Marine food web

Source: Wikipedia, the free encyclopedia.

marine microorganisms
in how the ocean imports nutrients from and then exports them back to the atmosphere and ocean floor
Part of a series of overviews on
Marine life

Compared to terrestrial environments, marine environments have

mature forests
, grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production.

Because of this inversion, it is the

secondary consumers).[1]

If phytoplankton dies before it is eaten, it descends through the

euphotic zone as part of the marine snow and settles into the depths of sea. In this way, phytoplankton sequester about 2 billion tons of carbon dioxide into the ocean each year, causing the ocean to become a sink of carbon dioxide holding about 90% of all sequestered carbon.[2] The ocean produces about half of the world's oxygen and stores 50 times more carbon dioxide than the atmosphere.[3]

An ecosystem cannot be understood without knowledge of how its food web determines the flow of materials and energy. Phytoplankton autotrophically produces biomass by converting

remineralises organic and inorganic matter, and then recycles the products either within the pelagic food web or by depositing them as marine sediment on the seafloor.[4]

Food chains and trophic levels

marine food chain
(typical)
  Sun
↓
phytoplankton
↓
herbivorous zooplankton
↓
carnivorous zooplankton
↓
  filter feeder
↓
  predatory vertebrate
Main articles:
trophic levels

Food webs are built from food chains. All forms of life in the sea have the potential to become food for another life form. In the ocean, a food chain typically starts with energy from the sun powering phytoplankton, and follows a course such as:

phytoplankton → herbivorous zooplankton → carnivorous zooplankton → filter feeder → predatory vertebrate

primary producers at the bottom or the first level of the marine food chain. Since they are at the first level they are said to have a trophic level of 1 (from the Greek
trophē meaning food). Phytoplankton are then consumed at the next trophic level in the food chain by microscopic animals called zooplankton.

primary consumers
.

In turn, the smaller herbivorous zooplankton are consumed by larger carnivorous zooplankters, such as larger predatory protozoa and

filter-feeding
fish. This makes up the third trophic level in the food chain.

A food web is network of food chains, and as such can be represented graphically and analysed using techniques from network theory.[5][6]
Classic food web for grey seals in the Baltic Sea containing several typical marine food chains[7]

The fourth trophic level consists of predatory fish, marine mammals and seabirds that consume forage fish. Examples are swordfish, seals and gannets.

Apex predators, such as orcas, which can consume seals, and shortfin mako sharks, which can consume swordfish, make up a fifth trophic level. Baleen whales can consume zooplankton and krill directly, leading to a food chain with only three or four trophic levels.

In practice, trophic levels are not usually simple integers because the same consumer species often feeds across more than one trophic level.[8][9] For example a large marine vertebrate may eat smaller predatory fish but may also eat filter feeders; the stingray eats crustaceans, but the hammerhead eats both crustaceans and stingrays. Animals can also eat each other; the cod eats smaller cod as well as crayfish, and crayfish eat cod larvae. The feeding habits of a juvenile animal, and, as a consequence, its trophic level, can change as it grows up.

The fisheries scientist Daniel Pauly sets the values of trophic levels to one in primary producers and detritus, two in herbivores and detritivores (primary consumers), three in secondary consumers, and so on. The definition of the trophic level, TL, for any consumer species is[10]

where is the fractional trophic level of the prey j, and represents the fraction of j in the diet of i. In the case of marine ecosystems, the trophic level of most fish and other marine consumers takes value between 2.0 and 5.0. The upper value, 5.0, is unusual, even for large fish,[11] though it occurs in apex predators of marine mammals, such as polar bears and killer whales.[12] As a point of contrast, humans have a mean trophic level of about 2.21, about the same as a pig or an anchovy.[13][14]

By taxon

Primary producers

Ocean surface chlorophyll concentrations in October 2019. The concentration of chlorophyll can be used as a proxy to indicate how many phytoplankton are present. Thus on this global map green indicates where a lot of phytoplankton are present, while blue indicates where few phytoplankton are present. – NASA Earth Observatory 2019.[15]
Further information: Marine primary production

At the base of the ocean food web are single-celled algae and other plant-like organisms known as

chemoautotrophs which use inorganic electron sources such as hydrogen sulfide, ferrous iron and ammonia.[16]

Marine phytoplankton form the basis of the marine food web, account for approximately half of global carbon fixation and oxygen production by photosynthesis

ocean carbon cycle.[15]

Prochlorococcus, an influential bacterium which produces much of the world's oxygen

Among the phytoplankton are members from a phylum of bacteria called

octillion (1027) individuals.[20] Prochlorococcus is ubiquitous between 40°N and 40°S and dominates in the oligotrophic (nutrient poor) regions of the oceans.[21] The bacterium accounts for about 20% of the oxygen in the Earth's atmosphere.[22]

In oceans, most

littoral zone and shallow waters, where they attach to the underlying substrate and are still within the photic zone
. But most of the primary production by algae is performed by the phytoplankton.

Thus, in ocean environments, the first bottom trophic level is occupied principally by

one-celled algae, that float in the sea. Most phytoplankton are too small to be seen individually with the unaided eye. They can appear as a (often green) discoloration of the water when they are present in high enough numbers. Since they increase their biomass mostly through photosynthesis they live in the sun-lit surface layer (euphotic zone
) of the sea.

The most important groups of phytoplankton include the diatoms and dinoflagellates. Diatoms are especially important in oceans, where according to some estimates they contribute up to 45% of the total ocean's primary production.[23] Diatoms are usually microscopic, although some species can reach up to 2 millimetres in length.

Primary consumers

The oligotrich ciliate has been characterised as the most important herbivore in the ocean

The second trophic level (

primary consumers) is occupied by zooplankton which feed off the phytoplankton. Together with the phytoplankton, they form the base of the food pyramid that supports most of the world's great fishing grounds. Many zooplankton are tiny animals found with the phytoplankton in oceanic surface waters, and include tiny crustaceans, and fish larvae and fry (recently hatched fish). Most zooplankton are filter feeders
, and they use appendages to strain the phytoplankton in the water. Some larger zooplankton also feed on smaller zooplankton. Some zooplankton can jump about a bit to avoid predators, but they can't really swim. Like phytoplankton, they float with the currents, tides and winds instead. Zooplankton can reproduce rapidly, their populations can increase up to thirty per cent a day under favourable conditions. Many live short and productive lives and reach maturity quickly.

The

cilia arranged like a collar and lapel. They are very common in marine plankton communities, usually found in concentrations of about one per millilitre. They are the most important herbivores in the sea, the first link in the food chain.[24]

Other particularly important groups of zooplankton are the

habitats. They are the biggest source of protein in the sea,[25] and are important prey for forage fish. Krill
constitute the next biggest source of protein. Krill are particularly large predator zooplankton which feed on smaller zooplankton. This means they really belong to the third trophic level, secondary consumers, along with the forage fish.

