ocean surface ecosystem

Neuston are key ecological links connecting ecosystems as far ranging as coral reefs, islands, the deep sea, and even freshwater habitats. In the North Pacific, 80% of the loggerhead turtle diet consists of neuston prey, and nearly 30% of the Laysan albatross's diet is neuston.[https://www.jstor.org/stable/3830593 "Hawaiian Seabird Feeding Ecology"], Wildlife Monographs, 85: 3-71. Wiley. Diverse pelagic and reef fish species live at the surface when young,{{cite journal |doi = 10.1073/pnas.1907496116|title = Prey-size plastics are invading larval fish nurseries|year = 2019|last1 = Gove|first1 = Jamison M.|last2 = Whitney|first2 = Jonathan L.|last3 = McManus|first3 = Margaret A.|last4 = Lecky|first4 = Joey|last5 = Carvalho|first5 = Felipe C.|last6 = Lynch|first6 = Jennifer M.|last7 = Li|first7 = Jiwei|last8 = Neubauer|first8 = Philipp|last9 = Smith|first9 = Katharine A.|last10 = Phipps|first10 = Jana E.|last11 = Kobayashi|first11 = Donald R.|last12 = Balagso|first12 = Karla B.|last13 = Contreras|first13 = Emily A.|last14 = Manuel|first14 = Mark E.|last15 = Merrifield|first15 = Mark A.|last16 = Polovina|first16 = Jeffrey J.|last17 = Asner|first17 = Gregory P.|last18 = Maynard|first18 = Jeffrey A.|last19 = Williams|first19 = Gareth J.|journal = Proceedings of the National Academy of Sciences|volume = 116|issue = 48|pages = 24143–24149|pmid = 31712423|pmc = 6883795| bibcode=2019PNAS..11624143G |doi-access = free}} including commercially important fish species like the Atlantic cod, salmon, and billfish. Neuston can be concentrated as living islands that completely obscure the sea surface, or scattered into sparse meadows over thousands of miles. Yet the role of the neuston, and in many cases their mere existence, is often overlooked.

One of the most well-known surface ecoregions is the Sargasso Sea, an ecologically distinct region packed with thick, neustonic brown seaweed in the North Atlantic. Multiple ecologically and commercially important species depend on the Sargasso Sea, but neustonic life exists in every ocean basin and may serve a similar, if unrecognised, role in regions across the planet. For example, over 50 years ago, USSR scientist A. I. Savilov characterised 7 neustonic ecoregions in the Pacific Ocean.Savilov, A.I. (1969) "Pleuston of the Pacific Ocean". In Zenkewich, LA (Ed.) Biology of the Pacific Ocean: Part 2 The deep sea bottom fauna. Each ecoregion possesses a unique combination of biotic and abiotic conditions and hosts a unique community of neustonic organisms. Yet these ecoregions have been largely forgotten.

But there is another reason to study neuston: The ocean's surface is on the front line of human impacts, from climate change to pollution, oil spills to plastic. The ocean's surface is hit hard by anthropogenic change, and the surface ecosystem is likely already dramatically different from even a few hundred years ago. For example, prior to widespread damming, logging, and industrialisation, more wood may have entered the open ocean,{{cite journal |doi = 10.1073/pnas.1913714116|title = Sustained wood burial in the Bengal Fan over the last 19 My|year = 2019|last1 = Lee|first1 = Hyejung|last2 = Galy|first2 = Valier|last3 = Feng|first3 = Xiaojuan|last4 = Ponton|first4 = Camilo|last5 = Galy|first5 = Albert|last6 = France-Lanord|first6 = Christian|last7 = Feakins|first7 = Sarah J.|journal = Proceedings of the National Academy of Sciences|volume = 116|issue = 45|pages = 22518–22525|pmid = 31636189|pmc = 6842586|bibcode = 2019PNAS..11622518L|doi-access = free}} while plastic had not yet been invented. And because floating life provides food and shelter for diverse species, changes in the surface habitat will cause changes in other ecosystems and have implications that are not currently fully understand or be able to be predicted.

File:World map of bathymetric data - GEBCO 2014.jpg| Ocean surfaces occupy 72% of the Earth's total surface. They can be divided into surfaces of the relatively shallow and nutrient rich coastal areas above the continental shelves (light blue), and surfaces of the more expansive and relatively deeper but nutrient poor ocean that lies beyond (deep blue).

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|quote = "Just before it was dark, as they passed a great island of Sargasso weed that heaved and swung in the light sea as though the ocean were making love with something under a yellow blanket, his small line was taken by a dolphin." — Ernest Hemingway, The Old Man and the Sea.

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File:Sargasses au large de Tintamare- RNN de Saint Martin.jpg| {{center|Sargassum off Tintamarre Island
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{{main|Neuston}}

Invoking images of the open ocean's surface, the imagination can conjure up an endless empty space. A flat line parting the blue below from the blue above. But in reality a diverse array of species occupy this unique boundary layer. A tangle of terms exist for different organisms occupying different niches of the ocean's surface. The most inclusive term, neuston, is used here to refer to all of them.

Neustonic animals and plants live hanging from the surface of the ocean as if suspended from the roof of a massive cave, and are incapable of controlling their direction of movement. They are considered permanent residents of the surface layer. Many genera are globally distributed. Many organisms have morphological features that enable them to remain at the ocean's surface, with the most noticeable adaptations being floats.

