Plankton are the diverse collection of
organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
s found in
water
Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
(or
air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
) that are unable to propel themselves against a
current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
(or
wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ho ...
). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as
bivalves,
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
and
whale
Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and ...
s.
Marine plankton include
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
,
archaea,
algae,
protozoa and drifting or floating
animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
s that inhabit the
saltwater
Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, ...
of
ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
s and the
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estu ...
waters of
estuaries
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...
. Freshwater plankton are similar to marine plankton, but are found in the
freshwaters of lakes and rivers. Plankton are usually thought of as inhabiting water, but there are also airborne versions, the
aeroplankton
Aeroplankton (or aerial plankton) are tiny lifeforms that float and drift in the air, carried by wind. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of ...
, that live part of their lives drifting in the atmosphere. These include
plant spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...
s,
pollen and wind-scattered
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s, as well as microorganisms swept into the air from terrestrial dust storms and oceanic plankton swept into the air by
sea spray
Sea spray are aerosol particles formed from the ocean, mostly by ejection into Earth's atmosphere by bursting bubbles at the air-sea interface. Sea spray contains both organic matter and inorganic salts that form sea salt aerosol (SSA). SSA ha ...
.
Though many planktonic
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
are
microscopic
The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...
in size, ''plankton'' includes organisms over a wide range of sizes, including large organisms such as
jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrell ...
. Plankton are defined by their
ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for ...
and level of
motility
Motility is the ability of an organism to move independently, using metabolic energy.
Definitions
Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...
rather than by any
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
or
taxonomic classification. Technically the term does not include organisms on the surface of the water, which are called ''
neuston
Neuston, also known as pleuston, are organisms that live at the surface of the ocean or an estuary, or at the surface of a lake, river or pond. Neuston can live on top of the water surface or may be attached to the underside of the water surface. ...
''—or those that swim actively in the water, which are called ''
nekton
Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...
''.
Terminology
The name ''plankton'' is derived from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
adjective (), meaning ''
errant'', and by extension, ''wanderer'' or ''drifter'', and was coined by
Victor Hensen
Christian Andreas Victor Hensen (10 February 1835 – 5 April 1924) was a German zoologist and marine biologist (planktology). He coined the term ''plankton'' and laid the foundation for biological oceanography and quantitative studies.
Family
...
in 1887. While some forms are capable of independent movement and can swim hundreds of meters vertically in a single day (a behavior called
diel vertical migration), their horizontal position is primarily determined by the surrounding water movement, and plankton typically flow with
ocean current
An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours ...
s. This is in contrast to
nekton
Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...
organisms, such as
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
,
squid and
marine mammal
Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their ...
s, which can swim against the ambient flow and control their position in the environment.
Within the plankton,
holoplankton
Holoplankton are organisms that are planktic (they live in the water column and cannot swim against a current) for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their lif ...
spend their entire
life cycle
Life cycle, life-cycle, or lifecycle may refer to:
Science and academia
*Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring
* Life-cycle hypothesis ...
as plankton (e.g. most
algae,
copepods,
salp
A salp (plural salps, also known colloquially as “sea grape”) or salpa (plural salpae or salpas) is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient ...
s, and some
jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrell ...
). By contrast,
meroplankton
Meroplankton are a wide variety of aquatic organisms which have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organism. Meroplankton can be contrasted with holoplankton, whi ...
are only planktic for part of their lives (usually the
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
l stage), and then graduate to either a nektic (swimming) or
benthic (sea floor) existence. Examples of meroplankton include the larvae of
sea urchins,
starfish,
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...
s, marine
worm
Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always).
Worms vary in size from microscopic to over in length for marine polychaete wo ...
s, and most
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...
.
The
amount
Quantity or amount is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value multiple of a unit ...
and
distribution Distribution may refer to:
Mathematics
*Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations
* Probability distribution, the probability of a particular value or value range of a vari ...
of plankton depends on available nutrients, the
state of water and a large amount of other plankton.
The study of plankton is termed
planktology
Planktology is the study of plankton, various small drifting plants, animals and microorganisms that inhabit bodies of water. Planktology topics include primary production, energy flow and the carbon cycle.
Plankton drive the "biological pump", ...
and a planktonic individual is referred to as a plankter. The adjective ''planktonic'' is widely used in both the scientific and popular literature, and is a generally accepted term. However, from the standpoint of prescriptive grammar, the less-commonly used ''planktic'' is more strictly the correct adjective. When deriving English words from their Greek or Latin roots, the gender-specific ending (in this case, "-on" which indicates the word is neuter) is normally dropped, using only the root of the word in the derivation.
Trophic groups
Plankton are primarily divided into broad functional (or
trophic level
The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it ...
