

ABSTRACT: A reach of the Pecos River, located in eastern New Mexico, was examined to evaluate losses of river flows due to evaporation, seepage, and transpiration. An accurate assessment of the water losses along this reach is critical for determining how water rights are adjudicated for water users in the Pecos basin and interstate compact accounting. Water losses significantly impact flows through critical habitat for species protected under the Endangered Species Act. Daily losses of river flows were analyzed for the study reach that extends from immediately below the Pecos River confluence with Taiban Creek to the United States Geological Survey (USGS) gage near Acme. The analysis was completed with consideration for other processes including flood wave travel times and attenuation along with stream bank storage and returns. The analysis was completed using daily stream flow data from USGS gages located along the study reach. Empirical seasonal functions were developed to relate flow loss to the flow rate in the river. The functions were ultimately developed to provide a method for comparing the effects of different river flows on the available water supply.     

Preservation of ancient DNA in thermally damaged archaeological bone

Evolutionary biologists are increasingly relying on ancient DNA from archaeological animal bones to study processes such as domestication and population dispersals. As many animal bones found on archaeological sites are likely to have been cooked, the potential for DNA preservation must be carefully considered to maximise the chance of amplification success. Here, we assess the preservation of mitochondrial DNA in a medieval cattle bone assemblage from Coppergate, York, UK. These bones have variable degrees of thermal alterations to bone collagen fibrils, indicative of cooking. Our results show that DNA preservation is not reliant on the presence of intact collagen fibrils. In fact, a greater number of template molecules could be extracted from bones with damaged collagen. We conclude that moderate heating of bone may enhance the retention of DNA fragments. Our results also indicate that ancient DNA preservation is highly variable, even within a relatively recent assemblage from contexts conducive to organic preservation, and that diagenetic parameters based on protein diagenesis are not always useful for predicting ancient DNA survival.     

Intensive fishing of marine consumers causes a dramatic shift in the benthic habitat on temperate rocky reefs

Intensive fishing can cause dramatic, long-lasting shifts in benthic habitat. This study used three approaches to test whether overharvesting of blacklip abalone (Haliotis rubra) can cause a shift in benthic habitat to a configuration that is unsuitable for abalone, on the east coast of Tasmania, Australia. After 18 months of removing abalone from rocks, encrusting red algae (ERA) became overgrown by filamentous and foliose algae, sessile invertebrates and accumulated sediment. The differences in the community composition between locations, sites nested within locations and rocks were minor. Throughout the study, abalone were largely associated with areas of rock covered in ERA but avoided other habitats. A transplant experiment demonstrated that abalone preferred areas of rock covered in ERA but move away from overgrown rocks. These results suggest overharvesting of abalone results in a shift to benthic habitat poorly preferred by abalone. This could form a positive feedback loop that limits recovery of abalone populations and ERA.     

Unified methodology for site-characterization and sampling of highway runoff

Hydrology, roadway traffic conditions, and atmospheric deposition are three essential data categories for the planning and implementation of highway-runoff monitoring and characterization programs. Causal variables pertaining to each data category could be site specific but have been shown to correlate with runoff pollutant loads. These data categories were combined to derive statistical relationships for characterization and prioritization of the respective pollutant loads at highway runoff sites. Storm runoff data of total suspended solids (TSS), total dissolved solid (TDS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) collected from three highway sites in Charlotte, North Carolina, USA, were used to illustrate the development of site-specific highway-runoff pollutant loading models. This unified methodology provides a basis for initial assessment of the pollutant-constituent loads from highway runoff using hydrologic component variables. Improved reliability is achievable when additional traffic and/or atmospheric component variables are incorporated into the basic hydrologic regression model. In addition, operational guidance is suggested for implementing highway-runoff monitoring programs that are subject to sampling and resources constraints.     

COVID-19: how a self-monitoring checklist can empower early intervention and slow disease progression

The SARS-CoV-2 novel coronavirus pandemic has revealed many scientific, social, and institutional challenges required to improve the health and wellbeing of individuals stricken by this disease. While organizations and governing institutions have risen to the task to concurrently prepare for and respond to this pandemic under conditions of high uncertainty and extreme pressure, another important aspect of this viral infection deserves attention and is not being fully considered, that is early intervention strategies and structured tools for individuals who test positive for the virus and begin developing symptoms. For those whose infection is progressing, we describe the potential benefits of a self-monitoring tool for use in combination with physician directed early medical interventions to slow COVID-19 progression.