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File:Sea surface microlayer as a biochemical microreactor.png Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].}} (I) Unique chemical orientation, reaction and aggregation{{hsp}}
(II) Distinct microbial communities processing dissolved and particulate organic matter{{hsp}}{{cite book |doi = 10.1007/978-94-009-7169-1_3|chapter = Microbiological and Organic-Chemical Processes in the Surface and Mixed Layers|title = Air-Sea Exchange of Gases and Particles|year = 1983|last1 = Sieburth|first1 = John McN.|pages = 121–172|isbn = 978-94-009-7171-4}}
(III) Highest exposure of solar radiation drives photochemical reactions and formation of radicals{{hsp}}{{cite book |doi = 10.1007/978-1-4684-5215-0_11|chapter = Photochemistry and the Sea-Surface Microlayer: Natural Processes and Potential as a Technique|title = Dynamic Processes in the Chemistry of the Upper Ocean|year = 1986|last1 = Zafiriou|first1 = Oliver C.|pages = 129–135|isbn = 978-1-4684-5217-4}}]]

{{main|Sea surface microlayer}}

The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of the Earth's surface. With an operationally defined thickness between 1 and 1000 μm, the SML has physicochemical and biological properties that are measurably distinct from underlying waters. Recent studies now indicate that the SML covers the ocean to a significant extent, and evidence shows that it is an aggregate-enriched biofilm environment with distinct microbial communities. Because of its unique position at the air-sea interface, the SML is central to a range of global biogeochemical and climate-related processes.

The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of the Earth's surface. The SML has physicochemical and biological properties that are measurably distinct from underlying waters. Because of its unique position at the air-sea interface, the SML is central to a range of global biogeochemical and climate-related processes. Although known for the last six decades, the SML often has remained in a distinct research niche, primarily as it was not thought to exist under typical oceanic conditions. Recent studies now indicate that the SML covers the ocean to a significant extent,{{cite journal |doi = 10.5194/bg-8-121-2011|title = Formation and global distribution of sea-surface microlayers|year = 2011|last1 = Wurl|first1 = O.|last2 = Wurl|first2 = E.|last3 = Miller|first3 = L.|last4 = Johnson|first4 = K.|last5 = Vagle|first5 = S.|journal = Biogeosciences|volume = 8|issue = 1|pages = 121–135|bibcode = 2011BGeo....8..121W|doi-access = free}} highlighting its global relevance as the boundary layer linking two major components of the Earth system – the ocean and the atmosphere.

File:Neuston, Plankton, Nekton, Benthos.jpg (organisms that drift with water currents), nekton (organisms that can swim against water currents) and benthos (organisms that live at the ocean floor).}}]]

In 1983, Sieburth hypothesised that the SML was a hydrated gel-like layer formed by a complex mixture of carbohydrates, proteins, and lipids. In recent years, his hypothesis has been confirmed, and scientific evidence indicates that the SML is an aggregate-enriched biofilm environment with distinct microbial communities.{{cite journal |doi = 10.1016/j.pocean.2012.08.004|title = Sea surface microlayers: A unified physicochemical and biological perspective of the air–ocean interface|year = 2013|last1 = Cunliffe|first1 = Michael|last2 = Engel|first2 = Anja|last3 = Frka|first3 = Sanja|last4 = Gašparović|first4 = Blaženka|last5 = Guitart|first5 = Carlos|last6 = Murrell|first6 = J Colin|last7 = Salter|first7 = Matthew|last8 = Stolle|first8 = Christian|last9 = Upstill-Goddard|first9 = Robert|last10 = Wurl|first10 = Oliver|journal = Progress in Oceanography|volume = 109|pages = 104–116|bibcode = 2013PrOce.109..104C}} In 1999 Ellison et al. estimated that 200 Tg C yr⁻¹ accumulates in the SML, similar to sedimentation rates of carbon to the ocean's seabed, though the accumulated carbon in the SML probably has a very short residence time.{{cite journal |doi = 10.1029/1999JD900073|title = Atmospheric processing of organic aerosols|year = 1999|last1 = Ellison|first1 = G. Barney|last2 = Tuck|first2 = Adrian F.|last3 = Vaida|first3 = Veronica|journal = Journal of Geophysical Research: Atmospheres|volume = 104|issue = D9|pages = 11633–11641|bibcode = 1999JGR...10411633E|doi-access = free}} Although the total volume of the microlayer is very small compared to the ocean's volume, Carlson suggested in his seminal 1993 paper that unique interfacial reactions may occur in the SML that may not occur in the underlying water or at a much slower rate there.{{cite book |doi = 10.1007/978-1-4615-2890-6_12|chapter = The Early Diagenesis of Organic Matter: Reaction at the Air-Sea Interface|title = Organic Geochemistry|series = Topics in Geobiology|year = 1993|last1 = Carlson|first1 = David J.|volume = 11|pages = 255–268|isbn = 978-1-4613-6252-4}} He therefore hypothesised that the SML plays an important role in the diagenesis of carbon in the upper ocean. Biofilm-like properties and highest possible exposure to solar radiation leads to an intuitive assumption that the SML is a biochemical microreactor.{{cite book | last=Liss | first=P. S. | title=The sea surface and global change | publisher=Cambridge University Press | publication-place=Cambridge New York | year=1997 | chapter=Photochemistry of the sea-surface microlayer | pages=383–424 | isbn=978-0-521-56273-7 | oclc=34933503}}

Historically, the SML has been summarized as being a microhabitat composed of several layers distinguished by their ecological, chemical and physical properties with an operational total thickness of between 1 and 1000 μm. In 2005 Hunter defined the SML as a "microscopic portion of the surface ocean which is in contact with the atmosphere and which may have physical, chemical or biological properties that are measurably different from those of adjacent sub-surface waters".Hunter, K. A. (1977) [https://books.google.com/books?id=HDDqxQEACAAJ&q=%22Chemistry+of+the+sea-surface+microlayer%22 Chemistry of the sea-surface microlayer] University of East Anglia. School of Environmental Sciences. He avoids a definite range of thickness as it depends strongly on the feature of interest. A thickness of 60 μm has been measured based on sudden changes of the pH,{{cite journal |doi = 10.1360/02yb0192|title = Direct determination of thickness of sea surface microlayer using a pH microelectrode at original location|year = 2003|last1 = Zhang|first1 = Zhengbin|journal = Science in China Series B|volume = 46|issue = 4|page = 339| doi-broken-date=2024-11-20 }} and could be meaningfully used for studying the physicochemical properties of the SML. At such thickness, the SML represents a laminar layer, free of turbulence, and greatly affecting the exchange of gases between the ocean and atmosphere. As a habitat for neuston (surface-dwelling organisms ranging from bacteria to larger siphonophores), the thickness of the SML in some ways depends on the organism or ecological feature of interest. In 2005, Zaitsev described the SML and associated near-surface layer (down to 5 cm) as an incubator or nursery for eggs and larvae for a wide range of aquatic organisms.{{cite book | last=Zaitsev | first=Y. | title=The sea surface and global change | publisher=Cambridge University Press | publication-place=Cambridge New York | year=1997 | pages=371–382 | chapter=Neuston of seas and oceans | veditors=Liss PS | isbn=978-0-521-56273-7 | oclc=34933503}}