Jellyfish are easy to capture and digest and may be more important as food sources than was previously thought.[26]

Together, phytoplankton and zooplankton make up most of the plankton in the sea. Plankton is the term applied to any small drifting organisms that float in the sea (Greek planktos = wanderer or drifter). By definition, organisms classified as plankton are unable to swim against ocean currents; they cannot resist the ambient current and control their position. In ocean environments, the first two trophic levels are occupied mainly by plankton. Plankton can be divided into producers and consumers. The producers are the phytoplankton (Greek phyton = plant) and the consumers, who eat the phytoplankton, are the zooplankton (Greek zoon = animal).

amphipods.[28][26] "Despite their low energy density, the contribution of jellyfish to the energy budgets of predators may be much greater than assumed because of rapid digestion, low capture costs, availability, and selective feeding on the more energy-rich components. Feeding on jellyfish may make marine predators susceptible to ingestion of plastics."[26]

Higher order consumers

Predator fish sizing up schooling forage fish
Marine invertebrates
Fish
  • Forage fish: Forage fish occupy central positions in the ocean food webs. The organisms it eats are at a lower trophic level, and the organisms that eat it are at a higher trophic level. Forage fish occupy middle levels in the food web, serving as a dominant prey to higher level fish, seabirds and mammals.[29]
  • Predator fish
  • Ground fish
Other marine vertebrates

In 2010 researchers found whales carry nutrients from the depths of the ocean back to the surface using a process they called the

defecate a liquid rich in nitrogen and iron. Instead of sinking, the liquid stays at the surface where phytoplankton consume it. In the Gulf of Maine the whale pump provides more nitrogen than the rivers.[31]

  • Humpback whales lunge from below to feed on forage fish
    lunge from below
    to feed on forage fish
  • Gannets plunge dive from above to catch forage fish
    plunge dive
    from above to catch forage fish

Microorganisms

On average there are more than one million microbial cells in every drop of seawater, and their collective metabolisms not only recycle nutrients that can then be used by larger organisms but also catalyze key chemical transformations that maintain Earth’s habitability.[32]
See also: marine microorganisms, microbial loop, microbial food web, viral shunt, marine microbial symbiosis, and marine prokaryotes § Roles in marine food webs

There has been increasing recognition in recent years that

taxonomic resolution and are revealing deeper complexities in the web of interactions.[34]

dissolved organic matter (DOM), which can be readily taken up by microorganisms.[35] Viral shunting helps maintain diversity within the microbial ecosystem by preventing a single species of marine microbe from dominating the micro-environment.[36] The DOM recycled by the viral shunt pathway is comparable to the amount generated by the other main sources of marine DOM.[37]

In general,

dissolved organic matter
(DOM) is readily utilizable to most marine organisms at higher trophic levels. This means that dissolved organic carbon is not available directly to most marine organisms; marine bacteria introduce this organic carbon into the food web, resulting in additional energy becoming available to higher trophic levels.

imaged by a satellite
in 2011
Cycling of marine phytoplankton. Phytoplankton live in the photic zone of the ocean, where photosynthesis is possible. During photosynthesis, they assimilate carbon dioxide and release oxygen. If solar radiation is too high, phytoplankton may fall victim to photodegradation. For growth, phytoplankton cells depend on nutrients, which enter the ocean by rivers, continental weathering, and glacial ice meltwater on the poles. Phytoplankton release dissolved organic carbon (DOC) into the ocean. Since phytoplankton are the basis of marine food webs, they serve as prey for zooplankton, fish larvae and other heterotrophic organisms. They can also be degraded by bacteria or by viral lysis. Although some phytoplankton cells, such as dinoflagellates, are able to migrate vertically, they are still incapable of actively moving against currents, so they slowly sink and ultimately fertilize the seafloor with dead cells and detritus.[39]
DOM, POM and the viral shunt
dissolved organic matter (DOM) and particulate organic matter
(POM) through the marine food web
Mavirus virophage (lower left) lurking alongside a giant CroV[41]
Viruses
See also: marine viruses

biogeochemical cycling via lysis of hosts.[42][43][45][46]

A giant marine virus

satellite virus, meaning it is able to replicate only in the presence of another specific virus, in this case in the presence of CroV.[50] This virus interferes with the replication of CroV, which leads to the survival of C. roenbergensis cells. Mavirus is able to integrate into the genome of cells of C. roenbergensis, and thereby confer immunity to the population.[51]

Fungi

Main article: Marine fungi

Parasitic

polyunsaturated fatty acids and cholesterols). Large colonies of host phytoplankton may also be fragmented by chytrid infections and become edible to zooplankton.[52]

biological carbon pump.[53][54]

By habitat

Pelagic webs

Food web structure in the euphotic zone. The linear food chain large phytoplankton-herbivore-predator (on the left with red arrow connections) has fewer levels than one with small phytoplankton at the base. The microbial loop refers to the flow from the dissolved organic carbon (DOC) via heterotrophic bacteria (Het. Bac.) and microzooplankton to predatory zooplankton (on the right with black solid arrows). Viruses play a major role in the mortality of phytoplankton and heterotrophic bacteria, and recycle organic carbon back to the DOC pool. Other sources of dissolved organic carbon (also dashed black arrows) includes exudation, sloppy feeding, etc. Particulate detritus pools and fluxes are not shown for simplicity.[55]

For pelagic ecosystems, Legendre and Rassoulzadagan proposed in 1995 a continuum of trophic pathways with the herbivorous food-chain and microbial loop as food-web end members.[56] The classical linear food-chain end-member involves grazing by zooplankton on larger phytoplankton and subsequent predation on zooplankton by either larger zooplankton or another predator. In such a linear food-chain a predator can either lead to high phytoplankton biomass (in a system with phytoplankton, herbivore and a predator) or reduced phytoplankton biomass (in a system with four levels). Changes in predator abundance can, thus, lead to trophic cascades.[57] The microbial loop end-member involves not only phytoplankton, as basal resource, but also dissolved organic carbon.[58] Dissolved organic carbon is used by heterotrophic bacteria for growth are predated upon by larger zooplankton. Consequently, dissolved organic carbon is transformed, via a bacterial-microzooplankton loop, to zooplankton. These two end-member carbon processing pathways are connected at multiple levels. Small phytoplankton can be consumed directly by microzooplankton.[55]

As illustrated in the diagram on the right, dissolved organic carbon is produced in multiple ways and by various organisms, both by primary producers and consumers of organic carbon. DOC release by primary producers occurs passively by leakage and actively during unbalanced growth during nutrient limitation.

particulate organic carbon and use this and other dissolved organic carbon resources for growth and maintenance. Part of the microbial heterotrophic production is used by microzooplankton; another part of the heterotrophic community is subject to intense viral lysis and this causes release of dissolved organic carbon again. The efficiency of the microbial loop depends on multiple factors but in particular on the relative importance of predation and viral lysis to the mortality of heterotrophic microbes.[55]
  • Mesopelagic food web
  • Impact of mesopelagic species on the global carbon budget.[63] DVM = diel vertical migration, NM = non-migration.
    Impact of mesopelagic species on the global carbon budget.[63] DVM = diel vertical migration, NM = non-migration.
  • Mesopelagic bristlemouths may be the most abundant vertebrates on the planet, though little is known about them.[64]
    Mesopelagic
    bristlemouths may be the most abundant vertebrates on the planet, though little is known about them.[64]
  • Gelatinous predators like this narcomedusan consume the greatest diversity of mesopelagic prey
    narcomedusan
    consume the greatest diversity of mesopelagic prey
An in situ perspective of a deep pelagic food web derived from ROV-based observations of feeding, as represented by 20 broad taxonomic groupings. The linkages between predator to prey are coloured according to predator group origin, and loops indicate within-group feeding. The thickness of the lines or edges connecting food web components is scaled to the log of the number of unique ROV feeding observations across the years 1991–2016 between the two groups of animals. The different groups have eight colour-coded types according to main animal types as indicated by the legend and defined here: red, cephalopods; orange, crustaceans; light green, fish; dark green, medusa; purple, siphonophores; blue, ctenophores and grey, all other animals. In this plot, the vertical axis does not correspond to trophic level, because this metric is not readily estimated for all members.[65]

Scientists are starting to explore in more detail the largely unknown twilight zone of the

mesopelagic, 200 to 1,000 metres deep. This layer is responsible for removing about 4 billion tonnes of carbon dioxide from the atmosphere each year. The mesopelagic layer is inhabited by most of the marine fish biomass.[64]

According to a 2017 study,

mesozooplankton to sequester carbon dioxide from the atmosphere as well as supply carbon needs for other mesopelagic organisms.[66]

