COPEPOD (main)   >   What are plankton and why are they important?

What are plankton and why are they important?

To understand the entire ecosystem ...
we need to better understand the plankton.

Plankton consist of drifting organisms ranging in size from microscopic viruses to krill and jellyfish.   By definition, a plankton drifts with the currents and flow of its environment.   Some organisms spend their entire lives as plankton ("holoplankton") while others only spend their larval stages as plankton ("meroplankton" and "ichthyoplankton").   Phytoplankton and microbial plankton generally play the role of capturing sunlight and recycling materials that are further transferred throughout the food web by larger and larger zooplankton (micro to meso to macro).  

Plankton play a key role in the oceanic food web ...

Photosynthetic plankton members account for almost half of global primary production and 90% of primary production in marine ecosystems.   They also provide the primary food source for zooplankton and together form the base of the oceanic food web.  Larger and larger zooplankton, fish, birds, and marine mammals depend on these plankton for their survival.   Tying it all together, the microbial plankton play an important role in the recycling and remineralization of materials and energy within the food chain. image of various phytoplankton

... and are frequently indicators of ecosystem change.

image of zooplankton Numerous studies have shown a strong relationship between larval fish survival and the timing and production of their food (i.e., plankton).   The timing and production of plankton are in turn directly dependent on water temperature and nutrient availability (which is indirectly controlled by temperature-driven circulation patterns).   Changes in climate can affect the timing of the seasonal plankton blooms, with effects that pass up the food chain.   Longer term changes in climate may even change the plankton species composition, changing the feeding environment of the larval fish and ultimately the entire food web and ecosystem.

National Marine Fisheries Service  -  Science & Technology  -  Marine Ecosystems Division

DOC logo (goto DOC home page) COPEPOD (Main Page)   |   Online Database   |   Products & Atlases   |   Site Map

[   Contact Us   |   Privacy Policy   |   Information Quality Guidelines   |   External Link Disclaimer external link indicator icon   ]
NOAA logo (goto NOAA home page)