Hunter's definition includes all interlinked layers from the laminar layer to the nursery without explicit reference to defined depths.{{cite book | last=Liss | first=P. S. | title=The sea surface and global change | publisher=Cambridge University Press | publication-place=Cambridge New York | year=1997 | chapter=Chemistry of the sea-surface microlayer | isbn=978-0-511-52502-5 | oclc=34933503}} In 2017, Wurl er al. proposed Hunter's definition be validated with a redeveloped SML paradigm that includes its global presence, biofilm-like properties and role as a nursery. The new paradigm pushes the SML into a new and wider context relevant to many ocean and climate sciences.

According to Wurl et al.m the SML can never be devoid of organics due to the abundance of surface-active substances (e.g., surfactants) in the upper ocean{{hsp}} and the phenomenon of surface tension at air-liquid interfaces.Levich VG (1962) Physicochemical hydrodynamics, Prentice Hall International. The SML is analogous to the thermal boundary layer, and remote sensing of the sea surface temperature shows ubiquitous anomalies between the sea surface skin and bulk temperature.{{cite journal |doi = 10.1029/JC095iC08p13341|title = On the bulk-skin temperature difference and its impact on satellite remote sensing of sea surface temperature|year = 1990|last1 = Schluessel|first1 = Peter|last2 = Emery|first2 = William J.|last3 = Grassl|first3 = Hartmut|last4 = Mammen|first4 = Theodor|journal = Journal of Geophysical Research|volume = 95|issue = C8|page = 13341|bibcode = 1990JGR....9513341S| hdl=21.11116/0000-0004-BC37-B |hdl-access = free}} Even so, the differences in both are driven by different processes. Enrichment, defined as concentration ratios of an analyte in the SML to the underlying bulk water, has been used for decades as evidence for the existence of the SML. Consequently, depletions of organics in the SML are debatable; however, the question of enrichment or depletion is likely to be a function of the thickness of the SML (which varies with sea state;{{cite journal |doi = 10.1016/0304-4203(82)90015-9|title = A field evaluation of plate and screen microlayer sampling techniques|year = 1982|last1 = Carlson|first1 = David J.|journal = Marine Chemistry|volume = 11|issue = 3|pages = 189–208| bibcode=1982MarCh..11..189C }} including losses via sea spray, the concentrations of organics in the bulk water, and the limitations of sampling techniques to collect thin layers .Cunliffe M, Wurl O.(2014) [http://www.scor-int.org/Publications/SCOR_GuideSeaSurface_2014.pdf Guide to best practices to study the ocean's surface], Plymouth Occasional Publications of the Marine Biological Association of the United Kingdom. Enrichment of surfactants, and changes in the sea surface temperature and salinity, serve as universal indicators for the presence of the SML. Organisms are perhaps less suitable as indicators of the SML because they can actively avoid the SML and/or the harsh conditions in the SML may reduce their populations. However, the thickness of the SML remains "operational" in field experiments because the thickness of the collected layer is governed by the sampling method. Advances in SML sampling technology are needed to improve our understanding of how the SML influences air-sea interactions.

File:Surface slick indicating a coastal front.jpg Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].}}]]

