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77-412: Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column . The pressure difference can be very significant (approximately one atmosphere for every 10 metres of water depth). Because light is absorbed before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to

154-436: 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

231-432: A buffer that prevents the collapse of ecosystems during times with little to no light. 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

308-617: A dormant state. Some Actinomycetota found in Siberia are estimated to be half a million years old. Zoobenthos, prefix from Ancient Greek zôion  'animal', animals belonging to the benthos. Examples include polychaete worms , starfish and anemones. Phytobenthos , prefix from Ancient Greek phutón  'plant', plants belonging to the benthos, mainly benthic diatoms and macroalgae ( seaweed ). Endobenthos (or endobenthic), prefix from Ancient Greek éndon  'inner, internal', lives buried, or burrowing in

385-475: 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 (of which sandhoppers are members) and seed shrimp are known to go dormant when dry and live in transient bodies of water too Gelatinous zooplankton are fragile animals that live in

462-830: A food source for fish , such as the California sheephead , and humans . Benthic macro-invertebrates play a critical role in aquatic ecosystems . These organisms can be used to indicate the presence, concentration , and effect of water pollutants in the aquatic environment. Some water contaminants—such as nutrients, chemicals from surface runoff , and metals—settle in the sediment of river beds, where many benthos reside. Benthos are highly sensitive to contamination, so their close proximity to high pollutant concentrations make these organisms ideal for studying water contamination. Benthos can be used as bioindicators of water pollution through ecological population assessments or through analyzing biomarkers . In ecological population assessments,

539-430: 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

616-421: A process known as volatilisation . When airborne, these microbes can be transported long distances to coastal regions. If they hit land they can have an effect on animal, vegetation and human health. 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%). These aerosols are able to remain suspended in

693-415: 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 . Holoplankton are organisms that are planktic for their entire life cycle. Holoplankton can be contrasted with meroplankton , which are planktic organisms that spend part of their life cycle in

770-497: A reduced level (because of reduced light). Despite significant macronutrient concentrations, some ocean regions are unproductive (so-called HNLC regions ). The micronutrient iron is deficient in these regions, and adding it can lead to the formation of phytoplankton algal blooms . Iron primarily reaches the ocean through the deposition of dust on the sea surface. Paradoxically, oceanic areas adjacent to unproductive, arid land thus typically have abundant phytoplankton (e.g.,

847-506: A relative value of water pollution can be detected. Observing the number and diversity of macro-invertebrates in a waterbody can indicate the pollution level. In highly contaminated waters, a reduced number of organisms and only pollution-tolerant species will be found. In biomarker assessments, quantitative data can be collected on the amount of and direct effect of specific pollutants in a waterbody. The biochemical response of macro-invertebrates' internal tissues can be studied extensively in

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924-424: A wide range of sizes, including large organisms such as jellyfish. This is because plankton are defined by their ecological niche and level of motility rather than by any phylogenetic or taxonomic classification. The "plankton" category differentiates these organisms from those that float on the water's surface, called neuston , those that can swim against a current, called nekton , and those that live on

1001-406: A wide variety of aquatic organisms that have both planktonic and benthic stages in their life cycles. Much of the meroplankton consists of larval stages of larger organisms. Meroplankton can be contrasted with holoplankton , which are planktonic organisms that stay in the pelagic zone as plankton throughout their entire life cycle. After some time in the plankton, many meroplankton graduate to

1078-407: Is a concept used in oceanography to describe the physical (temperature, salinity, light penetration) and chemical (pH, dissolved oxygen, nutrient salts) characteristics of seawater at different depths for a defined geographical point. Generally, vertical profiles are made of temperature, salinity, chemical parameters at a defined point along the water column. The water column is the largest, yet one of

1155-588: Is also a redundant synonym, Benton . Compared to the relatively featureless pelagic zone , the benthic zone offers physically diverse habitats. There is a huge range in how much light and warmth is available, and in the depth of water or extent of intertidal immersion. The seafloor varies widely in the types of sediment it offers. Burrowing animals can find protection and food in soft, loose sediments such as mud , clay and sand . Sessile species such as oysters and barnacles can attach themselves securely to hard, rocky substrates. As adults they can remain at

1232-409: 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. Of all animal fecal matter, it is whale feces that is the 'trophy' in terms of increasing nutrient availability. Phytoplankton are

