Search results for "lakes"

Planktivorous vendace (Coregonus albula) utilise algae-derived fatty acids for biomass increase and lipid deposition

2018

Spatial and seasonal variation in the abundance and composition of phytoplankton and other basal resources (bacteria, terrestrial detritus) influence the availability of essen-tial polyunsaturated fatty acids (PUFA) for upper trophic levels in lake food webs. We studied accumulation, composition and content of fatty acids in planktivorous ven-dace (Coregonus albula) muscle tissue during the summer feeding period (May to late September) in six boreal lakes. Vendace muscle fatty acid content increased from ~17.7 mg/g DW to ~28.1 mg/g DW from spring to summer, corresponding to a ~59% increase in total fatty acids. PUFA accounted for 45%–65% of all fatty acids, and the most abundant fatty acid …

Dikerogammarus villosus (Sowinsky, 1894) (Crustacea, Amphipoda) colonizes next alpine lake – Lac du Bourget, France.

2007

4 pages; Dikerogammarus villosus has been recorded for the first time in the alpine lake – Lac du Bourget, French Alps. Low abundance of the alien species in gathered samples suggests that the colonization is just in its initial stage. Two native gammarid species: Gammarus fossarum (Koch, 1835) and G. pulex (Linnaeus, 1758) are still present in the lake. The invader has most probably reached the lake through the Canal de Savières joining the lake to the Rhone River in which it has been already present since late 1990s.

The introduced signal crayfish and native noble crayfish have different effects on sublittoral macroinvertebrate assemblages in boreal lakes

2015

Lake zooplankton δ13C values are strongly correlated with the δ13C values of distinct phytoplankton taxa

2016

Analyses of carbon stable isotopes are often used to estimate the contributions of allochthonous and autochthonous dietary resources to aquatic consumers. Most pelagic food web studies assume that all phytoplankton taxa have a similar δ13C value. We studied pelagic food web compartments (dissolved inorganic carbon [DIC], phytoplankton, bacteria, seston, cladoceran zooplankton) in 12 small (< 0.1 km2) lakes in southern Finland. These lakes were classified as oligotrophic, mesotrophic, eutrophic, and dystrophic based on their concentrations of total phosphorus and dissolved organic carbon. Additionally, we studied phytoplankton photosynthetic carbon fractionation (εp) in laboratory conditions…

Alkane dehydrogenation on defective BN quasi-molecular nanoflakes: DFT studies

2020

Lower alkanes are feedstocks readily available but relatively inert. The con- version of low cost alkanes to industrially relevant alkenes is usually carried out on metal-based heterogeneous catalysts. Considering both the cost and the potential harmfulness of the metal involved in the dehydrogenation cat- alysts (typically, platinum or chromium), the study of metal-free processes represents an important challenge for the industrial chemistry in order to address more sustainable protocols and different routes either to activate or transform alkanes. Framed in this context, it was investigated, using a den- sity functional theory approach, the potential dehydrogenation activity of de- fectiv…

Distinct and diverse anaerobic bacterial communities in boreal lakes dominated by candidate division OD1

2012

Lakes have a central role in the carbon cycle of the boreal landscape. These systems typically stratify in summer and their hypolimnetic microbial communities influence burial of biogenic organic matter in sediments. The composition of bacterial communities in these suboxic habitats was studied by pyrosequencing of 16S rRNA amplicons from five lakes with variable dissolved organic carbon (DOC) concentrations. Bacterioplankton communities in the hypolimnetic waters were clearly different from the surface layer with candidate division OD1, Chlorobi and Bacteroidetes as dominant community members. Several operational taxonomic units (OTUs) affiliated with candidate division OD1 were abundant a…

Is there light after depth? Distribution of periphyton chlorophyll and productivity in lake littoral zones

2014

Periphyton and phytoplankton contribute to the base of lake food webs, and both groups of microalgae are influenced by resources and physical forcing. Spatial variation in light availability interacts with the physical dynamics of the water column to create predictable depth gradients in resources and disturbance that may differentially affect periphyton vs phytoplankton. We characterized the depth distribution of chlorophyll and productivity of periphyton on sediments (epipelon) and phytoplankton in the euphotic zones of 13 oligomesotrophic lakes that span a large size gradient (0.017–32,600 km2 ). Epipelic chlorophyll usually increased with depth in the epilimnion. Light was the primary d…

Factors controlling hydrochemical and trophic state variables in 86 shallow lakes in Europe

2003

In order to disentangle the causes of variations in water chemistry among European shallow lakes, we performed standardised sampling programs in 86 lakes along a latitudinal gradient from southern Spain to northern Sweden. Lakes with an area of 0.1 to 27 000 ha and mean depth of 0.4–5.6 m located in low to high altitudes were investigated within the EC project ECOFRAME 1–4 times during June–October 2000–2001. Several variables like conductivity, alkalinity, abundance of submerged plants, concentrations of suspended solids, total nitrogen and phosphorus were latitude-dependent decreasing from south to north. Secchi depth, concentrations of total nitrogen, total phosphorus, suspended solids, …

Influence of littoral periphyton on whole-lake metabolism relates to littoral vegetation in humic lakes

2017

The role of littoral habitats in lake metabolism has been underrated, especially in humic lakes, based on an assumption of low benthic primary production (PP) due to low light penetration into water. This assumption has been challenged by recent recognition of littoral epiphyton dominance of whole-lake PP in a small highly humic lake and of epiphyton as an important basal food source for humic lake biota. However, as these studies have mostly concerned single lakes, there is a need to test their wider generality. We studied the whole-lake PP and community respiration (CR) in eight small humic lakes in southern Finland during July 2015 using 14C incorporation to measure pelagic PP and the ch…

Rumicetum palustris (TIMÁR 1950) W. FISCHER 1978, new plant community from Bidentetea tripartiti R. Tx., LOHM. ET Prsg 1950 class in SW Poland

2016

Natural water reservoirs are very valuable floristic sites in Poland. Among them, the most important for preservation of biodiversity of plant communities are lakes, rivers, oxbow lakes and fishponds. The long-term process of human pressure on habitats of this type caused disturbance to their biological balance. Changes in the water regime, industrial development and chemisation of agriculture, especially in the period of last two hundred years, led to systematic disappearance of localities of many plant communities. Rumicetum palustris (Timár 1950) W. Fischer 1978, of Bidentetea tripartiti R. Tx., Lohm. et Prsg 1950 class, has been described for the first time in Hungary and Germany. This …