Slicks are meandering lines of smooth water on the ocean surface that are ubiquitous coastal features around the world.{{cite journal |doi = 10.1029/JC080i006p00865 |title = Observations of oceanic internal and surface waves from the earth resources technology satellite |year = 1975 |last1 = Apel |first1 = John R. |last2 = Byrne |first2 = H. Michael |last3 = Proni |first3 = John R. |last4 = Charnell |first4 = Robert L. |journal = Journal of Geophysical Research |volume = 80 |issue = 6 |pages = 865–881 |bibcode = 1975JGR....80..865A }} A variety of mechanisms can cause slick formation, including tidal and headland fronts, and as a consequence of subsurface waves called internal waves.{{cite journal |doi = 10.1111/j.1442-9993.1990.tb01465.x|title = Linear oceanographic features: A focus for research on recruitment processes|year = 1990|last1 = Kingsford|first1 = M. J.|journal = Austral Ecology|volume = 15|issue = 4|pages = 391–401}} Internal wave slicks are generated when internal waves interact with steep seafloor topography and drive areas of convergence and divergence at the ocean surface.{{cite journal |last1=Klymak |first1=Jody |last2=Legg |first2=Sonya |author-link2=Sonya Legg |last3=Alford |first3=Matthew |last4=Buijsman |first4=Maarten |last5=Pinkel |first5=Robert |last6=Nash |first6=Jonathan |year=2012 |title=The Direct Breaking of Internal Waves at Steep Topography |journal=Oceanography |volume=25 |issue=2 |pages=150–159 |doi=10.5670/oceanog.2012.50|doi-access=free }} The build-up of organic material (surfactants) at the surface modifies surface tension causing a smooth, oil slick-like appearance.{{cite journal |doi = 10.3389/fmars.2017.00165|doi-access = free|title = The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer|year = 2017|last1 = Engel|first1 = Anja|last2 = Bange|first2 = Hermann W.|last3 = Cunliffe|first3 = Michael|last4 = Burrows|first4 = Susannah M.|last5 = Friedrichs|first5 = Gernot|last6 = Galgani|first6 = Luisa|last7 = Herrmann|first7 = Hartmut|last8 = Hertkorn|first8 = Norbert|last9 = Johnson|first9 = Martin|last10 = Liss|first10 = Peter S.|last11 = Quinn|first11 = Patricia K.|last12 = Schartau|first12 = Markus|last13 = Soloviev|first13 = Alexander|last14 = Stolle|first14 = Christian|last15 = Upstill-Goddard|first15 = Robert C.|last16 = Van Pinxteren|first16 = Manuela|last17 = Zäncker|first17 = Birthe|journal = Frontiers in Marine Science|volume = 4 |display-authors = 4|hdl = 10026.1/16046|hdl-access = free}} Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License]. The convergent flow can accumulate dense aggregations of plankton including larval fish and invertebrates at or below the ocean surface.Jillett, J. B. & Zeldis, J. R. (1985) "Aerial observations of surface patchiness of a planktonic crustacean". Bull. Mar. Sci., 37: 609–619.{{cite journal |doi = 10.1007/BF00569432|title = Influence of surface slicks on the distribution and onshore movements of small fish|year = 1986|last1 = Kingsford|first1 = M. J.|last2 = Choat|first2 = J. H.|journal = Marine Biology|volume = 91|issue = 2|pages = 161–171|s2cid = 83769659}}{{cite journal |doi = 10.1016/0022-0981(87)90135-3|title = Internal-wave-mediated shoreward transport of cyprids, megalopae, and gammarids and correlated longshore differences in the settling rate of intertidal barnacles|year = 1987|last1 = l. Shanks|first1 = Alan|last2 = g. Wright|first2 = William|journal = Journal of Experimental Marine Biology and Ecology|volume = 114|pages = 1–13}}Shanks, A. L. (1988) [https://books.google.com/books?id=_G0UZLKVwP4C "Further support for the hypothesis that internal waves can cause shoreward transport of larval invertebrates and fish"]. Fish. Bull., 86: 703–714.{{cite journal |doi = 10.1007/BF01320244|title = Influence of tidally induced fronts and Langmuir circulations on distribution and movements of presettlement fishes around a coral reef|year = 1991|last1 = Kingsford|first1 = M. J.|last2 = Wolanski|first2 = E.|last3 = Choat|first3 = J. H.|journal = Marine Biology|volume = 109|pages = 167–180|s2cid = 86057295}}{{cite journal |doi = 10.3354/meps10777|title = Effect of nearshore surface slicks on meroplankton distribution: Role of larval behaviour|year = 2014|last1 = Weidberg|first1 = N.|last2 = Lobón|first2 = C.|last3 = López|first3 = E.|last4 = García Flórez|first4 = L.|last5 = Fernández Rueda|first5 = MdP|last6 = Largier|first6 = J.|last7 = Acuña|first7 = JL|journal = Marine Ecology Progress Series|volume = 506|pages = 15–30|bibcode = 2014MEPS..506...15W|hdl = 10651/28404|doi-access = free|hdl-access = free}}

Surface slicks are the focal point for numerous trophic and larval connections that are foundational for marine ecosystem function. Life for many marine organisms begins near the ocean surface. Buoyant eggs hatch into planktonic larvae that develop and disperse in the ocean for weeks to months before transitioning into juveniles and eventually finding suitable adult habitat.{{cite book |vauthors=Leis JM, McCormick MI |veditors=Sale P |title=Coral reef fishes: dynamics and diversity in a complex ecosystem |url=https://books.google.com/books?id=LMyCjBlAj5MC |chapter=The biology, behavior, and ecology of the pelagic, larval stage of coral reef fishes |pages=171–199 |publisher=Academic Press |location=Amsterdam |year=2002 |isbn=978-0-12-373609-3 |oclc=53963482}} The pelagic larval stage connects populations and serves as a source of new adults. Oceanic processes affecting the fate of larvae have profound impacts on population replenishment, connectivity, and ecosystem structure.{{cite book |vauthors=Cowen RK |veditors=Sale P |title=Coral reef fishes: dynamics and diversity in a complex ecosystem |url=https://books.google.com/books?id=LMyCjBlAj5MC |chapter=Oceanographic influences on larval dispersal and retention and their consequences for population connectivity |pages=149–170 |publisher=Academic Press |location=Amsterdam |year=2002 |isbn=978-0-12-373609-3 |oclc=53963482}} Although it is an important life stage, there is, as of 2021, limited knowledge of the ecology and behaviour of larvae. Understanding the biophysical interactions that govern larval fish survival and transport is essential for predicting and managing marine ecosystems, as well as the fisheries they support.{{cite journal |doi = 10.1126/science.263.5149.935|title = An Empirical Test of Recruitment Limitation in a Coral Reef Fish|year = 1994|last1 = Doherty|first1 = Peter|last2 = Fowler|first2 = Tony|journal = Science|volume = 263|issue = 5149|pages = 935–939|pmid = 17758633|bibcode = 1994Sci...263..935D|s2cid = 30258297}}{{cite journal |doi = 10.1890/0012-9658(2002)083[1092:RLPRAL]2.0.CO;2|issn = 0012-9658|year = 2002|volume = 83|page = 1092|title = Recruitment Limitation, Population Regulation, and Larval Connectivity in Reef Fish Metapopulations|last1 = Armsworth|first1 = Paul R.|journal = Ecology|issue = 4}}

File:Ecological connections and functions enhanced by surface slick nurseries.png Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].}}]]

