User:Vickeroodle/SandboxSeaFoam

Link to sea spray sandbox: User:Vickeroodle/SandboxSeaSpray

Sea spray sea foam connection

For other uses, see Sea foam (disambiguation).

Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignins, and lipids)[21] derived from sources such as the offshore breakdown of algal blooms^[1]. These compounds can act as surfactants or foaming agents. As the seawater is churned by breaking waves in the surf zone adjacent to the shore, the presence of these surfactants under these turbulent conditions traps air, forming persistent bubbles that stick to each other through surface tension. Sea foam is a global phenomenon [21], and populations of sea foam vary depending on their location and the potential influence of the surrounding marine, freshwater, and/or terrestrial environments [27]. Due to its low density and persistence, foam can be blown by strong on-shore winds from the beachface inland.

Formation

Sea foam is formed under conditions that are favorable for formation of sea spray, but one of the main distinctions from sea spray formation is the presence of higher concentrations of dissolves organic matter from macrophytes and phytoplankton. The dissolved organic matter in surface water provides some stability to the resulting sea foam [29]. The physical processes that are common to the formation of sea spray and sea foam are breaking of surface waves, and related phenomena like bubble entrainment and whitecap formation. Breaking of surface waves leads to entrainment of bubbles in the water column, the bubbles in the water column get transported around the top few meters of the surface ocean due to buoyancy effects. Smallest of the bubbles entrained in the water column dissolve entirely leading to higher ratios of dissolved gases in the wave affected surface ocean. The bubbles that do not dissolve eventually make it back to the surface, while traveling to the surface these bubbles accumulate hydrophobic substances. Once at the surface the bubble thins and eventually bursts releasing a slew sea spray into the atmosphere. Presence of dissolved organic matter stabilizes the bubble and these stabilized bubbles aggregates are together called as sea foam. Sometimes the sources of the sea foam is from the surrounding terrestrial vegetation [21]. Since wave breaking is one of the first steps in the formation of sea foam, there is an increased abundance of sea foam in the high winds condition [27]. Rain drops falling on the sea surface are one of the least studied mechanisms of sea spray and sea foam formation, these falling rain drops can lead to breaking of the sea surface into sprays and foam [cite Veron paper]. Thus there have been some non-mechanistic studies demonstrating increased sea foam formation due to high rainfall events [27]. Turbulence in the surface mixed layer can affect the concentration of dissolved organic matter and thus aid in the formation of nutrient-dense foam that is high in concentration of particulate organic matter [28]. Some studies on sea foam report that breaking of algal cells in times of heavy swells adds to the likelihood of sea foam production [29].

Composition

The composition of sea foam is generally a mixture of decomposed organic materials, including zooplankton, phytoplankton, algae (including diatoms^[3] [23]), bacteria, fungi, protozoans, and plant matter, though each occurrence of sea foam varies in its specific contents. In some areas, sea foam is found to be made up of 22.85% protein, dominant in both fresh and old foam, 10.76% lipids, and 3.07% carbohydrates. The high protein and low carbohydrate concentration suggest that sugars originally present in the surrounding mucilage created by algae or plant matter has been quickly consumed by bacteria. [29] Additional research has shown that between 0.05% and 0.16% of sea foam measured by dry weight is organic carbon, which contains phenolics, sugars, amino sugars, and amino acids. In the Bay of Fundy, high mortality rates of an abundant tube-dwelling amphipod (Corophium volutator) by natural die-offs as well as predation by migrating seabirds contributed to amino sugars released in the surrounding environment and thus, in sea foam. [28] It is thought that the carbon in sea foam is primarily derived from vascular plant detritus. [28] The organic matter in sea foam has been found to increase dramatically during phytoplankton blooms in the area. [19]

Some research has shown very high concentrations of microplankton in sea foam, with significantly higher numbers of autotrophic phytoplankton than heterotrophs. [23] Some foams are particularly rich in their diatom population which can make up 80.1-96.3% of the microalgal biomass in some cases^[3]. [23] A diversity of bacteria is also present in sea foam; old foam tends to have a higher density of bacteria. One study found that 95% of sea foam bacteria was rod-shaped, while the surrounding surface water contained mostly coccoid-form bacteria and only 5% - 10% rod-shaped bacteria. [29] There is also seasonal variability of sea foam composition [28]; in some regions there is a seasonal occurrence of pollen in sea foam which can alter its chemistry. [27] Though foam is not inherently toxic, it may contain high concentrations of contaminants. [21] The boundary layer between the air and ocean surface (surface microlayer, or SML) is a place where materials that will not be absorbed further into the water column gather. Foam bubbles can be coated with or contain these materials which can include petroleum compounds, pesticides, and herbicides. [21]