1309-411: Is defined mainly by its extremely uniform environmental conditions, as reflected in the distinct life forms inhabiting it. The abyss is largely unexplored, but it is known to contain animals found nowhere else on earth. It is also abundant in minerals frequently used in manufacturing. The bottom at these depths accounts for about one-third of the planet's seafloor. The sheer size of this area, coupled with

1386-476: 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

1463-541: Is loss from zooplankton in the form of respired CO 2 . 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 (DOC) and ammonium than omnivorous diets. The growth of phytoplankton populations

1540-501: Is made up of numerous microbes , including viruses , about 1000 different species of bacteria , around 40,000 varieties of fungi , and hundreds of species of protists , algae , mosses and liverworts that live some part of their life cycle as aeroplankton, often as spores , pollen , and wind-scattered seeds . 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

1617-462: Is only 2 to 3 percent of the entire ocean, the epipelagic zone is home to a massive number of organisms. Among other organisms, the photic zone is home to vital communities of phytoplankton, zooplankton, and algae. These primary producers become the food source for hundreds of other organisms such as sharks, stingrays, tuna, and sea turtles. The epipelagic zone is incredibly important due to its productivity and ability to help remove carbon dioxide from

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1694-555: Is present. In coastal waters and other places where light reaches the bottom, benthic photosynthesizing diatoms can proliferate. Filter feeders , such as sponges and bivalves , dominate hard, sandy bottoms. Deposit feeders, such as polychaetes , populate softer bottoms. Fish, such as dragonets , as well as sea stars , snails , cephalopods , and crustaceans are important predators and scavengers. Benthic organisms, such as sea stars , oysters , clams , sea cucumbers , brittle stars and sea anemones , play an important role as

1771-510: Is primarily determined by the surrounding water movement, and plankton typically flow with ocean currents . This is in contrast to nekton organisms, such as fish , squid and marine mammals , which can swim against the ambient flow and control their position in the environment. Within the plankton, holoplankton spend their entire life cycle as plankton (e.g. most algae , copepods , salps , and some jellyfish ). By contrast, meroplankton are only planktic for part of their lives (usually

1848-469: 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 (DOM) release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon

1925-669: Is the availability of light. All plankton ecosystems are driven by the input of solar energy (but see chemosynthesis ), confining primary production to surface waters, and to geographical regions and seasons having abundant light. A secondary variable is nutrient availability. Although large areas of the tropical and sub-tropical oceans have abundant light, they experience relatively low primary production because they offer limited nutrients such as nitrate , phosphate and silicate . This results from large-scale ocean circulation and water column stratification . In such regions, primary production usually occurs at greater depth, although at

2002-465: The Portuguese Man o' War , which are buoyant. Pseudoplankton are often found in the guts of filtering zooplankters . 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 or by disruption of

2079-433: The benthic zone . Examples of holoplankton include some diatoms , radiolarians , some dinoflagellates , foraminifera , amphipods , krill , copepods , and salps , 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 and vary in size. The most common plankton are protists . Meroplankton are

2156-403: The biological pump , is one reason that oceans constitute the largest carbon sink on Earth . 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

2233-766: The biological pump . In the long-term or at steady-state, i.e., the biomass of benthic organisms does not change, the benthic community can be considered a black box diverting organic matter into either metabolites or the geosphere (burial). The macrobenthos also indirectly impacts carbon cycling on the seafloor through bioturbation . Benthos are negatively impacted by fishing , pollution and litter, deep-sea mining , oil and gas activities, tourism , shipping , invasive species , climate change (and its impacts such as ocean acidification , ocean warming and changes to ocean circulation ) and construction such as coastal development , undersea cables , and wind farm construction. Water column The (oceanic) water column

2310-417: The larval stage), and then graduate to either a nektic (swimming) or benthic (sea floor) existence. Examples of meroplankton include the larvae of sea urchins , starfish , crustaceans , marine worms , and most fish . The amount and distribution of plankton depends on available nutrients, the state of water and a large amount of other plankton. The study of plankton is termed planktology and

2387-426: The nekton or adopt a benthic (often sessile ) lifestyle on the seafloor . The larval stages of benthic invertebrates make up a significant proportion of planktonic communities. The planktonic larval stage is particularly crucial to many benthic invertebrates in order to disperse their young. Depending on the particular species and the environmental conditions, larval or juvenile-stage meroplankton may remain in

