Aquatic Ecology Course Zoo 374

Aquatic Ecology Course

Zoo 374

• Zooplankton (Consumersالمستهلكات

)• Zooplankton are heterotrophic

(sometimes detritivorous) type of plankton.

• The name of zooplankton is derived from the Greek zoon meaning “animal”.

• Many zooplankton are too small to be seen individually with the naked eye.

Northern krill

Jelly fish

Copepods

Zooplankton are initially the sole prey item for almost all fish larvae.Fish larvae use up their yolk sacs and switch to external feeding for nutrition. Zooplankton limitation can in turn strongly affect the larval survival, and consequently breeding success and stock strength, of fish species.

•Importance of zooplankton To Fish

• Holoplankton Vs Meroplankton

• Holoplankton are those organisms that spend their entire life cycle as part of the plankton (e.g. most algae, copepods, salps, and some jellyfish).

• Meroplankton are those organisms that are only planktonic for part of their lives (usually the larval stage), and then graduate to either the nekton or a benthic (sea floor) existence. Examples of meroplankton include the larvae of sea urchins, starfish, crustaceans, marine worms, and most fish.

A chain of salps near the surface.

Copepods

Pennate and centric diatoms

Again

• Biozone

Pelagic

Neritic Oceanic

benthic

littoral

supralittoralintertidal

subtidal

High medium low

Prof.Dr.Hanan M Mitwally, Marine Biology

plankton

Nekton

Benthos

pelagic

Ass. Prof.Dr. Hanan M. Mitwally

BiozonesBiozonesBiological HabitatsBiological Habitats

Benthic zone

Pelagic zone

Pelagic

NeriticProductive Coastal

Water

OceanicDeep waters of

open ocean

•The word pelagic comes from •the Greek pélagos, = open sea.

• Neritic zone:• It is extending from low tide mark to the edge of the

continental shelf.• Characters of Neritic zone:

• Shallow depth ≈ 200 meters.• well-oxygenated water • Low water pressure.• Stable temperature and salinity levels. • High photosynthetic activities from phytoplankton

and floating sargassum . • At the edge of the neritic zone, the continental shelves

end rapidly descending to the deeper oceanic crust and the pelagic zone.

• Oceanic zone• Any water in the sea that starts

beyond the continental shelves.• offshore, high light levels,

upper regions of water column

• Conditions change with depth: the pressure increases and there is

less light.