A 2020 study reported that by 2050 global warming could be spreading in the deep ocean seven times faster than it is now, even if emissions of greenhouse gases are cut. Warming in

mesopelagic and deeper layers could have major consequences for the deep ocean food web, since ocean species will need to move to stay at survival temperatures.[67][68]
Oceanic pelagic food web showing energy flow from micronekton to top predators. Line thickness is scaled to the proportion in the diet.[71]

At the ocean surface

See also: Ocean surface ecosystem and Sea surface microlayer
Synthetic aperture radar (SAR) satellite remote sensing can detect areas with concentrated surfactants or sea slicks, which appear as dark areas on the SAR images.[72]

Ocean surface habitats sit at the interface between the ocean and the atmosphere. The

bacterioneuston, are of interest due to practical applications such as air-sea gas exchange of greenhouse gases, production of climate-active marine aerosols, and remote sensing of the ocean.[72] Of specific interest is the production and degradation of surfactants (surface active materials) via microbial biochemical processes. Major sources of surfactants in the open ocean include phytoplankton,[73] terrestrial runoff, and deposition from the atmosphere.[72]

Unlike coloured algal blooms, surfactant-associated bacteria may not be visible in ocean colour imagery. Having the ability to detect these "invisible" surfactant-associated bacteria using

synthetic aperture radar has immense benefits in all-weather conditions, regardless of cloud, fog, or daylight.[72] This is particularly important in very high winds, because these are the conditions when the most intense air-sea gas exchanges and marine aerosol production take place. Therefore, in addition to colour satellite imagery, SAR satellite imagery may provide additional insights into a global picture of biophysical processes at the boundary between the ocean and atmosphere, air-sea greenhouse gas exchanges and production of climate-active marine aerosols.[72]

At the ocean floor

seafloor massive sulfide.[74]
Further information: Hydrothermal vent microbial communities and Benthic-pelagic coupling

Ocean floor (

benthic
) habitats sit at the interface between the ocean and the interior of the Earth.

Seeps and vents
Conceptual diagram of faunal community structure and food-web patterns along fluid-flux gradients within Guaymas seep and vent ecosystems.[75][76][77]

Coastal webs

See also: Marine coastal ecosystem

Coastal waters include the waters in

continental shelves. They occupy about 8 per cent of the total ocean area[78] and account for about half of all the ocean productivity. The key nutrients determining eutrophication are nitrogen in coastal waters and phosphorus in lakes. Both are found in high concentrations in guano (seabird feces), which acts as a fertilizer for the surrounding ocean or an adjacent lake. Uric acid is the dominant nitrogen compound, and during its mineralization different nitrogen forms are produced.[79]

Ecosystems, even those with seemingly distinct borders, rarely function independently of other adjacent systems.[80] Ecologists are increasingly recognizing the important effects that cross-ecosystem transport of energy and nutrients have on plant and animal populations and communities.[81][82] A well known example of this is how seabirds concentrate marine-derived nutrients on breeding islands in the form of feces (guano) which contains ~15–20% nitrogen (N), as well as 10% phosphorus.[83][84][85] These nutrients dramatically alter terrestrial ecosystem functioning and dynamics and can support increased primary and secondary productivity.[86][87] However, although many studies have demonstrated nitrogen enrichment of terrestrial components due to guano deposition across various taxonomic groups,[86][88][89][90] only a few have studied its retroaction on marine ecosystems and most of these studies were restricted to temperate regions and high nutrient waters.[83][91][92][93] In the tropics, coral reefs can be found adjacent to islands with large populations of breeding seabirds, and could be potentially affected by local nutrient enrichment due to the transport of seabird-derived nutrients in surrounding waters. Studies on the influence of guano on tropical marine ecosystems suggest nitrogen from guano enriches seawater and reef primary producers.[91][94][95]

Reef building corals have essential nitrogen needs and, thriving in nutrient-poor tropical waters[96] where nitrogen is a major limiting nutrient for primary productivity,[97] they have developed specific adaptations for conserving this element. Their establishment and maintenance are partly due to their symbiosis with unicellular dinoflagellates, Symbiodinium spp. (zooxanthellae), that can take up and retain dissolved inorganic nitrogen (ammonium and nitrate) from the surrounding waters.[98][99][100] These zooxanthellae can also recycle the animal wastes and subsequently transfer them back to the coral host as amino acids,[101] ammonium or urea.[102] Corals are also able to ingest nitrogen-rich sediment particles[103][104] and plankton.[105][106] Coastal eutrophication and excess nutrient supply can have strong impacts on corals, leading to a decrease in skeletal growth,[99][107][108][109][95]

Pathways for guano-derived nitrogen to enter marine food webs[95]
Seabird colonies
Seabird colonies are nutrient hot spots, especially, for nitrogen and phosphorus[79]

In the diagram above on the right: (1) ammonification produces NH3 and NH4+ and (2) nitrification produces NO3− by NH4+ oxidation. (3) under the alkaline conditions, typical of the seabird feces, the NH3 is rapidly volatilised and transformed to NH4+, (4) which is transported out of the colony, and through wet-deposition exported to distant ecosystems, which are eutrophised. The phosphorus cycle is simpler and has reduced mobility. This element is found in a number of chemical forms in the seabird fecal material, but the most mobile and bioavailable is

orthophosphate, (5) which can be leached by subterranean or superficial waters.[79]

Filter feeding bivalves
filter feeding bivalves often resident in estuaries, in the form of nutrient extraction from phytoplankton. Blue mussels are used in the example but other bivalves like oysters also provide these nutrient extraction services.[110]
Venice Lagoon, involving 27 nodes or functional groups. Colors of flows depict different fishing target (artisanal fisheries in blue, and clam fishery in red) and non-target species (for clam harvesting, in green).[111][112]
Chesapeake waterbird food web
Generalized food web for some of the major waterbirds that frequent the Chesapeake Bay. Food sources and habitats of waterbirds are affected by multiple factors, including exotic and invasive species.[113][114]
Typical food web on a continental shelf
Puffin and herring food web[115]
coral reef fishes have likely been underestimated.[34][116]
Seagrass meadows
Cumulative visualization of a number of seagrass food webs from different regions and with different eutrophication levels Different coloured dots represent trophic groups from different trophic levels with black  =  primary producers, dark to light grey  =  secondary producers, and the lightest grey being top predators. The grey links represent feeding links.[117]
Coral reef diversity
Taxonomic phylogram derived from ToL-metabarcoding of eukaryotic diversity around the coral reefs at Coral Bay in Australia. Bar graphs indicate the number of families in each phyla, coloured according to kingdom.[118]
Sponge reefs
Generalised food web for sponge reefs[119]

DNA barcoding can be used to construct food web structures with better taxonomic resolution at the web nodes. This provides more specific species identification and greater clarity about exactly who eats whom. "DNA barcodes and DNA information may allow new approaches to the construction of larger interaction webs, and overcome some hurdles to achieving adequate sample size".[34]

A newly applied method for species identification is

High throughput sequencing DNA metabarcoding enables taxonomic assignment and therefore identification for the complete sample regarding the group specific primers chosen for the previous DNA amplification
.

