Extremophiles are living organisms that can thrive in environmental conditions that are inhospitable to most lifeforms. These species may be animals, plants or bacteria; the unusual conditions in which they may persist can involve extreme salinity, acidity, temperature, radiation or pressure. Such occurrences may take place in such unusual climate regimes as Antarctica, or in such unusual geographic features as hypersaline lakes.
They may also be found at extreme ocean depths where high pressures and unusual chemical environments, such as near hydrothermal ocean vents, are encountered. The image to the right shows tubeworms found near such hydrothermal vents.
An extremophile is an organism adapted to unusual limits of one or more abiotic factors in the environment. Some of the extreme conditions are temperature, pH, high salinity,...
Marine biodiversityLast Updated on 2014-12-15 19:53:24Biodiversity is now commonly defined as the variety of life in genes, species and habitats. According to the definition of the Convention on Biological Diversity, biodiversity is the variability among living organisms from all sources, including inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.
The three domains of life, bacteria, archaea and eukarya are present in the marine environment. In addition there are viruses. About 230,000 species of marine plants and animals have been scientifically described and a few thousand bacteria and archaea. This known biodiversity only represents a small fraction of the number of species existing, except for the macrophytes and seagrasses which are living in coastal environments and, in general, for the pelagic... More »
BacteriaLast Updated on 2014-10-12 18:54:28
Bacteria are any of a very large group of single-celled microorganisms that display a wide range of metabolic types, geometric shapes and environmental habitats—and niches—of occurrence. Normally only several micrometers in length, bacteria assume the form of spheres, rods, spirals and other shapes. Bacteria are found in a very broad gamut of habitats; for example, bacterial extremophiles that thrive in such places as hot springs, arctic environments, radioactive waste, deep sea oil seeps, deep Earth crustal environments, hypersaline ponds and within other living organisms. There are approximately 50 million bacterial organisms in a single gram of typical surface soil. The worldwide bacterial biomass exceeds that of all plants and animals on Earth. However, the majority of bacteria have not yet been characterised,
Bacteria are members of the prokaryote... More »
Marine virusesLast Updated on 2014-06-18 17:18:25
Viruses are parasites of living cells which invade cells and then use their biological machinery to propagate. Most viruses in the ocean consist of nucleic acids surrounded by a protein coat (called a capsid). Viruses are thought to have appeared several times during the evolution of cellular organisms as suggested by the type (DNA vs RNA) or structure of the nucleic acid (double-strand vs single strand; sense vs antisense). In marine environments, they are more numerous than the most abundant cell types, the prokaryotes. Prokaryotes are single-celled organisms without a nucleus and are now considered to consist of the two so-called domains of life, Bacteria and Archaea. Viruses are a major factor for the mortality of marine prokaryotes.
Most viruses in the ocean are thought to infect prokaryotes. They are typically DNA-containing viruses and, if they infect bacteria, are... More »
Marine microbesLast Updated on 2014-06-18 17:12:26
The term 'Marine microbes' encompasses all microscopic organisms generally found in saltwater. Most micro-organisms are acellular and fall into the major categories of viruses, prokaryotes ('bacteria'), and protists, groups which differ considerably in biological characteristics. While representatives of these groups are found in virtually everywhere in marine waters and they play nearly every ecological role imaginable, their most important function is that they form the base of the food chain in marine ecosystems.
Well-known to us as disease-causing agents, viruses are deceivingly simple organisms, little more than some nucleic acid within a protein container. They are 'parasitic particles' most about 40 nanometers in size. Viruses attach themselves to a living cell and inject a bit of nucleic acid into the cell; the injected nucleic acid... More »
Arctic marine environmentsLast Updated on 2014-06-18 16:42:07
This is Section 10.2.1 of the Arctic Climate Impact Assessment
Lead Author: Michael B. Usher; Contributing Authors:Terry V. Callaghan, Grant Gilchrist, Bill Heal, Glenn P. Juday, Harald Loeng, Magdalena A. K. Muir, Pål Prestrud
The arctic marine environment covers about 13 million km2, of which about 45% is a permanent ice cap that covers part of the Arctic Ocean. Seasonal sea ice forms during winter, and recedes during the short arctic summer, exposing large areas of open water. The marine environment is thus dominated by sea ice and by the dynamics of that ice and especially the location of the ice edge. The transition zone between the sea ice and the open water has intense algal growth in spring and summer, and it is the primary production by these phytoplankton that supports the arctic marine food webs. Only in exceptional cases can the energy that drives the marine food... More »
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