نتایج جستجو برای: aquatic ecosystems
تعداد نتایج: 72145 فیلتر نتایج به سال:
[1] Aquatic ecosystems are hotspots of decomposition and sources of carbon dioxide to the atmosphere that are globally significant. Carbon exported from land (allochthonous) also supplements the carbon fixed by photosynthesis in aquatic ecosystems (autochthonous), contributing to the organic matter (OM) that supports aquatic consumers. Although the presence of terrestrial compounds in aquatic O...
The antibacterial properties of nanosilver have led to a versatile application spectrum including medical purposes and personal care products. However, the increasing use of nanosilver has raised concerns about its environmental impacts. Long-term exposure studies with aquatic invertebrates are essential to assess possible adverse effects on aquatic ecosystems. In the present study, acute (48 h...
There has and continues to be concern about the effects of elevated nitrogen (N) deposition on natural ecosystems. In this paper, research on natural ecosystems, including wetlands, heathlands, grasslands, steppe, naturally regenerated forests and deserts, is evaluated to determine what is known about nitrogen cycling in these ecosystems, the effects of elevated nitrogen on them and to identify...
We examined how spawning Pacific salmon (genus Oncorhynchus) affect streamwater concentrations of inorganic nitrogen and phosphorus and dissolved organic matter in Peterson Creek, a stream in southeast Alaska. When spawning salmon were present, concentrations of ammonium (NH4-N) increased by more than 100 times over prespawning levels and concentrations of soluble reactive phosphorus increased ...
Many alien plants use animal vectors for dispersal of their diaspores (zoochory). If alien plants interact with native disperser animals, this can interfere with animal-mediated dispersal of native diaspores. Interference by alien species is known for frugivorous animals dispersing fruits of terrestrial plants by ingestion, transport and egestion (endozoochory). However, less attention has been...
Springs and spring runs represent a unique class of aquatic ecosystems typified by high water clarity and relatively constant water temperature and chemical conditions. Structurally, springs are best characterized by their basin morphometry (shape and volume), their position in the landscape, and their flora and fauna. A classic aquatic food web and biomass pyramid in spring ecosystems includes...
Diatoms are of significant ecological importance in aquatic ecosystems, which stems from their dynamic position at the base of the trophic web as primary producers. Because diatom communities have specific environmental requirements and respond rapidly to changes in environmental conditions they are often employed as a cost-effective method to assess anthropogenic impacts and health statuses of...
By now, all European freshwater and coastal marine ecologists should be familiar with the European Directive 2000/60/EC establishing a framework for Community action in the field of water policy, which is commonly referred to as the Water Framework Directive (WFD). The purpose of the directive is to establish a framework for the protection of inland surface waters, transitional waters, coastal ...
The current study investigated the potential of vegetated drainage ditches for mitigating the impact of agricultural irrigation runoff on downstream aquatic ecosystems. Water column toxicity to larval fathead minnow (Pimephales promelas),and the amphipod Hyalella azteca was measured for 12 h or less at the ditch inflow and outflow, using custom-built in situ exposure systems. In addition, water...
Context The rates and pathways of nutrient cycling through ecosystems depend on interactions between both bottom-up forces, including the chemical characteristics of biomass that influence its decomposition and consumption by higher trophic levels, and top-down forces, such as the nutritional requirements andmetabolic efficiencies of consumers and decomposers that influence their feeding and ex...
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