The diagram shows: (1) Larval and juvenile stages of fishes from many ocean habitats aggregate in slicks in order to capitalize on dense concentrations of prey (2, phytoplankton, 3, zooplankton, 4, larval invertebrates, 5, eggs, and 6, insects). The increased predator–prey overlap in slicks increases energy flow that propagates up the food-web (dotted blue lines show trophic links), enhancing energy available to higher trophic level predators (icons outlined in blue) including humans. More than 100 species of fishes develop and grow in surface slick nurseries before transitioning to adults (solid white lines radiating outward) in Coral Reefs (7–12), Epipelagic (13–15), and Deep-water (16–17) ocean habitats. As adults these taxa (icons outlined in white) play important ecological functions and provide fisheries resources to local human populations. For example, coastal schooling fishes (7, mackerel scad) are important food and bait fish for humans. Planktivorous fish (8, some damselfishes and triggerfishes) transfer energy from zooplankton up to reef predators like jacks (9),Hobson, E.S. (1991) [https://swfsc-publications.fisheries.noaa.gov/publications/CR/1991/9137.PDF "Trophic relationships of fishes specialized to feed on zooplankters above coral reefs"]. In: The ecology of fishes on coral reefs, Academic Press, pages 69-95. which provide top-down control of reefs{{hsp}}{{cite journal |doi = 10.1890/ES14-00292.1|title = Predators drive community structure in coral reef fish assemblages|year = 2015|last1 = Boaden|first1 = A. E.|last2 = Kingsford|first2 = M.J|journal = Ecosphere|volume = 6|issue = 4|pages = 1–33|doi-access = free}} and are important targets for shoreline recreational fisherfolk.Gaffney, R. (2004) "Evaluation of the status of the recreational fishery for ulua in Hawaiʻi, and recommendations for future management". Hawaii Department of Land and Natural Resources, Division of Aquatic Resources Technical Report 20–02, 1–42. Grazers (10, chubs) help keep coral reefs from being overgrown by macroalgae.{{cite journal |doi = 10.3354/meps10250|title = Density of herbivorous fish and intensity of herbivory are influenced by proximity to coral reefs|year = 2013|last1 = Downie|first1 = RA|last2 = Babcock|first2 = RC|last3 = Thomson|first3 = DP|last4 = Vanderklift|first4 = MA|journal = Marine Ecology Progress Series|volume = 482|pages = 217–225|bibcode = 2013MEPS..482..217D|doi-access = free}} Cryptobenthic fishes such as blennies (11) and benthic macrocrustaceans (12, shrimp, stomatopods, crabs) comprise most of the consumed biomass on reefs.{{cite journal |doi = 10.3354/meps058143|title = Fish communities of interacting shallow-water habitats in tropical oceanic regions|year = 1989|last1 = Parrish|first1 = JD|journal = Marine Ecology Progress Series|volume = 58|pages = 143–160|bibcode = 1989MEPS...58..143P|doi-access = free}}{{cite journal |doi = 10.1126/science.aaz1301|title = Response to Comment on "Demographic dynamics of the smallest marine vertebrates fuel coral reef ecosystem functioning"|year = 2019|last1 = Brandl|first1 = Simon J.|last2 = Morais|first2 = Renato A.|last3 = Casey|first3 = Jordan M.|last4 = Parravicini|first4 = Valeriano|last5 = Tornabene|first5 = Luke|last6 = Goatley|first6 = Christopher H. R.|last7 = Côté|first7 = Isabelle M.|last8 = Baldwin|first8 = Carole C.|last9 = Schiettekatte|first9 = Nina M. D.|last10 = Bellwood|first10 = David R.|journal = Science|volume = 366|issue = 6472|pmid = 31857447|s2cid = 209424415|doi-access = free}} In the pelagic ocean, flyingfishes (13) channel energy and nutrients from zooplankton to pelagic predators such as mahi-mahi (14) and billfish (15), both of which utilize slicks as nursery habitat. Larvae of mesopelagic fishes like lanternfish (16) and bathydemersal tripod fishes (17) utilize these surface hotspots before descending to deep-water adult habitat.