) groups:
*
Phytoplankton (from Greek ''phyton'', or plant), are
autotroph
An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Wo ...
ic
prokaryotic
A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connec ...
or
eukaryotic
Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the ...
alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
e that live near the water surface where there is sufficient
light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
to support
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
. Among the more important groups are the
diatoms,
cyanobacteria,
dinoflagellates and
coccolithophore
Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the king ...
s.
*
Zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
(from Greek ''zoon'', or animal), are small
protozoans or
metazoa
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...
ns (e.g.
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...
s and other
animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
s) that feed on other plankton. Some of the
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
and
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
e of larger nektonic animals, such as fish, crustaceans, and
annelids, are included here.
*
Mycoplankton include
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
and
fungus-like organisms, which, like bacterioplankton, are also significant in remineralisation and
nutrient cycling
A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cycli ...
.
*
Bacterioplankton include
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
and
archaea, which play an important role in
remineralising organic material down the water column (note that prokaryotic phytoplankton are also bacterioplankton).
*
Virioplankton are viruses. Viruses are more abundant in the plankton than bacteria and archaea, though much smaller.
Mixoplankton
*
Mixotroph A mixotroph is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is estimated that mixotrophs comp ...
s. Plankton have traditionally been categorized as producer, consumer and recycler groups, but some plankton are able to benefit from more than just one trophic level. In this mixed trophic strategy—known as mixotrophy—organisms act as both producers and consumers, either at the same time or switching between modes of nutrition in response to ambient conditions. This makes it possible to use photosynthesis for growth when nutrients and light are abundant, but switching to eat phytoplankton, zooplankton or each other when growing conditions are poor. Mixotrophs are divided into two groups; constitutive mixotrophs, CMs, which are able to perform photosynthesis on their own, and non-constitutive mixotrophs, NCMs, which use
phagocytosis
Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is ...
to engulf phototrophic prey that are either kept alive inside the host cell which benefit from its photosynthesis, or they digest their prey except for the plastids which continues to perform photosynthesis (
kleptoplasty
Kleptoplasty or kleptoplastidy is a symbiotic phenomenon whereby plastids, notably chloroplasts from algae, are sequestered by host organisms. The word is derived from ''Kleptes'' (κλέπτης) which is Greek for thief. The alga is eaten norma ...
).
Recognition of the importance of mixotrophy as an ecological strategy is increasing, as well as the wider role this may play in marine
biogeochemistry
Biogeochemistry is the scientific discipline that involves the study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment (including the biosphere, the cryosphere, ...
. Studies have shown that mixotrophs are much more important for the marine ecology than previously assumed, and comprise more than half of all microscopic plankton. Their presence act as a buffer that prevents the collapse of ecosystems during times with little to no light.
Size groups
Plankton are also often described in terms of size. Usually the following divisions are used:
::
However, some of these terms may be used with very different boundaries, especially on the larger end. The existence and importance of nano- and even smaller plankton was only discovered during the 1980s, but they are thought to make up the largest proportion of all plankton in number and diversity.
The microplankton and smaller groups are
microorganism
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s and operate at low
Reynolds numbers, where the viscosity of water is more important than its mass or inertia.
File:Plankton size.png,
Habitat groups
Marine plankton
Marine plankton includes
marine bacteria and archaea,
algae,
protozoa and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries.
Freshwater plankton
Freshwater plankton are similar to marine plankton, but are found inland in the freshwaters of lakes and rivers.
Aeroplankton
File:Ocean mist and spray 2.jpg, Sea spray
Sea spray are aerosol particles formed from the ocean, mostly by ejection into Earth's atmosphere by bursting bubbles at the air-sea interface. Sea spray contains both organic matter and inorganic salts that form sea salt aerosol (SSA). SSA ha ...
containing marine microorganisms
Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism (or microbe) is any microscopic livin ...
can be swept high into the atmosphere and may travel the globe as aeroplankton
Aeroplankton (or aerial plankton) are tiny lifeforms that float and drift in the air, carried by wind. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of ...
before falling back to earth.
Aeroplankton
Aeroplankton (or aerial plankton) are tiny lifeforms that float and drift in the air, carried by wind. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of ...
are tiny lifeforms that float and drift in the air, carried by the
current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
of the
wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ho ...
; they are the
atmospheric analogue to oceanic plankton. Most of the living things that make up aeroplankton are very small to
microscopic
The microscopic scale () is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly. In physics, the microscopic scale is sometimes regarded as the scale be ...
in size, and many can be difficult to identify because of their tiny size. Scientists can collect them for study in traps and sweep nets from
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...
, kites or balloons. Aeroplankton is made up of numerous
microbes
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
, including
virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsk ...
es, about 1000 different species of
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
, around 40,000 varieties of
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
, and hundreds of species of
protist
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...
s,
algae,
mosses and
liverworts that live some part of their life cycle as aeroplankton, often as
spores,
pollen, and wind-scattered
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s. Additionally, peripatetic microorganisms are swept into the air from terrestrial dust storms, and an even larger amount of airborne marine microorganisms are propelled high into the atmosphere in sea spray. Aeroplankton deposits hundreds of millions of airborne viruses and tens of millions of bacteria every day on every square meter around the planet.
