Ecology is the study of the interactions between organisms and their environment and other organisms.
The biosphere is the total of all Earth's ecosystems, ranging from the upper atmosphere to deep rock and ocean.
Abiotic factors and climate generally limit the large-scale distribution of organisms.
- Energy is required to drive ecosystems and comes primarily from light, but sometimes from chemicals.
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Water and temperature are important limiting factors for most organisms. -
Fluid flow (wind, currents) can affect rates of exchange, or present an important disturbance regime. -
Distribution of these factors across the globe help determine climate, and are largely explainable by planetary dynamics,
- the most important influence is variation in solar radiation intensity with latitude, followed by tilt of planet axis relative to plane of orbit
- produces polar, temperate and tropical zones.
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Organisms are adapted to abiotic/biotic factors of particular zones, which limits their distribution. Subdivisions of the planet based on typical climate and lifeforms are biomes.
Water biomes are first divided into marine and freshwater zones.
- Marine habitats are the most extensive according to area and volume, but the least explored by humans. Primary divisions are: benthic vs. pelagic, and photic vs. disphotic vs. aphotic.
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Aquatic (freshwater) habitats include lakes, ponds, rivers and streams, and show more seasonal variation than marine habitats. Running water biomes change with distance downstream from sources. -
Three important zones with both water and terrestrial components are: intertidal, wetland, and estuary.
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