The effects of two acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on pairing success in male Gammarus pulex (Crustacea: Amphipoda)

Parasites can decrease male mating success in host species in various ways, in particular by affecting male competitive ability for access to females. However, male-male competition can take different forms (i.e. interference vs exploitation competition) and which type of competition is most affected by parasites is not always clear. We investigated the influence of two acanthocephalan parasites Pomphorhynchus laevis and Polymorphus minutus on the pairing success of their intermediate host, Gammarus pulex, using field-based studies and complementary laboratory-based studies. We first studied male pairing success in the field using four large samples of paired and unpaired individuals collected at different dates. In three of the samples, the effects of size and parasite infection were significant, whereas for one sample only male size had a significant effect. There was no difference in size distributions between infected and uninfected gammarids. Large males were paired more often than smaller males, and uninfected males were paired more frequently than infected males, the pairing success of P. minutus-infected males being more severely affected than that of P. laevis-infected males. We then experimentally tested the ability to enter into precopula with a receptive female in the presence or absence of competitors. In competitive situations, the pairing success of P. laevis- and P. minutus-infected males was significantly lower than that of uninfected males, with pairing success being more affected in P. laevis-infected than in P. minutus-infected males. In the absence of competition, males infected with P. laevis were significantly less likely to enter into precopula compared with uninfected males and P. minutus-infected males, whereas there was no difference between uninfected and P. minutus-infected males in their inclination to pair with a receptive female. However, for both parasites, latency time to pair formation was significantly shorter for uninfected than for infected males. In a third experiment, we tested for a potential effect of vertical segregation on the pairing success of infected and uninfected males, but found no evidence for it. We conclude that infected males may be less competitive than uninfected males in competition by exploitation between males for females.     

Uncertainty in watershed response predictions induced by spatial variability of precipitation

Negligence to consider the spatial variability of rainfall could result in serious errors in model outputs. The objective of this study was to examine the uncertainty of both runoff and pollutant transport predictions due to the input errors of rainfall. This study used synthetic data to represent the “true” rainfall pattern, instead of interpolated precipitation. It was conducted on a synthetic case area having a total area of 20 km² with ten subbasins. Each subbasin has one rainfall gauge with synthetic precipitation records. Six rainfall storms with varied spatial distribution were generated. The average rainfall was obtained from all of the ten gauges by the arithmetic average method. The input errors of rainfall were induced by the difference between the actual rainfall pattern and estimated average rainfall. The results show that spatial variability of rainfall can cause uncertainty in modeling outputs of hydrologic, which would be transport to pollutant export predictions, when uniformity of rainfall is assumed. Since rainfall is essential information for predicting watershed responses, it is important to consider the properties of rainfall, particularly spatial rainfall variability, in the application of hydrologic and water quality models.     

Treatment of dairy manure using the microwave enhanced advanced oxidation process under a continuous mode operation

The microwave enhanced advanced oxidation process (MW/H(2)O(2)-AOP) was used to treat dairy manure for solubilization of nutrients and organic matters. This study investigated the effectiveness of the MW/H(2)O(2)-AOP under a continuous mode of operation, and compared the results to those of batch operations. The main factors affecting solubilization by the MW/H(2)O(2)-AOP were heating temperature and hydrogen peroxide dosage. Soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFA) increased with an increase of microwave (MW) heating temperature; very high concentrations were obtained at 90°C. Insignificant amounts of ammonia and reducing sugars were released in all runs. An acidic pH condition was required for phosphorus solubilisation from dairy manure. The best yield was obtained at 90°C with an acid dosage of 1.0 %; about 92 % of total phosphorus and 90 % of total chemical oxygen demand were in the soluble forms. The MW/H(2)O(2)-AOP operated in a continuous operation mode showed pronounced synergistic effects between hydrogen peroxide and microwave irradiation when compared to a batch system under similar operating conditions, resulting in much better yields.     