The
sea surface microlayer
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of Earth's surface. With an operationally defined thickness between 1 and , the SML has physicochemical and biological properties that ...
, compared to the sub-surface waters, contains elevated concentration of
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
and
viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsky's ...
.
[Blanchard, D.C., 1983. The production, distribution and bacterial enrichment of the sea-salt aerosol. In: Liss, P.S., Slinn, W.G.N. ŽEds.., Air–Sea Exchange of Gases and Particles. D. Reidel Publishing Co., Dordrecht, Netherlands, pp. 407-444.] These materials can be transferred from the sea-surface to the atmosphere in the form of wind-generated aqueous
aerosols due to their high vapour tension and a process known as
volatilisation
Volatilization is the process whereby a dissolved sample is vaporised. In atomic spectroscopy this is usually a two-step process. The analyte is turned into small droplets in a nebuliser which are entrained in a gas flow which is in turn volatilis ...
.
[Wallace Jr., G.T., Duce, R.A., 1978. Transport of particulate organic matter by bubbles in marine waters. Limnol. Oceanogr. 23 Ž6., 1155–1167.] When airborne, these
microbes
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
can be transported long distances to coastal regions. If they hit land they can have affect animal, vegetation and human health.
[WHO, 1998. Draft guidelines for safe recreational water environments: coastal and fresh waters, draft for consultation. World Health Organization, Geneva, EOSrDRAFTr98 14, pp. 207–299.] Marine aerosols that contain viruses can travel hundreds of kilometers from their source and remain in liquid form as long as the humidity is high enough (over 70%).
[Klassen, R. D., & Roberge, P. R. (1999). Aerosol transport modeling as an aid to understanding atmospheric corrosivity patterns. Materials & Design, 20, 159–168.][Moorthy, K. K., Satheesh, S. K., & Krishna Murthy, B.V. (1998). Characteristics ofspectral optical depths and size distributions of aerosols over tropical oceanic regions. Journal of Atmospheric and Solar–Terrestrial Physics, 60, 981–992.
] These aerosols are able to remain suspended in the atmosphere for about 31 days.
[Aller, J., Kuznetsova, M., Jahns, C., Kemp, P. (2005) The sea surface microlayer as a source of viral and bacterial enrichment in marine aerosols. Journal of aerosol science. Vol. 36, pp. 801-812.] Evidence suggests that bacteria can remain viable after being transported inland through aerosols. Some reached as far as 200 meters at 30 meters above sea level.
The process which transfers this material to the atmosphere causes further enrichment in both bacteria and viruses in comparison to either the SML or sub-surface waters (up to three orders of magnitude in some locations).
[Marks, R., Kruczalak, K., Jankowska, K., & Michalska, M. (2001). Bacteria and fungi in air over the GulfofGdansk and Baltic sea. Journal of Aerosol Science, 32, 237–250.]
Geoplankton
Many animals live in terrestrial environments by thriving in transient often microscopic bodies of water and moisture, these include
rotifers and
gastrotrich
The gastrotrichs (phylum Gastrotricha), commonly referred to as hairybellies or hairybacks, are a group of microscopic (0.06-3.0 mm), worm-like, acoelomate animals, and are widely distributed and abundant in freshwater and marine environmen ...
s which lay resilient eggs capable of surviving years in dry environments, and some of which can go dormant themselves. Nematodes are usually microscopic with this lifestyle. Water bears, despite only having lifespans of a few months, famously can enter suspended animation during dry or hostile conditions and survive for decades. This allows them to be ubiquitous in terrestrial environments despite needing water to grow and reproduce. Many microscopic crustacean groups like
copepods and
amphipods
Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far describ ...
(of which
sandhoppers are members) and
seed shrimp
Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typical ...
are known to go dormant when dry and live in transient bodies of water too
Other groups
Gelatinous zooplankton
Gelatinous zooplankton
Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All jellyfish are gelatinous zoopla ...
are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All
jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrell ...
are gelatinous zooplankton, but not all gelatinous zooplankton are jellyfish. The most commonly encountered organisms include
ctenophores,
medusae
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...
,
salps
A salp (plural salps, also known colloquially as “sea grape”) or salpa (plural salpae or salpas) is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient ...
, and
Chaetognatha
The Chaetognatha or chaetognaths (meaning ''bristle-jaws'') are a phylum of predatory marine worms that are a major component of plankton worldwide. Commonly known as arrow worms, about 20% of the known Chaetognatha species are benthic, and ca ...
in coastal waters. However, almost all marine phyla, including
Annelida,
Mollusca and
Arthropoda
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, ...
, contain gelatinous species, but many of those odd species live in the open ocean and the deep sea and are less available to the casual ocean observer.
