Pelagic food-web in the Southern Ocean Essay Example | Topics and Well Written Essays - 750 words

Pelagic food-web in the Southern Ocean - Essay Example Autotrophs are grazed by herbivores that in turn are consumed by carnivores. A number of trophic levels form the food web with primary producers at first level, the second level comprising herbivores, third level comprising carnivores and the next level comprising carnivores that eat carnivores. Pelagic food web exchanges take place in the water column. The primary producers of the food web are phytoplanktons which are consumed / grazed by the herbivores zooplanktons which are in turn consumed by filter feeding planktivores or piscivores – carnivores or eating fish that eat other types of animals. In pelagic food web omnivory is common with organisms obtaining food from one or two trophic levels. For example, salmon eats the planktivores juvenile fish but also eats zooplanktons that are euphausiids (Marine Biology). The pelagic food chain is comprised of a diversity of organisms including bacteria, heterotrophic and autotrophic nano and microplanktonic organism. The presence of microbial forms in Antarctic waters is underestimated due to the dogma that the region features a short and simple food web that are not accounted due to technical limitations. However, a research on the food web indicates an abundant distribution of heterotrophic ciliates and flagellates in polar waters with the presence of microbial assemblage that inhabit the water column and sea ice. Estimates of grazing point out that they are the important consumers of the Antarctic food web. Though seasonality is not accounted, heterotrophic nano and microplankton are formed after an autotrophic bloom and reach a maximum biomass during summer (Ross, R.M., Hofmann, E.E. & Quetin, L.B. 1996 p.155). The ecosystem in southern ocean is highly influenced by factors like climate, ocean currents and ice. The amount of ice cover results in a competition between species of the primary producers which in turns affects the competition among zooplankton species that