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2464-475: The stratification or mixing of thermal or chemically stratified layers in a lake, stream or ocean. Some of the common parameters analyzed in the water column are pH , turbidity , temperature , hydrostatic pressure , salinity , total dissolved solids , various pesticides , pathogens and a wide variety of chemicals and biota . Descriptively, the deep sea water column is divided into five parts— pelagic zones (from Greek πέλαγος (pélagos), 'open sea')—from

2541-453: The Greek mikrós 'small', comprises microscopic benthic organisms that are less than about 0.1 mm in size. Some examples are bacteria , diatoms , ciliates , amoeba , flagellates . Marine microbenthos are microorganisms that live in the benthic zone of the ocean – that live near or on the seafloor, or within or on surface seafloor sediments. Microbenthos are found everywhere on or about

2618-474: The Sun and nutrients from the water to produce their own nourishment or energy. In the process of photosynthesis , phytoplankton release molecular oxygen ( O 2 ) 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 plants . Furthermore, phytoplankton photosynthesis has controlled

2695-851: The atmosphere for about 31 days. 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). Many animals live in terrestrial environments by thriving in transient often microscopic bodies of water and moisture, these include rotifers and gastrotrichs 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

2772-466: 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 , compared to the sub-surface waters, contains elevated concentration of bacteria and viruses . 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

2849-429: The atmosphere. The mesopelagic zone is a layer of the oceanic zone lying beneath the epipelagic zone and above the bathypelagic zone , at depths generally between 200 and 1,000 m (656 and 3,280 ft). The mesopelagic zone receives very little sunlight and is home to many bioluminescent organisms. Because food is scarce in this region, most mesopelagic organisms migrate to the surface to feed at night or live off

2926-487: The atmospheric CO 2 / O 2 balance since the early Precambrian Eon. 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 production, and thus regulates how much organic material

3003-413: 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 periods, influencing populations of zooplankton, fishes, sea birds, and marine mammals . The effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Changes in

3080-401: The benthos are phytoplankton and organic detrital matter. In coastal locations, organic run off from land provides an additional food source. Meiofauna and bacteria consume and recycle organic matter in the sediments, playing an important role in returning nitrate and phosphate to the pelagic. The depth of water, temperature and salinity, and type of local substrate all affect what benthos

3157-456: The bottom of the ocean. Regardless of form, their shells sink to the seafloor after they die. These shells are widely used as climate proxies . The chemical composition of the shells are a consequence of the chemical composition of the ocean at the time the shells were formed. Past water temperatures can be also be inferred from the ratios of stable oxygen isotopes in the shells, since lighter isotopes evaporate more readily in warmer water leaving

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3234-404: The challenges of descending to depths where water pressure can reach 600 atmospheres, makes exploration difficult—but by no means impossible. The hadopelagic ( or hadal) zone, refers to depths below 6000 meters, which occur mostly in the deep ocean trenches. The term hadal is a reference to the Greek god of the underworld Hades . In these trenches, the temperature is just above freezing, and

3311-433: The deep sea floor, called benthos . The name plankton was coined by German marine biologist Victor Hensen in 1887 from shortening the word halyplankton from Greek ᾰ̔́λς háls "sea" and πλανάω planáō to "drift" or "wander". 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

3388-581: 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 , rising temperatures) can strongly affect zooplankton populations, which can in turn strongly affect fish larval survival, and therefore breeding success. It has 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

3465-458: The depths. This dead and decaying matter sustains the benthic food chain ; most organisms in the benthic zone are scavengers or detritivores . The term benthos , coined by Haeckel in 1891, comes from the Greek noun βένθος 'depth of the sea'. Benthos is used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water , such as lakes, rivers, and streams. There

3542-509: The eastern Atlantic Ocean , where trade winds bring dust from the Sahara Desert in north Africa ). While plankton are most abundant in surface waters, they live throughout the water column. At depths where no primary production occurs, zooplankton and bacterioplankton instead consume organic material sinking from more productive surface waters above. This flux of sinking material, so-called marine snow , can be especially high following

3619-470: The falling detritus from the epipelagic ecosystem. The bathypelagic zone extends from about 1000 to 4000 meters below the surface. The bathypelagic zone receives no sunlight and water pressure is considerable. The abundance and diversity of marine life decreases with depth through this and the lower zones. The abyssopelagic zone is the portion of the ocean deeper than about 4,000 m (13,000 feet) and shallower than about 6,000 m (20,000 feet). The zone

