Species dispersal rates alter diversity and ecosystem stability in pond metacommunities

Metacommunity theory suggests that relationships between diversity and ecosystem stability can be determined by the rate of species dispersal among local communities. The predicted relationships, however, may depend upon the relative strength of local environmental processes and disturbance. Here we evaluate the role of dispersal frequency and local predation perturbations in affecting patterns of diversity and stability in pond plankton metacommunities. Pond metacommunities were composed of three mesocosm communities: one of the three communities maintained constant "press" predation from a selective predator, bluegill sunfish (Lepomis macrochirus); the second community maintained "press" conditions without predation; and the third community experienced recurrent "pulsed" predation from bluegill sunfish. The triads of pond communities were connected at either no, low (0.7%/d), or high (20%/d) planktonic dispersal. Richness and composition of zooplankton and stability of plankton biomass and ecosystem productivity were measured at local and regional spatial scales. Dispersal significantly affected diversity such that local and regional biotas at the low dispersal rate maintained the greatest number of species. The unimodal local dispersal-diversity relationship was predator-dependent, however, as selective press predation excluded species regardless of dispersal. Further, there was no effect of dispersal on beta diversity because predation generated local conditions that selected for distinct community assemblages. Spatial and temporal ecosystem stability responded to dispersal frequency but not predation. Low dispersal destabilized the spatial stability of producer biomass but stabilized temporal ecosystem productivity. The results indicate that selective predation can prevent species augmentation from mass effects but has no apparent influence on stability. Dispersal rates, in contrast, can have significant effects on both species diversity and ecosystem stability at multiple spatial scales in metacommunities.     

Impacts of golf courses on macroinvertebrate community structure in Precambrian shield streams

The influence of golf course operation on benthic macroinvertebrate communities in Precambrian Shield streams was evaluated using rapid bioassessment and the reference condition approach. Streams were sampled for water chemistry and invertebrates in 1999 and 2000, six on operational golf courses, and seven in forested reference locations. Correspondence analysis (CA) was used to determine the major patterns in the macroinvertebrate taxa, and canonical correspondence analysis (CCA) was used to evaluate relationships with environmental variables. The reference streams were used to define the normal range of variation for a variety of summary indices to evaluate the golf course streams. In all cases, golf course streams were higher in nutrients and dissolved ions and more alkaline than the forested reference streams. There was considerable variability in the macroinvertebrate fauna from the golf course streams, which was related to differences in golf course land management practices and to the potential influence of highway runoff. Of the management practices evaluated, fertilizer application rates in particular were important, as was the presence of ponds upstream on the course. Invertebrate taxa with higher abundances in golf course streams included Turbellaria, Isopoda, Amphipoda, Zygoptera, and Trombidiformes. Taxa more common in the reference streams included Ephemeroptera, Megaloptera, Culicidae, and Plecoptera. There were marked differences in the overall benthic macroinvertebrate community in three of the six golf course streams studied relative to the forested reference streams, suggesting that golf course land management on the Precambrian Shield can be associated with significant differences in macroinvertebrate community structure.     

Regulation of discharge of organochlorines from pulp mills in Canada

Organochlorines are a group of chemicals including dioxins and furans, at least some of which are highly toxic to humans. Organochlorines are formed as a byproduct of the chlorine bleaching process in pulp mills, as well as in other ways. Current federal and provincial environmental protection legislation in Canada is too general to adequately deal with the problem of organochlorine discharge. In Sweden and Germany strict new guidelines have been set for the discharge of organochlorines; strict guidelines are also planned for Alberta. The author recommends that new regulations, dealing specifically with organochlorine discharge, be promulgated under the new Canadian Environmental Protection Act. The new regulations should apply equally to all pulp mills. Strict enforcement, through cooperation of federal and provincial authorities, is also advised.     

