Everything about Phytoplankton totally explained
Phytoplankton are the
autotrophic component of
plankton. The name comes from the
Greek terms,
phyton or "
plant" and πλαγκτος ("planktos"), meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the
unaided eye. However, when present in high enough numbers, they may appear as a green discoloration of the water due to the presence of
chlorophyll within their cells (although the actual color may vary with the species of phytoplankton present due to varying levels of chlorophyll or the presence of accessory pigments such as
phycobiliproteins,
xanthophylls, etc.).
Ecology
Phytoplankton obtain energy through a process called
photosynthesis and must therefore live in the well-lit surface layer (termed the
euphotic zone) of an
ocean,
sea,
lake, or other body of water. Through photosynthesis, phytoplankton are responsible for much of the
oxygen present in the
Earth's atmosphere – half of the total amount produced by all plant life. Their cumulative energy fixation in carbon compounds (
primary production) is the basis for the vast majority of oceanic and also many
freshwater food webs (
chemosynthesis is a notable exception). As a side note, one of the more remarkable
food chains in the ocean – remarkable because of the small number of links – is that of phytoplankton fed on by
krill (a type of shrimp) fed on by
baleen whales.
Phytoplankton are also crucially dependent on minerals. These are primarily
macronutrients such as
nitrate,
phosphate or
silicic acid, whose availability is governed by the balance between the so-called
biological pump and
upwelling of deep, nutrient-rich waters. However, across large regions of the
World Ocean such as the
Southern Ocean, phytoplankton are also limited by the lack of the
micronutrient iron. This has led to some scientists advocating
iron fertilization as a means to counteract the accumulation of human-produced carbon dioxide (CO
2) in the
atmosphere.
While almost all phytoplankton species are obligate
photoautotrophs, there are some that are
mixotrophic and other, non-pigmented species that are actually
heterotrophic (the latter are often viewed as
zooplankton). Of these, the best known are
dinoflagellate genera such as
Noctiluca and
Dinophysis, that obtain organic carbon by
ingesting other organisms or
detrital material.
The term phytoplankton encompasses all photoautotrophic microorganisms in aquatic
food webs. Phytoplankton serve as the base of the aquatic food web, providing an essential ecological function for all aquatic life. However, unlike terrestrial
communities, where most autotrophs are
plants, phytoplankton are a diverse group, incorporating
protistan
eukaryotes and both
eubacterial and
archaebacterial
prokaryotes. There are about 5,000 species of marine phytoplankton. There is uncertainty in how such diversity has evolved in an environment where competition for only a few resources would suggest limited potential for
niche differentiation.
In terms of numbers, the most important groups of phytoplankton include the
diatoms,
cyanobacteria and
dinoflagellates, although many other groups of
algae are represented. One group, the
coccolithophorids, is responsible (in part) for the release of significant amounts of
dimethyl sulfide (DMS) into the
atmosphere. DMS is converted to sulfate and these sulfate molecules act as
cloud condensation nuclei, increasing general cloud cover. In
oligotrophic oceanic regions such as the
Sargasso Sea or the
South Pacific gyre, phytoplankton is dominated by the small sized cells, called
picoplankton, mostly composed of
cyanobacteria (
Prochlorococcus,
Synechococcus) and picoeucaryotes such as
Micromonas.
Further Information
Get more info on 'Phytoplankton'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://phytoplankton.totallyexplained.com">Phytoplankton Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
