Sargassum
Sargassum | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Stramenopiles |
Phylum: | Gyrista |
Subphylum: | Ochrophytina |
Class: | Phaeophyceae |
Order: | Fucales |
Family: | Sargassaceae |
Genus: | Sargassum |
Species | |
See list |
Sargassum is a genus of brown macroalgae (
The size of annual blooms in the Atlantic increased by over a hundred-fold, starting in 2011, as a result of factors including increased fertilizer runoff in major rivers such as the Amazon and Congo.
History
Sargassum was named by the Portuguese sailors who found it in the Sargasso Sea. They called it after the wooly rock rose (Halimium lasianthum) that grew in their water wells at home,[citation needed] and that was called sargaço in Portuguese (Portuguese pronunciation: [sɐɾˈɣasu])[4] - from the Latin salicastrum.
The Florida Keys and mainland South Florida are well known for the high levels of Sargassum covering their shores. Sargassum or gulfweed was observed by Columbus. Although the seaweed acquired a legendary reputation for covering the entirety of the Sargasso Sea, making navigation impossible,[5] it has since been found to occur only in drifts.[6]
Sargassum species are cultivated and cleaned for use as an herbal remedy. Many Chinese herbalists prescribe powdered Sargassum—either the species S. pallidum, or more rarely, hijiki, S. fusiforme—in doses of 0.5 grams dissolved in warm water and drunk as a tea. It is called 海藻; hǎizǎo in traditional Chinese medicine, where it is used to resolve "heat phlegm".[7]
Sargassum (F. Sargassaceae) is an important seaweed excessively distributed in tropical and subtropical regions. Different species of Sargassum have folk applications in human nutrition and are considered a rich source of vitamins, carotenoids, proteins, and minerals. Many bioactive chemical compounds that are classified as terpenoids, sterols, sulfated polysaccharides, polyphenols, sargaquinoic acids, sargachromanol, and pheophytin were isolated from different Sargassum species. These isolated compounds and/or extracts exhibit diverse biological activities, including analgesic, anti-inflammatory, antioxidant, neuroprotective, anti-microbial, anti-tumor, fibrinolytic, immune-modulatory, anticoagulant, hepatoprotective, and anti-viral activities.[8]
Description
Species of this genus of
Ecology
Large,
The Sargasso Sea plays a major role in the
Organisms found in the pelagic Sargassum patches,[16][17][11]
- Arthropods
- Amphipods
- Skeleton shrimp
- Crabs
- Copepods
- Shrimp
- Sea Spiders
- Worms
- Annelid worms
- Flatworms
- Mollusks
- Nudibranchs
- Snails
- Squid
- Fish
- Sargassum fish
- Porcupinefish
- Triplefin
- Planehead filefish
- European eel
- American eel
- American conger eel
- Others
- Sea turtles
Sargassum is commonly found in the beach drift near Sargassum beds, where they are also known as gulfweed, a term that also can mean all seaweed species washed up on shore.