Ichthyoplankton
Ichthyoplankton
Ichthyoplankton (from Greek: ἰχθύς, , "fish"; and πλαγκτός, , "drifter") are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epi ...
are the
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
and
larvae of fish. They are mostly found in the sunlit zone of the
water column
A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...
, less than 200 metres deep, which is sometimes called the
epipelagic
The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological proc ...
or
photic zone. Ichthyoplankton are
planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into
juveniles. Fish larvae are part of the
zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals.
[What are Ichthyoplankton?]
Southwest Fisheries Science Center, NOAA. Modified 3 September 2007. Retrieved 22 July 2011. Fish can produce high numbers of eggs which are often released into the open water column. Fish eggs typically have a diameter of about . The newly hatched young of oviparous fish are called
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
e. They are usually poorly formed, carry a large
yolk sac
The yolk sac is a membranous sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac'' is ...
(for nourishment) and are very different in appearance from juvenile and adult specimens. The larval period in oviparous fish is relatively short (usually only several weeks), and larvae rapidly grow and change appearance and structure (a process termed
metamorphosis) to become juveniles. During this transition larvae must switch from their yolk sac to feeding on
zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
prey, a process which depends on typically inadequate zooplankton density, starving many larvae. In time fish larvae become able to swim against currents, at which point they cease to be plankton and become
juvenile fish
Fish go through various life stages between fertilization and adulthood. The life of a fish start as spawned eggs which hatch into immotile larvae. These larval hatchlings are not yet capable of feeding themselves and carry a yolk sac whic ...
.
Holoplankton
Holoplankton
Holoplankton are organisms that are planktic (they live in the water column and cannot swim against a current) for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their lif ...
are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with
meroplankton
Meroplankton are a wide variety of aquatic organisms which have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organism. Meroplankton can be contrasted with holoplankton, whi ...
, which are planktic organisms that spend part of their life cycle in the
benthic zone. Examples of holoplankton include some
diatoms,
radiolarian
The Radiolaria, also called Radiozoa, are protozoa of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell into the inner and outer portions of endoplasm and ectoplasm. The elab ...
s, some
dinoflagellates,
foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly ...
,
amphipods,
krill
Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often attributed to species of fish.
Krill are consi ...
,
copepods, and
salp
A salp (plural salps, also known colloquially as “sea grape”) or salpa (plural salpae or salpas) is a barrel-shaped, planktic tunicate. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient ...
s, as well as some
gastropod mollusk species. Holoplankton dwell in the
pelagic zone as opposed to the
benthic zone.
Holoplankton include both
phytoplankton and
zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and vary in size. The most common plankton are
protist
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...
s.
Meroplankton
Meroplankton
Meroplankton are a wide variety of aquatic organisms which have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organism. Meroplankton can be contrasted with holoplankton, whi ...
are a wide variety of aquatic organisms which have both planktonic and
benthic stages in their life cycles. Much of the meroplankton consists of
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
l stages of larger organism.
Meroplankton can be contrasted with
holoplankton
Holoplankton are organisms that are planktic (they live in the water column and cannot swim against a current) for their entire life cycle. Holoplankton can be contrasted with meroplankton, which are planktic organisms that spend part of their lif ...
, which are planktonic organisms that stay in the
pelagic zone as plankton throughout their entire life cycle. After a period of time in the plankton, many meroplankton graduate to the
nekton
Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...
or adopt a
benthic (often
sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
) lifestyle on the
seafloor
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth an ...
. The larval stages of benthic
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s make up a significant proportion of planktonic communities. The planktonic larval stage is particularly crucial to many benthic invertebrate in order to
disperse their young. Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in the pelagic zone for durations ranging from hour to months.
Pseudoplankton
Pseudoplankton are organisms that attach themselves to planktonic organisms or other floating objects, such as drifting wood,
buoyant
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pr ...
shells of organisms such as ''
Spirula
''Spirula spirula'' is a species of deep-water squid-like cephalopod mollusk. It is the only extant member of the genus ''Spirula'', the family Spirulidae, and the order Spirulida. Because of the shape of its internal shell, it is commonly known ...
'', or man-made
flotsam
In maritime law, flotsam'','' jetsam'','' lagan'','' and derelict are specific kinds of shipwreck. The words have specific nautical meanings, with legal consequences in the law of admiralty and marine salvage. A shipwreck is defined as the rema ...
. Examples include
goose barnacle
Goose barnacles, also called stalked barnacles or gooseneck barnacles, are filter-feeding crustaceans that live attached to hard surfaces of rocks and flotsam in the ocean intertidal zone. Goose barnacles formerly made up the taxonomic order P ...
s and the bryozoan ''
Jellyella''. By themselves these animals cannot
float
Float may refer to:
Arts and entertainment Music Albums
* ''Float'' (Aesop Rock album), 2000
* ''Float'' (Flogging Molly album), 2008
* ''Float'' (Styles P album), 2013
Songs
* "Float" (Tim and the Glory Boys song), 2022
* "Float", by Bush ...
