نتایج جستجو برای: freshwater
تعداد نتایج: 28555 فیلتر نتایج به سال:
Humanity shapes freshwater flows and biosphere dynamics from a local to a global scale. Successful management of target resources in the short term tends to alienate the social and economic development process from its ultimate dependence on the life-supporting environment. Freshwater becomes transformed into a resource for optimal management in development, neglecting the multiple functions of...
Critical habitat is defined under Section 2 of Canada’s Species at Risk Act (SARA) as, “the habitat necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in the recovery strategy or in an action plan for the species”. SARA requires the development of recovery strategies for species listed as Endangered, Threatened or Extirpat...
This chapter reviews tidal wetlands that occur along the Atlantic coast of the United States from the northern border of North Carolina to the northern distribution limit of mangroves in central Florida. The South Atlantic coast has a warm climate, a wide tidal range, and fewer anthropogenic impacts than the North and Central Atlantic coasts. It is a gently sloping coast that supports extensive...
Freshwater tidal wetlands are found in the upper estuaries of most Atlantic Coast river systems where there is sufficient freshwater flow to maintain salinities of less than one percent, but insufficient flow to dampen upstream tidal movement. Odum et al. (1979) conservatively estimate that there are 500,0001,000,000 ha of freshwater tidal wetlands along the Atlantic and Gulf Coasts, of which 1...
A study on motility of spermatozoa of the Persian sturgeon, Acipenser persicus were carried out. The time of relative cessation of sperm activity was evaluated using microscopic observation. Sperm was activated with three different swimming medium, freshwater pH 7.5, and two different buffered saline solutions, pH 7.5. Total period of the motility of A. persicus spermatozoa was shorter in fresh...
1. A highly significant linear correlation was found between glomerular filtration rate and urine flow rate in both freshwater and seawater trout. The percentage tubular reabsorption of water was approximately 33% greater in seawater trout than in freshwater trout. 2. As oxygen consumption increased, the urine flow rate increased in freshwater and seawater rainbow trout. The proportional increa...
The extraordinary species richness of teleost fishes has attracted much research on mechanisms and modes of speciation. We here review research on speciation in freshwater fish in light of speciation theory, and place this in a context of knowledge about broad-scale diversity patterns in freshwater fishes. We structure our review around the major axes of divergence during speciation in freshwat...
[1] The 8.2 kyr event is the largest abrupt climatic change recorded in the last 10,000 years, and is widely hypothesized to have been triggered by the release of thousands of kilometers cubed of freshwater into the North Atlantic Ocean. Using a high‐resolution (1/6°) global, ocean‐ice circulation model we present an alternative view that freshwater discharged from glacial Lake Agassiz would ha...
Drought is one of the most widespread extreme climate events with a potential to alter freshwater availability and related ecosystem services. Given the interconnectedness between freshwater availability and many ecosystem services, including food provisioning, it is important to evaluate the drought implications on freshwater provisioning and food provisioning services. Studies about drought i...
The diversity and ecological relevance of small haptophytes in marine systems is increasingly recognized. Similar investigations in freshwater remain scarce, despite some recent studies showing the existence of divergent haptophyte lineages and indicating that these microalgae can occur at high abundance in lakes. We studied the diversity of haptophytes in a wide variety of marine, salty contin...
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