Study Of Aquatic Systems Research Articles

Predator identity and additive effects in a treehole community.

Multiple predator species can interact as well as strongly affect lower trophic levels, resulting in complex, nonadditive effects on prey populations and community structure. Studies of aquatic systems have shown that interactive effects of predators on prey are not necessarily predictable from the direct effects of each species alone. To test for complex interactions, the individual and combined effects of a top and intermediate predator on larvae of native and invasive mosquito prey were examined in artificial analogues of water-filled treeholes. The combined effects of the two predators were accurately predicted from single predator treatments by a multiplicative risk model, indicating additivity. Overall survivorship of both prey species decreased greatly in the presence of the top predator Toxorhynchites rutilus. By itself, the intermediate predator Corethrella appendiculata increased survivorship of the native prey species Ochlerotatus triseriatus and decreased survivorship of the invasive prey species Aedes albopictus relative to treatments without predators. Intraguild predation did not occur until alternative prey numbers had been reduced by approximately one-half. Owing to changes in size structure accompanying its growth, T. rutilus consumed more prey as time progressed, whereas C. appendiculata consumed less. The intermediate predator, C. appendiculata, changed species composition by preferentially consuming A. albopictus, while the top predator, T. rutilus, reduced prey density, regardless of species. Although species interactions were in most cases predicted from pairwise interactions, risk reduction from predator interference occurred when C. appendiculata densities were increased and when the predators were similarly sized.

Habitat complexity and sex-dependent predation of mosquito larvae in containers

Studies in aquatic systems have shown that habitat complexity may provide refuge or reduce the number of encounters prey have with actively searching predators. For ambush predators, habitat complexity may enhance or have no effect on predation rates because it conceals predators, reduces prey detection by predators, or visually impairs both predators and prey. We investigated the effects of habitat complexity and predation by the ambush predators Toxorhynchites rutilus and Corethrella appendiculata on their mosquito prey Aedes albopictus and Ochlerotatus triseriatus in container analogs of treeholes. As in other ambush predator-prey systems, habitat complexity did not alter the effects of T. rutilus or C. appendiculata whose presence decreased prey survivorship, shortened development time, and increased adult size compared to treatments where predators were absent. Faster growth and larger size were due to predator-mediated release from competition among surviving prey. Male and female prey survivorship were similar in the absence of predators, however when predators were present, survivorship of both prey species was skewed in favor of males. We conclude that habitat complexity is relatively unimportant in shaping predator-prey interactions in this treehole community, where predation risk differs between prey sexes.

Vingt-cinq ans de recherches en hydroécologie à la Direction des Etudes et Recherches d'EDF

Hydroecology (or aquatic ecology) is the study of aquatic systems in their three interacting aspects: physical, chemical and biological. The creation in 1974 of the Environment Department at EDF Research and Development Division marked the start in France of quantitative hydroecology applied so power generation installations. The studies developed around several main themes, determined both by the expansion of the nuclear power programme and by changes in French environmental regulations, in particular the 1976 law on impact studies, the 1984 fishing and hydrobiology law and the 1992 water law.In this framework, the effect of artificial warming of rivers, eutrophication of continental and marine waters, transfers of mineral micropollutants and radionuclides in rivers, and problems specific to hydropower installations such as guaranteed instream flow or fish pass design, have been studied.This work, conducted in collaboration with many other research laboratories, has led to the development of original quantitative approaches, notably in the field of numerical modelling. The paper selects several of the tools developed whose scope of application is wider than the environment and management of thermal or hydropower plants. Two major applications grouping the experience acquired in hydroecology are presented: the AGIRE software and the global environmental study of the Singrauli area in India.

Feeding Preference of Pteronarcys pictetii (Plecoptera: Insecta) from a Small, Acidic, Woodland Stream

Laboratory experiments evaluated leaf preference, using the stonefly, Pteronarcys pictetii Hagen, and differentially incubated red titi leaves, Cyrilla racemiflora L., from naturally acidic streams in northwestern Florida. Leaves were incubated from 0-8 weeks in the field and provided as food to P. pictetii nymphs in the laboratory. Incubated leaves were strongly preferred over non-incubated leaves, with a tendency for increased preference with increased incubation length. This tendency paralleled a decrease in leaf ash-free dry weight, an increase in fungal colonization of the leaves, and an increase in leaf protein through microbial colonization. Plate counts revealed low numbers of bacteria on leaf surfaces throughout the study. These findings generally agree with those from similar studies in aquatic systems of higher pH.

Automated continuous flow analysis in the study of aquatic systems

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAutomated continuous flow analysis in the study of aquatic systemsWayne E. McDiffett , Hans Veening , and Robert Comte Cite this: J. Chem. Educ. 1972, 49, 7, 510Publication Date (Print):July 1, 1972Publication History Received3 August 2009Published online1 July 1972Published inissue 1 July 1972https://doi.org/10.1021/ed049p510RIGHTS & PERMISSIONSArticle Views33Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts