Jelly-falls

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A mass deposition of Pyrosoma atlanticum carcasses were found along an oil pipeline in West Africa in 2006. Pyrosoma atlanticum.JPG
A mass deposition of Pyrosoma atlanticum carcasses were found along an oil pipeline in West Africa in 2006.

Jelly-falls are marine carbon cycling events whereby gelatinous zooplankton, primarily cnidarians, sink to the seafloor and enhance carbon and nitrogen fluxes via rapidly sinking particulate organic matter. [1] These events provide nutrition to benthic megafauna and bacteria. [2] [3] Jelly-falls have been implicated as a major “gelatinous pathway” for the sequestration of labile biogenic carbon through the biological pump. [4] These events are common in protected areas with high levels of primary production and water quality suitable to support cnidarian species. These areas include estuaries and several studies have been conducted in fjords of Norway. [3]

Contents

Initiation

Jelly-falls are primarily made up of the decaying corpses of Cnidaria and Thaliacea (Pyrosomida, Doliolida, and Salpida). [1] Several circumstances can trigger the death of gelatinous organisms which would cause them to sink. These include high levels of primary production that can clog the feeding apparatuses of the organisms, a sudden temperature change, when an old bloom runs out of food, when predators damage the bodies of the jellies, and parasitism. [5] In general, however, jelly-falls are linked to jelly-blooms and primary production, with over 75% of the jelly falls in subpolar and temperate regions occurring after spring blooms, and over 25% of the jelly-falls in the tropics occurring after upwelling events. [1]

With global climates shifting towards creating warmer and more acidic oceans, conditions not favored by non-resilient species, jellies are likely to grow in population sizes. Eutrophic areas and dead zones can become jelly hot spots with substantial blooms. [6] As the climate changes and ocean waters warm, jelly blooms become more prolific and the transport of jelly-carbon to the lower ocean increases. [7] With a possible slowing of the classic biological pump, the transport of carbon and nutrients to the deep sea through jelly-falls may become more and more important to deep ocean. [8]

Decomposition

The decomposition process starts after death and can proceed in the water column as the gelatinous organisms are sinking. [5] Decay happens faster in the tropics than in temperate and subpolar waters as a result of warmer temperatures. [5] In the tropics, a jelly-fall may take less than 2 days to decay in warmer, surface water, but as many as 25 days when it is lower than 1000 m deep. [5] However, lone gelatinous organisms may spend less time on the sea floor as one study found that jellies could be decomposed by scavengers in the Norwegian deep sea in under two and a half hours. [9]

Decomposition of jelly-falls is largely aided by these kinds of scavengers. In general, echinoderms, such as sea stars, have emerged as the primary consumer of jelly-falls, followed by crustaceans and fish. [1] However, which scavengers find their way to jelly-falls is highly reliant on each ecosystem. For example, in an experiment in the Norwegian deep sea, hagfish were the first scavengers to find the traps of decaying jellies, followed by squat lobsters, and finally decapod shrimp. [9] Photographs taken off the coast of Norway on natural jelly-falls also revealed caridean shrimp feeding on jelly carcasses. [3]

With increased populations and blooms becoming more common, with favorable conditions and a lack of other filter feeders in the area to consume plankton, environments with jellies present will have carbon pumps be more primarily supplied with jelly-falls. This could lead to issues of habitats with established biological pumps succumbing to nonequilibrium as the presence of jellies would change the food web as well as changes to the amount of carbon deposited into the sediment. [10] Finally, decomposition is aided by the microbial community. In a case study on the Black Sea, the number of bacteria increased in the presence of jelly-falls, and the bacteria were shown to preferentially use nitrogen released from decaying jelly carcasses while mostly leaving carbon. [11] In a study conducted by Andrew Sweetman in 2016, it was discovered using core samples of the sediment in Norwegian fjords, the presence of jelly-falls significantly impacted the biochemical process of these benthic communities. Bacteria consume jelly carcasses rapidly, removing opportunities of acquiring sustenance for bottoming feeding macrofauna, which has impacts traveling up the trophic levels. [12] In addition, with the exclusion of scavengers, jelly-falls develop a white layer of bacteria over the decaying carcasses and emit a black residue over the surrounding area, which is from sulfide. [13] This high level of microbial activity requires a lot of oxygen, which can lead zones around jelly-falls to become hypoxic and inhospitable to larger scavengers. [13]

Research challenges

Researching jelly-falls relies on direct observational data such as video, photography, or benthic trawls. [1] A complication with trawling for jelly-falls is the gelatinous carcass easily falls apart and as a result, opportunistic photography, videography, and chemical analysis have been primary methods of monitoring. [3] [9] This means that jelly-falls are not always observed in the time period in which they exist. Because jelly-falls can be fully processed and degraded within a number of hours by scavengers [9] and the fact that some jelly-falls will not sink below 500 m in tropical and subtropical waters, [5] the importance and prevalence of jelly-falls may be underestimated.

See also

Related Research Articles

<span class="mw-page-title-main">Plankton</span> Organisms that are in the water column and are incapable of swimming against a current

Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales.

<span class="mw-page-title-main">Jellyfish</span> Soft-bodied, aquatic invertebrates

Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle; the medusa is normally the sexual phase, which produces planula larvae that disperse widely and enter a sedentary polyp phase before reaching sexual maturity.

<span class="mw-page-title-main">Zooplankton</span> Heterotrophic protistan or metazoan members of the plankton ecosystem

Zooplankton are the animal component of the planktonic community. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.

<span class="mw-page-title-main">Benthos</span> Community of organisms that live in the benthic zone

Benthos, also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

<span class="mw-page-title-main">Biological pump</span> Carbon capture process in oceans

The biological pump (or ocean carbon biological pump or marine biological carbon pump) is the ocean's biologically driven sequestration of carbon from the atmosphere and land runoff to the ocean interior and seafloor sediments. In other words, it is a biologically mediated process which results in the sequestering of carbon in the deep ocean away from the atmosphere and the land. The biological pump is the biological component of the "marine carbon pump" which contains both a physical and biological component. It is the part of the broader oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO3) formed into shells by certain organisms such as plankton and mollusks (carbonate pump).

The bathypelagic zone or bathyal zone is the part of the open ocean that extends from a depth of 1,000 to 4,000 m below the ocean surface. It lies between the mesopelagic above and the abyssopelagic below. The bathypelagic is also known as the midnight zone because of the lack of sunlight; this feature does not allow for photosynthesis-driven primary production, preventing growth of phytoplankton or aquatic plants. Although larger by volume than the photic zone, human knowledge of the bathypelagic zone remains limited by ability to explore the deep ocean.

<span class="mw-page-title-main">Benthic zone</span> Ecological region at the lowest level of a body of water

The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "the depths." Organisms living in this zone are called benthos and include microorganisms as well as larger invertebrates, such as crustaceans and polychaetes. Organisms here generally live in close relationship with the substrate and many are permanently attached to the bottom. The benthic boundary layer, which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud.

<span class="mw-page-title-main">Whale fall</span> Whale carcass falling to the ocean floor

A whale fall occurs when the carcass of a whale has fallen onto the ocean floor at a depth greater than 1,000 m (3,300 ft), in the bathyal or abyssal zones. On the sea floor, these carcasses can create complex localized ecosystems that supply sustenance to deep-sea organisms for decades. This is unlike in shallower waters, where a whale carcass will be consumed by scavengers over a relatively short period of time. Whale falls were first observed in the late 1970s with the development of deep-sea robotic exploration. Since then, several natural and experimental whale falls have been monitored through the use of observations from submersibles and remotely operated underwater vehicles (ROVs) in order to understand patterns of ecological succession on the deep seafloor.

The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word abyss comes from the Greek word ἄβυσσος (ábussos), meaning "bottomless". At depths of 4,000–6,000 m (13,000–20,000 ft), this zone remains in perpetual darkness. It covers 83% of the total area of the ocean and 60% of Earth's surface. The abyssal zone has temperatures around 2–3 °C (36–37 °F) through the large majority of its mass. The water pressure can reach up to 76 MPa.

