Marine Ecology Unit 3 Vocab

Vertical migration

Active movement of animals between shallow and deeper depths in the water column, typically occurring a diurnal cycle, allowing animals to exploit rich food near the surface at night while evading visual predators by moving to deeper water during the day

Pycnocline

The strong density discontinuity between the upper and lower layers of the ocean water column, a result of density stratification.

Epipelagic zone

The 0-150 m depth zone oceanward of the continental shelf-slope break also known as the sunlight zone because of the abundance of sunlight.

Mesopelagic zone

The 200-1000 m depth zone, also known as the twilight zone, which is the most biologically active of the deep ocean zones

Bathypelagic zone

he 1000-4000 m depth zone, also know as the midnight zone, lacking light and decreasing inputs from the surface, this zone is relatively rich in inorganic nutrients.

Abyssopelagic zone

The 4000-6000 m depth zone, also known as the Abyss, is the final resting place of deep layers of marine snow, dead carcasses, and increasing anthropogenic materials.

Hadal zone

The below 6000 m depth zone created at the boundaries of oceanic plates that create deep sea trenches below the surrounding ocean floor level

Photoautotroph

An organism that depends on sunlight for its energy and principally on carbon dioxide for its carbon.

Chemoautotroph

An organism that depends on inorganic chemicals for its energy and principally on carbon dioxide for its carbon.

The Paradox of the Plankton

why well-mixed pelagic environments of lakes or oceans maintain a large number of phytoplankton species (tens or hundreds), even though the component species largely require the same resources.

Chaos

An irregular pattern of species fluctuations that resembles randomness but arises deterministically from completely specified equations of population growth and interactions; sensitivity of a biological system to initial conditions.

The Microbial Loop

The portion of marine food web composed of microscopic organisms (mostly prokaryotes and protists) that produce, graze, and recycle organic matter among themselves with little of the energy or materials flowing to macroscopic organisms

Dissolved organic matter (DOM)

Dissolved molecules derived from degradation of dead organisms or excretion of molecules synthesized by organisms.

Bioluminescence

Light produced chemically by deep sea organisms and used to communicate, attract prey, or deter predators.

Benthic-pelagic coupling

The cycling of nutrients between the bottom sediments and overlying water.

Hydrothermal vent

Sites in the deep ocean floor where hot, sulfur-rich water is released from geothermally heated rock.

Mid-Ocean Ridge

The seismically active submarine ridges that mark the juncture of diverging tectonic plates; the mid-ocean ridges are sites of regular tectonic activity including sea floor spreading that result in upwelling of magma and outflux of mineral- rich water through hydrothermal vents, which in turn host unique biological communities supported by chemoautotrophy

Neritic zone

Shallow marine environment extending from mean low water down to 200-metre depths, generally corresponding to the continental shelf

Estuary

A semienclosed coastal body of water with a connection to the sea, where seawater is diluted with freshwater

Brackish water

A broad term used to describe water that is more saline than freshwater but less saline than the open ocean.

Epifauna

Living on the substrate surface

Infauna

Living within a soft sediment.

Meiofauna

Microscopic organisms living in the spaces between sand grains.

Deposit feeder

animals that ingest sediment and derive their nutrition mainly from microalgae and particulate organic detritus.

Suspension feeder

animals that collect food by means of morphological structures that protrude into the flow and capture food particles and DOM.

Anoxia

Lacking oxygen

Hypoxia

The presence of low oxygen concentrations in the water that is stressful to marine organisms.

Anaerobes

Organisms that carry out metabolic processes in the absence of oxygen.

Eutrophication

Addition of high nutrients concentrations to a water body.

Epiphyte

Microalga living on a surface – common on seagrasses

Rhizome

A system of runners below the sediment surface that allows sea grasses and salt marsh plants to extend coverage of a plant over large areas and permits transfer of nutrients to new areas where shoots can emerge at the sediment surface.

Trophic cascade

A strong interaction among trophic levels in a food chain, where changes in the density at one level results in indirect effects at a trophic level that does not directly interact with the first level

Bottom up control

A population control that comes from a change lower in a food web.

Top down control

A population control that comes from a change higher in a food web.

Ocean acidification

The decline of pH in the ocean (historically pH = 8.3), owning to additions of carbon dioxide in the atmosphere and subsequent dissolution in seawater.