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...
Zambezian halophyticsLast Updated on 2015-05-15 15:26:27
WWF Terrestrial Ecoregions Collection
The Zambezian halophytics ecoregion includes two spatially disjunctive units in Southern Africa: The Makgadikgadi Pan complex in Botswana and a smaller hypersaline unit in southern inland Mozambique. One of the largest saltpans in the world, the Makgadikgadi Pan complex in Botswana stretches out over 12,000 square kilometres. The ecoregion is classified within the Flooded Grasslands and Savanna biome.
Surrounded by the semi-arid Kalahari savannas, the pans experience a harsh climate, hot with little rain, and are normally a vast, glaring expanse of salt-saturated clay. These pans are sustained by freshwater from the Nata River, and more infrequently, from input from the Okavango Alluvial Fan by way of the Boteti River. Saline- and drought-tolerant plant species generally line the pan perimeters, with grasslands... More »
BiomeLast Updated on 2014-11-30 22:01:13Biomes organize the biological communities of the earth based on similarities in the dominant vegetation, climate, geographic location, and other characteristics. Aspects of the physical environment such as precipitation, temperature, and water depth, have a strong influence on the traits of species living in that natural environment, and thus biological communities experiencing similar environmental conditions often contain species that have evolved similar characteristics. There is no single classification of biomes that is agreed upon by all scientists because different scientists wish to emphasize different characteristics by their definition. Historically however, biomes have been identified and mapped based on general differences in vegetation type associated with regional variations in climate and terrain.
Terrestrial biomes characterize ecosystems on land, and are usually... More »
HydroelectricityLast Updated on 2014-11-30 21:32:21
Hydroelectricity is electricity generated by converting the kinetic energy of falling or flowing water. It is considered the most widely installed form of renewable energy, although most large dams have a finite lifetime unless dredging of silt is periodically conducted. Hydroelectricity has and has a considerably lower output level of the greenhouse gas carbon dioxide than fossil fuel powered energy plants, and less life cycle greenhouse gas impact than solar power. Furthermore, the ecological impacts of hydropower is arguably greater than any form of energy production, due to the large footprint of biological impact of reservoirs and other needed developed areas. Worldwide, an installed capacity of 777 Gigawatts was catalogued in the year 2006, sufficient to supply one fifth of the world power supply. Since most of the prime locations for hydroelectric power have been tapped, the... More »
Aquatic plantsLast Updated on 2014-11-09 18:55:53
Aquatic plants grow in shallow to deep water zones. The three main types of aquatic plants are (1) single-celled phytoplankton, (2) periphyton (algae growing attached to substrates) and (3) multicellular macrophytes. Phytoplankton includes several groups of algae (e.g., green algae, golden brown algae, euglenophytes, dinoflagelates, and diatoms) and one group of photosynthetic bacteria (Cyanobacteria). Planktonic algae may be either benthic (attached to a substrate) or planktonic (floating in the water column). There are large numbers of phytoplankton (> 400 species) in many bodies of freshwater; phytoplankton are most common in habitats with high nutrient levels.
Periphyton may grow attached to other plants (ephytic periphyton) or on rocks and other substrate (epibenthic periphyton). Typically, periphyton is made up of a diatoms, a variety of filamentous algae... More »
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 »
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