The open ocean

Mesopelagic zone

'twilight zone' only 1% of incident light reaches this zone

Marked by a thermocline

Thermocline issues

can restrict nutrient upwellings and limit productivity

organisms moving through the water column have to deal with large and sudden temperature changes

Bathypelagic zone

'Midnight zone' no light and constant temp of 4 degrees celsius

Abyssopelagic Zone

Near constant conditions 40% of global surface

Benthic lifeforms

Fuelled by marine snow

Waters originate at the air-sea interface in polar regions

Hadalpelagic zone

6000m to bottom

Mariana Trench 11022 metres deep

Pressure increase

1 atmosphere per 10 meters of depth

Pelagic zone marine organisms

Plankton and Nekton

Holoplankton

species of zooplankton that remain in a planktonic stage throught their lives

Meroplankton

Species of zooplankton that spend only part of their lives as members of the plankton community

Diel Vertical Migration (DVM)

upward migration of zooplankton towards the surface at night and the downward movement of the zooplankton to the deeper waters in the daytime to avoid harmful UV light and predators

Sampling techniques

Nets

Genomics

Underwater photography

Satellites

Sonar

How do animals stay afloat in pelagic zone

keep swimming

Increase water resistance - increase surface area

Increase buoyancy - increase lipids (blubber - liver - oil droplets) (swim bladders and gas in vacuoles)

Ontogenetic changes

changes in the form of an organism that occur as it matures