Search results for "macroinvertebrate"

Growth and population structure of perch in relation to diet in a small humic lake, Valkea-Kotinen

2011

Lake Valkea-Kotinen is a long-term ecological monitoring site in the Evo region of southern Finland .The aim of this study was to investigate the growth and population structure of perch (Perca fluviatilis L.) in relation to diet in Valkea-Kotinen in order to provide reference data for a study investigating effects of increased loading of dissolved organic matter to nearby Lake Alinen Mustajärvi. Valkea-Kotinen was predominantly inhabited by small benthivorous perch. The growth relationship between opercular bone and total length of perch in the lake is similar to those earlier analysed for nearby lakes. Compared to wider growth rates, the growth of perch was slow and similar to those in si…

Subtropical streams harbour higher genus richness and lower abundance of insects compared to boreal streams, but scale matters

2018

Aim: Biological diversity typically varies between climatically different regions, and regions closer to the equator often support higher numbers of taxa than those closer to the poles. However, these trends have been assessed for a few organism groups, and the existing studies have rarely been based on extensive identical surveys in different climatic regions. Location: We conducted standardized surveys of wadeable streams in a boreal (western Finland) and a subtropical (south-eastern Brazil) region, sampling insects identically from 100 streams in each region and measuring the same environmental variables in both regions. Taxon: Aquatic insects. Methods: Comparisons were made at the scale…

Oceka kačectva tekuŝih vod na osnovanii analiza kompleksa donnoj makrofauny. Primer monitoringa reki Śčinava Nemodlinska (Polʺša) v 1999-2005 godah

2008

Assessment of possibilities of the biotic index application in the biological monitoring of the running water quality

2003

Niche position drives interspecific variation in occupancy and abundance in a highly-connected lake system

2019

Highlights • We studied interspecific variation in occupancy and abundance of freshwater species. • Occupancy and abundance correlated positively for both diatoms and macroinvertebrates. • Niche position had clearest effects on variation in occupancy and abundance. • The more marginal the niche position, the rarer a species is. We examined how niche position, niche breadth, biological traits and taxonomic relatedness affect interspecific variation in occupancy and abundance of two commonly-used biological indicator groups, i.e. diatoms and macroinvertebrates. We studied 291 diatom and 103 macroinvertebrate species that occupied the littoral zones of a large (305 km2) highly-connected freshw…

The adaptations to tube-dwelling life of Propsilocerus akamusi (Diptera: Chironomidae) larvae and its eutrophication-tolerant mechanisms

2019

Propsilocerus akamusi (Diptera: Chironomidae) is a dominant macroinvertebrate species in many eutrophic lakes in subtropical and temperate zones. P. akamusi larvae can migrate deep into the sediment (>30 cm) during summer where is no oxygen. However, to our knowledge, the specific adaptive tactics of its tube-dwelling life (>30 cm) and underlying mechanisms why this species is favored by nutrient-rich lakes remain limited. With the understanding above-mentioned issues, we can provide important information for the development of sensitive biomonitoring. We examined monthly morphological dynamics and physiological adaptations of P. akamusi to anoxic conditions, and environmental relationships…

Predictive models in assessment of macroinvertebrates in boreal rivers

2009

Jukka Aroviita tutki väitöskirjassaan jokien ja purojen biologisen tilan mittaamismenetelmiä. Aroviita osoitti, että ihmistoiminnan aiheuttamat biologiset muutokset voivat jäädä havaitsematta, jos eliöyhteisöjen luonnollista taustavaihtelua ei oteta kunnolla huomioon.- Tällöin vesistöjen saatetaan arvioida olevan paremmassa kunnossa kuin ne todellisuudessa ovatkaan. Muutosten tunnistamistarkkuuden tulisi olla mahdollisimman hyvä, sillä tila-arvioilla on myös juridisesti määräytyviä yhteiskunnallisia ja taloudellisia seuraamuksia, Aroviita toteaa. Vielä 1990-luvulla järvien ja jokien tilaa arvioitiin suurelta osin ihmisen näkökulmasta ja veden kemian perusteella. Nykylainsäädäntö edellyttää …

Fish introductions and light modulate food web fluxes in tropical streams : a whole-ecosystem experimental approach

2016

Decades of ecological study have demonstrated the importance of top-down and bottom-up controls on food webs, yet few studies within this context have quantified the magnitude of energy and material fluxes at the whole-ecosystem scale. We examined top-down and bottom-up effects on food web fluxes using a field experiment that manipulated the presence of a consumer, the Trinidadian guppy Poecilia reticulata, and the production of basal resources by thinning the riparian forest canopy to increase incident light. To gauge the effects of these reach-scale manipulations on food web fluxes, we used a nitrogen (15N) stable isotope tracer to compare basal resource treatments (thinned canopy vs. con…

Improving statistical classification methods and ecological status assessment for river macroinvertebrates

2016

Aquatic ecosystems are facing a growing number of human-induced stressors and the need to implement more biomonitoring to assess the ecological status of water bodies is eminent. This dissertation aims at providing tools to reduce the costs and improve the accuracy of freshwater benthic macroinvertebrate biomonitoring. To improve the cost-e ciency, we consider automated classi cation and develop a novel classi er suitable for complex macroinvertebrate image data. To enhance the accuracy of macroinvertebrate biomonitoring, we study the statistical properties of the Percent Model A nity index crucial to current Finnish biomonitoring and the factors a ecting these statistics. Finally, we perfo…

Benthic foodweb structure in a large shallow lake studied by stable isotope analysis

2014

The benthic foodweb structure of Lake Võrtsjärv, a large (270 km2), shallow, and turbid Estonian lake, was evaluated based on C and N stable-isotope signatures (δ13C, δ15N). Variation in δ13C between sampling sites was not related to site proximity to the littoral zone or the more vegetated southern part of the lake, but rather appeared to be influenced by in-situ site peculiarities. δ13C was stable temporally and between functional feeding groups, a result implying that the whole benthic food web of the lake relies largely on the same C source admixture, essentially particulate organic matter (POM). Thus, the foodweb composition of Lake Võrtsjärv is remarkably homogeneous given the lake’s …