Freshwater Biomes

The atmosphere that surrounds the planet and sustains life forms in varying sizes and proportions is not only unique, but also within a well designed and controlled environment. The planet is replete with numerous life sustaining features that enhance our existence and definitely among the top rankers are the freshwater biomes. Freshwater is usually defined as water content with low salinity, usually below 1%. Plants and animals and other life forms that thrive in the freshwater regions are naturally adjusted to the low salt content. They are unique to this environ and hence do not survive in areas that have high salt concentration levels. The different types of freshwater regions we commonly identify with include the lakes and ponds, the rivers, streams, rivulets and the wet lands.

The freshwater biomes known as lakes and ponds are normally observed in regions that range in size from a few square meters to thousands of square kilometers. These areas are seen all over the earth. Quite a number of the freshwater ponds and lakes are glaciation remnants. The lakes and ponds are not perennial in nature and content the observed levels of water for just a couple of months each year. This is commonly observed in what we call the sessile pools. Lakes are credited with existence that could stretch for hundreds of years. The sustained species diversity observed in the lakes and ponds around the world are limited. This is due to the fact that these freshwater biomes are often isolated from other water sources. Lakes and ponds are further divided into three zones for a better understanding. The zones are determined by the depth and distance of the water body from the shoreline.

The Littoral zone is also the topmost zone that is observed near the shore of the lake or pond. This zone is the warmest and shallow and sustains diverse species like algae, fixed and floating aquatic plants, snails, insects, crustaceans and fish. The Limnetic zone is near the surface of the open water. It is well-lighted and flaunts the growth of phytoplankton and zooplankton, the small organisms that contribute largely to the food chain; and freshwater fish. The Profundal zone has the remnants of the dead plankton. This zone is colder and denser and home to heterotrophs that feed on the dead organisms. The temperature variations in the ponds and lakes are observed seasonally. During the summer, the variation ranges from 4° C at the bottom to 22° C above, while during the winter months the variation is around 4° C above to 0° C below! The intermediate Thermocline zone has rapid temperature changes.

These streams and rivers are freshwater biomes that contain flowing water that essentially moves in one direction. They initiate at 'headwaters' like springs or even lakes. The journey towards their mouths culminates in the merging of the waters of the ocean. The temperature of these water bodies is cooler at the source than at the mouth. The water has high oxygen levels and is home to freshwater fish and heterotrophs. It is observed that the width of these water bodies usually increases towards the middle. Toward the mouth, the water becomes saturated sediments picked up upstream. This region is also observed to have less diversity of flora and fish. Wet lands are regions where the 'standing water' supports aquatic flora and fauna. The commonly observed wet lands include marshes and bogs. Plant species that thrive in these freshwater biomes are naturally adapted varieties. They grow well in the moist and humid conditions. These hydrophytes include pond lilies and sedges and black spruce, in addition to cypress and gum. They are also home to amphibians, reptiles and wading birds. Not all wet lands are considered freshwater biomes and ecosystems though, all depending on the level of salinity. Freshwater biomes play an integral part in the balancing of the ecosystem and sustenance of life on the planet. Most of the water resources we depend on belong to this category.