, which contrasts them with true planktonic organisms, such as ''
Velella
''Velella'' is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is ''Velella velella'', a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raf ...
'' and the
Portuguese Man o' War
The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or blue bottle, which is ...
, which are buoyant. Pseudoplankton are often found in the guts of filtering
zooplankters.
Tychoplankton
Tychoplankton are organisms, such as free-living or attached
benthic organisms and other non-planktonic organisms, that are carried into the plankton through a disturbance of their benthic habitat, or by winds and currents.
This can occur by direct
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
or by disruption of the substrate and subsequent entrainment in the water column.
[ Tychoplankton are, therefore, a primary subdivision for sorting planktonic organisms by duration of lifecycle spent in the plankton, as neither their entire lives nor particular reproductive portions are confined to planktonic existence.] Tychoplankton are sometimes called ''accidental plankton''.
Mineralized plankton
tests." style="float:left">
File:Diatom Helipelta metil.jpg, Diatoms have glass shells (frustule
A frustule is the hard and porous cell wall or external layer of diatoms. The frustule is composed almost purely of silica, made from silicic acid, and is coated with a layer of organic substance, which was referred to in the early literature on ...
s) and produce much of the world's oxygen.
File:Haeckel Spumellaria detail.png, The elaborate silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is ...
shells of microscopic marine radiolarians can eventually produce opal
Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline form ...
.
File:Coccolithus pelagicus.jpg, Coccolithophore
Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the king ...
s have chalk
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...
plates called coccoliths
Coccoliths are individual plates or scales of calcium carbonate formed by coccolithophores (single-celled phytoplankton such as '' Emiliania huxleyi'') and cover the cell surface arranged in the form of a spherical shell, called a ''coccosphere'' ...
, and produced the Cliffs of Dover
The White Cliffs of Dover is the region of English coastline facing the Strait of Dover and France. The cliff face, which reaches a height of , owes its striking appearance to its composition of chalk accented by streaks of black flint, deposi ...
.
File:Cwall99 lg.jpg, Planktonic algae bloom
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompasse ...
of coccolithophore
Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the king ...
s off the southern coast of England
File:Planktic Foraminifera of the northern Gulf of Mexico.jpg, Foraminiferan
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an ...
s have calcium carbonate shells and produced the limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
in the Great Pyramids
The Giza pyramid complex ( ar, مجمع أهرامات الجيزة), also called the Giza necropolis, is the site on the Giza Plateau in Greater Cairo, Egypt that includes the Great Pyramid of Giza, the Pyramid of Khafre, and the Pyramid of ...
.
Distribution
Apart from aeroplankton, plankton inhabits oceans, seas, lakes and ponds. Local abundance varies horizontally, vertically and seasonally. The primary cause of this variability is the availability of light. All plankton ecosystems are driven by the input of solar energy (but see chemosynthesis
In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic compounds (e.g., hydrogen gas, hydrog ...
), confining primary production
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through ...
to surface waters, and to geographical regions and seasons having abundant light.
A secondary variable is nutrient availability. Although large areas of the tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and sub-tropical
The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north a ...
oceans have abundant light, they experience relatively low primary production because they offer limited nutrients such as nitrate, phosphate
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid .
The phosphate or orthophosphate ion is derived from phosph ...
and silicate. This results from large-scale ocean circulation
An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, ...
and water column stratification
Stratification may refer to:
Mathematics
* Stratification (mathematics), any consistent assignment of numbers to predicate symbols
* Data stratification in statistics
Earth sciences
* Stable and unstable stratification
* Stratification, or st ...
. In such regions, primary production usually occurs at greater depth, although at a reduced level (because of reduced light).
Despite significant macronutrient
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excre ...
concentrations, some ocean regions are unproductive (so-called HNLC regions). The micronutrient iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
is deficient in these regions, and adding it can lead to the formation of phytoplankton algal bloom
An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompass ...
s. Iron primarily reaches the ocean through the deposition of dust on the sea surface. Paradoxically, oceanic areas adjacent to unproductive, arid
A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ...
land thus typically have abundant phytoplankton (e.g., the eastern Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
, where trade winds
The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisp ...
bring dust from the Sahara Desert
, photo = Sahara real color.jpg
, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
, map =
, map_image =
, location =
, country =
, country1 =
, ...
in north Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
).
While plankton are most abundant in surface waters, they live throughout the water column. At depths where no primary production occurs, zooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and bacterioplankton instead consume organic material sinking from more productive surface waters above. This flux of sinking material, so-called marine snow
In the deep ocean, marine snow (also known as "ocean dandruff") is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to ...