  • Microbial DNA barcoding
  • Algae DNA barcoding
  • Fish DNA barcoding
  • DNA barcoding in diet assessment
  • Kelp forests
  • Byrnes, J.E., Reynolds, P.L. and Stachowicz, J.J. (2007) "Invasions and extinctions reshape coastal marine food webs". PLOS ONE, 2(3): e295.
    doi:10.1371/journal.pone.0000295

Polar webs

Polar topographies
The Antarctica is a frozen landmass surrounded by oceans
The Arctic is a frozen ocean surrounded by landmasses
The annual pulse of ice and snow at the poles

Arctic and Antarctic marine systems have very different

topographical structures and as a consequence have very different food web structures.[122] Both Arctic and Antarctic pelagic food webs have characteristic energy flows controlled largely by a few key species. But there is no single generic web for either. Alternative pathways are important for resilience and maintaining energy flows. However, these more complicated alternatives provide less energy flow to upper trophic-level species. "Food-web structure may be similar in different regions, but the individual species that dominate mid-trophic levels vary across polar regions".[123]

Humpback whale straining krill
Penguins and polar bears never meet
The Antarctic has penguins but no polar bears
The Arctic has polar bears but no penguins
Arctic
Polar bear food webs
microorganisms

The Arctic food web is complex. The loss of sea ice can ultimately affect the entire food web, from algae and plankton to fish to mammals. The impact of climate change on a particular species can ripple through a food web and affect a wide range of other organisms... Not only is the decline of sea ice impairing polar bear populations by reducing the extent of their primary habitat, it is also negatively impacting them via food web effects. Declines in the duration and extent of sea ice in the Arctic leads to declines in the abundance of ice algae, which thrive in nutrient-rich pockets in the ice. These algae are eaten by zooplankton, which are in turn eaten by Arctic cod, an important food source for many marine mammals, including seals. Seals are eaten by polar bears. Hence, declines in ice algae can contribute to declines in polar bear populations.[124]

In 2020 researchers reported that measurements over the last two decades on

carbon fixation in the future.[125][126]

Pteropod (sea angel)
Pteropods: Swimming snails of the sea
The bacterium Marinomonas arctica grows inside Arctic sea ice at subzero temperatures
Walrus are keystone species in the Arctic but are not found in the Antarctic.
Arctic food web with mixotrophy
heterotrophic ciliates; MCIL: mixotrophic ciliates; HNF: heterotrophic nanoflagellates; DOC: dissolved organic carbon; HDIN: heterotrophic dinoflagellates[127]
meltpond, infected with two chytrid-like [zoo-]sporangium fungal pathogens (in false-colour red). Scale bar = 10 µm.[128]
Antarctic
Importance of Antarctic krill in biogeochemical cycles
Processes in the biological pump. Numbers given are carbon fluxes (Gt C yr−1) in white boxes and carbon masses (Gt C) in dark boxes. Phytoplankton convert CO2, which has dissolved from the atmosphere into the surface oceans into particulate organic carbon (POC) during primary production. Phytoplankton are then consumed by krill and small zooplankton grazers, which in turn are preyed upon by higher trophic levels. Any unconsumed phytoplankton form aggregates, and along with zooplankton faecal pellets, sink rapidly and are exported out of the mixed layer. Krill, zooplankton and microbes intercept phytoplankton in the surface ocean and sinking detrital particles at depth, consuming and respiring this POC to CO2 (dissolved inorganic carbon, DIC), such that only a small proportion of surface-produced carbon sinks to the deep ocean (i.e., depths > 1000 m). As krill and smaller zooplankton feed, they also physically fragment particles into small, slower- or non-sinking pieces (via sloppy feeding, coprorhexy if fragmenting faeces), retarding POC export. This releases dissolved organic carbon (DOC) either directly from cells or indirectly via bacterial solubilisation (yellow circle around DOC). Bacteria can then remineralise the DOC to DIC (CO2, microbial gardening). Diel vertically migrating krill, smaller zooplankton and fish can actively transport carbon to depth by consuming POC in the surface layer at night, and metabolising it at their daytime, mesopelagic residence depths. Depending on species life history, active transport may occur on a seasonal basis as well.[131]
Antarctic marine food web. Potter Cove 2018. Vertical position indicates trophic level and node widths are proportional to total degree (in and out). Node colors represent functional groups.[132][133]
Common-enemy graph of Antarctic food web. Potter Cove 2018. Nodes represent basal species and links indirect interactions (shared predators). Node and link widths are proportional to number of shared predators. Node colors represent functional groups.[132]
Sea ice food web and the microbial loop.[134][135] AAnP = aerobic anaerobic phototroph, DOC = dissolved organic carbon, DOM = dissolved organic matter, POC = particulate organic carbon, PR = proteorhodopsins.

Polar microorganisms

In addition to the varied topographies and in spite of an extremely cold climate, polar aquatic regions are teeming with

biogeochemical cycling of nutrients that, in turn, impact community dynamics at seasonal and spatial scales.[46]

Microorganisms are at the heart of Arctic and Antarctic food webs. These polar environments contain a diverse range of

glacial ice, with only 0.4% of its area comprising exposed land dotted with lakes and ponds.[46]

Microbes, both

gene sequences and over 11,000 OTUs from 44 polar samples of the Arctic and the Southern Ocean. These OTUs cluster separately for the two polar regions and, additionally, exhibit significant differences in just the polar bacterioplankton communities from different environments (coastal and open ocean) and different seasons.[142][46]

The polar regions are characterised by truncated food webs, and the role of viruses in ecosystem function is likely to be even greater than elsewhere in the marine food web. Their diversity is still relatively under-explored, and the way in which they affect polar communities is not well understood,[140] particularly in nutrient cycling.[138][148][149][46]

Foundation and keystone species

Giant kelp is a foundation species for many kelp forests.[150]
predator
California mussels displace most other species unless ochre starfish control their numbers
  How starfish changed modern ecology
– Nature on PBS  

The concept of a foundation species was introduced in 1972 by Paul K. Dayton,[151] who applied it to certain members of marine invertebrate and algae communities. It was clear from studies in several locations that there were a small handful of species whose activities had a disproportionate effect on the rest of the marine community and they were therefore key to the resilience of the community. Dayton’s view was that focusing on foundation species would allow for a simplified approach to more rapidly understand how a community as a whole would react to disturbances, such as pollution, instead of attempting the extremely difficult task of tracking the responses of all community members simultaneously.

Foundation species are species that have a dominant role structuring an ecological community, shaping its environment and defining its ecosystem. Such ecosystems are often named after the foundation species, such as seagrass meadows, oyster beds, coral reefs, kelp forests and mangrove forests.[152] For example, the red mangrove is a common foundation species in mangrove forests. The mangrove’s root provides nursery grounds for young fish, such as snapper.[153] A foundation species can occupy any trophic level in a food web but tend to be a producer.[154]

Sea otters predate sea urchins, making them a keystone species for kelp forests
Sea urchins damage kelp forests by chewing through kelp holdfasts
                    Sea otters versus urchins – Pew                    

The concept of the

sea stars prey on sea urchins, mussels, and other shellfish that have no other natural predators. If the sea star is removed from the ecosystem, the mussel population explodes uncontrollably, driving out most other species.[157]

Keystone species are species that have large effects, disproportionate to their numbers, within ecosystem food webs.

Sea otters limit the damage sea urchins inflict on kelp forests. When the sea otters of the North American west coast were hunted commercially for their fur, their numbers fell to such low levels that they were unable to control the sea urchin population. The urchins in turn grazed the holdfasts of kelp so heavily that the kelp forests largely disappeared, along with all the species that depended on them. Reintroducing the sea otters has enabled the kelp ecosystem to be restored.[160][161]

Topological position

See also: Marine coastal ecosystem § Network ecology

Networks of trophic interactions can provide a lot of information about the functioning of marine ecosystems. Beyond feeding habits, three additional traits (mobility, size, and habitat) of various organisms can complement this trophic view.[162]

Topological positions versus mobility:[162] (A) bottom-up groups (sessile and drifters), (B) groups at the top of the food web. Phyto, phytoplankton; MacroAlga, macroalgae; Proto, pelagic protozoa; Crus, Crustacea; PelBact, pelagic bacteria; Echino, Echinoderms; Amph, Amphipods; HerbFish, herbivorous fish; Zoopl, zooplankton; SuspFeed, suspension feeders; Polych, polychaetes; Mugil, Mugilidae; Gastropod, gastropods; Blenny, omnivorous blennies; Decapod, decapods; Dpunt, Diplodus puntazzo; Macropl, macroplankton; PlFish, planktivorous fish; Cephalopod, cephalopods; Mcarni, macrocarnivorous fish; Pisc, piscivorous fish; Bird, seabirds; InvFeed1 through InvFeed4, benthic invertebrate feeders.

