Search results for "Aquatic ecosystem"
showing 10 items of 124 documents
Modeling the Effects of Climate Change on the Supply of Phosphate-Phosphorus
2009
The transfer of phosphorus from terrestrial to aquatic ecosystems is a key route through which climate can influence aquatic ecosystems. A number of climatic factors interact in complex ways to regulate the transfer of phosphorus and modulate its ecological effects on downstream lakes and reservoirs. Processes influencing both the amount and timing of phosphorus export from terrestrial watersheds must be quantified before we can assess the direct and indirect effects of the weather on the supply and recycling of phosphorus. Simulation of the export of phosphorus from the terrestrial environment is complicated by the fact that it is difficult to describe seasonal and inter-annual variations …
Unionid shells (Hyriopsis cumingii) record manganese cycling at the sediment-water interface in a shallow eutrophic lake in China (Lake Taihu)
2017
Abstract Aquatic eutrophication is becoming a serious environmental problem throughout the world. The utility of bivalves as bio-filters to improve water quality and reduce algal blooms has been widely acknowledged, but the potential usefulness of bivalve shells as retrospective monitors of eutrophication-induced environmental change has received little attention. Here, we present the first multi-year, high-resolution Mn/Ca shell records of the freshwater mussel, Hyriopsis cumingii (Lea, 1852) from a shallow eutrophic lake (Lake Taihu, China). Mn/Ca shell time-series of the two studied shells exhibit a high degree of synchrony after being placed in a precise temporal context by means of gro…
Photoreduction of gaseous oxidized mercury changes global atmospheric mercury speciation, transport and deposition
2018
9 pags, 8 figs. -- Correction autor: https://doi.org/10.1038/s41467-022-28455-w http://hdl.handle.net/10261/268181
Response of the aquatic plants and mollusc communities in Lake Kojle (central Europe) to climatic changes between 250 BCE and 1550 CE
2018
Abstract Sediments of Lake Kojle, located in the transition zone between the nemoral and boreal biogeographic zones in NE Poland, were analysed to verify the response of the aquatic ecosystem to major environmental changes. High-resolution plant macrofossil, mollusc and pollen data were derived from two replicate parallel cores and revealed several shifts in the biota composition within the littoral zone between 250 BCE and 1550 CE. The reaction of the aquatic ecosystem to temperature changes was found to be minor, which is ascribed to the mitigating influence of water and the wide ecological tolerance of most of the taxa. Najas marina, considered as an indicator of warmer conditions, was t…
Molecular composition of dissolved organic matter from a wetland plant (Juncus effusus) after photochemical and microbial decomposition (1.25 yr): Co…
2013
We hypothesized that microbial and photochemical processing of dissolved organic matter (DOM) determines its molecular formula composition in aquatic systems to a greater degree than does the original source of the DOM. To test this hypothesis, we exposed DOM from a leachate of a wetland plant (Juncus effusus) to solar radiation or incubated it in the dark for 1.25 yr. Analysis of the extracted DOM of the leachates via Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) identified 2800 molecular formulae. Of the formulae in the initial DOM, 11% were lost during microbial decomposition in the dark and 54% under solar radiation. Solar radiation also produced a large number…
Reevaluating the Role of Organic Matter Sources for Coastal Eutrophication, Oligotrophication, and Ecosystem Health
2019
Organic matter (OM) in aquatic systems is either produced internally (autochthonous OM) or delivered from the terrestrial environment (ter-OM). For eutrophication (or the reverse – oligotrophication), the amount of autochthonous OM plays a key role for coastal ecosystem health. However, the influence of ter-OM on eutrophication or oligotrophication processes of coastal ecosystems is largely unclear. Therefore, ter-OM, or ter-OM proxies are currently not included in most policies or monitoring programs on eutrophication. Nevertheless, ter-OM is increasingly recognized as a strong driver of aquatic productivity: By influencing underwater light conditions and nutrient- and carbon availability,…
Eco‐evolutionary dynamics driven by fishing : from single species models to dynamic evolution within complex food webs
2020
Evidence of contemporary evolution across ecological time scales stimulated research on the eco‐evolutionary dynamics of natural populations. Aquatic systems provide a good setting to study eco‐evolutionary dynamics owing to a wealth of long‐term monitoring data and the detected trends in fish life‐history traits across intensively harvested marine and freshwater systems. In the present study, we focus on modelling approaches to simulate eco‐evolutionary dynamics of fishes and their ecosystems. Firstly, we review the development of modelling from single‐species to multispecies approaches. Secondly, we advance the current state‐of‐the‐art methodology by implementing evolution of life‐history…
Ultraviolet radiation exposure of a high arctic lake in Svalbard during the Holocene
2014
Long-term fluctuations in lake-water optical properties were examined using a Holocene sediment sequence and multi-proxy palaeolimnological approach in Lake Einstaken, Nordaustlandet, Svalbard. UV-absorbance of sedimentary cladoceran remains provided information on underwater UV exposure and changes in lake-catchment coupling processes were inferred from sediment geochemistry. In addition, aquatic community succession was used as an indicator for lake-water bio-optical properties and a Holocene record of sun activity (sunspots) was utilized to evaluate long-term solar forcing. The results indicated that the UV-absorbance of cladoceran remains was highest (i.e. maximum UV-induced pigmentatio…
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…
Influence of chlorophyllaquantification methods in ecological quality indices
2019
Chlorophyll a concentration in aquatic ecosystems is strongly related to the phytoplankton community biomass, the growth of which depends on nutrient availability. Thus, chlorophyll a concentration...