Invertebrate community responses to recreational clam digging

Marine reserves can help in maintaining biodiversity and potentially be useful as a fishery management tool by removing human-mediated impacts. Intertidal, soft-sediment habitats can often support robust recreational and commercial shellfish harvests, especially for clams; however, there is limited research on the effects of reserves in these habitats. In San Juan County, Washington, several reserves prohibit recreational clam digging. We examined the effects of these reserves on infaunal community composition through comparison with non-reserve beaches during a 6-week period. Clam abundance, overall species richness and total polychaete family richness were greater on reserve beaches compared to non-reserve beaches. Additionally, an experiment within a reserve demonstrated negative impacts of digging on non-target infauna. These effects probably resulted from local disruption and disturbance of the sediment habitat and not from increased post-digging predation, which was controlled. Intertidal reserves could play an important role in sustaining local and potentially regional biodiversity.     

Is There a Risk for Introducing Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Through the Legal Importation of Pork?

Since the appearance of porcine reproductive and respiratory syndrome virus (PRRSV) in the late 1980s, the virus has become endemic throughout the world, with only the countries of Sweden, Switzerland, Finland, Norway, Australia, and New Zealand historically free of PRRS virus. Biosecurity is maintained largely through restrictions on the importation of pigs and semen. The risk for a PRRSV outbreak via the legal importation of fresh/chilled/frozen pork from PRRSV-positive countries remains controversial. However, examination of the historical record shows that countries retained a PRRSV-negative status during the importation of more than 500,000 tons of fresh/chilled/frozen pork from PRRSV-positive trading partners. This review describes some of the unique properties of PRRSV, including the poor stability of the virus in the environment, the low probability for airborne transmission, and the inability to sustain infections in feral swine, which make PRRSV a poor candidate for disease introduction through the legal importation of pork.     

Response of red deer stags (Cervus elaphus) to playback of harsh versus common roars

Red deer stags (Cervus elaphus) give two distinct types of roars during the breeding season, the “common roar” and the “harsh roar.” Harsh roars are more frequent during contexts of intense competition, and characterized by a set of features that increase their perceptual salience, suggesting that they signal heightened arousal. While common roars have been shown to encode size information and mediate both male competition and female choice, to our knowledge, the specific function of harsh roars during male competition has not yet been studied. Here, we investigate the hypothesis that the specific structure of male harsh roars signals high arousal to competitors. We contrast the behavioral responses of free ranging, harem-holding stags to the playback of harsh roars from an unfamiliar competitor with their response to the playback of common roars from the same animal. We show that males react less strongly to sequences of harsh roars than to sequences of common roars, possibly because they are reluctant to escalate conflicts with highly motivated and threatening unfamiliar males in the absence of visual information. While future work should investigate the response of stags to harsh roars from familiar opponents, our observations remain consistent with the hypothesis that harsh roars may signal motivation during male competition, and illustrate how intrasexual selection can contribute to the diversification of male vocal signals.     

Perfluorochemicals in water reuse

Faced with freshwater shortages, water authorities are increasingly utilizing wastewater reclamation to augment supplies. However, concerns over emerging trace contaminants that persist through wastewater treatment need to be addressed to evaluate potential risks. In the present study, perfluorinated surfactant residues were characterized in recycled water from four California wastewater treatment plants that employ tertiary treatment and one that treats primary sewage in a wetland constructed for both treatment and wildlife habitat. Effluent concentrations were compared with surface and groundwater from a creek where recycled water was evaluated as a potential means to augment flow (Upper Silver and Coyote Creeks, San Jose, CA). In the recycled water, 90-470 ng/l perfluorochemicals were detected, predominantly perfluorooctanoate (PFOA; 10-190 ng/l) and perfluorooctanesulfonate (PFOS; 20-190 ng/l). No significant removal of perfluorochemicals was observed in the wetland (total concentration ranged 100-170ng/l across various treatment stages); in this case, 2-(N-ethylperfluorooctanesulfonamido) acetic acid (N-EtFOSAA), perfluorodecanesulfonate (PFDS), and PFOS were dominant. Though there is currently no wastewater discharge into the creeks, perfluorochemicals were found in the surface water and underlying groundwater at a total of 20-150 ng/l with PFOS and PFOA again making the largest contribution. With respect to ecotoxicological effects, perfluorochemical release via recycled water into sensitive ecosystems requires evaluation.     