Sargassum species are found throughout tropical areas of the world and are often the most obvious macrophyte in near-shore areas where Sargassum beds often occur near
"Coastal inundations" by washed-ashore Sargassum
In limited amounts, washed-ashore Sargassum plays an important role in maintaining Atlantic and Caribbean coastal ecosystems.[20] Once ashore, Sargassum provides vital nutrients such as carbon, nitrogen, and phosphorus to coastal ecosystems which border the nutrient-poor waters of the western North Atlantic tropics and subtropics.[21][22] Additionally, it decreases coastal erosion.[22]
Beginning in 2011, unprecedented quantities of Sargassum began inundating coastal areas in record amounts.[23] Coastlines in Brazil, the Caribbean, Gulf of Mexico, and the east coast of Florida saw quantities of Sargassum wash ashore up to three feet deep.[24][20] The first major Sargassum inundation event occurred in 2011 and had a biomass increase of 200 fold compared to the previous eight years average bloom size.[25] Since 2011 increasingly stronger inundation events have occurred every 2–3 years. During a Sargassum inundation event in 2018, one Sargassum bloom measured over 1600 square kilometers, more than three times the average size.[25][26] Recent inundation events have caused millions of dollars of lost revenue in the tourism industry, especially hurting small Caribbean countries whose economies are highly dependent on seasonal tourism.[25]
While the Sargasso Sea is a known source of Sargassum blooms, variations in the Sargassum types composing these inundation events have led researchers to believe that the Sargasso Sea is not the point of origin of inundating Sargassum.[25][27] Sargassum natans I and Sargassum fluitans III are the dominant Sargassum species found in the Sargasso Sea.[28] Recent net sampling studies have found Sargassum natans VIII, a previously rare type, is constituting a dominating percentage of Sargassum biodiversity in the Western Atlantic and Sargasso Sea.[28][29][30]
Biological impacts
Unprecedented Sargassum inundation events cause a range of biological and ecological impacts in affected regions. The decomposition of large quantities of Sargassum along coastlines consumes oxygen, creating large oxygen-depleted zones resulting in fish kills.[31] Decomposing Sargassum additionally creates hydrogen sulfide gas (H2S), which causes a range of health impacts in humans.[32] During the Sargassum inundation event in 2018, 11,000 Acute Sargassum Toxicity cases were reported in an 8-month span on just the Caribbean islands of Guadeloupe and Martinique.[33] Massive amounts of floating Sargassum present a physical barrier preventing corals and seagrasses from receiving sufficient light, fouling boat propellers, and entangling marine turtles and mammals.[34][35] With every Sargassum inundation event, large amounts of nutrients are transported from the open ocean to coastal environments. This greatly increases nutrient transport, and its effect on marine and coastal ecosystems are still unknown. Understanding the causes and drivers of Sargassum inundations is critical as they become more commonplace.[36]
Nutrient factors
The Sargasso Sea, a known source area for Sargassum blooms, is classified as an oligotrophic region.[37] With warm, oxygen-poor waters and low nutrient contents, biomass production is limited by what little nutrients are present.[38] Historically, low nutrient levels in the Sargasso Sea have limited Sargassum production. New influxes of nitrogen and phosphorus are driving factors in increased biomass production.[39][40][41]
Recent studies have found three likely drivers of nutrient influx linked to increasing Sargassum biomass: an increase in nutrient output from the Amazon River, increased nutrients in the Gulf of Mexico, and coastal upwelling off the West African Coast which transfers deep nutrient-rich waters to the upper water column where Sargassum resides.[42][43][41] Nutrient output from the Amazon River has been shown to have a direct delayed effect on large inundation events, which occur one to two years after years of high nutrient output.[42] Phosphates and iron transported via the trade winds from North Africa have been reported to have a fertilizing effect on Sargassum growth; further data is required to understand its role in causing inundating blooms.[25] Researchers globally agree that continued research is required to quantify the effect of marine chemical changes and other environmental factors in the recent increase in Sargassum biomass and inundation events.[42]
Currents and winds
The physical drivers behind Sargassum inundation events are prevailing winds and ocean surface currents.[44] The Caribbean is located in a region heavily affected by Trade winds. Trade winds are strong, consistent northeasterlies winds which blow dust-filled dry air from the Sahara across the Atlantic.[45] Trade winds additionally play a critical role in the annual hurricane season in the Western Atlantic.[46] The Caribbean Current and Antilles branch of the Atlantic North Equatorial Current are the major current transporters of Sargassum in the region.[47][48]
Researchers have recently begun using Moderate Resolution Imaging Spectroradiometer satellite imagery and ocean current data to track and forecast inundation events with a high level of accuracy.[49]
Human effects
The effects of deforestation, waste-water runoff, and commercial agriculture fertilizer on facilitating the excess accumulation of nutrients in aquatic and marine environments have been well studied and shown to be driving factors in eutrophication.[50][51] Since detrimental Sargassum inundation events did not begin until 2011, it is likely that an unknown nutrient threshold was reached and surpassed. Given current agricultural policies and practices, it is unlikely these inundation events will disappear on their own without human intervention.
As food
Climate change
Variations in sea level, salinity, water temperature, chemical composition, rainfall patterns, and water acidity all play roles in regulating algae blooms.[52] As anthropogenic forces increase the variability of these factors, the frequency, duration, severity and geographic range of harmful algae blooms have increased, causing millions of dollars of lost revenue as well as damaging fragile coastal and coral ecosystems.[53]
References
- ^ Guiry, M.D.; Guiry, G.M., eds. (2023). "Sargassum C.Agardh, 1820, nom. et typ. cons". AlgaeBase. National University of Ireland. Retrieved 4 July 2023.
- ^ Hogan, C. Michael (2011). Monosson, E.; Cleveland, C.J. (eds.). "Algae § 1.3 Brown_algae". Encyclopedia of Earth. Washington DC: National Council for Science and the Environment.
- ^ "Sargasso". Straight Dope.
- ISBN 968-16-2812-8, p. 627.
- ^
ISBN 9780134349404. Retrieved 11 July 2022.
Since Columbus's time, many legends about the Sargasso Sea have spread. The seaweed covering its surface was believed to be so thick that no ship could escape from it. Early writers described ancient ghost ships, rotting away as they remained trapped forever in the seaweed.
- ^ David McFadden (August 10, 2015). "Stinking mats of seaweed piling up on Caribbean beaches". Archived from the original on August 13, 2015. Retrieved August 10, 2015.
- ISBN 978-1-901149-02-9.
- PMID 35517468.
- ISBN 978-0-8047-2152-3.
- ^ US Department of Commerce, National Oceanic and Atmospheric Administration. (2013, June 01). What is the Sargasso Sea? Retrieved November 28, 2017 [1]
- ^ a b c Laffoley, D.d’A., Roe, H.S.J., Angel, M.V., Ardron, J., Bates, N.R., Boyd, I.L., Brooke, S., Buck, K.N., Carlson, C.A., Causey, B., Conte, M.H., Christiansen, S., Cleary, J., Donnelly, J., Earle, S.A., Edwards, R., Gjerde, K.M., Giovannoni, S.J., Gulick, S., Gollock, M., Hallett, J., Halpin, P., Hanel, R., Hemphill, A., Johnson, R.J., Knap, A.H., Lomas, M.W., McKenna, S.A., Miller, M.J., Miller, P.I., Ming, F.W., Moffitt, R., Nelson, N.B., Parson, L., Peters, A.J., Pitt, J., Rouja, P., Roberts, J., Roberts, J., Seigel, D.A., Siuda, A.N.S., Steinberg, D.K., Stevenson, A., Sumaila, V.R., Swartz, W., Thorrold, S., Trott, T.M., and V. Vats. (2011). The protection and management of the Sargasso Sea: The golden floating rainforest of the Atlantic Ocean. Summary Science and Supporting Evidence Case. Sargasso Sea Alliance, 44 pp.
- .
- ^ Casazza, T.L.; Ross, S.W. "Sargassum: A Complex 'Island' Community at Sea". NOAA Ocean Explorer. Retrieved 27 September 2018.
- ^ "Turtles return home after UK stay". BBC News. 2008-06-30. Retrieved 2010-05-23.
- ^ "Satellites track turtle 'lost years'". BBC News. 2014-03-05. Retrieved 2014-03-05.
- ^ "NOAA Ocean Explorer: Life on the Edge: Sargassum". oceanexplorer.noaa.gov. Retrieved 2021-11-22.
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- .
- S2CID 19551247.
- ^ a b "Sargassum Seaweed: An important element for beaches and shoreline stability. | Government of the Virgin Islands". bvi.gov.vg.
- ISBN 978-0-309-04826-2– via www.nap.edu.
- ^ a b Crist, Carolyn (July 26, 2019). "Toxic seaweed a menace to Caribbean tourists". Reuters – via www.reuters.com.
- .
- ^ "Fact sheet" (PDF). www.nps.gov. Retrieved 2020-09-29.
- ^ a b c d e "The Great Sargassum Disaster of 2018". essa.com. February 7, 2019.
- ^ "The Sargassum Mass-Bloom of 2018". nereusprogram.org.
- JSTOR 24861895.
- ^ .