Ombrotrophic peat as a medium for historical monitoring of heavy metal pollution

Knowledge of historical trends in heavy metal deposition can aid the study and impact prediction of contemporary pollution. For this purpose, analysis of ombrotrophic peat cores has proved a valuable complement to other sedimentary analyses. However, doubts still remain concerning the mobility of heavy metals in peat. The debate cannot be resolved until the behaviour of these elements in peat is better understood. Peat cores were collected from hollows and hummocks on Ringinglow Bog in the southern Pennines. The cores were sliced into contiguous 1-cm slices. Samples were analysed for total concentrations of major elements (Al, Ca, K, Mg, Na) and trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) using atomic absorption spectrophotometry. Multivariate statistical analysis was conducted on the data. Preliminary results indicate relatively high concentrations of Cd, Cu, Fe, Pb and Zn reflecting the influence of industrial activities in Sheffield and Manchester. As aluminium, cadmium, copper, lead and zinc exhibit similar profiles they may be suitable surrogates for monitoring historical pollution. However, other elements (e.g. Fe, K, Mn, Na) are clearly influenced by bog hydrology or plant translocation and would be inappropriate monitors.     

Upstream Channel Changes Following Dam Construction and Removal Using a GIS/Remote Sensing Approach1

Abstract: This study used an innovative GIS/remote sensing approach to study historical river channel changes in the Huron River, a wandering gravel‐bedded river in northern Ohio. Eight sets of historical aerial photographs (1958‐2003) span the construction of a low‐head dam (1969), removal of the spillway (1994), and removal of the dam itself (2002). Construction of the dam modified stream gradients >4 km upstream of the small impounded reservoir. This study tracked changes in the polygon size, shape, and centroid position of 12 sand‐gravel bars through a study reach 0.2‐4.1 km upstream of the dam. These bars were highly responsive, tending to migrate obliquely downstream and toward the outer bank at rates up to 9 m/year. Historical changes in the size and position of the bars can be interpreted as the downstream translation of one or more sediment waves. Prior to dam construction, a sediment wave moved downstream through the study reach. Following construction of the dam, this sediment wave became stationary and degraded in situ by dispersion. The growth of bars throughout the study reach during this time interval resulted in a progressive increase in channel sinuosity. Removal of the spillway rejuvenated downstream translation of a sediment wave through the study reach and was followed by a reduction in channel sinuosity. These results illustrate that important geomorphologic changes can occur upstream of low‐head dams. This may be a neglected area of research about the effects of dams and dam removals.     

Prevalence and Molecular Characterization of the Hepatitis E Virus in Retail Pork Products Marketed in Canada

Infection with the hepatitis E virus (HEV) is very common worldwide. HEV causes acute viral hepatitis with approximately 20 million cases per year. While HEV genotypes 1 and 2 cause large waterborne and foodborne outbreaks with a significant mortality in developing countries, genotypes 3 and 4 are more prevalent in developed countries with transmission being mostly zoonotic. In North America and Europe, HEV has been increasingly detected in swine, and exposure to pigs and pork products is considered to be the primary source of infection. Therefore we set out to investigate the prevalence of HEV in retail pork products available in Canada, by screening meal-size portions of pork pâtés, raw pork sausages, and raw pork livers. The presence of the HEV genomes was determined by RT-PCR and viral RNA was quantified by digital droplet PCR. Overall, HEV was detected in 47% of the sampled pork pâtés and 10.5% of the sampled raw pork livers, but not in the sampled pork sausages, and sequencing confirmed that all HEV strains belonged to genotype 3. Further phylogenetic analysis revealed that except for one isolate that clusters with subtype 3d, all isolates belong to subtype 3a. Amino acid variations between the isolates were also observed in the sequenced capsid region. In conclusion, the prevalence of HEV in pâtés and raw pork livers observed in this study is in agreement with the current HEV distribution in pork products reported in other developed countries.     