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The distribution of prey and predators in the ocean is patchy.{{cite journal |doi = 10.1111/j.1095-8649.1997.tb06093.x|title = Patterns and trends in larval-stage growth and mortality of teleost fish|year = 1997|last1 = Houde|first1 = E. D.|journal = Journal of Fish Biology|volume = 51|pages = 52–83}}{{cite book |doi = 10.1007/978-1-4899-2195-6_12|chapter = Patterns and Processes in the Time-Space Scales of Plankton Distributions|title = Spatial Pattern in Plankton Communities|year = 1978|last1 = Haury|first1 = L. R.|last2 = McGowan|first2 = J. A.|last3 = Wiebe|first3 = P. H.|pages = 277–327|isbn = 978-1-4899-2197-0}} Larval survival depends on prey availability, predation, and transport to suitable habitat, all of which are influenced by ocean conditions.{{cite journal |doi = 10.1139/f95-241|title = Variability in survival of larval fish: Disentangling components with a generalized individual-based model|year = 1996|last1 = Letcher|first1 = B. H.|last2 = Rice|first2 = J. A.|last3 = Crowder|first3 = L. B.|last4 = Rose|first4 = K. A.|journal = Canadian Journal of Fisheries and Aquatic Sciences|volume = 53|issue = 4|pages = 787–801}} Ocean processes that drive convergent flow such as fronts, internal waves, and eddies, can structure plankton, enhance overlap of predators and prey, and influence larval dispersal.{{cite journal |doi = 10.3354/meps013311 |title = Surface slicks associated with tidally forced internal waves may transport pelagic larvae of benthic invertebrates and fishes shoreward |year = 1983 |last1 = Shanks |first1 = AL |journal = Marine Ecology Progress Series |volume = 13 |pages = 311–315 |bibcode = 1983MEPS...13..311S |doi-access = free }}{{cite journal |doi = 10.1357/0022240943077046|title = Internal tidal bores in the nearshore: Warm-water fronts, seaward gravity currents and the onshore transport of neustonic larvae|year = 1994|last1 = Pineda|first1 = Jesús|journal = Journal of Marine Research|volume = 52|issue = 3|pages = 427–458}}{{cite journal |doi = 10.4319/lo.2000.45.1.0230|title = Demonstration of the onshore transport of larval invertebrates by the shoreward movement of an upwelling front|year = 2000|last1 = Shanks|first1 = Alan L.|last2 = Largier|first2 = John|last3 = Brink|first3 = Laura|last4 = Brubaker|first4 = John|last5 = Hooff|first5 = Rian|journal = Limnology and Oceanography|volume = 45|issue = 1|pages = 230–236|bibcode = 2000LimOc..45..230S| s2cid=83672860 |url = https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=2645&context=vimsarticles|url-access = subscription}}{{cite journal |doi = 10.4319/lo.2002.47.3.0803 |title = Larval distributions in inner-shelf waters: The roles of wind-driven cross-shelf currents and diel vertical migrations |year = 2002 |last1 = Garland |first1 = Elizabeth D. |last2 = Zimmer |first2 = Cheryl Ann |last3 = Lentz |first3 = Steven J. |journal = Limnology and Oceanography |volume = 47 |issue = 3 |pages = 803–817 |bibcode = 2002LimOc..47..803G |s2cid = 86452791 }}{{cite journal |doi = 10.4319/lo.2005.50.4.1033 |title = Florida Current frontal eddies and the settlement of coral reef fishes |year = 2005 |last1 = Sponaugle |first1 = Su |last2 = Lee |first2 = Thomas |last3 = Kourafalou |first3 = Vassiliki |last4 = Pinkard |first4 = Deanna |journal = Limnology and Oceanography |volume = 50 |issue = 4 |pages = 1033–1048 |bibcode = 2005LimOc..50.1033S |s2cid = 16048164 }}{{cite journal |doi = 10.1016/j.pocean.2014.05.010 |title = The role of internal waves in larval fish interactions with potential predators and prey |year = 2014 |last1 = Greer |first1 = Adam T. |last2 = Cowen |first2 = Robert K. |last3 = Guigand |first3 = Cedric M. |last4 = Hare |first4 = Jonathan A. |last5 = Tang |first5 = Dorothy |journal = Progress in Oceanography |volume = 127 |pages = 47–61 |bibcode = 2014PrOce.127...47G }}{{cite journal |doi = 10.1098/rsbl.2014.0746|title = Close encounters with eddies: Oceanographic features increase growth of larval reef fishes during their journey to the reef|year = 2015|last1 = Shulzitski|first1 = Kathryn|last2 = Sponaugle|first2 = Su|last3 = Hauff|first3 = Martha|last4 = Walter|first4 = Kristen|last5 = d'Alessandro|first5 = Evan K.|last6 = Cowen|first6 = Robert K.|journal = Biology Letters|volume = 11|issue = 1|pmid = 25631227|pmc = 4321146}}{{cite journal |doi = 10.1073/pnas.1601606113|title = Encounter with mesoscale eddies enhances survival to settlement in larval coral reef fishes|year = 2016|last1 = Shulzitski|first1 = Kathryn|last2 = Sponaugle|first2 = Su|last3 = Hauff|first3 = Martha|last4 = Walter|first4 = Kristen D.|last5 = Cowen|first5 = Robert K.|journal = Proceedings of the National Academy of Sciences|volume = 113|issue = 25|pages = 6928–6933|pmid = 27274058|pmc = 4922168| bibcode=2016PNAS..113.6928S |doi-access = free}} Convergent features can also lead to a cascade of effects that ultimately drive food web structure and increase ecosystem productivity.{{cite journal |doi = 10.1073/pnas.1417143112 |title = Ocean fronts drive marine fishery production and biogeochemical cycling |year = 2015 |last1 = Woodson |first1 = C. Brock |last2 = Litvin |first2 = Steven Y. |journal = Proceedings of the National Academy of Sciences |volume = 112 |issue = 6 |pages = 1710–1715 |pmid = 25624488 |pmc = 4330775 |bibcode = 2015PNAS..112.1710W |doi-access = free }}

File:Life history mechanisms of neustonic organisms - (a) eggs.png spp.), while others require surface floating objects for early life cycle stages (e.g., Dosima fascicularis), still others may remain at or near the surface throughout a life cycle due to a dependence on endosymbiotic photosynthetic zooxanthellae (a hypothesis proposed for Velella{{cite journal |doi = 10.1093/plankt/2.3.183|title = The Medusa of Velella velella (Linnaeus, 1758) (Hydrozoa, Chondrophorae)|year = 1980|last1 = Larson|first1 = Ronald J.|journal = Journal of Plankton Research|volume = 2|issue = 3|pages = 183–186}}).]]

Life histories connect disparate ecosystems; species that live at the surface during one life history stage may occupy the deep sea, benthos, reefs, or freshwater ecosystems during another. A diversity of fish species utilize the ocean's surface,{{cite journal |doi=10.1038/s41598-020-79139-8 |title=Plasma Hsp90 levels in patients with systemic sclerosis and relation to lung and skin involvement: A cross-sectional and longitudinal study |year=2021 |last1=Štorkánová |first1=Hana |last2=Oreská |first2=Sabína |last3=Špiritović |first3=Maja |last4=Heřmánková |first4=Barbora |last5=Bubová |first5=Kristýna |last6=Komarc |first6=Martin |last7=Pavelka |first7=Karel |last8=Vencovský |first8=Jiří |last9=Distler |first9=Jörg H. W. |last10=Šenolt |first10=Ladislav |last11=Bečvář |first11=Radim |last12=Tomčík |first12=Michal |journal=Scientific Reports |volume=11 |issue=1 |page=1 |pmid=33414495 |pmc=7791137 |bibcode=2021NatSR..11....1S}} either as adults or as nursery habitat for eggs and young. In contrast, species floating on the ocean's surface during one life cycle stage often (though not always) have pelagic larval stages. Velella and Porpita release jellyfish (medusae),Brinckmann-Voss, A. (1970) Anthomedusae, Athecatae:(Hydrozoa, Cnidaria) of the Mediterranean. 1. Capitata. Stazione zoologica. and while little is known about Porpita medusae, Velella medusae could possibly sink into deeper water, or remain near the surface, where they derive nutrients from zooxanthellae. Janthina have pelagic veliger larvae,Laursen, D. (1953) The genus Ianthina: a monograph. The Carlsberg Foundation's Oceanographical Expedition Round the World 1928–30 and Previous "Dana" Expeditions. CA Reitzels. and Physalia may release reproductive clusters that drift in the water column. Halobates lay eggs on a variety of objects, including floating objects{{hsp}} and pelagic snail shells.Miller Andersen N, Cheng L (2010) "The Marine Insecthalobates(Heteroptera: Gerridae)". In: Oceanography and Marine Biology. CRC Press, 119–179.