In order to sustain the proper functioning of ecosystems, there is a need to better understand the simple question asked by Lawton in 1994: What do species do in ecosystems?[163] Since ecological roles and food web positions are not independent,[164] the question of what kind of species occupy various of network positions needs to be asked.[162] Since the very first attempts to identify keystone species,[165][166] there has been an interest in their place in food webs.[167][168] First they were suggested to have been top predators, then also plants, herbivores, and parasites.[169][170] For both community ecology and conservation biology, it would be useful to know where are they in complex trophic networks.[162]

An example of this kind of network analysis is shown in the diagram, based on data from a marine food web.[171] It shows relationships between the topological positions of web nodes and the mobility values of the organism's involved. The web nodes are shape-coded according to their mobility, and colour-coded using indices which emphasise (A) bottom-up groups (sessile and drifters), and (B) groups at the top of the food web.[162]

The relative importance of organisms varies with time and space, and looking at large databases may provide general insights into the problem. If different kinds of organisms occupy different types of network positions, then adjusting for this in food web modelling will result in more reliable predictions. Comparisons of

degree centrality and closeness centrality,[172] keystone and keystoneness indexes,[173] and centrality indices versus trophic level (most high-centrality species at medium trophic levels)[174] were done to better understand critically important positions of organisms in food webs. Extending this interest by adding trait data to trophic groups helps the biological interpretation of the results. Relationships between centrality indices have been studied for other network types as well, including habitat networks.[175]
[176] With large databases and new statistical analyses, questions like these can be re-investigated and knowledge can be updated.[162]

Cryptic interactions

ontogenetic and species differences; purple: microbial cross‐feeding; orange: auxotrophy
; blue: cellular carbon partitioning.
Further information:
Mixotrophy

Cryptic interactions, interactions which are "hidden in plain sight", occur throughout the marine planktonic foodweb but are currently largely overlooked by established methods, which mean large‐scale data collection for these interactions is limited. Despite this, current evidence suggests some of these interactions may have perceptible impacts on foodweb dynamics and model results. Incorporation of cryptic interactions into models is especially important for those interactions involving the transport of nutrients or energy.[177]

The diagram illustrates the material fluxes, populations, and molecular pools that are impacted by five cryptic interactions:

ontogenetic and species differences, microbial cross‐feeding, auxotrophy and cellular carbon partitioning. These interactions may have synergistic effects as the regions of the food web that they impact overlap. For example, cellular carbon partition in phytoplankton can affect both downstream pools of organic matter utilised in microbial cross‐feeding and exchanged in cases of auxotrophy, as well as prey selection based on ontogenetic and species differences.[177]

Simplifications such as "zooplankton consume phytoplankton", "phytoplankton take up inorganic nutrients", "gross primary production determines the amount of carbon available to the food web", etc. have helped scientists explain and model general interactions in the aquatic environment. Traditional methods have focused on quantifying and qualifying these generalisations, but rapid advancements in genomics, sensor detection limits, experimental methods, and other technologies in recent years have shown that generalisation of interactions within the plankton community may be too simple. These enhancements in technology have exposed a number of interactions which appear as cryptic because bulk sampling efforts and experimental methods are biased against them.[177]

Complexity and stability

See also:
Ecological complexity and Ecological stability
Schematic representation of the changes in abundance between trophic groups in a temperate rocky reef ecosystem. (a) Interactions at equilibrium. (b) Trophic cascade following disturbance. In this case, the otter is the dominant predator and the macroalgae are kelp. Arrows with positive (green, +) signs indicate positive effects on abundance while those with negative (red, -) indicate negative effects on abundance. The size of the bubbles represents the change in population abundance and associated altered interaction strength following disturbance.[178][179]

primary producer or autotroph, an organism, such as an alga or a plant, which is able to manufacture its own food. Next in the chain is an organism that feeds on the primary producer, and the chain continues in this way as a string of successive predators. The organisms in each chain are grouped into trophic levels, based on how many links they are removed from the primary producers. The length of the chain, or trophic level, is a measure of the number of species encountered as energy or nutrients move from plants to top predators.[180] Food energy flows from one organism to the next and to the next and so on, with some energy being lost at each level. At a given trophic level there may be one species or a group of species with the same predators and prey.[181]

In 1927, Charles Elton published an influential synthesis on the use of food webs, which resulted in them becoming a central concept in ecology.[182] In 1966, interest in food webs increased after Robert Paine's experimental and descriptive study of intertidal shores, suggesting that food web complexity was key to maintaining species diversity and ecological stability.[183] Many theoretical ecologists, including Robert May and Stuart Pimm, were prompted by this discovery and others to examine the mathematical properties of food webs. According to their analyses, complex food webs should be less stable than simple food webs.[184]: 75–77 [185]: 64  The apparent paradox between the complexity of food webs observed in nature and the mathematical fragility of food web models is currently an area of intensive study and debate. The paradox may be due partially to conceptual differences between persistence of a food web and equilibrial stability of a food web.[184][185]

A trophic cascade can occur in a food web if a trophic level in the web is suppressed.

For example, a top-down cascade can occur if predators are effective enough in predation to reduce the abundance, or alter the behavior, of their

primary consumer population. In turn, the primary producer population thrives. The removal of the top predator can alter the food web dynamics. In this case, the primary consumers would overpopulate and exploit the primary producers. Eventually there would not be enough primary producers to sustain the consumer population. Top-down food web stability depends on competition and predation in the higher trophic levels. Invasive species can also alter this cascade by removing or becoming a top predator. This interaction may not always be negative. Studies have shown that certain invasive species have begun to shift cascades; and as a consequence, ecosystem degradation has been repaired.[186][187] An example of a cascade in a complex, open-ocean ecosystem occurred in the northwest Atlantic during the 1980s and 1990s. The removal of Atlantic cod (Gadus morhua) and other ground fishes by sustained overfishing resulted in increases in the abundance of the prey species for these ground fishes, particularly smaller forage fishes and invertebrates such as the northern snow crab (Chionoecetes opilio) and northern shrimp (Pandalus borealis). The increased abundance of these prey species altered the community of zooplankton that serve as food for smaller fishes and invertebrates as an indirect effect.[188] Top-down cascades can be important for understanding the knock-on effects of removing top predators from food webs, as humans have done in many places through hunting and fishing
.

In a bottom-up cascade, the population of primary producers will always control the increase/decrease of the energy in the higher trophic levels. Primary producers are plants, phytoplankton and zooplankton that require photosynthesis. Although light is important, primary producer populations are altered by the amount of nutrients in the system. This food web relies on the availability and limitation of resources. All populations will experience growth if there is initially a large amount of nutrients.[189][190]

Terrestrial comparisons

Biomass pyramids
. Compared to terrestrial biomass pyramids, aquatic pyramids are generally inverted at the base.
Marine producers use less biomass than terrestrial producers
The minute but ubiquitous and highly active bacterium Prochlorococcus runs through its life cycle in one day, yet collectively generates about 20% of all global oxygen.
By contrast, a single bristlecone pine can tie up a lot of relatively inert biomass for thousands of years with little photosynthetic activity.[191]

Marine environments can have inversions in their biomass pyramids. In particular, the biomass of consumers (copepods, krill, shrimp, forage fish) is generally larger than the biomass of primary producers. This happens because the ocean's primary producers are mostly tiny phytoplankton which have

K-strategist traits of growing and reproducing slowly, so a much larger mass is needed to achieve the same rate of primary production. The rate of production divided by the average amount of biomass that achieves it is known as an organism's Production/Biomass (P/B) ratio.[192]
Production is measured in terms of the amount of movement of mass or energy per area per unit of time. In contrast, the biomass measurement is in units of mass per unit area or volume. The P/B ratio utilizes inverse time units (example: 1/month). This ratio allows for an estimate of the amount of energy flow compared to the amount of biomass at a given trophic level, allowing for demarcations to be made between trophic levels. The P/B ratio most commonly decreases as trophic level and organismal size increases, with small, ephemeral organisms containing a higher P/B ratio than large, long-lasting ones.

