The influence of suburban land use on habitat and biotic integrity of coastal Rhode Island streams

Watershed land use in suburban areas can affect stream biota through degradation of instream habitat, water quality, and riparian vegetation. By monitoring stream biotic communities in various geographic regions, we can better understand and conserve our watershed ecosystems. The objective of this study was to examine the relationship between watershed land use and the integrity of benthic invertebrate communities in eight streams that were assessed over a 3-year period (2001-2003). Sites were selected from coastal Rhode Island watersheds along a residential land-use gradient (4-59%). Using the rapid bioassessment protocol, we collected biological, physicochemical, habitat, and nutrient data from wadeable stream reaches and compared metrics of structure and integrity. Principal component analyses showed significant negative correlation of indicators for stream physicochemical, habitat, and instream biodiversity with increasing residential land use (RLU) in the watershed. The physicochemical variables that were most responsive to percent RLU were conductivity, instream habitat, nitrate, and dissolved inorganic nitrogen (DIN). The positive correlation of DIN with percent RLU indicated an anthropogenic source of pollution affecting the streams. The biotic composition of the streams shifted from sensitive to insensitive taxa as percent RLU increased; the most responsive biological variables were percent Ephemeroptera, percent Scrapers, percent Insects, and the Hilsenhoff biotic index. These data show the importance of land management and conservation at the watershed scale to sustaining the biotic integrity of coastal stream ecosystems.     

Predicting coral bleaching in response to environmental stressors using 8 years of global-scale data

Coral reefs have experienced extensive mortality over the past few decades as a result of temperature-induced mass bleaching events. There is an increasing realization that other environmental factors, including water mixing, solar radiation, water depth, and water clarity, interact with temperature to either exacerbate bleaching or protect coral from mass bleaching. The relative contribution of these factors to variability in mass bleaching at a global scale has not been quantified, but can provide insights when making large-scale predictions of mass bleaching events. Using data from 708 bleaching surveys across the globe, a framework was developed to predict the probability of moderate or severe bleaching as a function of key environmental variables derived from global-scale remote-sensing data. The ability of models to explain spatial and temporal variability in mass bleaching events was quantified. Results indicated approximately 20% improved accuracy of predictions of bleaching when solar radiation and water mixing, in addition to elevated temperature, were incorporated into models, but predictive accuracy was variable among regions. Results provide insights into the effects of environmental parameters on bleaching at a global scale.     

Liver lesions in demersal fishes near a large ocean outfall on the San Pedro Shelf, California

The prevalence of toxicopathic liver lesions in demersal fish on the San Pedro Shelf, California was determined for a 15-year period (1988–2003). Fish livers were sampled at fixed locations as part of the Orange County Sanitation Districts (OCSD) ocean monitoring program. Histopathological examination of selected fish liver tissues was studied to determine whether the wastewater discharge had affected fish health. The prevalence of toxicopathic lesion classes neoplasms (NEO), preneoplastic foci of cellular alteration (FCA), and hydropic vacuolation (HYDVAC) varied among species and locations. For all species sampled, severe lesions occurred in 6.2% of the fish examined (n = 7,694). HYDVAC (4.1%) was the most common toxicopathic lesion type followed by FCA (1.4%) and NEO (0.7%). HYDVAC occurred only in white croaker (Genyonemus lineatus), accounting for 84.8% of the toxicopathic lesions for this species. Prevalence of HYDVAC, NEO, and FCA in white croaker was 15.2, 2.0, and 0.7%, respectively. The prevalence of HYDVAC and NEO in white croaker increased with age and size but there was no sexual difference. A linear regression model was used for hypothesis testing to account for significant differences in fish size (and age for croakers) at the different sampling locations. This analysis showed that for HYDVAC there was no spatial or location effect for lesion rate or size/age of onset. For NEO, the model predicted that white croaker near the wastewater outfall may acquire these lesions at a smaller size/younger age, and at a higher rate, than at other sites. However, this result may be biased due to the unequal size frequency distributions and the low prevalence of NEO in white croaker at the different sampling sites. Bigmouth sole (Hippoglossina stomata) had a prevalence of FCA and NEO of 1.3 and 0.35%, respectively, but the prevalence and distribution of lesions was too few for statistical testing. There was no sexual difference for lesion prevalence in hornyhead turbot (Pleuronichthys verticalis) and the prevalence of FCA and NEO was 3.4 and 0.37%, respectively. FCA prevalence increased with size in hornyhead turbot and there were no significant spatial differences for lesion rates and fish size at lesion onset. Overall, consistent spatial differences for lesion prevalence were not demonstrated and highlight the analytical difficulties of detecting a possible point source impact when the effect is rare, correlated with the size/age structure of the population, and may be caused by exposure to unknown multiple sources. Thus, the usefulness of liver histopathology as a point-source monitoring tool is best applied to where the spatial scale of impact generally exceeds the home range of the target species.     