Ecology of drowning risk at a public swimming pool

INTRODUCTION: The fourth-leading cause of death in middle childhood is drowning, but there is remarkably little known about swimmer or lifeguard behavior patterns at public swimming pools. METHOD: This study used non-intrusive observational methodology to examine risk-taking by swimming patrons (predominantly children) and surveillance habits of lifeguards at a public swimming pool. The study also examined whether risk-taking behavior might be associated with density of swimmers, temperature, or lifeguard behaviors. RESULTS: Results suggested risk-taking behavior was common, with dangerous incidents observed over 90 times per hour. Particularly high were rates of running on the deck, which exceeded 100 incidents per hour near the deepest water of the pool, and jumping into the water dangerously close to other swimmers, which was witnessed about once every two minutes in the shallow water of the pool. Lifeguards tended to scan the pool well, and remain attentive to the areas under their responsibility, but they were distracted about 10 times per hour and warned patrons only about once for every 14 dangerous incidents observed. CONCLUSIONS: No consistent correlates to risk-taking behavior by swimming pool patrons were identified. Results are discussed with respect to previous findings and implications for intervention. Impact on Industry: Findings emphasize the need to increase awareness and adherence to safety rules by swimmers at swimming pools; to educate and remind lifeguards about proper swimming pool surveillance techniques; and to consider environmental changes at public swimming pools that might increase swimmer safety.     

Text analysis tools for identification of emerging topics and research gaps in conservation science

Keeping track of conceptual and methodological developments is a critical skill for research scientists, but this task is increasingly difficult due to the high rate of academic publication. As a crisis discipline, conservation science is particularly in need of tools that facilitate rapid yet insightful synthesis. We show how a common text‐mining method (latent Dirichlet allocation, or topic modeling) and statistical tests familiar to ecologists (cluster analysis, regression, and network analysis) can be used to investigate trends and identify potential research gaps in the scientific literature. We tested these methods on the literature on ecological surrogates and indicators. Analysis of topic popularity within this corpus showed a strong emphasis on monitoring and management of fragmented ecosystems, while analysis of research gaps suggested a greater role for genetic surrogates and indicators. Our results show that automated text analysis methods need to be used with care, but can provide information that is complementary to that given by systematic reviews and meta‐analyses, increasing scientists’ capacity for research synthesis.     

Effects of initial resources on the development of strains during a stressful training situation: Some counterintuitive results

Resource theories of occupational stress argue that employees' personal and environmental resources protect them from too much distress or strain during stressful work experiences. We examined four resources (emotional stability, previous experience, low drain on pre‐existing resources, and workgroup quality) available to soldiers at the beginning of a stressful 3‐month training experience as predictors of the trajectories of their strains over that period of time. Based on conservation of resources theory and the job demands–resources model, we predicted that the trends of strains would be more favorable (would increase more slowly or decline more quickly) if participants started the training with greater resources. The resources, primarily emotional stability and lack of pre‐existing resource drain, tended to be negatively related to strains, consistent with the idea that they can reduce strains. Significant interactions predicting trends were found predicting two of the three strains (post‐traumatic stress symptoms and depression, but not reports of physical health). Contrary to expectations, however, the three resources that significantly predicted trends over time (emotional stability, previous experience, and low pre‐existing resource drain) were associated with worsening rather than improving strains. Copyright © 2014 John Wiley & Sons, Ltd.     

The Influence of Two‐Stage Ditches with Constructed Floodplains on Water Column Nutrients and Sediments in Agricultural Streams

The two‐stage ditch is a novel management practice originally implemented to increase bank stability through floodplain restoration in channelized agricultural streams. To determine the effects of two‐stage construction on sediment and nutrient loads, we monitored turbidity, and also measured total suspended solids (TSS), dissolved inorganic nitrogen (N) species, and phosphorus (P) after two‐stage ditch construction in reference and manipulated reaches of four streams. Turbidity decreased during floodplain inundation at all sites, but TSS and P, soluble reactive phosphorus (SRP) and total phosphorus (TP) decreased only in the two‐stage ditches with longer duration of inundation. Both TSS and TP were positively correlated within individual streams, but neither were correlated with turbidity. Phosphorus was elevated in the stream to which manure was applied adjacent to the two‐stage reach, but not the reference reach, suggesting that landscape nutrient management plans could restrict nutrient transport to the stream, ultimately determining the efficacy of instream management practices. In addition, ammonium and nitrate decreased in two‐stage reaches with lower initial N concentrations. Overall, results suggest that turbidity, TSS, and TP were reduced during floodplain inundation, but the two‐stage alone may not be effective for managing high inorganic N loads.