Limnology is the scientific field of knowledge that investigates terrestrial freshwater and saline aquatic systems. This includes the study of streams, lakes, ponds, rivers, springs, wetlands and even human-made reservoirs. Limnologists often utilize academic perspectives from a variety of disciplines, including biology, chemistry, geology, ecology, environmental science, hydrology and physics for their investigations.
Benthos is one of three major ecological groups into which marine organisms are divided, the other two being the nekton and the plankton. The benthos are organisms and...
FreshwaterLast Updated on 2014-09-06 18:32:23
The definition of freshwater is water containing less than 1000 milligrams per liter of dissolved solids, most often salt. The global distribution of freshwater resources varies greatly from region to region (see Figure 1). An 'inventory' of Earth's waters shows that approximately 97% of the global water supply is found in the oceans, which are saline. A very small amount of salty water is also located in saline lakes (e.g., the Caspian Sea). The remaining water inventory (3%) is 'freshwater'. Permanent ice (e.g., continental and mountain glaciers) is the largest freshwater storage on Earth, accounting for about 2% of the total global supply - or nearly 69% of the total freshwater supply. Freshwater is also found beneath the Earth's surface as groundwater (approximately 30% of the total freshwater supply) and in surface water storages such as lakes, streams,... More »
Lake MalawiLast Updated on 2014-07-07 18:09:35Lake Malawi is a lacustrine freshwater body and a national park in the country of Mozambique in east Africa. Located on a peninsula between distant mountains at the southern end of Lake Malawi, this water body with its deep clear waters and varied habitats, is home to over six hundred species of cichlid fish, nearly all endemic. Their importance for the study of evolution by adaptive radiation is comparable with that of the Galapagos Islands finches.
The Lake Malawi World Heritage Site was inscribed in the year 1984 by the United Nations on the World Heritage List under Natural Criteria vii, ix and x. The site is placed in the IUCN Management Category II (National Park). The Biogeographical Province is denoted: Lake Malawi (3.29.14)
The National Park is at the southern end of Lake Malawi (also called Lake Nyasa) on and around the Nankhumba Peninsula. The Park includes the... More »
WatershedLast Updated on 2014-07-03 15:11:40
The term watershed is used (especially in North America and Europe) to indicate an area of land from which all water falling as rain or snow would flow toward a single point. This includes both surface water flow, such as rivers, streams and creeks, and the underground movement of water. The boundaries and the area of such a watershed are determined by first specifying geographic point on land. A line is then drawn which connects all of the points of highest elevation immediately adjacent to that point. The watershed area would be the land area within those boundaries. The watershed of the Amazon River would include all of the tributaries that flow into it so it would actually contain several hundred smaller watersheds. The watershed is thus defined hydrologically, that is, by the specific river or stream. Watershed and drainage basin or catchment are used synonymously and all of... More »
Enriquillo wetlandsLast Updated on 2014-06-30 17:20:34
WWF Terrestrial Ecoregions Collection
Consisting of a series of lagoons, this ecoregion corresponds to the remains of an old marine channel that divided the island of Hispaniola (Dominican Republic and Haiti) into two paleoislands more than 5000 years ago. The largest lake in this ecoregion, Lake Enriquillo in the Dominican Republic is the largest and most hypersaline lake in all of the Antilles. It consists of a depression that is approximately 44 meters (m) below sea level, surrounded by thorny subtropical mountains and dry forests of great biological interest. This lake is home to the largest population of American crocodile (Crocodylus acutus), although currently its populations are at risk. It is also the habitat for the iguana cornuda (Cyclura cornuta), which is endemic to the island of Hispaniola and the iguana de Ricord (C. ricordi), the... More »
DiatomiteLast Updated on 2014-06-15 18:57:41
A diatom is an organism that is a member of the phylum of algae called Bacillariophyta. There are about 60,000 species of these algae presently known. Experts estimate that there are more likely 600,000 to 6,000,000 species in total!
Diatoms are single-celled (unicellular) organisms that live as individuals or in groups called colonies. They exist in all the waters of the Earth, both salt and fresh. They form shells made out of silica (the mineral name of this silica is opal) which they extract from the water. Their microscopic shells are very intricate and beautiful and have rightly been called "the jewels of the sea." Diatoms are very abundant and provide food for many aquatic animals.
When diatoms die, their silica shells accumulate on the floor of the body of water in which they lived. Thick layers of these diatom shells have been fossilized (that is, preserved)... More »
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