Examples: The bristlecone pine can live for thousands of years, and has a very low production/biomass ratio. The cyanobacterium Prochlorococcus lives for about 24 hours, and has a very high production/biomass ratio.

In oceans, most

vascular plants
.

Comparison of productivity in marine and terrestrial ecosystems[193]
Ecosystem Net primary productivity (
Gt/y
) 		Total plant biomass (Gt) Turnover time (y)
Marine 45–55 1–2 0.02–0.06
Terrestrial 55–70 600–1000 9–20
Ocean or marine biomass, in a reversal of terrestrial biomass, can increase at higher trophic levels.[194]

Aquatic producers, such as planktonic algae or aquatic plants, lack the large accumulation of

Energy pyramids, however, will always have an upright pyramid shape if all sources of food energy are included, since this is dictated by the second law of thermodynamics."[196][197]

Most

inorganic carbon. The rate at which organic matter is preserved via burial by accumulating sediments is only between 0.2 and 0.4 billion tonnes per year, representing a very small fraction of the total production.[55] Global phytoplankton production is about 50 billion tonnes per year and phytoplankton biomass is about one billion tonnes, implying a turnover time of one week. Marine macrophytes have a similar global biomass but a production of only one billion tonnes per year, implying a turnover time of one year.[198] These high turnover rates (compared with global terrestrial vegetation turnover of one to two decades)[193] imply not only steady production, but also efficient consumption of organic matter. There are multiple organic matter loss pathways (respiration by autotrophs and heterotrophs, grazing, viral lysis, detrital route), but all eventually result in respiration and release of inorganic carbon.[55]

Mature forests have a lot of biomass invested in secondary growth which has low productivity

Anthropogenic effects

Fishing down the food web[199]
Further information: Human impact on marine life
Overfishing
Acidification

Pteropods and brittle stars together form the base of the Arctic food webs and both are seriously damaged by acidification. Pteropods shells dissolve with increasing acidification and brittle stars lose muscle mass when re-growing appendages.[200] Additionally the brittle star's eggs die within a few days when exposed to expected conditions resulting from Arctic acidification.[201] Acidification threatens to destroy Arctic food webs from the base up. Arctic waters are changing rapidly and are advanced in the process of becoming undersaturated with aragonite.[202] Arctic food webs are considered simple, meaning there are few steps in the food chain from small organisms to larger predators. For example, pteropods are "a key prey item of a number of higher predators – larger plankton, fish, seabirds, whales".[203]

Effects of ocean acidification
Pteropods and brittle stars
form the base of Arctic food webs
Climate change

Ecosystems in the ocean are more sensitive to climate change than anywhere else on Earth. This is due to warmer temperatures and ocean acidification. With the ocean temperatures increasing, it is predicted that fish species will move from their known ranges and locate new areas. During this change, the numbers within each species will drop significantly. Currently there are many relationships between predators and prey, where they rely on one another to survive.[204] With a shift in where species will be located, the predator-prey relationships/interactions will be greatly impacted. Studies are still being done to understand how these changes will affect the food-web dynamics.

Using modeling, scientists are able to analyze the trophic interactions that certain species thrive in and due to other species also found in these areas. Through recent models, it is seen that many of the larger marine species will end up shifting their ranges at a slower pace than climate change suggests. This would impact the predator-prey relationship even more. As the smaller species and organisms are more likely to be influenced from the oceans warming and moving sooner than the larger mammals.[204] These predators are seen to stay longer in their historical ranges before moving because of the movement of the smaller species moving. With “new” species entering the space of the larger mammals, the ecology changes and more prey for them to feed upon.[204] The smaller species would end up having a smaller range, whereas the larger mammals would have extended their range. The shifting dynamics will have great effects on all species within the ocean and will result in many more changes impacting our entire ecosystem. With the movement in where predators can find prey within the ocean, will also impact the fisheries industry.[205] Where fishermen currently know where certain fish species occupy, as the shift occurs it will be more difficult to figure out where they are spending their time, costing them more money as they may have to travel further.[206] As a result this could impact the current fishing regulations set up for certain areas with the movement of these fish populations.

Marine Species Changes in Latitude and Depth in three different ocean regions(1973-2019)[207][208]

Through a survey conducted at Princeton University, researchers found that the marine species are consistently keeping pace with “climate velocity” or speed and direction in which it is moving. Looking at data from 1968 to 2011, it was found that 70 per cent of the shifts in animals’ depths and 74 per cent of changes in latitude correlated with regional-scale fluctuations in ocean temperature.[209] These movements are causing species to move between 4.5 and 40 miles per decade further away from the equator. With the help of models, regions can predict where the species may end up. Models will have to adapt to the changes as more is learned about how climate is affecting species.

"Our results show how future climate change can potentially weaken marine food webs through reduced energy flow to higher trophic levels and a shift towards a more detritus-based system, leading to food web simplification and altered producer–consumer dynamics, both of which have important implications for the structuring of benthic communities."[210][211]

"...increased temperatures reduce the vital flow of energy from the primary food producers at the bottom (e.g. algae), to intermediate consumers (herbivores), to predators at the top of marine food webs. Such disturbances in energy transfer can potentially lead to a decrease in food availability for top predators, which in turn, can lead to negative impacts for many marine species within these food webs... "Whilst climate change increased the productivity of plants, this was mainly due to an expansion of cyanobacteria (small blue-green algae)," said Mr Ullah. "This increased primary productivity does not support food webs, however, because these cyanobacteria are largely unpalatable and they are not consumed by herbivores. Understanding how ecosystems function under the effects of global warming is a challenge in ecological research. Most research on ocean warming involves simplified, short-term experiments based on only one or a few species."[211]

The distribution of anthropogenic stressors faced by marine species threatened with extinction in various marine regions of the world. Numbers in the pie charts indicate the percentage contribution of an anthropogenic stressors’ impact in a specific marine region.[178][212]
Anthropogenic stressors to marine species threatened with extinction[178]

