Sea lettuce
The sea lettuces comprise the genus Ulva, a group of edible green algae that are widely distributed along the coasts of the world's oceans. The type species within the genus Ulva is Ulva lactuca, lactuca being Latin for "lettuce". The genus also includes the species previously classified under the genus Enteromorpha, which are known under the common name green nori.
Description
Individual blades of Ulva can grow to be more than 400 mm in size, but this occurs only when the plants are growing in sheltered areas. A macroscopic alga which is light to dark green in colour, it is attached by disc holdfast. Their structure is a leaflike flattened thallus.Nutrition and contamination
Sea lettuce is eaten by a number of different sea animals, including manatees and the sea slugs known as sea hares.Many species of sea lettuce are a food source for humans in Scandinavia, Great Britain, Ireland, China, and Japan. Sea lettuce as a food for humans is eaten raw in salads and cooked in soups. It is high in protein, soluble dietary fiber, and a variety of vitamins and minerals, especially iron. Enhances flavor and fortifies bread when chopped and mixed into the dough before baking.
Contamination with toxic heavy metals at certain sites where it can be collected makes it dangerous for human consumption.
Health concerns
In August 2009, unprecedented amounts of these algae washed up on the beaches of Brittany, France, causing a major public health scare as it decomposed. The rotting leaves produced large quantities of hydrogen sulfide, a toxic gas. In one incident near Saint-Michel-en-Grève, a horse rider lost consciousness and his horse died after breathing the seaweed fumes; in another, a lorry driver driving a load of decomposing sea lettuce passed out, crashed, and died, with toxic fumes claimed to be the cause. Environmentalists blamed the phenomenon on excessive nitrogenous compounds washed out to sea from improper disposal of pig and poultry slurry from industrial farms, and from chemical products and slurry used as fertilisers in arable farming.Species
Species in the genus Ulva include:;Accepted species
- Ulva acanthophora Hayden, Blomster, Maggs, P.C. Silva, Stanhope & J.R. Waaland, 2003
- Ulva anandii Amjad & Shameel, 1993
- Ulva arasakii Chihara, 1969
- Ulva atroviridis Levring, 1938
- Ulva australis Areschoug, 1854
- Ulva beytensis Thivy & Sharma, 1966
- Ulva bifrons Ardré, 1967
- Ulva brevistipita V.J. Chapman, 1956
- Ulva burmanica De Toni, 1889
- Ulva californica Wille, 1899
- Ulva chaetomorphoides Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva clathrata C. Agardh, 1811
- Ulva compressa Linnaeus, 1753
- Ulva conglobata Kjellman, 1897
- Ulva cornuta Lightfoot, 1777
- Ulva covelongensis V. Krishnamurthy & H. Joshi, 1969
- Ulva crassa V.J. Chapman, 1956
- Ulva crassimembrana Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva curvata De Toni, 1889
- Ulva denticulata P.J.L. Dangeard, 1959
- Ulva diaphana Hudson, 1778
- Ulva elegans Gayral, 1960
- Ulva enteromorpha Le Jolis, 1863
- Ulva erecta Fries
- Ulva expansa Setchell & N.L. Gardner, 1920
- Ulva fasciata Delile, 1813
- Ulva flexuosa Wulfen, 1803
- Ulva geminoidea V.J. Chapman, 1956
- Ulva gigantea Bliding, 1969
- Ulva grandis Saifullah & Nizamuddin, 1977
- Ulva hookeriana Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland
- Ulva hopkirkii P. Crouan & H. Crouan
- Ulva howensis Kraft, 2007
- Ulva indica Roth, 1806
- Ulva intestinalis Linnaeus, 1753
- Ulva intestinaloides Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva javanica N.L. Burman, 1768
- Ulva kylinii Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva lactuca Linnaeus, 1753
- Ulva laetevirens J.E. Areschoug, 1854
- Ulva laingii V.J. Chapman, 1956
- Ulva linearis P.J.L. Dangeard, 1957
- Ulva linza Linnaeus, 1753
- Ulva lippii Lamouroux
- Ulva litoralis Suhr ex Kützing
- Ulva littorea Suhr
- Ulva lobata Harvey, 1855
- Ulva maeotica P.M.Tsarenko, 2011
- Ulva marginata Le Jolis
- Ulva micrococca Gobi
- Ulva mutabilis Föyn, 1958
- Ulva neapolitana Bliding, 1960
- Ulva nematoidea Bory de Saint-Vincent, 1828
- Ulva ohnoi Hiraoka & Shimada, 2004
- Ulva olivascens P.J.L. Dangeard
- Ulva pacifica Endlicher
- Ulva papenfussii Pham-Hoang Hô, 1969
- Ulva parva V.J. Chapman, 1956
- Ulva paschima Bast
- Ulva patengensis Salam & Khan, 1981
- Ulva percursa C. Agardh
- Ulva pertusa Kjellman, 1897
- Ulva phyllosa Papenfuss
- Ulva polyclada Kraft, 2007
- Ulva popenguinensis P.J.L. Dangeard, 1958
- Ulva porrifolia J.F. Gmelin
- Ulva profunda W.R. Taylor, 1928
- Ulva prolifera O.F.Müller, 1778
- Ulva pseudocurvata Koeman & Hoek, 1981
- Ulva pseudolinza Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva pulchra Jaasund, 1976
- Ulva quilonensis Sindhu & Panikkar, 1995
- Ulva radiata Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva ralfsii Le Jolis, 1863
- Ulva ranunculata Kraft & A.J.K. Millar, 2000
- Ulva reticulata Forsskål, 1775
- Ulva rhacodes Papenfuss, 1960
- Ulva rigida C. Agardh, 1823
- Ulva rotundata Bliding, 1968
- Ulva saifullahii Amjad & Shameel, 1993
- Ulva serrata A.P.de Candolle
- Ulva simplex Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003
- Ulva sorensenii V.J. Chapman, 1956
- Ulva spinulosa Okamura & Segawa, 1936
- Ulva stenophylla Setchell & N.L. Gardner, 1920
- Ulva sublittoralis Segawa, 1938
- Ulva subulata Naccari
- Ulva taeniata Setchell & N.L. Gardner, 1920
- Ulva tanneri H.S. Hayden & J.R. Waaland, 2003
- Ulva tenera Kornmann & Sahling
- Ulva torta Trevisan, 1841
- Ulva tuberosa Palisot de Beauvois
- Ulva uncialis Montagne, 1850
- Ulva uncinata Mohr
- Ulva uncinata Mertens
- Ulva usneoides Bonnemaison
- Ulva utricularis C. Agardh
- Ulva utriculosa C. Agardh
- Ulva uvoides Bory de Saint-Vincent
- Ulva ventricosa A.P.de Candolle
- Ulva costata Wollny, 1881
- Ulva repens Clemente, 1807
- Ulva tetragona A.P.de Candolle, 1807
Ten new species have been discovered in New Caledonia: Ulva arbuscula, Ulva planiramosa, Ulva batuffolosa, Ulva tentaculosa, Ulva finissima, Ulva pluriramosa, Ulva scolopendra and Ulva spumosa.