, can be especially high following the termination of spring bloom
The spring bloom is a strong increase in phytoplankton abundance (i.e. stock) that typically occurs in the early spring and lasts until late spring or early summer. This seasonal event is characteristic of temperate North Atlantic, sub-polar, and ...
s.
The local distribution of plankton can be affected by wind-driven Langmuir circulation
In physical oceanography, Langmuir circulation consists of a series of shallow, slow, counter-rotating vortices at the ocean's surface aligned with the wind.
These circulations are developed when wind blows steadily over the sea surface.
Ir ...
and the biological effects of this physical process.
Ecological significance
Food chain
Aside from representing the bottom few levels of a food chain
A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), de ...
that supports commercially important fisheries, plankton ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...
s play a role in the biogeochemical cycles of many important chemical element
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
s, including the ocean's carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major componen ...
. Fish larvae mainly eat zooplankton, which eat phytoplankton
Carbon cycle
Primarily by grazing on phytoplankton, zooplankton provide carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...
to the planktic foodweb, either respiring it to provide metabolic energy, or upon death as biomass or detritus. Organic material tends to be denser than seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appr ...
, so it sinks into open ocean ecosystems away from the coastlines, transporting carbon along with it. This process, called the biological pump
The biological pump (or ocean carbon biological pump or marine biological carbon pump) is the ocean's biologically driven sequestration of carbon from the atmosphere and land runoff to the ocean interior and seafloor sediments.Sigman DM & GH ...
, is one reason that oceans constitute the largest carbon sink
A carbon sink is anything, natural or otherwise, that accumulates and stores some carbon-containing chemical compound for an indefinite period and thereby removes carbon dioxide () from the atmosphere.
Globally, the two most important carbon si ...
on Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. However, it has been shown to be influenced by increments of temperature. In 2019, a study indicated that at ongoing rates of seawater acidification, Antarctic phytoplanktons could become smaller and less effective at storing carbon before the end of the century.
It might be possible to increase the ocean's uptake of carbon dioxide
Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
() generated through human activities
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and exceptional cognitive skills due to a large and complex Human brain, brain. This has enabled the development of ad ...
by increasing plankton production through iron fertilization
Iron fertilization is the intentional introduction of iron to iron-poor areas of the ocean surface to stimulate phytoplankton production. This is intended to enhance biological productivity and/or accelerate carbon dioxide () sequestration fr ...
– introducing amounts of iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
into the ocean. However, this technique may not be practical at a large scale. Ocean oxygen depletion
Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 p ...
and resultant methane production (caused by the excess production remineralising at depth) is one potential drawback.
Oxygen production
Phytoplankton absorb energy from the Sun and nutrients from the water to produce their own nourishment or energy. In the process of photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
, phytoplankton release molecular oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
() into the water as a waste byproduct. It is estimated that about 50% of the world's oxygen is produced via phytoplankton photosynthesis. The rest is produced via photosynthesis on land by plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...
s. Furthermore, phytoplankton photosynthesis has controlled the atmospheric / balance since the early Precambrian Eon.
Absorption efficiency
The ''absorption efficiency'' (AE) of plankton is the proportion of food absorbed by the plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Depending on the feeding rate and prey composition, variations in absorption efficiency may lead to variations in fecal pellet
Feces ( or faeces), known colloquially and in slang as poo and poop, are the solid or semi-solid remains of food that was not digested in the small intestine, and has been broken down by bacteria in the large intestine. Feces contain a relati ...
production, and thus regulates how much organic material is recycled back to the marine environment. Low feeding rates typically lead to high absorption efficiency and small, dense pellets, while high feeding rates typically lead to low absorption efficiency and larger pellets with more organic content. Another contributing factor to dissolved organic matter
Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called part ...
(DOM) release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon is loss from zooplankton in the form of respired . The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more “sloppily”, that is more biomatter is released through inefficient consumption. There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon
Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called partic ...
(DOC) and ammonium than omnivorous diets.
Biomass variability
The growth of phytoplankton populations is dependent on light levels and nutrient availability. The chief factor limiting growth varies from region to region in the world's oceans. On a broad scale, growth of phytoplankton in the oligotrophic tropical and subtropical gyres is generally limited by nutrient supply, while light often limits phytoplankton growth in subarctic gyres. Environmental variability at multiple scales influences the nutrient and light available for phytoplankton, and as these organisms form the base of the marine food web, this variability in phytoplankton growth influences higher trophic levels. For example, at interannual scales phytoplankton levels temporarily plummet during El Niño
El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...
periods, influencing populations of zooplankton, fishes, sea birds, and marine mammal
Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their ...
s.
The effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Changes in the vertical stratification of the water column, the rate of temperature-dependent biological reactions, and the atmospheric supply of nutrients are expected to have important impacts on future phytoplankton productivity. Additionally, changes in the mortality of phytoplankton due to rates of zooplankton grazing may be significant.
