Search results for "Plankton"

Turonian-Maastrichtian biostratigraphy and isotope stratigraphy of the Kopet-Dagh Basin deposits, northeastern Neo-Tethys, Iran

2021

Abstract Planktonic foraminiferal biostratigraphy and isotope stratigraphy analyses of Turonian-Maastrichtian deposits have been carried out in the western part of the Kopet-Dagh Basin. The identification of the planktonic foraminiferal assemblages has led to the recognition of twelve Upper Cretaceous zones (Helvetoglobotruncana helvetica Zone to the Contusotruncana contusa-Abathomphalus mayaroensis zone) from the Tethyan realm. The obtained stable carbon isotope profile correlates with other reference curves, revealing many Late Cretaceous events including the Hitchwood, Navigation, Light Point, East Cliff, White Fall, Late Campanian Event (LCE), Campanian-Maastrichtian Boundary Event (CMB…

Millenial-scale paleoenviromental changes in the central Mediterranean during the Last Interglacial: comparison with European and North Atlantic reco…

2010

Abstract The environment of the central Mediterranean Sea is investigated on the basis of high-resolution planktonic foraminifera and calcareous nannofossil data (mean sampling resolutions of about 80 and 160 yr, respectively). MIS 5 is characterized by warm, oligotrophic and stratified waters, while coccolithophore communities developed a vertical zonation that, in today's oceans, is typical of the low-latitude gyres. The temperate-subtropical configuration of planktonic foraminifera and calcareous nannofossil assemblages is repeatedly transformed into a temperate-subpolar one during the suborbital cooling episodes C25-C18. A comparison with European pollen sequences and North Atlantic cor…

Biomarker responses along a pollution gradient: Effects of pulp and paper mill effluents on caged whitefish

1995

Abstract Lake Saimaa (SE Finland) is a large oligotrophic lake receiving biologically treated effluent from a bleached kraft pulp and paper mill. Hatchery-reared juvenile whitefish ( Coregonus lavaretus L. s.l.), a species known to feed on plankton and other particulates, were caged using a technique developed and optimized for this species and were exposed for one month in five downstream stations (3.3–16 km). Two reference stations (4.5–8.5 km) upstream from the effluent outlet were used. An exposure gradient of chlorinated organics was assessed by determining concentrations of conjugated chlorophenolics (CPs) in bile and CPs as well as extractable organic halogens (EOX) in gut lipids. Ac…

Calcifying zooplankton standing stocks and in the North Pacific from the R/V Kilo Moana cruise KM1712

2022

This dataset compiles the standing stocks (ind/m³), the integrated standing stocks (ind/m²) and the integrated CaCO3 standing stocks (mg/m²) for three groups of zooplanktonic calcifying organisms: pteropods, heteropods and foraminifers. The organisms were collected by oblique towing (Ø 0.5 m, 90 μm mesh size, SeaGear mechanical flowmeter) in the North Pacific between Hawaii and the Gulf of Alaska during the R/V Kilo Moana cruise KM1712 in August 2017. The sampling strategy was designed to capture an integrated sample of all foraminifers, pteropods and heteropods from juveniles to adults living throughout the upper water column. Pteropods and heteropods were quantified and shell diameter mea…

Kasviplanktonin kevättalvinen kehitys Lammin Pääjärvessä

2006

Parameter Sensitivity and the Quality of Model Predictions

1994

Using SIM-PEL, a comprehensive model for the pelagic compartment of lake ecosystems, we analyse synergistic toxicant effects in lake ecosystems. We show, that — even for a rather simple model — model predictions may be strongly dependent on the time horizon of the prediction and on the quality of input parameters. For longer time spans, small errors in parameter estimation may lead to qualitatively wrong prediction of toxicant effects. Monte Carlo simulations allow to take errors in parameter estimation into account, but they need rather good estimates of parameter variance.

Early Cambrian origin of modern food webs: evidence from predator arrow worms.

2007

7 pages; International audience; Although palaeontological evidence from exceptional biota demonstrates the existence of diverse marine communities in the Early Cambrian (approx. 540-520 Myr ago), little is known concerning the functioning of the marine ecosystem, especially its trophic structure and the full range of ecological niches colonized by the fauna. The presence of a diverse zooplankton in Early Cambrian oceans is still an open issue. Here we provide compelling evidence that chaetognaths, an important element of modern zooplankton, were present in the Early Cambrian Chengjiang biota with morphologies almost identical to Recent forms. New information obtained from the lowermost Cam…

Eutrophication control by lime addition: A preliminary approach in Sicilian reservoirs

2003

Sicilian reservoirs, a vital resource for this densely populated island, are undergoing increased eutrophication processes, due to the lack of urban waste treatment plants and to intense agriculture. Massive blooms of toxic cyanobacteria represent one of the most obvious consequences, and can be dangerous for population health. The possibility of a fast, even if only short term, recovery of water quality through application of lime, was tested through analysis of ion dynamics in two reservoirs, to develop an `emergency plan', to counteract cyanobacterial blooms and to decrease the risk for human health. The results indicate that these water bodies are suitable for lime treatments, even thou…

Morphological stasis of two species belonging to the L-morphotype in the Brachionus plicatilis species complex

2006

Detection and characterization of sibling species complexes in zooplankton are critical to understanding their ecological responses and patterns of evolution. The taxon Brachionus plicatilis is a complex of at least 14 species with three major, deeply diverged clades, which are morphologically distinct. We studied morphometric differences between two species — B. plicatilis sensu stricto and B. ‘Manjavacas’ — which belong to the L-(large) morphotype and often co-occur in ponds or lakes. B. plicatilis s.s. was on average 6% longer than B. ‘Manjavacas’. They differed significantly in the measurements related to lorica spines. A significant discriminant function relating spine measurements was…

Aquatic invertebrate assemblages in ponds from coastal Mediterranean wetlands

2014

Invertebrate aquatic assemblages in ponds from Mediterranean wetlands are composed of organisms belonging to different taxonomic groups, which present a wide range of sizes (from small rotifers to large crustaceans or insects). Although they are often sampled and analyzed separately, the ecological links among these organisms should be considered, especially in very shallow waters. In our study, invertebrate assemblages (including micro-, macrozooplankton and macroinvertebrates) were characterized in eight shal- low lakes from Mediterranean wetlands in Southeastern Spain. A great spatial and temporal variability in the assemblages and in some environmental features was observed. The communi…