     

Spatial and temporal changes in group dynamics and range use enable anti-predator responses in African buffalo

The reintroduction of large predators provides a framework to investigate responses by prey species to predators. Considerable research has been directed at the impact that reintroduced wolves (Canis lupus) have on cervids, and to a lesser degree, bovids, in northern temperate regions. Generally, these impacts alter feeding, activity, and ranging behavior, or combinations of these. However, there are few studies on the response of African bovids to reintroduced predators, and thus, there is limited data to compare responses by tropical and temperate ungulates to predator reintroductions. Using the reintroduction of lion (Panthera leo) into the Addo Elephant National Park (AENP) Main Camp Section, South Africa, we show that Cape buffalo (Syncerus caffer) responses differ from northern temperate ungulates. Following lion reintroduction, buffalo herds amalgamated into larger, more defendable units; this corresponded with an increase in the survival of juvenile buffalo. Current habitat preference of buffalo breeding herds is for open habitats, especially during the night and morning, when lion are active. The increase in group size and habitat preference countered initial high levels of predation on juvenile buffalo, resulting in a return in the proportion of juveniles in breeding herds to pre-lion levels. Our results show that buffalo responses to reintroduced large predators in southern Africa differ to those of northern temperate bovids or cervids in the face of wolf predation. We predict that the nature of the prey response to predator reintroduction is likely to reflect the trade-off between the predator selection and hunting strategy of predators against the life history and foraging strategies of each prey species.     

A test of reproductive power in snakes

Reproductive power is a contentious concept among ecologists, and the model has been criticized on theoretical and empirical grounds. Despite these criticisms, the model has successfully predicted the modal (optimal) size in three large taxonomic groups and the shape of the body size distribution in two of these groups. We tested the reproductive power model on snakes, a group that differs markedly in physiology, foraging ecology, and body shape from the endothermic groups upon which the model was derived. Using detailed field data from the published literature, snake-specific constants associated with reproductive power were determined using allometric relationships of energy invested annually in egg production and population productivity. The resultant model accurately predicted the mode and left side of the size distribution for snakes but failed to predict the right side of that distribution. If the model correctly describes what is possible in snakes, observed size diversity is limited, especially in the largest size classes.     

Mimics and magnets: the importance of color and ecological facilitation in floral deception

Plants that lack floral rewards can attract pollinators if they share attractive floral signals with rewarding plants. These deceptive plants should benefit from flowering in close proximity to such rewarding plants, because pollinators are locally conditioned on floral signals of the rewarding plants (mimic effect) and because pollinators are more abundant close to rewarding plants (magnet effect). We tested these ideas using the non-rewarding South African plant Eulophia zeyheriana (Orchidaceae) as a study system. Field observations revealed that E. zeyheriana is pollinated solely by solitary bees belonging to a single species of Lipotriches (Halictidae) that appears to be closely associated with the flowers of Wahlenbergia cuspidata (Campanulaceae), a rewarding plant with which the orchid is often sympatric. The pale blue color of the flowers of E. zeyheriana differs strongly from flowers of its congeners, but is very similar to that of flowers of W. cuspidata. Analysis of spectral reflectance patterns using a bee vision model showed that bees are unlikely to be able to distinguish the two species in terms of flower color. A UV-absorbing sunscreen was applied to the flowers of the orchid in order to alter their color, and this resulted in a significant decline in pollinator visits, thus indicating the importance of flower color for attraction of Lipotriches bees. Pollination success in the orchid was strongly affected by proximity to patches of W. cuspidata. This was evident from one of two surveys of natural populations of the orchid, as well as experiments in which we translocated inflorescences of the orchid either into patches of W. cuspidata or 40 m outside such patches. Flower color and location of E. zeyheriana plants relative to rewarding magnet patches are therefore key components of the exploitation by this orchid of the relationship between W. cuspidata and Lipotriches bee pollinators.     

Foodweb modeling for polychlorinated biphenyls (PCBs) in the Twelvemile Creek Arm of Lake Hartwell,South Carolina,USA

PCBs from the Sangamo-Weston Superfund Site near Clemson, South Carolina, USA, were released into the Twelvemile Creek Arm of Lake Hartwell until the early 1990s. Monitoring data have shown that while PCB concentration in sediments declined since 1995, PCB concentrations in fish have remained elevated, e.g., largemouth bass (Micropterus salmoides) concentrations have ranged from 5 to 10 ppm. The EPA aquatic ecosystem model AQUATOX was applied to this system to better characterize foodweb dynamics that lead to biomagnification of PCBs. The model was calibrated with observed fish biomass data. Simulated PCB loading over a 12-year period provided a reasonable fit to observed PCB data in fish. The model demonstrated that contaminated labile detritus loaded to the system was incorporated into the foodweb rather than deposited, thereby maintaining the PCB concentrations in fish while concentrations in the sediment declined. A dominant PCB pathway was from detritus to daphnia to shad to largemouth bass. Fish PCB concentrations showed moderate sensitivity to toxicant parameters; model runs incorporating uncertainty in these parameters predicted recovery (<2 ppm PCB) for all species in the range of years from 2008 to 2013. The high sensitivity of the model to parameters related to growth strongly affected PCB concentrations in fish and should be considered in future AQUATOX applications.