See also

References

  1. ^ U S Department of Energy (2008) Carbon Cycling and Biosequestration page 81, Workshop report DOE/SC-108, U.S. Department of Energy Office of Science.
  2. ^ Campbell, Mike (22 June 2011). "The role of marine plankton in sequestration of carbon". EarthTimes. Retrieved 22 August 2014.
  3. ^ Why should we care about the ocean? NOAA: National Ocean Service. Updated: 7 January 2020. Retrieved 1 March 2020.
  4. doi:10.1007/978-3-030-20389-4_15
    .
  5. doi:10.1073/pnas.192407699
    .
  6. ISBN 9780199775057
    .
  7. doi:10.1007/s13280-019-01201-1
  8. Odum, W. E.
    ; Heald, E. J. (1975) "The detritus-based food web of an estuarine mangrove community". Pages 265–286 in L. E. Cronin, ed. Estuarine research. Vol. 1. Academic Press, New York.
  9. S2CID 4161183
    .
  10. ^ Pauly, D.; Palomares, M. L. (2005). "Fishing down marine food webs: it is far more pervasive than we thought" (PDF). Bulletin of Marine Science. 76 (2): 197–211. Archived from the original (PDF) on 14 May 2013.
  11. doi:10.1006/jmsc.1999.0489
    .
  12. doi:10.1006/jmsc.1997.0280
    .
  13. ^ Researchers calculate human trophic level for first time Phys.org . 3 December 2013.
  14. doi:10.1073/pnas.1305827110
    .
  15. ^ a b Chlorophyll NASA Earth Observatory. Accessed 30 November 2019.
  16. PMID 30319587
    .
  17. PMID 9657713
    .
  18. S2CID 54551421
    .
  19. PMID 18159947
    .
  20. ^ Nemiroff, R.; Bonnell, J., eds. (27 September 2006). "Earth from Saturn". Astronomy Picture of the Day. NASA.
  21. PMID 10066832
    .
  22. ^ "The Most Important Microbe You've Never Heard Of". npr.org.
  23. doi:10.2216/i0031-8884-38-6-437.1
    .
  24. ISBN 978-1-4020-8239-9
    .
  25. Carl von Ossietzky University of Oldenburg
  26. ^
    doi:10.1016/j.tree.2018.09.001
  27. ^
    doi:10.1038/531432a
  28. doi:10.1371/journal.pone.0031329
  29. National Public Radio
    , 7 April 2016.
  30. PMID 20949007
    . e13255.
  31. ^ Brown, Joshua E. (12 October 2010). "Whale poop pumps up ocean health". Science Daily. Retrieved 18 August 2014.
  32. doi:10.1128/mSystems.00150-17. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  33. ISBN 978-1-904455-87-5
    .
  34. ^
    doi:10.1139/gen-2015-0229
    .
  35. JSTOR 1313569
    .
  36. ^ Weinbauer, Markus G., et al. "Synergistic and antagonistic effects of viral lysis and protistan grazing on bacterial biomass, production and diversity." Environmental Microbiology 9.3 (2007): 777-788.
  37. ^ Robinson, Carol, and Nagappa Ramaiah. "Microbial heterotrophic metabolic rates constrain the microbial carbon pump." The American Association for the Advancement of Science, 2011.
  38. doi:10.4319/lo.2004.49.3.0862
    .
  39. doi:10.1007/978-3-319-93284-2_5. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  40. doi:10.1007/978-3-030-20389-4_15
    .
  41. doi:10.1371/journal.ppat.1007592. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  42. ^
    S2CID 4658457
    .
  43. ^
    PMID 29057790
    .
  44. S2CID 4271861
    .
  45. PMID 26200428
    .
  46. ^
    PMID 30813316. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  47. PMID 20974979
    .
  48. PMID 20974979
    .
  49. S2CID 30191542
    .
  50. S2CID 206530677
    .
  51. S2CID 4458402
    .
  52. doi:10.3389/fmicb.2014.00166. Modified text was copied from this source, which is available under a Creative Commons Attribution 3.0 International License
    .
  53. doi:10.1128/mBio.01189-18. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  54. doi:10.1111/1462-2920.13257
    .
  55. ^
    S2CID 104330175. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  56. ^ Legendre L, Rassoulzadegan F (1995) "Plankton and nutrient dynamics in marine waters". Ophelia, 41:153–172.
  57. ^ Pace ML, Cole JJ, Carpenter SR, Kitchell JF (1999) "Trophic cascades revealed in diverse ecosystems". Trends Ecol Evol, 14: 483–488.
  58. ^ Azam F, Fenchel T, Field JG, Gray JS, Meyer-Reil LA, Thingstad F (1983) "The ecological role of water-column microbes in the sea". Mar Ecol-Prog Ser, 10: 257–263.
  59. ^ Anderson TR and LeB Williams PJ (1998) "Modelling the seasonal cycle of dissolved organic carbon at station E1 in the English channel". Estuar Coast Shelf Sci, 46: 93–109.
  60. ^ Van den Meersche K, Middelburg JJ, Soetaert K, van Rijswijk P, Boschker HTS, Heip CHR (2004) "Carbon–nitrogen coupling and algal–bacterial interactions during an experimental bloom: modeling a 13C tracer experiment". Limnol Oceanogr, 49: 862–878.
  61. ^ Suttle CA (2005) "Viruses in the sea". Nature, 437: 356–361.
  62. doi:10.3389/fmars.2016.00022. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  63. doi:10.3389/fmars.2018.00522
    .
  64. ^
    doi:10.1038/d41586-020-00520-8
    .
  65. ^
    doi:10.1098/rspb.2017.2116. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  66. doi:10.3389/fmars.2019.00508
    .
  67. ^ Climate change in deep oceans could be seven times faster by middle of century, report says The Guardian, 25 May 2020.
  68. doi:10.5281/zenodo.3596584
    .
  69. doi:10.1038/ncomms4271
  70. ^ Fish biomass in the ocean is 10 times higher than estimated EurekAlert, 7 February 2014.
  71. doi:10.3354/meps11680
    .
  72. ^
    doi:10.1038/srep19123. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  73. doi:10.1016/0304-4203(81)90004-9
    .
  74. doi:10.3389/fmars.2016.00072
  75. doi:10.1371/journal.pone.0162263
    .
  76. doi:10.1371/journal.pone.0033515
    .
  77. doi:10.5194/bg-12-5455-2015
    .
  78. doi:10.1016/j.margeo.2014.01.011
    .
  79. ^
    doi:10.1038/s41467-017-02446-8. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  80. doi:10.1111/j.0030-1299.2005.13728.x
    .
  81. S2CID 84701185
    .
  82. JSTOR 10.1641/0006-3568(2002)052[0917:PSIAAT]2.0.CO;2
    .
  83. ^
    PMID 23593452
    .
  84. doi:10.1016/j.atmosenv.2012.02.007
    .
  85. PMID 18837063
    .
  86. ^
    PMID 22723945
    .
  87. ISBN 9780199735693
    .
  88. S2CID 6021420
    .
  89. S2CID 12110520
    .
  90. PMID 26504209
    .
  91. ^
    S2CID 87850538
    .
  92. doi:10.3354/meps08791
    .
  93. S2CID 83734364
    .
  94. doi:10.3354/meps124189
    .
  95. ^
    S2CID 6539261. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  96. ISBN 9781351092777
    .
  97. PMID 21232343
    .
  98. JSTOR 1312147
    .
  99. ^
    S2CID 85085823
    .
  100. ^ Muscatine, L. (1990) "The role of symbiotic algae in carbon and energy flux in reef corals", Ecosystem World, 25: 75–87.
  101. S2CID 25973061
    .
  102. PMID 21676806
    .
  103. S2CID 13212636
    .
  104. S2CID 84698653
    .
  105. doi:10.3354/meps282151
    .
  106. S2CID 44869188
    .
  107. S2CID 83654833
    .
  108. doi:10.3354/ame021203
    .
  109. doi:10.3354/meps293069
    .
  110. ISBN 9783319967769
  111. ^ Heymans, J.J., Coll, M., Libralato, S., Morissette, L. and Christensen, V. (2014). "Global patterns in ecological indicators of marine food webs: a modelling approach". PLOS ONE, 9(4). doi:10.1371/journal.pone.0095845.
  112. ^ Pranovi, F., Libralato, S., Raicevich, S., Granzotto, A., Pastres, R. and Giovanardi, O. (2003). "Mechanical clam dredging in Venice lagoon: ecosystem effects evaluated with a trophic mass-balance model". Marine Biology, 143(2): 393–403. doi:10.1007/s00227-003-1072-1.
