Articles on this page are available in 1 other language: Dutch (1) (learn more)

Overview

Brief Summary

During a walk on the mudflats, you are bound to find ulva growing in certain areas. The fishermen call it 'flap'. In Brittany, this green seaweed forms a plague. It is still a common species in the tidal regions around the North Sea however it has been declining in the past decennia in the Wadden Sea. This is because there are fewer nutrients in the water. Ulva readily tears off from its root, but continues to grow further just the same. Sometimes you see what looks like toilet paper on the flats or in the flood mark on the beach. In most cases, it is dried up ulva that has been bleached by the sun.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Copyright Ecomare

Source: Ecomare

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ulva is a genus of green algae known commonly as sea lettuce or green laver. Ulva seaweeds are found worldwide in nitrogen-rich marine habitats attached to rocks in the mid to low intertidal zone (Lee 2008; Kirby 2001). The fronds of Ulva usually grow as sheets, but some species exist in a hollow cylindrical form. These cylindrical species were previously classified as a distinct genus, Enteromorpha, but are now included in Ulva. (Lee 2008; Hayden et al 2003). The blades can grow up to 40 cm long, but are very thin—only 2 cells thick (Lee 2008).

Ulva is eaten by humans in soups, salads, and sushi (Lee 2008 and references within; Kirby 2001).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution

Ulva is found worldwide.

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Physical Description

Morphology

The fronds of Ulva usually grow as sheets, but some species exist in a hollow cylindrical form. These cylindrical species were previously classified as a distinct genus, Enteromorpha, but have been synonymized with Ulva. The blade morphology of Ulva is dependent on bacterial composition in the environment (Lee 2008; Hayden et al 2003).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Size

The blades can grow up to 40 cm long, but are very thin - only 2 cells thick (Lee 2008).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
Creative Commons Attribution 3.0 (CC BY 3.0)

© WoRMS for SMEBD

Source: World Register of Marine Species

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Lives in marine environments, and sometimes found in brackish waters in estuaries, however, Ulva needs nitrogen-rich waters. Ulva attaches to rocks in the mid to low intertidal zone (Lee 2008; Kirby 2001).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Depth range based on 1583 specimens in 54 taxa.
Water temperature and chemistry ranges based on 249 samples.

Environmental ranges
  Depth range (m): 0 - 2824.53
  Temperature range (°C): 1.634 - 27.678
  Nitrate (umol/L): 0.066 - 43.393
  Salinity (PPS): 34.579 - 38.044
  Oxygen (ml/l): 1.433 - 6.339
  Phosphate (umol/l): 0.020 - 3.034
  Silicate (umol/l): 0.406 - 169.201

Graphical representation

Depth range (m): 0 - 2824.53

Temperature range (°C): 1.634 - 27.678

Nitrate (umol/L): 0.066 - 43.393

Salinity (PPS): 34.579 - 38.044

Oxygen (ml/l): 1.433 - 6.339

Phosphate (umol/l): 0.020 - 3.034

Silicate (umol/l): 0.406 - 169.201
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Associations

Known predators

Ulva (Chaetomorpha, Ulva, other algae) is prey of:
Anatidae
Chelon labrosus
Liza ramada
Liza aurata
Acmaea
Crepidula
Littorina saxatilis
Littorina littorea
Littorina obtusata
Onoba

Based on studies in:
USA: Rhode Island (Marine)
Portugal (Estuarine)
USA: Massachusetts, Cape Ann (Littoral, Rocky shore)

This list may not be complete but is based on published studies.
  • L. Saldanha, Estudio Ambiental do Estuario do Tejo, Publ. no. 5(4) (CNA/Tejo, Lisbon, 1980).
  • R. W. Dexter, The marine communities of a tidal inlet at Cape Ann, Massachusetts: a study in bio-ecology, Ecol. Monogr. 17:263-294, from p. 278 (1947).
  • R. W. Dexter, The marine communities of a tidal inlet at Cape Ann, Massachusetts: a study in bio-ecology, Ecol. Monogr. 17:263-294, from p. 284 (1947).
  • S. W. Nixon and C. A. Oviatt, Ecology of a New England salt marsh, Ecol. Monogr. 43:463-498, from p. 491 (1973).
Creative Commons Attribution 3.0 (CC BY 3.0)

