Seasonal water level fluctuations: Implications for reservoir limnology and management

With the purpose of finding out whether seasonal water level fluctuations could affect water quality in a reservoir subjected to those changes, trends in environmental variables and in phytoplankton and zooplankton assemblages were analysed. The reservoir’s hydrological cycle was characterized by three regimes. The maximum level phase lasted from January to the beginning of June, the emptying phase existed between mid-June to the beginning of September and the minimum level phase lasted from mid-September to the beginning of the first autumn/winter rain events. The highest values of total phosphorus, soluble reactive phosphorus, nitrate, water colour and chlorophyll a were found during the minimum level phase. The phytoplankton assemblage was dominated by taxa typical of meso-eutrophic environments during the emptying and minimum level phases. However, during the maximum level phase, taxa generally found in more oligotrophic systems were observed here also. Similar to other disturbed systems, the zooplankton assemblage was dominated by Rotifera, except in summer and autumn when the cladoceran Ceriodaphnia quadrangula and/or the copepod Tropocyclops prasinus became dominant. Although those shifts seem to be related to water level variations, further research is needed to evaluate to what extent they might also be induced by other seasonal factors acting independently of water fluctuations. Based upon the obtained data, suggestions for reservoir management are proposed

A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000

Quantitative image analysis for the characterization of microbial aggregates in biological wastewater treatment : a review

Quantitative image analysis techniques have gained an undeniable role in several fields of research during the last decade. In the field of biological wastewater treatment (WWT) processes, several computer applications have been developed for monitoring microbial entities, either as individual cells or in different types of aggregates. New descriptors have been defined that are more reliable, objective, and useful than the subjective and time-consuming parameters classically used to monitor biological WWT processes. Examples of this application include the objective prediction of filamentous bulking, known to be one of the most problematic phenomena occurring in activated sludge technology. It also demonstrated its usefulness in classifying protozoa and metazoa populations. In high-rate anaerobic processes, based on granular sludge, aggregation times and fragmentation phenomena could be detected during critical events, e.g., toxic and organic overloads. Currently, the major efforts and needs are in the development of quantitative image analysis techniques focusing on its application coupled with stained samples, either by classical or fluorescent-based techniques. The use of quantitative morphological parameters in process control and online applications is also being investigated. This work reviews the major advances of quantitative image analysis applied to biological WWT processes.The authors acknowledge the financial support to the project PTDC/EBB-EBI/103147/2008 and the grant SFRH/BPD/48962/2008 provided by Fundacao para a Ciencia e Tecnologia (Portugal)

Benthic Invertebrates of a Large, Sandy River System: The Green and Colorado Rivers of Canyonlands National Park, Utah

From July, 1994 to November, 1995 we sampled the benthos of the Green and Colorado Rivers of Canyonlands National Park, Utah at the request of the United States National Park Service. This study was conceived with a goal of establishing baseline densities of invertebrates in these rivers in preparation for a long-term biomonitoring program. Four remote sites were sampled on each river during each of seven trips. At each site, benthic organisms retained by a 63-mu m mesh were collected from three habitats: sand runs - regions of strong downstream flow and a coarse, shifting substrate; sand beaches - depositional regions with slower currents and finer substrates; and backwaters - cut-off channels with no downstream flow, typically with the finest substrate and no current. Densities of meiofauna and macroinvertebrates were estimated. Three taxa dominated the community: Nematoda, Rotifera, and Oligochaeta. Ostracods and cladocera were common under certain conditions. We identified 28 genera of chironomids and 29 species from 11 families of rotifers. Analysis of variance indicated that total invertebrate densities were different in the three sampled habitats and in the two rivers at different discharge levels. Eighteen separate analyses of variance were employed to test whether the densities of 18 taxa differed significantly between the two rivers, among three habitats, and at different times and discharge levels. Nine taxa exhibited significant differences in density for interactions involving the rivers. Densities of 13 taxa were significantly different between the three habitats or in some interaction involving these habitats. The effects of discharge and/or habitat age were significant for 11 of the taxa. However, these two variables were often significant in the same analyses and in high-order interactions, suggesting that complex dynamics influence the distribution of these organisms

Appendix A. Taxa and taxonomic groups found in the invertebrate gut contents in Broadstone stream, southeast England.

Taxa and taxonomic groups found in the invertebrate gut contents in Broadstone stream, southeast England