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Concept
Ephemerality
Summary
Ephemerality (from the Greek word ἐφήμερος, meaning 'lasting only one day') is the concept of things being transitory, existing only briefly. Academically, the term ephemeral constitutionally describes a diverse assortment of things and experiences, from digital media to types of streams. "There is no single definition of ephemerality". With respect to unique performances, for example, it has been noted that "[e]phemerality is a quality caused by the ebb and flow of the crowd's concentration on the performance and a reflection of the nostalgic character of specific performances". Because different people may value the passage of time differently, ephemerality may be a relative, perceptual concept: "In brief, what is short-lived may not be the object itself, but the attention we afford it".
An ephemeral stream is that which only exists following precipitation. They are not the same as intermittent or seasonal waterbodies, which exist for longer periods, but not all year round. Ephemeral streams can be difficult to "conceptually defin[e]"; those that are discontinuous, due to altering between aggradation or degradation, have the appearance of continual change. Furthermore, the characteristics of terrain and rainfall are profound in affecting ephemeral streams. Ephemeral waterbodies experience formative change upon the end of a hydroperiod. "Due to lack of continuous hydrology data, the designation of sites as ephemeral or intermittent is necessarily tenuous". Ephemeral streams feature a low degree of hydrological connectivity.
Small wetlands are often ephemeral and ephemeral ecosystems are often aquatic; ephemeral wetlands, streams and ponds are a varied and global occurrence. In northeastern United States, ephemeral freshwater systems are abundant and are "critical to the maintenance of forest biodiversity". Hydroperiod, predation, competition and food availability are among the "highly heterogeneous" elements of these features.
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Andrea Rinaldo, Theophile Mande, Francisco Javier Perez Saez
Background Despite their importance for designing and evaluating schistosomiasis control trials, little attention in the literature has been dedicated to sampling protocols for the parasite's snail intermediate hosts since their first development. We propo ...
2019Related people (3)
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River
A river is a natural flowing watercourse, usually a freshwater stream, flowing on the surface or inside caves towards another waterbody at a lower elevation, such as an ocean, sea, bay, lake, wetland, or another river. In some cases, a river flows into the ground or becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to by names such as creek, brook, and rivulet. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities, a stream is defined by its size.
Lake
A lake is a naturally occurring, relatively large body of water localized in a basin surrounded by dry land. A lake generally has a slower-moving flow than the inflow or outflow stream(s) that serve to feed or drain it. Lakes lie completely on land and are separate from the ocean, although, like the much larger oceans, they form part of the Earth's water cycle by serving as large standing pools of storage water. Most lakes are freshwater and account for almost all the world's surface freshwater, but some are salt lakes with salinities even higher than that of seawater.
Wetland
Wetlands, or simply a wetland, is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The primary factor that distinguishes wetlands from terrestrial land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique anoxic hydric soils.