<span class="mw-page-title-main">Salp</span> Family of marine animals in the subphylum Tunicata

A salp or salpa is a barrel-shaped, planktonic tunicate in the family Salpidae. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient examples of jet propulsion in the animal kingdom. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton.

<span class="mw-page-title-main">Deep sea</span> Lowest layer in the ocean

The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low temperatures, darkness and high pressure. The deep sea is considered the least explored Earth biome as the extreme conditions make the environment difficult to access and explore.

<i>Deepstaria enigmatica</i> Species of jellyfish

Deepstaria enigmatica is a very rarely seen giant jellyfish of the family Ulmaridae first described in 1967 by F. S. Russell.

<span class="mw-page-title-main">Gelatinous zooplankton</span> Fragile and often translucent animals that live in the water column

Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All jellyfish are gelatinous 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 the open ocean and the deep sea and are less available to the casual ocean observer. Many gelatinous plankters utilize mucous structures in order to filter feed. Gelatinous zooplankton have also been called Gelata.

<span class="mw-page-title-main">Deep-sea community</span> Groups of organisms living deep below the sea surface, sharing a habitat

A deep-sea community is any community of organisms associated by a shared habitat in the deep sea. Deep sea communities remain largely unexplored, due to the technological and logistical challenges and expense involved in visiting this remote biome. Because of the unique challenges, it was long believed that little life existed in this hostile environment. Since the 19th century however, research has demonstrated that significant biodiversity exists in the deep sea.

<span class="mw-page-title-main">Marine snow</span> Shower of organic detritus in the ocean

In the deep ocean, marine snow is a continuous shower of mostly organic detritus falling from the upper layers of the water column. It is a significant means of exporting energy from the light-rich photic zone to the aphotic zone below, which is referred to as the biological pump. Export production is the amount of organic matter produced in the ocean by primary production that is not recycled (remineralised) before it sinks into the aphotic zone. Because of the role of export production in the ocean's biological pump, it is typically measured in units of carbon. The term was coined by explorer William Beebe as observed from his bathysphere. As the origin of marine snow lies in activities within the productive photic zone, the prevalence of marine snow changes with seasonal fluctuations in photosynthetic activity and ocean currents. Marine snow can be an important food source for organisms living in the aphotic zone, particularly for organisms that live very deep in the water column.

The Southern Pacific Gyre is part of the Earth's system of rotating ocean currents, bounded by the Equator to the north, Australia to the west, the Antarctic Circumpolar Current to the south, and South America to the east. The center of the South Pacific Gyre is the oceanic pole of inaccessibility, the site on Earth farthest from any continents and productive ocean regions and is regarded as Earth's largest oceanic desert. With an area of 37 million square kilometres it makes up ~10 % of the Earth's ocean surface. The gyre, as with Earth's other four gyres, contains an area with elevated concentrations of pelagic plastics, chemical sludge, and other debris known as the South Pacific garbage patch.

<span class="mw-page-title-main">Particulate organic matter</span>

Particulate organic matter (POM) is a fraction of total organic matter operationally defined as that which does not pass through a filter pore size that typically ranges in size from 0.053 millimeters (53 μm) to 2 millimeters.

<span class="mw-page-title-main">Benthic-pelagic coupling</span>

Benthic-pelagic coupling are processes that connect the benthic zone and the pelagic zone through the exchange of energy, mass, or nutrients. These processes play a prominent role in both freshwater and marine ecosystems and are influenced by a number of chemical, biological, and physical forces that are crucial to functions from nutrient cycling to energy transfer in food webs.

<span class="mw-page-title-main">Jellyfish bloom</span>

Jellyfish blooms are substantial growths in population of species under the phyla Cnidaria and Ctenophora.

<span class="mw-page-title-main">Martin curve</span> Mathematical representation of particulate organic carbon export to ocean floor

The Martin curve is a power law used by oceanographers to describe the export to the ocean floor of particulate organic carbon (POC). The curve is controlled with two parameters: the reference depth in the water column, and a remineralisation parameter which is a measure of the rate at which the vertical flux of POC attenuates. It is named after the American oceanographer John Martin.

References

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