© SPIRE project

Source: SPIRE

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History and Behavior

Life Cycle

Ulva goes through an isomorphic alternation of generations. Adult gametophytes produce only female or male gamets, which are positively phototactic, and move with flagella. They are released in swarms coordinated by lunar cycles and tides. When the zygote is formed it becomes negatively phototactic and swims to the bottom to settle, and germinates within a few days. The haploid phase of the life cycle (the sporophyte), produces sporophytes which, like the gametes, are also motile using a set of four flagella to swim (Lee 2008; Guiry and Guiry 2011).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records:2370
Specimens with Sequences:2156
Specimens with Barcodes:1270
Species:403
Species With Barcodes:401
Public Records:1385
Public Species:392
Public BINs:0
Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Barcode data

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Relevance to Humans and Ecosystems

Benefits

Uses

Ulva is eaten by humans, although the literature has some disagreement about how tasty and digestible it is. It is eaten in soups, salads and sushi (Lee 2008 and references within; Kirby 2001).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Risks

Risk Statement

Ulva is considered the main component of "green tide" events in bays especially near large cities in Japan and elsewhere. Its prolific growth becomes a nuisance, especially in run-off waters containing high nutrient levels. In these environments it can outcompete other organisms and reduce diversity in benthic communities. It also creates a nuisance on beaches when it is washed up and decomposes in large amounts as the rotting algae produces hydrogen sulfide gas (Lee 2008; Yabe 2009).

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© Campbell, Dana

Source: EOL Rapid Response Team

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Sea lettuce

The sea lettuces comprise the genus Ulva, a group of edible green algae that is 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,[1] the former members of which are known under the common name green nori.[2] Individual blades of Ulva can grow to be more than 400mm (16") in size, but this only occurs when the plants are growing in sheltered areas.

Genetics[edit]

There are some indications that this genus is of tropical in origin. In an extensive phylogeographical assessment of this genus conducted in India revealed a strong endemism, irrespective of thallus characteristics, viz., branched or unbranched. Previously, branched tubular Ulva was grouped under Ulva compressa, and unbranched under Ulva intestinalis. As per uniqueness of OTUs, a new endemic species irrespective of the thallus branching characteristics had been formally established as Ulva paschima Bast.[3] In tropics, diversity of Ulva is so much higher than that in temperate or sub-polar regions.

Nutrition[edit]

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 (where this food is known as aosa). 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.[citation needed]

Aquarium Trade[edit]

Sea lettuce is a commonly found species of algae in the saltwater aquarium trade, where it is valued for its high nutrient uptake and edibility. Many reef aquarium keepers use sea lettuce species in refugiums or grow it as a food source for herbivorous fish. Sea lettuce is very easy to keep, tolerating a wide range of lighting and temperature conditions. In the refugium, sea lettuce can be attached to live rock or another surface, or simply left to drift in the water.

Health concerns[edit]

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.[4] Environmentalists blamed the phenomenon on excessive use of nitrates by pig and poultry farmers.

Species[edit]

Species in the genus Ulva include the following:[5]

Accepted species
Nomina dubia

See also[edit]

References[edit]

  1. ^ a b Hillary S. Hayden, Jaanika Blomster, Christine A. Maggs, Paul C. Silva, Michael J. Stanhope, & J. Robert Waaland (2003). "Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera". European Journal of Phycology (British Phycological Society) 38: 277–294. doi:10.1080/1364253031000136321. ISSN 1469-4433. 
  2. ^ M.D. Guiry & G.M. Guiry (2012). "Enteromorpha Link in Nees, 1820". AlgaeBase. National University of Ireland. Retrieved February 11, 2012. 
  3. ^ 1. BAST, F., JOHN, A.A. AND BHUSHAN, S. 2014. Strong endemism of bloom-forming tubular Ulva in Indian west coast, with description of Ulva paschima Sp. Nov. (Ulvales, Chlorophyta. PLoS ONE 9(10): e109295. doi:10.1371/journal.pone.0109295
  4. ^ "Seaweed suspected in French death". BBC. September 7, 2009. Retrieved September 7, 2009. 
  5. ^ M.D. Guiry (2012). M. D. Guiry & G. M. Guiry, ed. "Ulva Linnaeus, 1753". AlgaeBase. National University of Ireland, Galway. World Register of Marine Species. Retrieved February 11, 2012. 
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!