Methods to estimate solar radiation dosimetry in coral reefs using remote sensed, modeled, and in situ data

Solar irradiance has been increasingly recognized as an important determinant of bleaching in coral reefs, but measurements of solar radiation exposure within coral reefs have been relatively limited. Solar radiation dosimetry within multiple coral reef areas of South Florida was assessed using remote sensed, modeled, and measured values during a minor bleaching event during August 2005. Coral reefs in the Dry Tortugas and Upper Keys had similar diffuse downwelling attenuation coefficients (Kd, m(-1)), whereas Kd values were significantly greater in the Middle and Lower Keys. Mean 1% attenuation depths varied by reef region for ultraviolet B (UVB; 9.7 to 20 m), ultraviolet A (UVA; 22 to 40 m) and visible (27 to 43 m) solar radiation. Solar irradiances determined from remote sensed data were significantly correlated with measured values, but were generally overestimated at the depth of corals. Solar irradiances modeled using an atmospheric radiative transfer model parameterized with site specific approximations of cloud cover showed close agreement with measured values. Estimated daily doses (W h/m(2)) of UVB (0.01-19), UVA (2-360) and visible (29-1,653) solar radiation varied with coral depth (2 to 24 m) and meteorological conditions. These results indicate large variation in solar radiation dosimetry within coral reefs that may be estimated with reasonable accuracy using regional Kd measurements and radiative transfer modeling.     

Climate-Smart Design for Ecosystem Management: A Test Application for Coral Reefs

Environmental Management - The interactive and cumulative impacts of climate change on natural resources such as coral reefs present numerous challenges for conservation planning and management....     

Barriers to sharing water quality data: experiences from the Shale Network

The Shale Network is a group of stakeholders collating, publishing, and conducting research on water quality data collected in the northeastern United States experiencing natural gas extraction from shale using hydraulic fracturing. In developing the Shale Network, we have experienced reluctance to share data from all participating sectors. This paper explores this reluctance, identifying barriers to greater collaboration among multiple stakeholders in natural resource management projects. Findings are derived from participant observation of the Shale Network team, surveys conducted during Shale Network workshops, interviews with water quality stakeholders, and participant observation of water quality monitoring training sessions. The barriers identified include perceptions about data problems and quality, technical capacity, regulatory and legal limitations, competition for resources, and resource allocation decisions. This paper identifies strategies the Shale Network has used to overcome data-sharing barriers to expand a culture of data sharing that supports enhanced nature resource management and citizen engagement.     

Homeowner Attitudes and Practices Towards Residential Landscape Management in Ohio, USA

This study describes the results of a survey of 432 homeowners in Ohio, USA concerning their perceptions and practices regarding management of residential landscapes. The results reveal that outdoor residential environments are extremely important to homeowners, who tend to view their yards as serving multiple functions: a place to observe nature and to socialize as well as a place of beauty and recreation. Use of a lawn care company to apply chemicals is reported by 22 % of respondents, while 40 % either apply chemicals themselves or have someone other than a lawn care company do it. Logistic regressions reveal that factors influencing a homeowner's decision to employ a lawn care company or to apply chemicals themselves include: household income (+), perceived impacts on the environment (-), whether the next door neighbor does it (+), and type of residential environment (rural -, suburban and urban +). A theme that emerges throughout the study is the perceived importance of the role of the lawn in residents' sense of social status or acceptance in the neighborhood. This perception can be viewed as a positive in ensuring that residential environments are well maintained, but also as a negative resulting in environmental degradation or presenting a barrier to creativity in the development of alternative residential environments. Specific policy implications of these findings are that efforts aimed at educating homeowners about the environmental impacts of their lawn care choices are likely to have more success if they are directed at neighborhood groups rather than individuals, show that alternatives are easy to adopt, affordable, and can produce the characteristics of lawns that homeowners seek.     

