Phosphorus Loadings Associated with a Park Tourist Attraction: Limnological Consequences of Feeding the Fish

The Linesville spillway of Pymatuning State Park is one of the most visited tourist attractions in Pennsylvania, USA, averaging more than 450,000 visitors · year⁻¹. Carp (Cyprinus carpio Linnaeus) and waterfowl congregate at the spillway where they are fed bread and other foods by park visitors. We hypothesized that the “breadthrowers” constitute a significant nutrient vector to the upper portion of Pymatuning Reservoir. In the summer of 2002, we estimated phosphorus loadings attributable to breadthrowers, and compared these values to background loadings from Linesville Creek, a major tributary to the upper reservoir. Items fed to fish included bread, donuts, bagels, canned corn, popcorn, corn chips, hot dogs, birthday cakes, and dog food. Phosphorus loading associated with park visitors feeding fish was estimated to be 3233 g day⁻¹, and estimated P export from the Linesville Creek watershed was 2235 g·day⁻¹. P loading attributable to breadthrowers exceeded that of the entire Linesville Creek watershed on 33 of the 35 days of study, with only a heavy rainfall event triggering watershed exports that exceeded spillway contributions. Averaged across 5 weeks, breadthrowers contributed 1.45-fold more P to Pymatuning Reservoir than the Linesville Creek watershed. If Linesville Creek P exports are extrapolated to the entire Sanctuary Lake watershed, spillway contributions of P added 48% to the non-point source watershed P entering the lake. Park visitors feeding fish at the Linesville Spillway are a significant source of nutrients entering Sanctuary Lake.     

The problem and promise of scale dependency in community phylogenetics

The problem of scale dependency is widespread in investigations of ecological communities. Null model investigations of community assembly exemplify the challenges involved because they typically include subjectively defined "regional species pools." The burgeoning field of community phylogenetics appears poised to face similar challenges. Our objective is to quantify the scope of the problem of scale dependency by comparing the phylogenetic structure of assemblages across contrasting geographic and taxonomic scales. We conduct phylogenetic analyses on communities within three tropical forests, and perform a sensitivity analysis with respect to two scaleable inputs: taxonomy and species pool size. We show that (1) estimates of phylogenetic overdispersion within local assemblages depend strongly on the taxonomic makeup of the local assemblage and (2) comparing the phylogenetic structure of a local assemblage to a species pool drawn from increasingly larger geographic scales results in an increased signal of phylogenetic clustering. We argue that, rather than posing a problem, "scale sensitivities" are likely to reveal general patterns of diversity that could help identify critical scales at which local or regional influences gain primacy for the structuring of communities. In this way, community phylogenetics promises to fill an important gap in community ecology and biogeography research.     

Particle size relationships at the Fresno Supersite

Aerosol size distributions are presented for a winter intensive study at the Fresno Supersite. The size distributions were consistent with and predictive for continuous PM2.5 measured by beta attenuation. They varied temporally with respect to source type and intensity, with the smallest mean diameters associated with high NOx concentrations during weekday morning rush hours. Conversely, small and large particle and black carbon (BC) concentrations were higher during Sunday and weekday evenings in response to traffic and residential wood combustion emissions. Ambient PM2.5 light scattering (Bsp) was precisely but systematically underestimated during winter, probably because of heating in the sample shelter.     

Modelling the fate of sulphur-35 in crops. 2. Development and validation of the CROPS-35 model

Gas-cooled nuclear power plants in the UK release sulphur-35 during their routine operation, which can be readily assimilated by vegetation. It is therefore necessary to be able to model the uptake of such releases in order to quantify any potential contamination of the food chain. A model is described which predicts the concentration of (35)S in crop components following an aerial gaseous release. Following deposition the allocation to crop components is determined by an export function from a labile pool, the leaves, to those components growing most actively post exposure. The growth rates are determined by crop growth data, which is also used to determine the concentration. The loss of activity is controlled by radioactive decay only. The paper describes the calibration and the validation of the model. To improve the model, further experimental work is required particularly on the export kinetics of (35)S. It may be possible to adapt such a modelling approach to the prediction of crop content for gaseous releases of (3)H and (14)C from nuclear facilities.     