Longevity and stability

Structurally, sea foam is thermodynamically unstable, though some sea foam can persist in the environment for several days at most. There are two types of sea foam categorized based on their stability: 1) Unstable or transient foams have very short lifetimes of only seconds. The bubbles formed in sea foam may burst releasing aerosols into the air, contributing to sea spray. 2) Metastable foams can have a lifetime of several hours to several days; their duration is sometimes attributed to small particles of silica, calcium, or iron which contribute to foam stability and longevity. [21] Additionally, seawater that contains released dissolved organic material from phytoplankton and macrophytic algae that is then agitated in its environment is most likely to produce stable, longer-lasting foam when compared with seawater lacking one of those components. For example, filtered seawater with added with the fronds of the kelp, Ecklonia maxima, produced foam but it lacked the stability that unfiltered seawater provided. Additionally, kelp fronds that were maintained in flowing water therefore reducing their mucus coating, were unable to help foam form. [29] Different types of salt are also found to have varying effects on bubble proximity within sea foam, therefore contributing to its stability. [21]

Ecological role

The presence of sea foam in the marine environment plays a number of ecological roles including providing sources of food, creating habitat, and acting as a mode of transport for both organisms and nutrients within the marine environment and, at times, into the intertidal or terrestrial environments. As a food source, sea foam with a stable composition is more important ecologically, as it is able to persist longer and can transport nutrients within the marine environment. [29] In the Bay of Fundy, for example, a tube-dwelling amphipod, Corophium volutator, can potentially attain 70% of its nutritional requirements from the sugars and amino acids derived from sea foam in its environment. At times, however, the sea foam was found to be toxic to this species. It is thought that high concentrations of phenolics and/or the occasional presence of heavy metals or pesticides incorporated into the sea foam from the sea surface contributed to its toxicity. [28] On the west coast of Cape Peninsula, South Africa, sea foam often occurs in nearshore marine areas with large kelp beds during periods of strong westerly winds. It is thought that the foam generated in these conditions is an important food source for local organisms due to the presence of organic detritus in the sea foam. [29]

Wave action can deposit foam into intertidal areas where it can remain when the tide recedes, contributing nutrients to the intertidal zone. [28] Additionally, sea foam can become airborne with an abundance of wind, resulting in sea spray and therefore serving as a mode of transport for materials between marine and terrestrial environments. [27] Longer decay times result in a higher chance that energy contained in sea foam will move up the food web into higher trophic levels. [29] The ability of sea foam to transport materials is also thought to benefit macroalgal organisms, as macroalgae propagules can be carried to different microenvironments, thus influencing the tidal landscape and contributing to new possible ecological interactions. [20] As sea foam is a wet environment, it is conducive habitat to algal spores where propagules can attach and advect to the substrate and avoid risk of dissemination. [20] When sea foam contains fungi, it can also aid in the decomposition of plant and animal remains in coastal ecosystems. [27] Additionally, sea foam is a habitat for a number of marine microorganisms. Some research has shown the presence of various microphytoplanktonic, nanophytoplanktonic, and diatom groups in seafoam; the phytoplankton groups appeared in significantly higher abundance than in sea surface film and the top pelagic zone. [23]

Hazards

Toxicity

Naturally occurring sea foam is not inherently toxic; however, it can be exposed to high concentrations of contaminants in the sea surface microlayer derived from the breakdown of algal blooms, fossil fuel production and transport, and stormwater runoff (21). These contaminants contribute to the formation of noxious sea foam through adsorption onto bubbles in the surface layer. Bubbles may burst and release toxins into the atmosphere in the form of sea spray or aerosol, or they may persist in foams. Toxins released through aerosols and breaking of bubbles as foams degrade can be inhaled by humans. The microorganisms that occupy sea foams as habitat have increased susceptibility for contaminant exposure (38). Consequently, these toxic substances can be integrated into the trophic food chain (21).

