Search results for "freshwater"
showing 10 items of 285 documents
Effects of predation pressure and resource use on morphological divergence in omnivorous prey fish
2013
Background. Body shape is one of the most variable traits of organisms and responds to a broad array of local selective forces. In freshwater fish, divergent body shapes within single species have been repeatedly observed along the littoral-pelagic axes of lakes, where the structural complexity of near shore habitats provides a more diverse set of resources compared to the open-water zones. It remains poorly understood whether similar resource-driven polymorphism occurs among lakes that vary in structural complexity and predation pressure, and whether this variation is heritable. Here, we analyzed body shape in four populations of omnivorous roach (Rutilus rutilus) inhabiting shallow lakes.…
Comparison of Diatoms and Dinoflagellates from Different Habitats as Sources of PUFAs
2019
Recent studies have clearly shown the importance of omega-3 (&omega
Isolation and determination of phenolic compounds from freshwater Cladophora glomerata
2020
Abstract Marine algae biomass has gained widespread interest in the world of science and many industries. The growing number of publications proves that these algae are an interesting and essential natural resource. This interest is due to the presence of a variety of biologically active compounds that give algae extracts a broad spectrum of biological and functional properties. However, there is little data on the chemical composition of algae obtained from freshwater. This work focuses on the isolation and determination of phenolic compounds from freshwater algae of the species Cladophora glomerata. Different types of extraction and extractants were used to isolate these bioactive compoun…
Stream restorations with meanders increase dragonfly and damselfly diversity and abundance, including an endangered species.
2021
10 pages; International audience; This study presents examples of successful restoration projects for biodiversity conservation. In West France, the Pinail National Nature Reserve is a protected wetland interspersed with more than 6000 ponds. This wetland is inhabited by 50 species of Odonata and thus is a key biodiversity area for damselflies and dragonflies conservation. In the past, when the limestone was exploited, the streams of the plateau were artificially channeled rectilinearly, running to the Vienne River. Eventually streams were blocked by biomass and sediments resulting in water flowing mainly underground. In 2011, two restoration projects dug and recreated lost habitats such as…
Climate Warming as a Possible Trigger of Keystone Mussel Population Decline in Oligotrophic Rivers at the Continental Scale
2018
AbstractThe effects of climate change on oligotrophic rivers and their communities are almost unknown, albeit these ecosystems are the primary habitat of the critically endangered freshwater pearl mussel and its host fishes, salmonids. The distribution and abundance of pearl mussels have drastically decreased throughout Europe over the last century, particularly within the southern part of the range, but causes of this wide-scale extinction process are unclear. Here we estimate the effects of climate change on pearl mussels based on historical and recent samples from 50 rivers and 6 countries across Europe. We found that the shell convexity may be considered an indicator of the thermal effe…
Temperature controls organic carbon sequestration in a subarctic lake
2016
AbstractWidespread ecological reorganizations and increases in organic carbon (OC) in lakes across the Northern Hemisphere have raised concerns about the impact of the ongoing climate warming on aquatic ecosystems and carbon cycling. We employed diverse biogeochemical techniques on a high-resolution sediment record from a subarctic lake in northern Finland (70°N) to examine the direction, magnitude and mechanism of change in aquatic carbon pools prior to and under the anthropogenic warming. Coupled variation in the elemental and isotopic composition of the sediment and a proxy-based summer air temperature reconstruction tracked changes in aquatic production, depicting a decline during a coo…
Long-Term Phytoplankton Dynamics in a Complex Temporal Realm
2019
AbstractFaced with an environment of accelerated change, the long-term dynamics of biotic communities can be approached to build a consistent and causal picture of the communities’ life. We have undertaken a 25-year monthly-sampling study on the phytoplankton of a meso-oligotrophic lake, paying attention to controlling factors of overall biomass (TB) and taxonomical group biomass (TGBs). Long-term series included decreased trends of TB and TGBs, and multi-scale periodicity. A decadal TB periodicity emerged related to nitrogen concentration and Cryptophytes. Annual periodicities were mainly related to air and water temperature controlling the abundance of Chlorophytes or Dinoflagellates. Int…
Resource polymorphism in European whitefish: Analysis of fatty acid profiles provides more detailed evidence than traditional methods alone
2019
Published version, licensed CC BY-NC-ND 4.0. , available at: http://dx.doi.org/10.1371/journal.pone.0221338 Resource polymorphism—whereby ancestral generalist populations give rise to several specialised morphs along a resource gradient—is common where species colonise newly formed ecosystems. This phenomenon is particularly well documented in freshwater fish populations inhabiting postglacial lakes formed at the end of the last ice age. However, knowledge on how such differential exploitation of resources across contrasting habitats might be reflected in the biochemical compositions of diverging populations is still limited, though such patterns might be expected. Here, we aimed to assess …
Resource Partitioning in Food, Space and Time between Arctic Charr (Salvelinus alpinus), Brown Trout (Salmo trutta) and European Whitefish (Coregonus…
2017
Arctic charr and European whitefish are considered to be strong competitors in lakes, with the latter usually being the superior species. However, high niche plasticity and lake morphometry may suggestively facilitate resource partitioning and coexistence between charr and whitefish. Here, we explore the trophic niche utilization (diet and habitat use) of charr and whitefish co-occurring with brown trout in the deep and oligotrophic Lake Fyresvatnet, southern Norway (59˚05’N, 8˚10’E). Using CPUE, stomach contents and stable isotope analyses, a distinct resource partitioning was revealed between brown trout and the other two species. Brown trout typically occupied the littoral zone, feeding …
Distribution and seasonal dynamics of Cryptomonads in Sicilian water bodies
2003
Several species with a relevant ecological importance belong to Cryptophyta. Nevertheless, species-level identification from microscopic observations is problematic, lacking recent taxonomic keys. In this study we report our observations on distribution and seasonal dynamics of Cryptomonads in 33 Sicilian water bodies, as well as the main taxonomical problems we encountered. Species of the genera Cryptomonas and Plagioselmis are the most common in the examined water bodies. Their biomass seasonal trends usually show a peak in late winter and early spring. In advanced spring, and also in summer, due to the higher grazing pressure, the Cryptomonads biomass reaches its lowest values. Moreover,…