All species with pelagic stages must eventually find their way back to the surface. For Velella and Porpita, larvae generated by sexual reproduction of medusae develop small floats, which carry them to the surface.Leloup E. (1929) [https://core.ac.uk/download/pdf/35104425.pdf "Research on the anatomy and development of Velella spirans Forsk"]. Liege.Delsman, H.C. (1923) [https://core.ac.uk/download/pdf/327688628.pdf "Beiträge zur Entwickelungsgeschichte von Porpita (Contributions to the history of the development of Porpita)"]. Treubia, 3: 243-266. For the larvae of Janthina, the transition to surface life includes the degradation of their eyes and vestibule system, and at the same time, the production of an external structure, which has been reported as either a small parachute made of mucus, or a cluster of bubbles, which they ride to the surface.{{cite journal |doi = 10.1017/S0025315400010146|title = A contribution to the biology of Ianthina janthina (L.)|year = 1956|last1 = Wilson|first1 = Douglas P.|last2 = Wilson|first2 = M. Alison|journal = Journal of the Marine Biological Association of the United Kingdom|volume = 35|issue = 2|pages = 291–305| s2cid=83752461 |url = http://plymsea.ac.uk/1709/1/A_contribution_to_the_biology_of_Ianthina_janthina_%28L.%29.pdf}}{{cite book | last=Lalli | first=Carol | title=Pelagic snails : the biology of holoplanktonic gastropod mollusks | url=https://books.google.com/books?id=yIAfwz5cxPMC | publisher=Stanford University Press | publication-place=Stanford, Calif | year=1989 | isbn=978-0-8047-1490-7 | oclc=18256759}} Young Halobates may hatch either above or below the surface, and for those below, the surface tension proves a formidable barrier. It may take Halobates nymphs several hours to break through the surface film. Despite the challenges of reaching the surface, there may be benefits to a temporary pelagic life.

File:Life history mechanisms of neustonic organisms - (b) wind.png may proliferate in one region (large circle) and be transported by wind and/or currents to high-density regions of low proliferation (small circles).{{cite journal |doi=10.1080/01431161003639660 |title=Distribution of floating Sargassum in the Gulf of Mexico and the Atlantic Ocean mapped using MERIS |year=2011 |last1=Gower |first1=J. F. R. |last2=King |first2=S. A. |journal=International Journal of Remote Sensing |volume=32 |issue=7 |pages=1917–1929 |bibcode=2011IJRS...32.1917G |s2cid=130180590}}]]

[[File:Life history mechanisms of neustonic organisms - (c) deep water.png|thumb|upright=2| {{center|(c) Life history involving deep water{{hsp}}}} (c) Neuston may also occupy deep water for one part of their life history (a hypothesis proposed for Velella)Woltereck R. (1904) "Ueber die Entwicklung der Velella aus einer in der tiefe vorkommenden Larve". Fischer.

(d) these deep-water habitats may allow them to take advantage of counter currents for transport in the direction opposite surface currents (a hypothesis proposed for Velella)Savilov, A.I. (1969) "Pleuston of the Pacific ocean". Biology of the Pacific Ocean, 264-353.]]

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Connectivity of ocean surface ecosystems may be facilitated by the life history of species living there. One hypothesis is that species have pelagic stages to "escape" surface sink regions and repopulate surface source regions, where one life cycle stage drifts on surface currents in one direction, and a pelagic stage either remains geographically localised{{hsp}}Bieri, R. (19770 "The ecological significance of seasonal occurrence and growth rate of Velella (Hydrozoa)". Publications of the Seto Marine Biological Laboratory, 24(1–3): 63-76. or drifts in the opposite direction.Savilov, A.I. (1969) "Pleuston of the Pacific ocean". In: Biology of the Pacific Ocean, pages 264-353. However, some surface species, such as the endemic species of the Sargasso Sea, may remain geographically isolated throughout their life history. While these hypotheses are intriguing, it is not known if or how life history shapes population/species distribution for most neustonic species. Understanding how life history varies by species is a critical component of assessing both connectivity and conservation of neustonic ecosystems.

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File:Ocean mist and spray 2.jpg containing marine microorganisms can be swept high into the atmosphere and may travel the globe before falling back to earth.]]

{{See also|Sea spray|Aeroplankton}}

A stream of airborne microorganisms circles the planet above weather systems but below commercial air lanes.[https://www.smithsonianmag.com/science-nature/living-bacteria-are-riding-earths-air-currents-180957734/ Living Bacteria Are Riding Earth’s Air Currents] Smithsonian Magazine, 11 January 2016. Some peripatetic microorganisms are swept up from terrestrial dust storms, but most originate from marine microorganisms in sea spray. In 2018, scientists reported that hundreds of millions of viruses and tens of millions of bacteria are deposited daily on every square meter around the planet.{{cite news |last=Robbins |first=Jim |title=Trillions Upon Trillions of Viruses Fall From the Sky Each Day |url=https://www.nytimes.com/2018/04/13/science/virosphere-evolution.html |date=13 April 2018 |work=The New York Times |access-date=14 April 2018}}{{cite journal |last1=Reche |first1=Isabel |last2=D’Orta |first2=Gaetano |last3=Mladenov |first3=Natalie |last4=Winget |first4= Danielle M |last5=Suttle |first5= Curtis A |title=Deposition rates of viruses and bacteria above the atmospheric boundary layer |journal=ISME Journal |volume=12 |issue=4 |pages=1154–1162 |date=29 January 2018 |doi=10.1038/s41396-017-0042-4 |pmid=29379178 |pmc=5864199}}

