Published in Encyclopedia of Inland Waters
Density-driven flows play an important role for deep-water renewal in lakes and are often essential for nutrient transport and oxygenation of the deep hypolimnion. Here, we give a qualitative description of the characteristics of density plumes, describe several processes that lead to density-driven flows and discuss the relevance of these processe...
Published in Encyclopedia of Inland Waters
Published in Encyclopedia of Inland Waters
There are 304 million natural lakes on continents and these natural lakes cover more than 2.8% of the land surface, not including temporary water bodies and wetlands. Impounded waters cover another 0.22% of the land area and the number of small impoundments is growing rapidly as human water needs increase. Although the largest, often deepest, lakes...
Published in Encyclopedia of Inland Waters
At the beginning, phytoplankton primary productivity is defined and a terminology presented. Methods for estimating production are outlined and the most common techniques, such as oxygen evolution, carbon uptake, and fluorometry, are briefly described. Then the physiology of photosynthesis is emphasized, starting with the light harvesting mechanism...
Published in Encyclopedia of Inland Waters
Zooplankton consist of many species other than copepods and cladocerans. Some are predators and structure zooplankton communities. They spend the day in dark (mysids, amphipods, water mites), or deoxygenated water (phantom midge larva, Chaoboridae) to avoid visually feeding fish. During the night they migrate into the water column to feed. Mysids a...
Published in Encyclopedia of Inland Waters
Decapod crustaceans (crayfish, shrimp, and crabs) are the largest invertebrates inhabiting freshwater systems. They can be found in lakes, ponds, rivers, streams, wetlands, and caves. Decapods often play important roles in the systems they inhabit. They can directly influence the abundance of algae, aquatic macrophytes, and other invertebrates. The...
Published in Encyclopedia of Inland Waters
Cladocera are a diverse group of small crustaceans common in aquatic habitats, ranging from shallow temporary ponds to deep lakes and large rivers. Some groups (e.g., Podonidae) are widespread in the oceans. With the exception of predaceous onychopods and Leptodora, cladocerans consume algae and microbes, either grazing with filtering limbs from th...
Published in Encyclopedia of Inland Waters
Sediments are an important habitat component in aquatic ecosystems, as they provide a substrate or support medium for aquatic organisms. In addition, sediments are biogeochemically active, in that they may transport organic or inorganic substances attached to their surfaces, and because they provide a large surface for abundance of microbes. Sedime...
Published in Encyclopedia of Inland Waters
Aquatic ecosystem goods and services are the stocks and flows derived from ecosystem processes that have some value to humankind. These values may be direct and apparent, such as the economic value of fisheries, or they may be generated from indirect or unapparent means, such as the benefits accrued from ground water processes that purify drinking ...
Published in Encyclopedia of Inland Waters
The expanding human population and continuing pollution of aquatic resources threaten the survival of life on earth by reducing the quality and quantity of available water. Pollution sources are highly varied but can be categorized as point- and nonpoint source. Point source pollution is highly localized, easily identified, and relatively easily re...
