2 Departamento de Biologia Marinha – Universidade Federal do Rio de Janeiro – UFRJ – CCS – bloco A –sala 089 – Ilha do Fundão, Rio de Janeiro
The Antarctic marine environment is characterized by the extreme seasonality of the primary production in the water column and the low but stable temperatures. Both are considered the main factors in the adaptative evolution of Antarctic ectothermic organisms. Studies about physiological and biochem...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.455.2491 http://www.oecologiaaustralis.org/ojs/index.php/oa/article/download/165/91/ |
| Summary: | The Antarctic marine environment is characterized by the extreme seasonality of the primary production in the water column and the low but stable temperatures. Both are considered the main factors in the adaptative evolution of Antarctic ectothermic organisms. Studies about physiological and biochemical processes of the cold-adapted species revealed the presence of antifreeze glycoproteins in the biological fluids and cold-adapted proteins. The low and stable temperatures have resulted in the appearence of enzymes with high catalytic efficiency and the absence of the thermal stress proteins in some Antarctic fishes. The austral winter promotes a seasonal food shortage, submitting the benthic ectotherms to long periods of starvation. This is particularly true for the organisms that depend on phytoplankton as their primary source of food. The Antarctic marine environment also presents areas of high copper concentrations on the sediment surface as well as cadmium in the water column. The bivalve Laternula elliptica, a circumpolar species, has been proposed as bioindicator for long term monitoring of heavy metals in the shallow waters of Antarctica due to its capacity to accumulate metals, especially cadmium and zinc. Like other Antarctic ectothermic organisms, L. elliptica changes its metabolism from aerobic to anaerobic as a function of temperature, being 6 ºC critical and 9 ºC lethal. This bivalve also shows a marked seasonality in its metabolism, with low oxygen consumption in winter as compared |
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