  113. ^ US Geological Survey (USGS). "Chapter 14: Changes in Food and Habitats of Waterbirds." Figure 14.1. Synthesis of U.S. Geological Survey Science for the Chesapeake Bay Ecosystem and Implications for Environmental Management. USGS Circular 1316. Public Domain This article incorporates text from this source, which is in the public domain.
  114. ^ Perry, M.C., Osenton, P.C., Wells-Berlin, A.M., and Kidwell, D.M., 2005, Food selection among Atlantic Coast sea ducks in relation to historic food habits, [abs.] in Perry, M.C., Second North American Sea Duck Conference, November 7–11, 2005, Annapolis, Maryland, Program and Abstracts, USGS Patuxent Wildlife Research Center, Maryland, 123 p. (p. 105).
  115. doi:10.1371/journal.pone.0083152
  116. doi:10.7717/peerj.1047
    .
  117. doi:10.1371/journal.pone.0022591. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  118. doi:10.1038/s41598-017-12501-5
    .
  119. ISSN 2296-7745. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  120. ISBN 9783319319834
  121. ISBN 9780511763175
  122. ISBN 9780521015004
  123. PMID 27928038
    .
  124. ^ Climate Impacts on Ecosystems: Food Web Disruptions EPA. Accessed 11 February 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  125. ^ "A 'regime shift' is happening in the Arctic Ocean, scientists say". phys.org. Retrieved 16 August 2020.
  126. S2CID 220433818
    . Retrieved 16 August 2020.
  127. doi:10.3389/fmars.2018.00292
  128. S2CID 216033140. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  129. S2CID 92529531
    .
  130. PMID 25473469
    .
  131. PMID 31628346.. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  132. ^
    PMID 30225167
    .
  133. hdl:11336/39918
    .
  134. PMID 24832507
    .
  135. ^
  136. ^
    S2CID 20798336
    .
  137. PMC 4009764
    .
  138. ^
    S2CID 33598792
    .
  139. S2CID 23089203
    .
  140. ^
    PMID 21130655
    .
  141. ^
    PMID 22000675
    .
  142. ^
    PMID 23045668
    .
  143. ISSN 0091-7613
    .
  144. PMID 26069354
    .
  145. S2CID 129578736
    .
  146. ^ Adie, R.J. (1962) "The geology of Antarctica". In" Antarctic Research: The Matthew Fontaine Maury Memorial Symposium, John Wiley & Sons.
  147. doi:10.3354/ame041091
    .
  148. S2CID 32607904
    .
  149. S2CID 2927907
    .
  150. doi:10.1002/ecy.2987
    .
  151. ^ Dayton, P. K. 1972. Toward an understanding of community resilience and the potential effects of enrichments to the benthos at McMurdo Sound, Antarctica. pp. 81–96 in Proceedings of the Colloquium on Conservation Problems Allen Press, Lawrence, Kansas.
  152. ^ Giant kelp gives Southern California marine ecosystems a strong foundation, National Science Foundation, 4 February 2020.
  153. doi:10.1525/bio.2011.61.10.8
    .
  154. hdl:11603/29165
    .
  155. S2CID 83780992
    .
  156. ^ "Keystone Species Hypothesis". University of Washington. Archived from the original on 10 January 2011. Retrieved 3 February 2011.
  157. S2CID 85265656
    .
  158. doi:10.1046/j.1523-1739.1995.09040962.x
    .
  159. ^ Davic, Robert D. (2003). "Linking Keystone Species and Functional Groups: A New Operational Definition of the Keystone Species Concept". Conservation Ecology. Archived from the original on 26 August 2003. Retrieved 3 February 2011.
  160. S2CID 84866250
    .
  161. JSTOR 1313259
    .
  162. ^
    doi:10.3389/fmars.2021.636042. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  163. JSTOR 3545824
    .
  164. PMID 12468282
    .
  165. S2CID 38675566
    .
  166. JSTOR 1936888
    .
  167. JSTOR 1312122
    .
  168. JSTOR 1312990
    .
  169. ISBN 978-3-540-58103-1
    .
  170. PMID 21238094
    .
  171. doi:10.1016/J.ECOLMODEL.2003.09.010
    .
  172. doi:10.1016/j.ecolmodel.2007.02.032
    .
  173. doi:10.1016/j.ecolmodel.2017.11.015
    .
  174. doi:10.1556/comec.11.2010.1.9
    .
  175. doi:10.1016/j.ecolind.2011.02.003
    .
  176. S2CID 90319704
    .
  177. ^
    doi:10.1002/lol2.10084. Modified text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License
    .
  178. ^
    doi:10.1007/978-3-030-20389-4_4
    .
  179. doi:10.1126/science.282.5388.473
    .
  180. doi:10.1016/S0169-5347(02)02455-2
    .
  181. ISBN 978-0-470-45546-3
    .
  182. ^ Elton CS (1927) Animal Ecology. Republished 2001. University of Chicago Press.
  183. S2CID 85265656
    .
  184. ^
    ISBN 978-0-691-08861-7
    .
  185. ^
    ISBN 978-0-226-66832-1
    .
  186. PMID 29651152
    .
  187. ^ Megrey, Bernard and Werner, Francisco. "Evaluating the Role of Topdown vs. Bottom-up Ecosystem Regulation from a Modeling Perspective" (PDF).{{cite web}}: CS1 maint: multiple names: authors list (link)
  188. S2CID 45088691
    .
  189. S2CID 46996957
    .
  190. PMID 28167770
    .
  191. ^ "Oldlist". Rocky Mountain Tree Ring Research. Retrieved 8 January 2013.
  192. ISBN 9780127447605
    .
  193. ^
    PMID 9657713
    .
  194. doi:10.1073/pnas.1711842115
    .
  195. ISBN 978-1-4200-5544-3
    .
  196. ISBN 978-0-534-42066-6. Archived from the original
    on 20 August 2011.
  197. doi:10.1016/j.ecolmodel.2009.03.005. Archived from the original
    (PDF) on 7 October 2011.
  198. PMID 17740399
    .
  199. doi:10.1371/journal.pone.0182826
  200. ^ "Effects of Ocean Acidification on Marine Species & Ecosystems". Report. OCEANA. Archived from the original on 25 December 2014. Retrieved 13 October 2013.
  201. ^ "Comprehensive study of Arctic Ocean acidification". Study. CICERO. Archived from the original on 10 December 2013. Retrieved 14 November 2013.
  202. ^ Lischka, S.; Büdenbender J.; Boxhammer T.; Riebesell U. (15 April 2011). "Impact of ocean acidification and elevated temperatures on early juveniles of the polar shelled pteropod Limacina helicina : mortality, shell degradation, and shell growth" (PDF). Report. Biogeosciences. pp. 919–932. Retrieved 14 November 2013.
  203. ^ "Antarctic marine wildlife is under threat, study finds". BBC Nature. Retrieved 13 October 2013.
  204. ^ a b c Tekwa, E. W., J.R. Watson., M. L. Pinsky. “Body Size and Food–Web Interactions Mediate Species Range Shifts under Warming.” Proceedings of the Royal Society B: Biological Sciences, vol. 289, no. 1972, 2022, https://doi.org/10.1098/rspb.2021.2755.
  205. ^ Chapman, Eric J., C.J. Byron., R. Lasley-Rasher., C. Lipsky., J.R. Stevens., R. Peters. “Effects of Climate Change on Coastal Ecosystem Food Webs: Implications for Aquaculture.” Marine Environmental Research, vol. 162, 2020, p. 105103., https://doi.org/10.1016/j.marenvres.2020.105103
  206. ^ “Climate Change Impacts on the Ocean and Marine Resources.” EPA, Environmental Protection Agency, https://www.epa.gov/climateimpacts/climate-change-impacts-ocean-and-marine-resources
  207. ^ “Climate Change Indicators: Marine Species Distribution.” EPA, Environmental Protection Agency, https://www.epa.gov/climate-indicators/climate-change-indicators-marine-species-distribution#ref4.
  208. ^ NOAA (National Oceanic and Atmospheric Administration) and Rutgers University. 2021. OceanAdapt. Accessed January 2021 https://oceanadapt.rutgers.edu
  209. ^ Pinsky, Malin L., B. Worm., M.J. Forgarty., J.L. Sarmiento., S.A. Levin . “Marine Taxa Track Local Climate Velocities.” Science, vol. 341, no. 6151, 2013, pp. 1239–1242., https://doi.org/10.1126/science.1239352
  210. doi:10.1371/journal.pbio.2003446
  211. ^ a b Climate change drives collapse in marine food webs ScienceDaily. 9 January 2018.
  212. ^ IUCN (2018) The IUCN Red List of Threatened Species: Version 2018-1
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