Harmful algal blooms

Foams can form following the degradation of harmful algal blooms (HABs), primarily composed of algal species, but can also consist of dinoflagellates and cyanobacteria (30). Sea foam serves as a critical wet environment for algal spores where propagules can attach to bubbles (20). Biomass from algae in the bloom is integrated into sea foam in the sea surface microlayer (19). When the impacted sea foam deteriorates, toxins from the algae are released into the air causing breathing issues and occasionally initiating asthma attacks (37).

Phaeocystis globosa is one algal species that is considered problematic. Its high biomass accumulation allows it to create large quantities of toxic foam that often wash onto beaches (30). P. globosa blooms are initiated in areas of high nutrient availability, often affiliated with coastal locations with a lot of freshwater or stormwater runoff, and eutrophication. Studies suggest that the development of foam is directly correlated to blooms caused by P. globosa, despite that foam formation typically occurs approximately two weeks after the appearance of an algal bloom offshore (30). Organic material from P. globosa was observed decomposing while suspended at the sea surface, but was not observed lower in the water column. P. globosa is also considered a nuisance species whose large foam formations impairs the public’s ability to enjoy the beach (30).

Human activities

While sea foam is a common result of the agitation of seawater mixing with organic material in the surface ocean, human activities can contribute to the production of excess and often toxic foam (21). In addition to the organic oils, acids, and proteins that amass in the sea surface microlayer, compounds derived from petroleum production and transport, synthetic surfactants, and pesticide use can enter the sea surface and be incorporated into foam (21). The pollutants present can also affect the persistence of the foam produced. Crude oil discharged from tankers, motor oil, sewage, and detergents from polluted runoff can create longer-lasting foams (21). In one study, polychlorinated biphenyls (PCBs), a persistent organic pollutant, were found to amass in sea foams (38).

Natural gas terminals have been cited as contributors to the production of modified foams due to the process of using seawater to convert natural gas to liquified natural gas (25). One study showed a much greater abundance of heterotrophic prokaryotes (archaea and bacteria) and cyanobacteria in foam that was generated near a liquified natural gas terminal. These prokaryotes were able to recycle chemical materials discharged from the terminal, which enhanced microbial growth (25). Additionally, higher levels of total organic carbon (TOC) and plankton biomass were recorded in foam generated in close proximity to the terminal. Organic carbon was transferred readily into the pelagic food web after uptake my prokaryotes and ingestion by grazers (25).

Notable occurrences

**Tori add news links, puppies, sea snakes, danger!

• Southern Barents Sea, August 31, 1987 [23]
• There is a notable summer occurrence of sea foam in the North Sea due to the presence of Phaeocystis cf. pouchetii, a phytoplankton species that produces a large quantity of mucilaginous material in the process of primary production. The mucus collects in a dissolved form and easily foams as it is polymeric in structure. There is an observed increase in the phenomenon as levels of nutrients such as nitrogen, phosphorus, and silica rise due to anthropogenic input.   [26]
• The water turns reddish-brown. Meters tall. Bätje and Michaelis (1986) [21]
• ** There are a lot more listed in [21]
  • A large buildup of sea foam occurred on the coast of Yamba, northern New South Wales, 29°26′S 153°21′E on 24 August 2007, and attracted world-wide media attention.
  • Other sea foam occurrences at Caloundra 26°48′S 153°08′E and Point Cartwright, 26°40′47.8″S 153°08′18.1″E, on Queensland's Sunshine Coast in January–February 2008, also attracted world-wide media attention.
  • During live coverage of Hurricane Irene in Ocean City, Maryland, Tucker Barnes was covered in sea foam.
  • In December 2011, the coast road at Cleveleys, Lancashire was swamped by metre high drifts of sea foam.
  • Following storms and high winds on 24/25 September 2012, the beach front of the Footdee area of Aberdeen was engulfed with sea foam.
  • Between 27 and 28 January 2013, the Sunshine Coast in Queensland, Australia, had masses of foam wash up on land from ex-tropical cyclone Oswald.
  • June 2016: sea foam across the East coast of Australia, whipped up by storms.
  • 28 March 2017: sea foam brought by Cyclone Debbie at Sarina Beach in Queensland, Australia.
  • 16 October 2017: Hurricane Ophelia covered Cleveleys, Lancashire with spume.
  • 12 December 2017 large amount of sea foam brought by thunderstorm and strong winds to the Ostia beach shore, in Rome. A rare event for the Mediterranean Sea.
  • January 2018: Storm Eleanor causes widespread foam across Europe.