3696-438: 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

3773-475: The freshwaters of lakes and rivers. Aeroplankton are tiny lifeforms that float and drift in the air, carried by the current of the wind ; they are the atmospheric analogue to oceanic plankton. 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 their tiny size. Scientists can collect them for study in traps and sweep nets from aircraft , kites or balloons. Aeroplankton

3850-412: The heavier isotopes in the shells. Information about past climates can be inferred further from the abundance of forams and diatoms, since they tend to be more abundant in warm water. The sudden extinction event which killed the dinosaurs 66 million years ago also rendered extinct three-quarters of all other animal and plant species. However, deep-sea benthic forams flourished in the aftermath. In 2020 it

3927-503: The influence of currents. Although plankton are usually thought of as inhabiting water, there are also airborne versions that live part of their lives drifting in the atmosphere. These aeroplankton include plant spores , pollen and wind-scattered seeds . They may also include microorganisms swept into the air from terrestrial dust storms and oceanic plankton swept into the air by sea spray . Though many planktonic species are microscopic in size, plankton includes organisms over

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4004-432: The laboratory. The concentration of a chemical can cause many changes, including changing feeding behaviors, inflammation , and genetic damage, effects that can be detected outside of the stream environment. Biomarker analysis is important for mitigating the negative impacts of water pollution because it can detect water pollution before it has a noticeable ecological effect on benthos populations. Organic matter produced in

4081-775: The larger, visible to the naked eye, benthic organisms greater than about 1 mm in size. In shallow waters, seagrass meadows , coral reefs and kelp forests provide particularly rich habitats for macrobenthos. Some examples are polychaete worms , bivalves , echinoderms , sea anemones , corals , sponges , sea squirts , turbellarians and larger crustaceans such as crabs , lobsters and cumaceans . Meiobenthos , prefix from Ancient Greek meîon  'less', comprises tiny benthic organisms that are less than about 1 mm but greater than about 0.1 mm in size. Some examples are nematodes , foraminiferans , tardigrades , gastrotriches and smaller crustaceans such as copepods and ostracodes . Microbenthos, prefix from

4158-499: The largest proportion of all plankton in number and diversity. The microplankton and smaller groups are microorganisms and operate at low Reynolds numbers , where the viscosity of water is more important than its mass or inertia. 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 are similar to marine plankton, but are found inland in

4235-498: The most under-explored, habitats on the planet; it is explored to better understand the ocean as a whole, including the huge biomass that lives there and its importance to the global carbon and other biogeochemical cycles. Studying the water column also provides understanding on the links between living organisms and environmental parameters, large-scale water circulation and the transfer of matter between water masses. Water columns are used chiefly for environmental studies evaluating

4312-449: 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 that eat smaller plankton, while fish eggs carry their food supply. Both eggs and larvae are themselves eaten by larger animals. Fish can produce high numbers of eggs which are often released into

4389-465: The ocean's carbon cycle . Fish larvae mainly eat zooplankton, which in turn eat phytoplankton Primarily by grazing on phytoplankton, zooplankton provide carbon 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 , so it sinks into open ocean ecosystems away from the coastlines, transporting carbon along with it. This process, called

4466-451: The ocean's uptake of carbon dioxide ( CO 2 ) generated through human activities by increasing plankton production through iron fertilization – introducing amounts of iron into the ocean. However, this technique may not be practical at a large scale. Ocean oxygen depletion and resultant methane production (caused by the excess production remineralising at depth) is one potential drawback. Phytoplankton absorb energy from

4543-578: The ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves , fish , and baleen whales . Marine plankton include bacteria , archaea , algae , protozoa , microscopic fungi , and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries . Freshwater plankton are similar to marine plankton, but are found in lakes and rivers. Mostly, plankton just drift where currents take them, though some, like jellyfish , swim slowly but not fast enough to generally overcome

4620-408: The open ocean and the deep sea and are less available to the casual ocean observer. Ichthyoplankton 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 epipelagic or photic zone . Ichthyoplankton are planktonic , meaning they cannot swim effectively under their own power, but must drift with

4697-606: The open water column. Fish eggs typically have a diameter of about 1 millimetre (0.039 in). The newly hatched young of oviparous fish are called larvae . They are usually poorly formed, carry a large yolk sac (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 prey,

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4774-416: 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

4851-453: The pelagic zone for durations ranging from hours to months. Pseudoplankton are organisms that attach themselves to planktonic organisms or other floating objects, such as drifting wood, buoyant shells of organisms such as Spirula , or man-made flotsam . Examples include goose barnacles and the bryozoan Jellyella . By themselves these animals cannot float , which contrasts them with true planktonic organisms, such as Velella and

