Plankton The basis of life. Objectives Definition Functional groups. Phytoplankton. Zooplankton Bacterioplankton. Ecological factors affecting plankton.

PlanktonPlanktonThe basis of lifeThe basis of life

ObjectivesObjectives• Definition• Functional groups.• Phytoplankton.• Zooplankton• Bacterioplankton.• Ecological factors affecting plankton distribution• Distribution.• Diel vertical migration Vs horizontal position.• Holoplankton Vs Meroplankton.• Importance to fish • Food chain.

• Definition• Plankton consist of any drifting organisms (animals,

plants, or bacteria) that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. .

• They are base of food to aquatic life.• The name plankton is derived from the Greek word

"planktos“, meaning "wanderer" or "drifter".

Functional Groups

Plankton

Phytoplankton Zooplankton Bacterioplankton

This division is based on functional groups or trophic levels

• Phytoplankton (Primary Producers)

• Phytoplankton are the autotrophic component of the plankton.

• The name comes from the Greek words phyton, or “plant“.

• Most phytoplankton are too small to be individually seen with the naked eye.

• When those small cells present in high enough numbers, they may appear as a green or red discoloration of the water due to the presence of chlorophyll or carotein within their cells.

Dinoflagellates

Phytoplankton blooms

Diatoms

DinoflagellatesDinoflagellates

Cyanobacteria

• Zooplankton (Consumers)

• 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

• Bacterioplankton (Recyclers)• Bacterioplankton refers to the bacterial component

of the plankton that drifts in the water column. • They are found in both sea and fresh water.• Many are saprophytic: They obtain energy by

consuming organic material produced by other organisms.

• Many other Bacterioplankton species are autotrophic, and derive energy from either photosynthesis or chemosynthesis.

• Like other small plankton, the Bacterioplankton are preyed upon by zooplankton (usually protozoans).

Photomicrograph of tiny marine bacteria (~1 m) attached to the larger diatoms.

Bacteria Morphology

Bacterioplankton

The Ecological Importance

Of

Bacterioplankton

Nitrification

Nitrogen fixation

Methanogenesis

Remineralization Denitrification

Water Bacteria can be divided into:

Natural water bacteriaNumerous species of bacteria

that remain in water constantly.They are beneficial species:

1) Assist in keeping the world’s Food Supply in circulation.

2) Certain species altering the complex organic compounds.

3) Attack protein and produce ammonia.

Nitrifying bacteriaAttacking ammonia

changing it to simpler compounds into two steps:

1) Certain specie oxidize ammonia into nitrite.

2) Another species oxidizes nitrites to nitrates.

Then the stores nitrogen that are gathered together within the living bodies of Plants and animals are again released for further use

Simple nitrateare proper food for green algae

• Ecological Factors Affecting Plankton Distribution

• Plankton abundance and distribution are strongly dependent on factors such as

Ambient nutrientsconcentrations

Physical state of water column

The abundance of Other plankton

• Diel Vertical migration Vs Horizontal position

• Some forms of plankton are capable of independent movement and can swim up to several hundreds of meters vertically in a single day (a behavior called diel vertical migration).

• A the same time, the horizontal position is primarily determined by currents in the body of water they inhabit.

• By definition, organisms classified as plankton are unable to resist ocean currents.

• This is in contrast to nekton organisms that can swim against the ambient flow of the water environment and control their position (e.g. squid, fish, and marine mammals).

• 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

sea urchins

starfishjellyfish

worms

•Importance of Plankton To Fish

• 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.

•Food chain•Each step in a food chain is a•different “trophic level.”•Phytoplankton are at level1.• Zooplankton are at level 2.•Small fish are at level 3.•Larger fish are at level 4.