BIOTIC Species Information for Ulva intestinalis
|Researched by||Georgina Budd & Paolo Pizzola||Data supplied by||MarLIN|
|Refereed by||This information is not refereed.|
|Scientific name||Ulva intestinalis||Common name||Gut weed|
|MCS Code||ZS156||Recent Synonyms||Enteromorpha intestinalis (Linnaeus) Link 1820|
Origin of species name
A recent molecular study suggested that the genus Enteromorpha is synonymous with the genus Ulva (Hayden et al., 2003). Species within the genus Ulva are difficult to identify. Identification is heavily reliant on cell detail and cell arrangement, in addition to gross morphology, but complicated by the fact that the morphology of a single species can vary in response to environmental conditions. For instance, Ulva intestinalis and Ulva compressa (as Enteromorpha) are two distinct, genetically divergent and reproductively isolated species (Blomster et al., 1998). They are, however, difficult to distinguish. The presence or absence of branching fronds was the most useful gross morphological characteristic distinguishing these two species (Ulva intestinalis being unbranched). But ambiguity exists because low salinity or salinity shock can induce branching in Ulva intestinalis. However, if environmental factors, such as salinity are taken into account, branching can be used to identify the great majority of thalli correctly (Blomster et al., 1998).
|Taxonomy References||Dickinson, 1963, Hayward et al., 1996, Fish & Fish, 1996, Howson & Picton, 1997, Blomster et al., 1998, Burrows, 1991, Clay, 1960b, Guiry & Nic Dhonncha, 2002, Hayden et al., 2003,|
|Growth form||Straplike / Ribbonlike
|Mobility/Movement||See additional information
|Typical food types||Photoautotroph||Habit||Attached|
|Bioturbator||Not relevant||Flexibility||High (>45 degrees)|
|Height||10 -30 cm.||Growth Rate||0.15-0.25 cm/day|
|Adult dispersal potential||Not relevant||Dependency||Independent|
|General Biology Additional Information||Growth rate
Parchevskij & Rabinovich (1991) cultivated Ulva intestinalis (as Enteromorpha intestinalis) on horizontally and vertically suspended ropes in coastal Black Sea areas polluted with sewage and waste water effluents. Specific growth rate of the seaweed during the spring-summer period was found to be 0.15-0.25 cm/day. A harvest weight of 2600-3000 g/m2 and 3400-4700 g/m2 was obtained within two weeks on horizontal and vertical ropes respectively.
Ulva intestinalis may become detached from the substratum, and buoyed up by gas, float to the surface where they continue to grow. Such mats of unattached Ulva intestinalis are most frequent in summer. For instance, the occurrence of a summer mass of unattached Ulva intestinalis (as Enteromorpha intestinalis) was studied by Baeck et al. (2000) on the Finnish Baltic Sea west coast. The thalli of the seaweed lost their tubular shape, spread, and formed unattached monostromatic sheets. Mats were between 5-15 cm thick, with a biomass of 97 tonnes in an area of 3.7 km2 in 1993.
|Biology References||McAllen, 1999, Baeck et al., 2000, Parchevskij & Rabinovich, 1991, Clay, 1960b,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Common all round the coasts of Britain and Ireland.|
|Global distribution||More or less world-wide in its distribution.|
|Biogeographic range||Not researched||Depth range||Intertidal to a few metres sublittorally|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||None entered|
|Substratum preferences||Small boulders
Large to very large boulders
|Physiographic preferences||Strait / sound
Ria / Voe
Enclosed coast / Embayment
Upper Littoral Fringe
Lower Littoral Fringe
|Wave exposure||Moderately Exposed
|Tidal stream strength/Water flow||Insufficient information
||Salinity||Full (30-40 psu)
Variable (18-40 psu)
Low (<18 psu)
Reduced (18-30 psu)
|Habitat Preferences Additional Information||Ulva intestinalis is remarkably euryhaline, in that it can grow in freshwater. However, there is evidence for the existence of genetic strains adapted to high and low salinities (Reed & Russell, 1979).|
|Distribution References||Dickinson, 1963, Hayward et al., 1996, Fish & Fish, 1996, Amsler & Searles, 1980, Reed & Russel, 1979, JNCC, 1999, Guiry & Nic Dhonncha, 2002,|
Alternation of generations
|Developmental mechanism||Spores (sexual / asexual)
|Reproductive Season||All year with summer maximum||Reproductive Location||Water column|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||<1 year||Age at reproductive maturity||See additional information|
|Generation time||<1 year||Fecundity||Not relevant|
|Egg/propagule size||Not relevant||Fertilization type||External|
|Reproduction Preferences Additional Information||Species of the genus Ulva are rapidly growing opportunists, favoured by the frequency and speed of their reproduction. The short lived plants reach maturity at a certain stage of development rather than relying on an environmental trigger.
Ulva intestinalis can be found in reproductive condition at all times of the year but maximum development and reproduction occur during the summer months especially towards the northern end of the distribution of the species (Burrows, 1991).
The life history consists of an isomorphic (indistinguishable except for the type of reproductive bodies produced) alternation between haploid gametophytic and diploid sporophytic generations but can be modified by environmental conditions (Burrows, 1959; Moss & Marsland, 1976; Reed & Russell, 1978).
McArthur & Moss (1979) examined the process of gametogenesis and gamete structure using scanning and transmission electron microscopy.
The haploid gametophytes of Ulva produce enormous numbers of biflagellate motile gametes which cluster and fuse to produce a sporophyte (diploid zygote). The sporophyte matures and produces by meiosis large numbers of quadriflagellate zoospores that mature as gametophytes, and the cycle is repeated. Both gametes and spores may be released in such quantities into rock pools or slack water that the water mass is coloured green (Little & Kitching, 1996). Together spores and gametes are termed 'swarmers'. Swarmers are often released in relation to tidal cycles, with the release being triggered by the incoming tide as it wets the thallus. However, the degree of release is usually related to the stage of the spring/neap tidal cycle, so allowing regular periodicity and synchronization of reproduction (Little & Kitching, 1996). Christie & Evans (1962) found that swarmer release of Ulva intestinalis (as Enteromorpha intestinalis) from the Menai Straits, Wales, peaked just before the highest tides of each neap-spring cycle.
Mobility of swarmers belonging to Ulva intestinalis (as Enteromorpha intestinalis) can be maintained for as long as 8 days (Jones & Babb, 1968). Algae such as Ulva intestinalis tend to have large dispersal shadows, with propagules being found far from the nearest adult plants, e.g. 35 km (Amsler & Searles, 1980).
|Reproduction References||Amsler & Searles, 1980, Knight & Parke, 1931, Little & Kitching, 1996, Burrows, 1959, Jones & Babb, 1968, Moss & Marsland, 1976, Reed & Russel, 1978, McArthur & Moss, 1979,|