Enhanced nutrient removal by oxidation-reduction potential (ORP) control in laboratory-scale extended aeration reactors

A study was conducted to examine N and P removal by a laboratory-scale extended aeration treatment system employing oxidation-reduction potential (ORP) controlled aeration. The system was provided with a 90-L aeration tank. When ORP controlled aeration was applied, the aeration tank was divided into three zones, namely the ORP zone (45 L), the anaerobic zone (27 L) and the aerobic zone (18 L). An external anoxic selector of 3.8 L in volume was also added. An ORP set point of 70 mV was used for the ORP zone. The extended aeration treatment system operating without the ORP controlled aeration was used as the control.COD removal (97%) was not affected, but both N and P removal were enhanced significantly in the ORP reactor. Total N removal efficiency was increased from 49.1% (control) to 83.5%. Almost all P was captured (99%), leaving an average of 0.09 mg L⁻¹ P in the effluent. The ORP reactor yielded a sludge P content of 3.1%, compared to only 1.8% for the control. This indicated luxury P uptake in ORP reactor. Very significant P release and denitrification were found in the anoxic selector. Fairly good simultaneous nitrification and denitrification had occurred in the ORP zone. However, P release was very limited in the anoxic zone. However, anoxic P uptake and nitrification were found in this zone.Low F/M bulking was observed in both the control and ORP operation before the installation of a selector. Bacterial Type 0041 was identified as the predominant bulking organism. For the Control, an aerobic selector cured the bulking problem in one sludge age while an anoxic selector fixed up the problem during the ORP operation.     

Climate change and population genetic structure of marine species

Climate change influences populations by reducing or extirpating local populations, by disrupting patterns of migration and by shifting geographical distributions. These events can affect genetic population structure in several ways. Molecular markers have been used in numerous population genetic and phylogeographical studies of marine species and have detected population responses to climate change in the last few decades, such as range expansions, adaptative shifts and declines or increases in abundance. Little is known, however, about the molecular and physiological basis of adaptive responses to climate change in marine Mediterranean species. The Mediterranean Sea ecosystem is a ‘living laboratory’ with native species that are challenged by environmental change and by invasive species and a ‘gene-climate’ approach should be adopted as a way of focusing on the relationship between climate warming and genetic diversity.     

Agricultural Land Use and Best Management Practices to Control Nonpoint Water Pollution

In recent years, improvements in point-source depuration technologies have highlighted the problems regarding agricultural nonpoint (diffuse) sources, and this issue has become highly relevant from the environmental point of view. The considerable extension of the areas responsible for this kind of pollution, together with the scarcity of funds available to local managers, make minimizing the impacts of nonpoint sources on a whole basin a virtually impossible task. This article presents the results of a study intended to pinpoint those agricultural areas, within a basin, that contribute most to water pollution, so that operations aimed at preventing and/or reducing this kind of pollution can be focused on them. With this aim, an innovative approach is presented that integrates a field-scale management model, a simple regression model, and a geographic information system (GIS). The Lake Vico basin, where recent studies highlighted a considerable increase in the trophic state, mainly caused by phosphorus (P) compounds deriving principally from the intensive cultivation of hazelnut trees in the lake basin, was chosen as the study site. Using the management model Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), the consequences, in terms of sediment yield and phosphorus export, of hazelnut tree cultivation were estimated on different areas of the basin with and without the application of a best management practice (BMP) that consists of growing meadow under the trees. The GLEAMS results were successively extended to basin scale thanks to the application of a purposely designed regression model and of a GIS. The main conclusions can be summarized as follows: The effectiveness of the above-mentioned BMP is always greater for erosion reduction than for particulate P reduction, whatever the slope value considered; moreover, the effectiveness with reference to both particulate P and sediment yield production decreases as the slope increases. The proposed approach, being completely distributed, represents a considerable step ahead compared to the semidistributed or lumped approaches, which are traditionally employed in research into tools to support the decision-making process for land-use planning aimed at water pollution control.