Search results for "Periphyton"
showing 10 items of 22 documents
Within-lake variability in carbon and nitrogen stable isotope signatures
2006
SUMMARY 1. We assessed spatial and temporal variation in carbon and nitrogen isotopic signatures in different compartments of a single lake ecosystem. Stable isotope analyses were made on samples of particulate organic matter (POM), zooplankton, periphyton, macrophytes, macroinvertebrates and fish collected from several locations throughout the ice-free period. 2. No spatial variation in d 13 Co rd 15 N values was found for pelagic samples of POM and zooplankton. However, pelagic d 15 N signatures increased steadily through the summer resulting in an almost 6& average increase in POM and zooplankton. A concurrent decrease in epilimnetic nitrate concentrations suggested that the increase in …
Restoration of two small Mediterranean lagoons: The dynamics of submerged macrophytes and factors that affect the success of revegetation
2013
Abstract Two small, shallow lagoons newly created from former rice fields in the Mediterranean coast (Albufera de Valencia Natural Park, Spain) were restored by planting several species of submerged macrophytes (Myriophyllum spicatum, Ceratophyllum demersum, Potamogeton spp., Zannichellia peltata and Ranunculus peltatus) in 2008. Charophytes also appeared spontaneously. M. spicatum was the species that dominated both lagoons and almost completely covered their surface. M. spicatum reached a high biomass and displayed a seasonal pattern, declining during the cold season and reappearing in the spring. No submerged vegetation was observed in the lagoons from 2011 onward. The major purpose of t…
Effects of fish-farm biodeposition on periphyton assemblages on artificial substrates in the southern Tyrrhenian Sea (Gulf of Castellammare, Sicily)
2007
An algal assemblage growing on artificial substrata of fish-farm cages was investigated. Specifically, algal response to the effects of fish-farm facilities was studied, in order to identify a possible future descriptor of biodeposition impact. Some sites were positioned upstream of the farms (at least 750 m; ‘controls’) and other sites were positioned downstream of the farms (‘impacts’). All sites were situated in the Tyrrhenian Sea. Control and impact sites differed significantly with regard to the dissolved nutrient profile. The fouling community (samples were scraped from buoys) displayed a reduction gradient in diversity which increased with the effect of fish farms. A total of 51 taxa…
Exposure of benthic microbial communities to pharmaceuticals and resulting adaptation including tolerance, biodegradation and antibiotic resistance: …
2022
International audience; Since the early 1920’s, pharmaceuticals, including antibiotics, have been massively producedand consumed for the benefit of both human and animal health. Pharmaceuticals residues havethen reached the aquatic environment through diffuse and point (wastewater) sources. Amongthe pharmaceutical residues, the ubiquitous presence of antibiotics could exert a selectivepressure on microbial communities leading to the acquisition and dissemination of antibioticresistance in the environment.We present here the synthesis of recent research projects (e.g. PANDORE, Antibio-tools,Antibiotox, PharmaTox...) investigating the dissemination of pharmaceuticals, includingantibiotics, in…
Effects of an invasive crayfish on the littoral macroinvertebrates of large boreal lakes are habitat specific
2013
Summary Invasive crayfish are widely acknowledged to have negative effects on benthic food webs in lakes, but few studies have investigated such effects at wider spatial scales and in varying habitats under natural conditions. We examined the effects of introduced signal crayfish (Pacifastacus leniusculus) on the macroinvertebrate assemblages of different habitats in two large boreal lakes. We evaluated whether the density, taxon richness and species composition are altered by the non-native crayfish and whether the responses are similar for stony and vegetated habitats and across a depth gradient. We also studied the influence of crayfish on periphyton biomass at stony sites, as a potentia…
Atrazine uptake, elimination, and bioconcentration by periphyton communities and Daphnia magna: effects of dissolved organic carbon.
2001
The bioconcentration and toxicokinetics of atrazine in three different periphyton communities and in laboratory reared Daphnia magna were studied in natural and artificial waters with different dissolved organic carbon (DOC) concentrations and qualities. The exposure concentrations were similar to those short-lived peak concentrations found in contaminated waters. Atrazine uptake and elimination were very fast, and the bioconcentration was low both in periphyton and D. magna. The bioconcentration factors in D. magna were approx. 16% of those in periphyton. The uptake and elimination rates were also higher in periphyton than in Daphnia. The periphyton properties affected the bioconcentration…
Periphyton pigment analyses using paper chromatography
1983
Paper chromatography was used to study the community structure, the proportion of degraded chlorophylls to the total pigment content, and the chlorophyll and carotenoid content of the epilithic periphyton algae from Lake Tahoe, California-Nevada. Analyses were made using both samples directly from the lake and cultured periphytic algae. The extraction was made with boiling 100% methanol; two dimensional chromatography was used to separate the pigments. The relative contribution of different pigment fractions to total light absorption by the complete periphyton extract was estimated by planimetric integration of absorption curves. From the pigment structure, estimates were made of the propor…
Littoral energy pathways in highly humic boreal lakes
2017
Littoral zones in lakes are among the most productive habitats in the world, but have been seriously understudied, as most limnological studies have concerned only pelagic habitats. The likely importance of littoral zones in clear lakes is widely acknowledged, but in contrast their role in dystrophic humic lakes has generally been assumed to be minor. In this thesis, littoral importance in whole-lake metabolism was studied in small and highly humic lakes in Southern Finland, where Lake Mekkojärvi was the principal study lake. Primary production (PP) measurements revealed that littoral periphyton, growing on surrounding aquatic vegetation, can dominate the whole-lake PP, and the highly autot…
Littoral contribution to whole-lake primary production in highly humic Lake Mekkojärvi
2013
Suurin osa koko järven perustuotantoa käsittelevistä tutkimusta on tehty oligotrofisissa tai eutrofisissa järvissä ja vähän on tutkittu dystrofisten järvien toimintaa. Tämän tutkimuksen tarkoitus oli selvittää litoraalivyöhykkeen perustuotannon osuutta koko järven perustuotannosta dystrofisessa Mekkojärvessä vuonna 2012. Mekkojärvessä on korkeat liuennen orgaanisen hiilen (DOC) ja humushappojen pitoisuudet ja näiden tuloksena erittäin matala valon tunkeutuvuus, suhteellisen matala ravinnepitoisuus ja suhteellisen korkea keskisyvyyden suhde maksimisyvyyteen. Mallit, jotka perustuvat edellä mainittuihin parametreihin, ennustavat pohjaleville vain 5 % osuutta kokonaisperus…
Accounting for littoral primary production by periphyton shifts a highly humic boreal lake towards net autotrophy
2016
1. The prevailing view that many humic lakes are net heterotrophic is commonly based on pelagicmeasurements alone. Poor light conditions in humic lakes are assumed to constrain littoral primaryproduction (PP), such that the littoral zone has been considered an insignificant contributor towhole-lake PP. However, that assumption is based on models and inferences from pelagic processeswhich do not take littoral zone structure into account. Many lakes have an extensive ring of aquaticvegetation lying near the water surface, which provides substratum for epiphytic algae under well-illuminated conditions.2. We measured both pelagic and littoral PP and community respiration (CR) in Mekkoj€arvi, a s…