Conservation planning at the landscape scale: A landscape ecology method for regional land trusts

This paper illustrates a landscape ecology approach for land trusts undertaking conservation at the watershed scale. A conservation plan was created for the Grand Traverse Regional Land Conservancy (GTRLC) in the headwaters of Michigan's Manistee River Watershed (USA). Eight conservation drivers were devised to identify Conservation Focus Areas (CFAs) of highest ecological importance. The CFAs were ranked based on ecological importance, feasibility of protection and size. Parcels were ranked, totalling nearly 5000 ha, within the three highest-ranking CFAs in one key county. This approach is useful to land trusts trying to operationalize three distinct goals in conservation planning: to find areas of high ecological importance, to promote the landscape's spatial integrity and to delineate threats to ecological systems and processes.     

Ozone uptake by citrus trees exposed to a range of ozone concentrations

The Citrus genus includes a large number of species and varieties widely cultivated in the Central Valley of California and in many other countries having similar Mediterranean climates. In the summer, orchards in California experience high levels of tropospheric ozone, formed by reactions of volatile organic compounds (VOC) with oxides of nitrogen (NO_x). Citrus trees may improve air quality in the orchard environment by taking up ozone through stomatal and non-stomatal mechanisms, but they may ultimately be detrimental to regional air quality by emitting biogenic VOC (BVOC) that oxidize to form ozone and secondary organic aerosol downwind of the site of emission. BVOC also play a key role in removing ozone through gas-phase chemical reactions in the intercellular spaces of the leaves and in ambient air outside the plants. Ozone is known to oxidize leaf tissues after entering stomata, resulting in decreased carbon assimilation and crop yield. To characterize ozone deposition and BVOC emissions for lemon (Citrus limon), mandarin (Citrus reticulata), and orange (Citrus sinensis), we designed branch enclosures that allowed direct measurement of fluxes under different physiological conditions in a controlled greenhouse environment. Average ozone uptake was up to 11 nmol s^?1 m^?2 of leaf. At low concentrations of ozone (40 ppb), measured ozone deposition was higher than expected ozone deposition modeled on the basis of stomatal aperture and ozone concentration. Our results were in better agreement with modeled values when we included non-stomatal ozone loss by reaction with gas-phase BVOC emitted from the citrus plants. At high ozone concentrations (160 ppb), the measured ozone deposition was lower than modeled, and we speculate that this indicates ozone accumulation in the leaf mesophyll.     

Biological Integrity in Mid-Atlantic Coastal Plains Headwater Streams

The objective of this study was to assess the applicability of using landscape variables in conjunction with water quality and benthic data to efficiently estimate stream condition of select headwater streams in the Mid-Atlantic Coastal Plains. Eighty-two streams with riffle sites were selected from eight-two independent watersheds across the region for sampling and analyses. Clustering of the watersheds by landscape resulted in three distinct groups (forest, crop, and urban) which coincided with watersheds dominant land cover or use. We used non-parametric analyses to test differences in benthos and water chemistry between groups, and used regression analyses to evaluate responses of benthic communities to water chemistry within each of the landscape groups. We found that typical water chemistry measures associated with urban runoff such as specific conductance and dissolved chloride were significantly higher in the urban group. In the crop group, we found variables commonly associated with farming such as nutrients and pesticides significantly greater than in the other two groups. Regression analyses demonstrated that the numbers of tolerant and facultative macroinvertebrates increased significantly in forested watersheds with small shifts in pollutants, while in human use dominated watersheds the intolerant macroinvertebrates were more sensitive to shifts in chemicals present at lower concentrations. The results from this study suggest that landscape based clustering can be used to link upstream landscape characteristics, water chemistry and biotic integrity in order to assess stream condition and likely cause of degradation without the use of reference sites. Notice: Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.