Search results for "Periphyton"
showing 10 items of 22 documents
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 14 C incorporation to measure pelagic PP and the c…
Periphyton support for littoral secondary production in a highly humic boreal lake
2016
Steep stratification and poor light penetration in highly humic lakes typically restrict oxygenated littoral areas to narrow lake margins. However, in some instances, surrounding floating vegetation mats can sustain highly productive periphyton and more diverse invertebrate communities than pelagic areas. Little is known about how these littoral food webs function or the extent to which the pelagic and littoral food webs are coupled. We added 15N-labeled ammonium nitrate to the floating moss mat surrounding the littoral zone of Mekkojärvi, a small highly humic and fishless lake in southern Finland. Our goal was to increase the δ15N values of periphyton to investigate the diets of littoral i…
Diet and trophic niche of the invasive signal crayfish in the first invaded Italian stream ecosystem.
2021
The occurrence of the signal crayfsh Pacifastacus leniusculus in the Valla Stream was the frst established population of this invasive species recorded in an Italian stream ecosystem. We evaluated the seasonality of diet and trophic niche of invasive signal crayfsh in order to estimate the ecological role and efects on native communities of the stream ecosystem. We studied the diferences in food source use between sexes, life stages and seasons using carbon and nitrogen stable isotope analyses. To supplement stable isotope analyses, we evaluated food source usage using traditional stomach content analysis. We tested the hypothesis that juveniles have a diferent diet, showing diferent trophi…
Responses of marine benthic microalgae to elevated CO2
2011
Increasing anthropogenic CO emissions to the atmosphere are causing a rise in pCO concentrations in the ocean surface and lowering pH. To predict the effects of these changes, we need to improve our understanding of the responses of marine primary producers since these drive biogeochemical cycles and profoundly affect the structure and function of benthic habitats. The effects of increasing CO levels on the colonisation of artificial substrata by microalgal assemblages (periphyton) were examined across a CO gradient off the volcanic island of Vulcano (NE Sicily). We show that periphyton communities altered significantly as CO concentrations increased. CO enrichment caused significant increa…
Epiphytic bacteria make an important contribution to heterotrophic bacterial production in a humic boreal lake
2017
Bacterial production (BP) in lakes has generally only been measured in the pelagic zone without accounting for littoral BP, and studies of BP at the whole-lake scale are very scarce. In the dystrophic humic lakes, which are common throughout the boreal region, low light penetration through water has been assumed to seriously limit available habitats for littoral organisms. However, many highly humic boreal lakes have extensive partly submerged vegetation around the lake perimeter which can provide well-lit substrata for highly productive epiphyton. We measured epiphytic BP on the littoral vegetation and pelagic BP in a small highly humic boreal lake in Finland during an open-water season an…
Mesocosm experiments on nutrient and fish effects on shallow lake food webs in a Mediterranean climate
2004
Summary 1. Nutrient and fish manipulations in mesocosms were carried out on food-web interactions in a Mediterranean shallow lake in south-east Spain. Nutrients controlled biomass of phytoplankton and periphyton, while zooplankton, regulated by planktivorous fish, influenced the relative percentages of the dominant phytoplankton species. 2. Phytoplankton species diversity decreased with increasing nutrient concentration and planktivorous fish density. Cyanobacteria grew well in both turbid and clear-water states. 3. Planktivorous fish increased concentrations of soluble reactive phosphorus (SRP). Larger zooplankters (mostly Ceriodaphnia and copepods) were significantly reduced when fish wer…
Periphyton growth and diatom community structure in a cooling water pond
1982
Periphyton (Aufwuchs) accumulation was measured on artificial substrates in a pond in central Finland which receives warm cooling-water effluent from a power plant. The growth of periphyton was generally more rapid on the substrates during the first two weeks of colonization near the inflow of the warm water effluent than in the middle of the pond. The maximum accumulation of periphyton was in spring and autumn (dry weight maximum at warm effluent was in spring 3.5 mg DW cm−2,2.65 mg AFDW cm−2; chlorophyll a maximum 3.96 µg cm−2 was found in autumn at pond-middle station). During mid-winter months the growth was strongly limited by solar radiation, but the growth was also slow at both stati…
Linking nutrient limitation and water chemistry in upland lakes to catchment characteristics
2003
The relationship between catchment characteristics and lake water chemistry, phytoplankton and periphyton biomass, and phytoplankton and periphyton nutrient limitation was investigated for 30 upland lakes in the U.K. These catchment characteristics included the proportion of different land cover categories in the catchment and some hydrological information. Multiple regression models could predict alkalinity, pH, total dissolved phosphorus, dissolved inorganic nitrogen, dissolved organic nitrogen, dissolved organic carbon and phytoplankton chlorophyll a from the proportional contribution of between two and six land cover categories within the catchment and explain between 42 and 73% of the …
The stream-dwelling larva of the Ruwenzori River Frog, Amietia ruwenzorica, its buccal cavity and pathology of chytridiomycosis
2012
Tadpoles of Amietia ruwenzorica (Pyxicephalidae, Cacosterninae) were collected in the Ruwenzori Mountains, Uganda(identified by DNA barcoding). The ventrally directed enlarged oral disc with a high number of labial tooth rows (LTRF9(4)/9(1)) and the narrow tail with robust caudal musculature characterise them as stream-dwellers. We name this mor-photype the 'common or standard type of stream-adaptation', because special additional adhesive organs are missing in A.ruwenzorica. The uniserially arranged oral teeth of the spoon-shaped type with 16 to 18 cusps per tooth are known fromother anuran larvae, especially from pyxicephalids. The buccal morphology resembles generalized tadpoles with som…
Seasonal succession of phytoplankton in an ice-free pond warmed by a thermal power plant
1982
In a pond receiving warmed cooling waters from a thermal power plant, the physical and chemical properties of the water, phytoplankton, periphyton and zooplankton were monitored on a weekly sampling schedule. In winter the phytoplankton growth was limited by poor light conditions. In mid-February a rapid phytoplankton growth started, simultaneously with increasing light energy, high nutrient concentrations and small herbivorous zooplankton populations. The increase of phytoplankton biomass was stopped by lack of free nutrients and silica at the end of March. From May until August the phytoplankton standing crop was mainly regulated by herbivorous zooplankton. The autumnal maximum of phytopl…