Search results for "Benthic zone"
showing 10 items of 265 documents
Use of the preliminary Jedlice Reservoir for water protection in the Turawa Reservoir on the Mała Panew River
2009
Abstract Physico-chemical variables of water quality and benthic community structure were assessed in order to evaluate the need for reinstating the use of the preliminary Jedlice Reservoir. The waters of the Mała Panew River carry a significant load of nutrient compounds, particularly nitrates and phosphates. Deteriorating water quality results in permanent algal blooms and changes in the macrofauna structure. It was confirmed that the use of a preliminary reservoir could contribute to the protection of the Turawa Dam Reservoir against pollutants transported by the waters of the Mała Panew River.
Ordination analysis and bioindices based on zoobenthos communities used to assess pollution of a lake in southern Finland
1990
The suitability of an ordination method, detrended correspondence analysis (DCA), was tested in assessing the degree of pollution of a large lake on the basis of the zoobenthos communities. Lake Etela-Saimaa, in southern Finland, was originally oligotrophic but is now heavily loaded by effluents from the wood-processing industry. Comparison between areas was complicated by variation in the water depths of the lake sub-basins. A horizontal pollution gradient could, however, easily be detected by means of the DCA in both the profundal and sublittoral zones. The benthic quality index (BQI) based on the composition of the profundal chironomid fauna failed at some stations because the indicator …
Role of hydrological and hydromorphological factors in ecological quality of medium-sized lowland streams
2010
The development of biological communities is an important research issue regarding biological quality elements. However, it is still uncertain how different organism groups and their metrics are affected by different environmental factors. A study of high-quality sites of medium-sized lowland streams typical for Latvia (ecoregion Baltic province) was carried out with an emphasis on hydrological and hydromorphological characteristics. The investigations were carried out within the STAR project using the project designated standard methods. We found that the level of saprobity according to benthic macroinvertebrates was mainly linked with substrate type and stream depth. The trophic diatom in…
Late Turonian climate variability in the Bohemian Cretaceous Basin – A sclerochronological study of Inoceramus hercules shells from the Úpohlavy quar…
2020
Abstract The δ18O record of well-preserved shells of the inoceramid Inoceramus hercules from the Upohlavy working quarry (Czech Republic) provides an insight into the climate variability in the late Turonian benthic environment of the Bohemian Cretaceous Basin. Similar to modern bivalves, this inoceramid species built its shell near equilibrium with the oxygen isotope value of the ambient water. Due to the nearly year-round shell growth, sequentially sampled δ18O values allowed to estimate the narrowest sub-annual temperatures fluctuations that prevailed during lifetime of the organisms. In accordance with previous studies, reconstructed temperatures suggest colder water conditions (19.0 ± …
Additions to knowledge of the biodiversity of benthic hydroids (Cnidaria: Hydrozoa) in the Balleny Islands (Antarctica)
2021
The Balleny Islands, an isolated archipelago located 240 km off the coast of Victoria Land (East Antarctica), are separated from the Antarctic continental shelf by waters more than 2000 m deep. The benthic hydroid fauna of these islands is little known, with only 25 species reported so far. The present study contributes to a better knowledge of the benthic hydrozoans inhabiting this archipelago by studying a small collection held at the National Institute of Water and Atmospheric Research Invertebrate Collection at Wellington, New Zealand. Sixteen species of benthic hydroids were found in the collection, belonging to nine families and 12 genera of Leptothecata. Kirchenpaueriidae and Oswalde…
A hidden species becoming visible : biogeography and ecology of Rhynchotalona latens (Cladocera, Anomopoda, Chydoridae)
2019
A long hidden chydorid (Chydoridae, Cladocera) taxon, first found as fossil specimens and recently redefined as Rhynchotalona latens (Sarmaja-Korjonen et al., Hydrobiologia 436: 165-169, 2000) is investigated for its biogeography and ecology. Late Holocene sediment sequence from Lake Sylvilampi, NE Finnish Lapland, and R. latens spatial distribution in relation to limno-climatic attributes in Finland were examined. Principal component analyses of fossil cladoceran communities showed that R. latens is mostly affiliated with Alonella excisa-Alonopsis elongata-Alonella nana species pool. Generalized linear modeling of R. latens responses to limno-climatic variation indicated that it prefers ac…
Comparison of sampling methods for semipelagic animals in two deep basins of Lake Saimaa
1996
The efficiency of different methods for sampling semipelagic animals was compared in the deep basins of Lake Paasivesi and Lake Puruvesi of the complex Lake Saimaa, Finland, during 1990–92. Certain semipelagic animals, such as Mysis relicta, amphipods and larvae of Chaoborus flavicans, are important bioindicators of water and benthic quality. However, owing to their high mobility and vertical migrations they are difficult to sample quantitatively with traditional benthic methods.
Predicting the bioaccumulation of polyaromatic hydrocarbons and polychlorinated biphenyls in benthic animals in sediments
2016
There were two main objectives in this study. The first was to compare the accuracy of different prediction methods for the chemical concentrations of polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the organism, based on the measured chemical concentrations existing in sediment dry matter or pore water. The predicted tissue concentrations were compared to the measured ones after 28-day laboratory test using oligochaeta worms (Lumbriculus variegatus). The second objective was to compare the bioaccumulation of PAHs and PCBs in the laboratory test with the in situ bioaccumulation of these compounds. Using the traditional organic carbon-water partitioning model, tissue…
Fullerenes(nC60) affect the growth and development of the sediment-dwelling invertebrate Chironomus riparius larvae
2015
Abstract The possible toxicity of nanoparticles (NPs) to aquatic organisms needs to be investigated for chronic effects at low concentrations. Chronic effects of carbon NPs, fullerenesC60, on the midges of Chironomus riparius at different life stages on larvae and adult midges were investigated. Sediment associated fullerenesC60 were studied by 10-day growth and 42-day emergence tests with artificial sediment at nominal concentration ranges 0.0004–80 mg/kg dry weight. The body length decreased in the lower tested concentrations (0.0025–20 mg/kg), but the effect vanished with higher concentrations. Delayed emergence rate observed at 0.5 mg/kg. The observed effects correlated with analyzed se…
The polychaete Platynereis dumerilii (Annelida): a laboratory animal with spiralian cleavage, lifelong segment proliferation and a mixed benthic/pela…
2004
Platynereis dumerilii, a marine polychaetous annelid with indirect development, can be continuously bred in the laboratory. Here, we describe its spectacular reproduction and development and address a number of open research problems. Oogenesis is easily studied because the oocytes grow while floating in the coelom. Unlike the embryos of other model spiralians, the Platynereis embryo is transparent giving insight into the dynamic structures and processes inside the cells that accompany the prevailing anisotropic cleavages. Functional studies on cell specification and differential gene expression in embryos, larvae, and later stages are underway. Lifelong proliferation of uniform trunk segme…