These airborne microorganisms form part of the aeroplankton. The 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 collect them for study in traps and sweep nets from aircraft, kites or balloons.A. C. Hardy and P. S. Milne (1938) Studies in the Distribution of Insects by Aerial Currents. Journal of Animal Ecology, 7(2):199-229

The environmental role of airborne cyanobacteria and microalgae is only partly understood. While present in the air, cyanobacteria and microalgae can contribute to ice nucleation and cloud droplet formation. Cyanobacteria and microalgae can also impact human health.{{cite journal |doi = 10.3402/tellusb.v64i0.15598|title = Primary biological aerosol particles in the atmosphere: A review|year = 2012|last1 = Després|first1 = Vivianer.|last2 = Huffman|first2 = J.Alex|last3 = Burrows|first3 = Susannah M.|last4 = Hoose|first4 = Corinna|last5 = Safatov|first5 = Aleksandrs.|last6 = Buryak|first6 = Galina|last7 = Fröhlich-Nowoisky|first7 = Janine|last8 = Elbert|first8 = Wolfgang|last9 = Andreae|first9 = Meinrato.|last10 = Pöschl|first10 = Ulrich|last11 = Jaenicke|first11 = Ruprecht|journal = Tellus B: Chemical and Physical Meteorology|volume = 64|page = 15598|bibcode = 2012TellB..6415598D|s2cid = 98741728|doi-access = free}}{{cite journal |doi = 10.1016/j.envint.2019.104964|title = The importance of cyanobacteria and microalgae present in aerosols to human health and the environment – Review study|year = 2019|last1 = Wiśniewska|first1 = K.|last2 = Lewandowska|first2 = A.U.|last3 = Śliwińska-Wilczewska|first3 = S.|journal = Environment International|volume = 131|page = 104964|pmid = 31351382|doi-access = free}}{{cite journal |doi = 10.2741/e285|title = Airborne Algae and Cyanobacteria Occurrence and Related Health Effects|year = 2011|last1 = Moustaka-Gouni|first1 = Maria|last2 = Kormas|first2 = K. A.|last3 = Moustaka-Gouni|first3 = M.|journal = Frontiers in Bioscience|volume = 3|issue = 2|pages = 772–787|pmid = 21196350|doi-access = free}}{{cite journal |doi = 10.1016/0021-8707(66)90039-6|title = Sensitivity of skin and bronchial mucosa to green algae|year = 1966|last1 = Bernstein|first1 = I.Leonard|last2 = Safferman|first2 = Robert S.|journal = Journal of Allergy|volume = 38|issue = 3|pages = 166–173|pmid = 5223702}}{{cite journal |doi = 10.5194/acp-12-9817-2012|title = Heterogeneous ice nucleation on atmospheric aerosols: A review of results from laboratory experiments|year = 2012|last1 = Hoose|first1 = C.|last2 = Möhler|first2 = O.|journal = Atmospheric Chemistry and Physics|volume = 12|issue = 20|pages = 9817–9854|bibcode = 2012ACP....12.9817H|doi-access = free}}{{cite journal |doi = 10.3389/fmicb.2018.02681|doi-access = free|title = Ice Nucleation Activity and Aeolian Dispersal Success in Airborne and Aquatic Microalgae|year = 2018|last1 = Tesson|first1 = Sylvie V. M.|last2 = Šantl-Temkiv|first2 = Tina|journal = Frontiers in Microbiology|volume = 9|page = 2681|pmid = 30483227|pmc = 6240693}} Depending on their size, airborne cyanobacteria and microalgae can be inhaled by humans and settle in different parts of the respiratory system, leading to the formation or intensification of numerous diseases and ailments, e.g., allergies, dermatitis, and rhinitis.{{cite journal |doi = 10.1016/j.ecoenv.2006.08.006|title = Allergenicity of airborne cyanobacteria Phormidium fragile and Nostoc muscorum|year = 2008|last1 = Sharma|first1 = Naveen Kumar|last2 = Rai|first2 = Ashwani K.|journal = Ecotoxicology and Environmental Safety|volume = 69|issue = 1|pages = 158–162|pmid = 17011621}}{{cite journal |doi = 10.1016/j.marpolbul.2017.07.064|title = Identification of cyanobacteria and microalgae in aerosols of various sizes in the air over the Southern Baltic Sea|year = 2017|last1 = Lewandowska|first1 = Anita Urszula|last2 = Śliwińska-Wilczewska|first2 = Sylwia|last3 = Woźniczka|first3 = Dominika|journal = Marine Pollution Bulletin|volume = 125|issue = 1–2|pages = 30–38|pmid = 28823424| bibcode=2017MarPB.125...30L }}{{cite journal |doi = 10.3389/fmicb.2019.00243|title = Methods to Investigate the Global Atmospheric Microbiome|year = 2019|last1 = Dommergue|first1 = Aurelien|last2 = Amato|first2 = Pierre|last3 = Tignat-Perrier|first3 = Romie|last4 = Magand|first4 = Olivier|last5 = Thollot|first5 = Alban|last6 = Joly|first6 = Muriel|last7 = Bouvier|first7 = Laetitia|last8 = Sellegri|first8 = Karine|last9 = Vogel|first9 = Timothy|last10 = Sonke|first10 = Jeroen E.|last11 = Jaffrezo|first11 = Jean-Luc|last12 = Andrade|first12 = Marcos|last13 = Moreno|first13 = Isabel|last14 = Labuschagne|first14 = Casper|last15 = Martin|first15 = Lynwill|last16 = Zhang|first16 = Qianggong|last17 = Larose|first17 = Catherine|journal = Frontiers in Microbiology|volume = 10|page = 243|pmid = 30967843|pmc = 6394204|doi-access = free}} 50px Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].

• Marine larval ecology
• Ocean surface topography
• Surface layer
• Sea spray
• Sea air
• Surface Ocean Lower Atmosphere Study
• Joint Global Ocean Flux Study
• Regional Ocean Modeling System

{{reflist}}

Category:Aquatic organisms