Plankton diversity
File:Pelagibacter.jpg, ''Pelagibacter ubique
"''Candidatus'' Pelagibacter", with the single species "''Ca.'' P. communis", was isolated in 2002 and given a specific name, although it has not yet been described as required by the bacteriological code. It is an abundant member of the SAR11 c ...
'', the most common bacteria in the ocean, plays a major role in global carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. Carbon is the main component of biological compounds as well as a major componen ...
s
File:Prochlorococcus marinus (cropped).jpg, The tiny cyanobacterium
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...
''Prochlorococcus
''Prochlorococcus'' is a genus of very small (0.6 μm) marine cyanobacteria with an unusual pigmentation ( chlorophyll ''a2'' and ''b2''). These bacteria belong to the photosynthetic picoplankton and are probably the most abundant photosynth ...
'' is a major contributor to atmospheric oxygen
File:Noctiluca scintillans varias.jpg, The sea sparkle
Milky seas, also called mareel, is a luminous phenomenon in the ocean in which large areas of seawater (up to ) appear to glow translucently (in varying shades of blue). Such occurrences glow brightly enough at night to be visible from satellit ...
dinoflagellate glows in the night to produce the milky seas effect
Milky seas, also called mareel, is a luminous phenomenon in the ocean in which large areas of seawater (up to ) appear to glow translucently (in varying shades of blue). Such occurrences glow brightly enough at night to be visible from satelli ...
File:Copepodkils.jpg, Copepod from Antarctica, a translucent ovoid animal with two long antennae
File:Clupeaharenguslarvaeinsitukils.jpg, Herring larva imaged with the remains of the yolk
Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example ...
and the long gut visible in the transparent animal
File:Icefishuk.jpg, Icefish larvae from Antarctica have no haemoglobin
File:Mnemiopsis leidyi 2.jpg, The sea walnut ctenophore has a transient anus which forms only when it needs to defecate
File:LeptocephalusConger.jpg, Eel larva drifting with the gulf stream
File:Krill666.jpg, Antarctic krill, probably the largest biomass of a single species on the planet
File:Dinoflagellates and a tintinnid ciliate.jpg, Microzooplankton are major grazers of the plankton: two dinoflagellates and a tintinnid
Tintinnids are ciliates of the choreotrich order Tintinnida, distinguished by vase-shaped shells, the name deriving from a Latin source meaning a small tinkling bell, that are called'' loricae'', which are mostly protein but may incorporate min ...
ciliate.
File:Sargassum on the beach, Cuba.JPG, Sargassum
''Sargassum'' is a genus of brown (class Phaeophyceae) macroalgae ( seaweed) in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral ...
seaweed drifts with currents using air bladders to stay afloat
File:Plankton creates sea foam 2.jpg, Planktonic sea foam
Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignins, and lipids) derived from sources ...
bubbles with image of photographer
File:Janthina.jpg, Macroplankton: a ''Janthina janthina
''Janthina janthina'' is a species of holoplanktonic sea snail, a marine gastropod mollusk in the family Epitoniidae. Its common names include violet sea-snail, common violet snail, large violet snail and purple storm snail.
Distribution
This ...
'' snail (with bubble float) cast up onto a beach in Maui
Planktonic Relationships
Fish & plankton
Zooplankton are the initial prey item for almost all fish larva
Ichthyoplankton (from Greek: ἰχθύς, , "fish"; and πλαγκτός, , "drifter") are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epi ...
e as they switch from their yolk sac
The yolk sac is a membranous sac attached to an embryo, formed by cells of the hypoblast layer of the bilaminar embryonic disc. This is alternatively called the umbilical vesicle by the Terminologia Embryologica (TE), though ''yolk sac'' is ...
s to external feeding. Fish rely on the density and distribution of zooplankton to match that of new larvae, which can otherwise starve. Natural factors (e.g., current variations, temperature changes) and man-made factors (e.g. river dams, ocean acidification
Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...
, rising temperatures) can strongly affect zooplankton, which can in turn strongly affect larval survival, and therefore breeding success.
It's been shown that plankton can be patchy in marine environments where there aren't significant fish populations and additionally, where fish are abundant, zooplankton dynamics are influenced by the fish predation rate in their environment. Depending on the predation rate, they could express regular or chaotic behavior.
A negative effect that fish larvae can have on planktonic algal blooms is that the larvae will prolong the blooming event by diminishing available zooplankton numbers; this in turn permits excessive phytoplankton growth allowing the bloom to flourish .
The importance of both phytoplankton and zooplankton is also well-recognized in extensive and semi-intensive pond fish farming. Plankton population-based pond management strategies for fish rearing have been practiced by traditional fish farmers for decades, illustrating the importance of plankton even in man-made environments.
Whales & plankton
Of all animal fecal matter, it is whale feces that is the 'trophy' in terms of increasing nutrient availability. Phytoplankton are the powerhouse of open ocean primary production and they can acquire many nutrients from whale feces. In the marine food web, phytoplankton are at the base of the food web and are consumed by zooplankton & krill, which are preyed upon by larger and larger marine organisms, including whales, so it can be said that whale poop fuels the entire food web.