4928-433: 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. Plankton have many direct and indirect effects on humans. Around 70% of

5005-476: The same site, shaping depressions and crevices where mobile animals find refuge. This greater diversity in benthic habitats has resulted in a higher diversity of benthic species. The number of benthic animal species exceeds one million. This far exceeds the number of pelagic animal species (about 5000 larger zooplankton species, 22,000 pelagic fish species and 110 marine mammal species). Macrobenthos, prefix from Ancient Greek makrós  'long', comprises

5082-418: The seafloor of continental shelves, as well as in deeper waters, with greater diversity in or on seafloor sediments. In photic zones benthic diatoms dominate as photosynthetic organisms. In intertidal zones changing tides strongly control opportunities for microbenthos. Both foraminifera and diatoms have planktonic and benthic forms, that is, they can drift in the water column or live on sediment at

5159-414: The secondary consumers that prey on the primary consumers. In some cases, plankton act as an intermediate host for deadly parasites in humans. One such case is that of cholera , an infection caused by several pathogenic strains of Vibrio cholerae . These species have been shown to have a symbiotic relationship with chitinous zooplankton species like copepods . These bacteria benefit not only from

5236-418: The sediment, often in the oxygenated top layer, e.g., a sea pen or a sand dollar . Epibenthos (or epibenthic), prefix from Ancient Greek epí  'on top of', lives on top of the sediments, e.g., sea cucumber or a sea snail. Hyperbenthos (or hyperbenthic), prefix from Ancient Greek hupér  'over', lives just above the sediment, e.g., a rock cod . The main food sources for

5313-538: 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 . Apart from aeroplankton, plankton inhabits oceans, seas, lakes and ponds. Local abundance varies horizontally, vertically and seasonally. The primary cause of this variability

5390-403: The sunlit layer of the ocean and delivered to the sediments is either consumed by organisms or buried. The organic matter consumed by organisms is used to synthesize biomass (i.e. growth) converted to carbon dioxide through respiration , or returned to the sediment as faeces. This cycle can occur many times before either all organic matter is used up or eventually buried. This process is known as

5467-416: The surface to below the floor. The term water column is also commonly used in scuba diving to describe the vertical space through which divers ascend and descend. The pelagic zones are as follows: The epipelagic zone, otherwise known as the sunlit zone or the euphotic zone, goes to a depth of about 200 meters (656 feet). It is the depth of water to which sunlight is able to penetrate. Although it

5544-406: The termination of spring blooms . The local distribution of plankton can be affected by wind-driven Langmuir circulation and the biological effects of this physical process. As well as representing the lower levels of a food chain that supports commercially important fisheries , plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements , including

5621-477: 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. Zooplankton are the initial prey item for almost all fish larvae as they switch from their yolk sacs to external feeding. Fish rely on

5698-522: 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 zooplankton, but not all gelatinous zooplankton are jellyfish. The most commonly encountered organisms include ctenophores , medusae , salps , and Chaetognatha in coastal waters. However, almost all marine phyla, including Annelida , Mollusca and Arthropoda , contain gelatinous species, but many of those odd species live in

5775-678: The water pressure is enormous. For example, the hadopelagic zone extends into the ocean's deepest trench, the Mariana Trench, located in the western Pacific Ocean basin, with a maximum depth of nearly 11,000 meters. At that depth, the water column above is exerting a pressure of over one thousand atmospheres. Planktonic This is an accepted version of this page Plankton are the diverse collection of organisms that drift in water (or air ) but are unable to actively propel themselves against currents (or wind ). The individual organisms constituting plankton are called plankters . In

5852-521: The word is neuter) is normally dropped, using only the root of the word in the derivation. Plankton are primarily divided into broad functional (or trophic level ) groups: Recognition of the importance of mixotrophy as an ecological strategy is increasing, as well as the wider role this may play in marine biogeochemistry . Studies have shown that mixotrophs are much more important for marine ecology than previously assumed and comprise more than half of all microscopic plankton. Their presence acts as

5929-426: Was reported that researchers have examined the chemical composition of thousands of samples of these benthic forams and used their findings to build the most detailed climate record of Earth ever. Some endoliths have extremely long lives. In 2013 researchers reported evidence of endoliths in the ocean floor, perhaps millions of years old, with a generation time of 10,000 years. These are slowly metabolizing and not in

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