The Epipelagic

• The pelagic realm of the ocean describes the vast, open ocean.

– The epipelagic realm is the upper part of this environment.

• Depths only to about 200m• Corresponds to the depth of the euphotic

zone– Euphotic depth the depth below which where there is

no longer enough light for organisms to grow.

– Divided into coastal, or neritic waters that lie over the continental shelf, and oceanic waters.

Net Tows

Plankton by Size

• Plankton: organisms that can’t swim against a current– Picoplankton (0.2 – 2 m) and Nanoplankton (2 –

20m)» Mostly bacteria and very small single celled algae

– Netplankton (>20m)» Includes the larger phytoplankton and all of the

zooplankton

Plankton by Size

Phytoplankton

– Responsible for >95% of the photosynthesis in the oceans and over ½ the primary production on earth

• Most important members are diatoms and dinoflagellates.

• Cyanobacteria are also important phytoplankton because they are able to fix nitrogen, ie. turn inorganic nitrogen into organic nitrogen that can be used by phytoplankton.

Figure 15.03

Epipelagic Food Web

Copepod

Figure 15.07b

Larvacean

Pteropod

Figure 15.11b

Figure 15.11c

Figure 15.11d

Figure 15.11e

Fish Larva

Chaetognath (Arrow Worm)

Comb Jelly

Polychaete Worm

Copepod

Figure 15.13b

Crab Zoea

Fish Larva

Figure 15.13e

Snail and a Jelly

Nekton

Nekton

Diel Vertical Migration

Neuston

Nekton

Staying Afloat

Camouflage

Epipelagic Food Web

Global Productivity

Figure 15.25b

Figure 15.26

Seasonal Productivity-Tropics

Seasonal Productivity- Temperate

Seasonal Productivity- Polar

Wind-Driven Upwelling

Global Upwelling

Figure 15.32