Humans & plankton
Plankton have many direct and indirect effects on humans.
Around 70% of the oxygen in the atmosphere is produced in the oceans from phytoplankton performing photosynthesis, meaning that the majority of the oxygen available for us and other organisms that respire aerobically is produced by plankton.
Plankton also make up the base of the marine food web, providing food for all the trophic levels above. Recent studies have analyzed the marine food web to see if the system runs on a top-down or bottom-up approach. Essentially, this research is focused on understanding whether changes in the food web are driven by nutrients at the bottom of the food web or predators at the top. The general conclusion is that the bottom-up approach seemed to be more predictive of food web behavior. This indicates that plankton have more sway in determining the success of the primary consumer species that prey on them than do the secondary consumers that prey on the primary consumers.
In some cases, plankton act as an intermediate host
A host is a person responsible for guests at an event or for providing hospitality during it.
Host may also refer to:
Places
* Host, Pennsylvania, a village in Berks County
People
*Jim Host (born 1937), American businessman
* Michel Host ...
for deadly parasites in humans. One such case is that of cholera, an infection caused by several strains of Vibrio cholerae
''Vibrio cholerae'' is a species of Gram-negative, facultative anaerobe and comma-shaped bacteria. The bacteria naturally live in brackish or saltwater where they attach themselves easily to the chitin-containing shells of crabs, shrimps, and oth ...
. These species have been shown to have a symbiotic relationship with chitinous zooplankton species like copepods. These bacteria benefit not only from the food provided by the chiton from the zooplankton, but also from the protection from acidic environments. Once the copepods have been ingested by a human host, the chitinous exterior protects the bacteria from the stomach acids in the stomach and proceed to the intestines. Once there, the bacteria bind with the surface of the small intestine and the host will start developing symptoms, including extreme diarrhea, within five days.
See also
* Aeroplankton
Aeroplankton (or aerial plankton) are tiny lifeforms that float and drift in the air, carried by wind. Most of the living things that make up aeroplankton are very small to microscopic in size, and many can be difficult to identify because of ...
* Gelatinous zooplankton
Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All jellyfish are gelatinous zoopla ...
* Ichthyoplankton
Ichthyoplankton (from Greek: ἰχθύς, , "fish"; and πλαγκτός, , "drifter") are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epi ...
* Nekton
Nekton or necton (from the ) refers to the actively swimming aquatic organisms in a body of water. The term was proposed by German biologist Ernst Haeckel to differentiate between the active swimmers in a body of water, and the passive organisms t ...
* Paradox of the plankton
In aquatic biology, the paradox of the plankton describes the situation in which a limited range of resources supports an unexpectedly wide range of plankton species, apparently flouting the competitive exclusion principle which holds that whe ...
* Seston
Seston can simply be defined as the particles suspended in bodies of water such as lakes, oceans, ponds and rivers. The term "seston" applies to plankton, organic detritus, and minerals. Detritus is dead organic material and a mineral is a solid c ...
* Veliger
A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells.
Description
The veliger is the characteristic larva of the gastropod, bivalve and scaphopod ...
References
Further reading
*Kirby, Richard R. (2010). ''Ocean Drifters: A Secret World Beneath the Waves''. Studio Cactus Ltd, UK. .
*Dusenbery, David B. (2009). ''Living at Micro Scale: The Unexpected Physics of Being Small''. Harvard University Press, Cambridge, Massachusetts .
*Kiørboe, Thomas (2008). ''A Mechanistic Approach to Plankton Ecology''. Princeton University Press, Princeton, N.J. .
*Dolan, J.R., Agatha, S., Coats, D.W., Montagnes, D.J.S., Stocker, D.K., eds. (2013).''Biology and Ecology of Tintinnid Ciliates: Models for Marine Plankton''. Wiley-Blackwell, Oxford, UK .
External links
Ocean Drifters
– Short film narrated by David Attenborough about the varied roles of plankton
Plankton Chronicles
– Short documentary films and photos
COPEPOD: The Global Plankton Database
– Global coverage database of zooplankton biomass and abundance data
Plankton*Net
– Taxonomic database of images of plankton species
Guide to the marine zooplankton of south eastern Australia
– Tasmanian Aquaculture and Fisheries Institute
Sir Alister Hardy Foundation for Ocean Science
– Continuous Plankton Recorder Survey
– Integrated Marine Observing System
Sea Drifters
– BBC Audio slideshow
– Images of planktonic microorganisms
Plankton, planktic, planktonic
– Essays on nomenclature
Journal of Plankton Research
– Scientific periodical devoted to plankton
{{Authority control
Plankton,
Biological oceanography
Aquatic ecology
Oceanographical terminology