Ocean and Deep Sea Terms

A steep gradient in temperature through the water column.

The degradation of commonly owned resources due to the lack of incentive for individual users to conserve them.

Commons were originally shared grazing areas, which were generally overgrazed. The full expression was coined by Garrett Hardin in 1968.

The study of ecosystem productivity, based on food-chain theory.

Something that occurs when surface waters sink to the bottom, slowly migrate across the deep oceanic basins, and rise to the surface.

These waters contain nutrients from the sunken carcasses of small organisms. This surfacing thus brings nutrients to the surface, nourishing plankton, and is an important aspect of the marine food web.

Existing at a depth of 650 (2,132 feet) to at least 1,500 meters (4,921 feet), the vampire squid (literally, "vampire squid from hell"), in spite of its name, is actually a harmless animal that lives suspended in the dark strata of the oceans, sometimes unfurled in a typical umbrella posture.

Like other animals living at such great depth, its musculature is much reduced, although it is capable of surprising bursts of speed over short distances. When fleeing an enemy, it may create confusion by activating its various bioluminescent organs.

The upper level of a saturated area of soil and rock, where it meets unsaturated soil and rock below it: Water tables tend to be higher under elevated zones and lower under valleys; they may be at the surface as in the case of swamps, or thousands of feet down in reservoirs under deserts.

In dry seasons, the water table may drop several feet in some areas before rising again during the next wet season.

The weight of an organism, or sample, that still retains its natural internal water content.

Planktonic organisms belonging to the animal kingdom.

The majority are small crustaceans (copepods, krill), arrowworms, and gelatinous creatures that feed primarily on phytoplankton.

The symbiotic algae that reside within many species of tropical shallow-water corals, whkose photosynthesis contributes to the corals' nutrition, thereby enabling them to thrive in tropical waters where there is little prey available.