Defending dissensus: participatory governance and the politics of water measurement in Montana’s Yellowstone River Basin

The role of a particular aspect of collaboration, dissensus, in stimulating critical reconsideration of ‘prior appropriation’, a historically hegemonic condition related to water rights in the western United States, is examined via a collaborative planning effort in Montana. Consensual support for a water-use measuring proposal was undermined by strong libertarian resistance to governmental regulation, and an unwavering embrace of the status quo. However, based on insights from scholars engaged in the ‘post-political’ dimensions of contemporary forms of rule – dissensus – understood as the manifestation of consensus-forestalling disagreement articulated between oppositional voices – is revealed as a condition to be actively nurtured, rather than purged. This case reveals how dissensus can open discursive spaces for hegemony-disrupting modes of inquiry, alternative perspectives, and innovative possibilities, even among sanctioned participant voices operating within otherwise established, depoliticized governing arenas. The study thus deepens our understanding of the complex political dynamics of participatory water planning.     

Water quality guidelines for chemicals: learning lessons to deliver meaningful environmental metrics

Many jurisdictions around the globe have well-developed regulatory frameworks for the derivation and implementation of water quality guidelines (WQGs) or their equivalent (e.g. environmental quality standards, criteria, objectives or limits). However, a great many more still do not have such frameworks and are looking to introduce practical methods to manage chemical exposures in aquatic ecosystems. There is a potential opportunity for learning and sharing of data and information between experts from different jurisdictions in order to deliver efficient and effective methods to manage potential aquatic risks, including the considerable reduction in the need for aquatic toxicity testing and the rapid identification of common challenges. This paper reports the outputs of an international workshop with representatives from 14 countries held in Hong Kong in December 2011. The aim of the workshop and this paper was to identify ‘good practice’ in the development of WQGs to deliver to a range of environmental management goals. However, it is important to broaden this consideration to cover often overlooked facets of implementable WQGs, such as demonstrable field validation (i.e. does the WQG protect what it is supposed to?), fit for purpose of monitoring frameworks (often an on-going cost) and finally how are these monitoring data used to support management decisions in a manner that is transparent and understandable to stakeholders. It is clear that regulators and the regulated community have numerous pressures and constraints on their resources. Therefore, the final section of this paper addresses potential areas of collaboration and harmonisation. Such approaches could deliver a consistent foundation from which to assess potential chemical aquatic risks, including, for example, the adoption of bioavailability-based approaches for metals, whilst reducing administrative and technical burdens in jurisdictions.     

Aqueous uptake and sublethal toxicity of p,p'-DDE in non-feeding larval stages of Antarctic krill (Euphausia superba)

This study evaluated the toxicological sensitivity of non-feeding larval stages of a key Antarctic species (Antarctic krill, Euphausia superba) to p,p'-dichlorodiphenyl dichloroethylene (p,p'-DDE) exposure. The aqueous uptake clearance rate of 84 mL g(-1) preserved weight (p.w.) h(-1) determined for p,p'-DDE in Antarctic krill larvae is comparable to previous findings for small cold water crustaceans and five times slower than the rates reported for an amphipod inhabiting warmer waters. Natural variations in larval physiology appear to influence contaminant uptake and larval krill behavioural responses, strongly highlighting the importance of time of measurement for ecotoxicological testing. Sublethal narcosis (immobility) was observed in larval Antarctic krill from p,p'-DDE body residues of 0.2 mmol/kg p.w., which is in agreement with findings for adult krill and temperate aquatic species. The finding of comparable body residue-based toxicity of p,p'-DDE between polar and temperate species supports the tissue residue approach for environmental risk assessment of polar ecosystems.