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- ^ "Ramlogan et al 2017 sargassum influx barbados fish". 2018-06-15. Archived from the original on 2018-06-15. Retrieved 2021-11-22.
- ^ Burton, Rebecca (2018-07-15). "Sargassum: Seaweed or Brown Algae". Florida Museum. Retrieved 2020-09-29.
- ^ "Sargassum seaweed: limit the exposure of residents and workers to hydrogen sulphide - Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail". Anses. 9 November 2018. Retrieved 2020-09-29.
- ^ Crist, Carolyn (2019-07-26). "Toxic seaweed a menace to Caribbean tourists". U.S. Retrieved 2020-09-29.
- ^ "Tracking Sargassum's ocean path could help predict coastal inundation events". University of Maryland Center for Environmental Science. 2018-08-22. Retrieved 2020-09-29.
- ^ "The Great Sargassum Disaster of 2018". ESSA. 2019-02-07. Retrieved 2020-09-29.
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- PMID 31222051.
- ^ Bulger, Faith. "Functionality of World Ocean". Sargasso Sea Commission.
- ^ "Satellite Data Reveal Growth and Decline of Sargassum". Eos. 29 July 2019.
- ^ Kornei, Katherine (2019-07-29). "Satellite Data Reveal Growth and Decline of Sargassum". Eos. Retrieved 2020-09-29.
- ^ .
- ^ a b c "Scientists discover the biggest seaweed bloom in the world". phys.org.
- ^ "Tracking Sargassum's ocean path could help predict coastal inundation events". ScienceDaily.
- ^ "Tracking Sargassum's ocean path could help predict coastal inundation events". phys.org.
- ^ News, Chelsea Harvey, E&E. "Saharan Dust Plume Slams U.S., Kicking Up Climate Questions". Scientific American.
{{cite web}}
:|last=
has generic name (help)CS1 maint: multiple names: authors list (link) - ^ "Movement of Hurricanes: steered by the global winds". ww2010.atmos.uiuc.edu.
- ^ "Antilles Current | current, Atlantic Ocean". Encyclopedia Britannica.
- ^ "The Caribbean Current". oceancurrents.rsmas.miami.edu.
- .
- ^ "The Effects of Deforestation on Nutrient Concentrations in Tributaries of Lake Tanganyika" (PDF). www.geo.arizona.edu. Retrieved 2020-09-29.
- ^ US EPA, OW (March 12, 2013). "The Sources and Solutions: Agriculture". US EPA.
- ^ US EPA, OW (September 5, 2013). "Climate Change and Harmful Algal Blooms". US EPA.
- ^ "Impacts of Climate Change on the Occurrence of Harmful Algal Blooms" (PDF). www.epa.gov. 2013. Retrieved 2020-09-29.
Further reading
- Critchley, A.T.; Farnham, W.F.; Morrell, S.L. (1983). "A chronology of new European sites of attachment for the invasive brown alga, Sargassum muticum, 1973–1981". S2CID 84790037.
- Boaden, P. J. S. (1995). "The Adventive Seaweed Sargassum muticum (Yendo) Fensholt in Strangford Lough, Northern Ireland". The Irish Naturalists' Journal. 25 (3): 111–113. JSTOR 25535928.
- Davison, D.M. (1999). "Sargassum muticum in Strangford Lough, 1995–1998; a review of the introduction and colonisation of Strangford Lough MNR and cSAC by the invasive brown alga Sargassum muticum". Environment and Heritage Service Research and Development Series (99): 27. ISSN 1367-1979.
- Griffiths, Sarah (28 June 2023). "The real story behind the Atlantic's record-breaking seaweed blobs". bbc.com. Retrieved 3 July 2023.
External links
- algaebase.org
- seaweed.ie
- marlin.ac.uk Archived 2018-05-01 at the Wayback Machine
- Sargassum in Northern Ireland. Archived 2009-04-20 at the Wayback Machine
- The SuriaLink Seaplants Handbook – Sargassum
- habitas.org.uk
- irishseaweed.com
- Sargassum reproduction.
- Sargassum Early Advisory System Texas
- What is the Sargasso Sea? US Department of Commerce, National Oceanic and Atmospheric Administration. (2013, June 1).