Palmaria palmata

Researched By	Jacqueline Hill	Data Supplied By	MarLIN
Refereed by	Dr Thomas Wiedemann
Taxonomy
Scientific name	Palmaria palmata	Common name	Dulse
MCS Code	ZM170	Recent Synonyms	None/85
Phylum	Rhodophycota	Subphylum
Superclass		Class	Rhodophyceae
Subclass	Florideophycidae	Order	Palmariales
Suborder		Family	Palmariaceae
Genus	Palmaria	Species	palmata
Subspecies
Additional Information	Sometimes the blade divisions are wedge-shaped and finely dissected above or the blade has numerous linear divisions throughout. This phenomenon seems to occur under fairly sheltered, silty conditions. Such plants are difficult to identify without examining the anatomical structure and the cortical cells in surface view, and have been confused with Callophyllis cristata (L. ex Turn.) Kütz. and Gracilaria foliifera (Forsk.) Børk (Irvine, 1983). Palmaria palmata has a multiaxial, pseudoparenchymatous construction and, in section, can be seen to consist of a large-celled medulla bounded on each side by a small-celled cortex.
Taxonomy References	Irvine, 1983, Hayward et al., 1996
General Biology
Growth form	Crustose soft, Foliose	Feeding method	Photoautotroph
Mobility/Movement		Environmental position	Epilithic, Epiphytic
Typical food types	Not relevant	Habit	Attached
Bioturbator	Not relevant	Flexibility	High (>45 degrees)
Fragility	Intermediate	Size	Large(>50cm)
Height	Up to 1m	Growth Rate	100 % body wt/week
Adult dispersal potential	None	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
Additional Information	The life-cycle of Palmaria palmata is diplohaplontic and strongly heteromorphic, with a reduced crustose female gametophyte and a macroscopic foliose male gametophyte. Where competition for space and light restricts the occurance of Palmaria palmata on rock the species often has an epiphytic habit on other algae, especially kelps.
Biology References	Irvine, 1983, Guiry & Blunden, 1991, Hoek van den et al., 1995, Morgan & Simpson, 1981, Meer van der & Todd, 1980
Distribution and Habitat
Distribution in Britain & Ireland	Generally distributed throughout Britain and Ireland, but apparently absent from significant stretches of coast in eastern England.
Global distribution	Arctic Russia to Portugal; Baltic. Artic Canada to USA (New Jersey); USA (Alaska to California); Japan, Korea.
Biogeographic range	Not researched	Depth range	To a depth of 20m
Migratory	Non-migratory / Resident
Distribution Additional Information	No text entered
Substratum preferences	Bedrock, Algae, Large to very large boulders	Physiographic preferences	Open coast, Strait / sound, Enclosed coast / Embayment
Biological zone	Sublittoral Fringe, Lower Eulittoral, Upper Infralittoral	Wave exposure	Moderately Exposed, Sheltered
Tidal stream strength/Water flow	Strong (3-6 kn), Moderately Strong (1-3 kn), Weak (<1 kn)	Salinity	Full (30-40 psu)
Habitat Additional Information
Distribution References	Irvine, 1983, Hardy & Guiry, 2003
Reproduction/Life History
Reproductive type	Gonochoristic, Oogamous	Developmental mechanism	Spores (sexual / asexual)
Reproductive Season	Insufficient information	Reproductive Location	As adult
Reproductive frequency	Annual episodic	Regeneration potential	No
Life span	Insufficient information	Age at reproductive maturity	<1 year
Generation time	Insufficient information	Fecundity	Insufficient information
Egg/propagule size	Insufficient information	Fertilization type	External
Larvae/Juveniles Larval/Juvenile dispersal potential <10m Larval settlement period Not relevant Duration of larval stage Not relevant
Additional Information	Life span: Palmaria palmata is a perennial species with new growth every year. Therefore, the holdfast could remain for several years.. The unusual life cycle of Palmaria palmata is diplohaplontic and strongly heteromorphic, with a reduced female gametophyte, a macroscopic male gametophyte and a foliose tetrasporophyte. The foliose plants seen on the shore and in the shallow subtidal are generally tetrasporophytes and scarcer male gametophytes. The female is a small crust-like plant, in which the carpogonia are borne directly by the vegetative cells. The male gametophyte, on the other hand, is blade-like and produces spermatia that can fertilize the carpogonia of the female crusts. After fertilization the carpogonium does not produce carpospores but instead develops into a blade-like tetrasporophyte. When young, the tetrasporophyte grows attached to the female gametophyte, later its own basal system develops and completely overgrows the tiny female thallus. The adult foliose tetrasporophyte, which is diploid, produces tetraspores meiotically and these in turn develop into crust-like female gametophytes and foliose male gametophytes. Male plants became fertile within 9-12 months. Females need only a few days to become sexually mature. Dispersal distances are short. Females do not release carpospores so male gametophytes release spermatia that then sink rapidly so that male and female gametes can come into contact for fertilization.
Reproduction References	Hoek van den et al., 1995