A corporate approach to social monitoring and assessment for development in a fragile environment

The prevailing corporate trend regardingdevelopment of energy resources in the tropics emphasizesfinancial gain over long-term societal benefits. Somecorporations are beginning to find a competitive advantage linkedto proactive relations with host communities and adequateprotection of fragile ecosystems. Herein, we describe a casestudy where an international energy production company workedwith stakeholders to achieve social capital and sustainabledevelopment. The strategies aimed to strengthen local capacity toimprove social welfare and to ensure conservation and wise use ofbiodiversity. We provide examples, discuss lessons learned andmake recommendations for future development projects.     

Understanding long-term baseflow water quality trends using a synoptic survey of the ground water-surface water interface, central Wisconsin

The relationship between stream water quality and landscape activities is difficult to evaluate where the principal source of stream flow is ground water seepage because the average travel time from ground water recharge areas to stream discharge positions can be on the order of decades. We tested the idea that past and future baseflow water quality can be predicted based on a synoptic survey of ground water recharge age-dates (based on chlorofluorocarbon [CFC] measurements) and water quality measurements obtained at the ground water-surface water interface. In this study we (i) characterize the discharge-weighted age distribution and water quality of ground water seepage into the Little Plover River (LPR); (ii) use this information to backcast and forecast baseflow NO(3)(-) concentrations; and (iii) evaluate NO(3)(-) backcasts against historical baseflow data (1960 to 2000). The discharge-weighted apparent CFC age of ground water seepage into the LPR was 23.7 (+/-7) yr. Baseflow backcasts matched the four decade rise of baseflow NO(3)(-) from 2 to 8 mg L(-1). Baseflow forecasts included three scenarios. Scenario A projects the historical rise of NO(3)(-) in the LPR basin's ground water recharge through 2050. Scenario B projects a leveling off of NO(3)(-) in ground water recharge in the year 2000. Scenario C projects a leveling off in the year 1985. Under Scenario A, LPR baseflow NO(3)(-) will increase steadily from 8 to 19 mg L(-1) between 2000 and 2050. Under scenarios B and C baseflow NO(3)(-) will plateau at 13 mg L(-1) in 2030 and at 10 mg L(-1) in 2010, respectively. The approach developed in this study can be used to (i) reconstruct historical baseflow water quality patterns in the absence of long-term monitoring data and (ii) project the effects of potential management decision on future water quality.     

How Science Contributes to Environmental Reporting in British Newspapers: A Case Study of the Reporting of Global Warming and Climate Change

This article examines the role of science in environmental reporting in a number of British newspapers. The findings indicated that in reporting about global warming and climate change, the views of scientists were used to give legitimacy to the content of articles. However, in both the tabloids and broadsheets, there was little evidence provided, in the form of data, to substantiate the claims being made. Furthermore, uncertainties about global warming were not explored effectively. Newspaper reports tended to focus on the potential consequences of global warming, but made little attempt to address the suspected causes that would inevitably involve criticism of highly consumptive lifestyles in the west.     

Carryover aquatic effects on survival of metamorphic frogs during pond emigration.

In organisms with complex life cycles, physiological stressors during early life stages may have fitness-level impacts that are delayed into later stages or habitats. We tested the hypothesis that body size and date of metamorphosis, which are highly responsive to aquatic stressors, influence post-metamorphic survival and movement patterns in the terrestrial phase of an ephemeral pond-breeding frog by examining these traits in two populations of northern red-legged frogs (Rana aurora aurora). To increase variation of body size at metamorphosis, we manipulated food availability for 314 of 1045 uniquely marked tadpoles and estimated the probability that frogs survived and emigrated using concentric rings of drift fencing surrounding ponds and Bayesian capture-recapture modeling. The odds of surviving and emigrating from the ponds to the innermost drift fences, approximately 12 m, increased by factors of 2.20 (95% credibility intervals 1.39-4.23) and 2.54 (0.94-4.91) with each millimeter increase in snout-vent length and decreased by factors of 0.91 (0.85-0.96) and 0.89 (0.80-1.00) with each day's delay in metamorphosis for the two ponds. The odds of surviving and moving to the next ring of fencing, 12 m to approximately 40 m from the ponds, increased by a factor of 1.20 (0.45-4.06) with each millimeter increase in size. Our results demonstrated that body size and timing of metamorphosis relate strongly to the performance of newly metamorphosed frogs during their initial transition into terrestrial habitat. Carryover effects of aquatic stressors that reduce size and delay metamorphosis may have population-level impacts that are not expressed until terrestrial stages. Since changes in both aquatic and terrestrial systems are implicated in many amphibian declines, quantifying both immediate and delayed effects of stressors on demographic rates is critical to sound management.