Fucus distichus
Encyclopedia
Fucus distichus or rockweed is a species
of brown alga in the family Fucaceae
to be found in the intertidal zone
s of rocky seashore
s in the northern hemisphere
, mostly in rock pools
. The genome
has been sequenced.
and the north and west coasts of Ireland
where it is found on rock faces and in rock pools
in the upper littoral zone. It also occurs on the eastern coast of North America. and on the west coast from Alaska
to California
.
. The fronds are fairly rigid and cartilaginous, partially flattened, and olive green to yellowish green in colour. The plant is branched and has a basal discoid holdfast
. The midrib is conspicuous and near the holdfast the stalk is narrowed because of the thickening of the midrib and the erosion of the margins. The apices of the frond are rounded and the swollen receptacles at the tips are yellowish and up to six centimetres long.
The brown colour is due to the xanthophyll
, fucoxanthin
which masks the colour of the other pigments, beta-carotene
, chlorophyll
a and c and other xanthophylls. Fucus distichus has a high content of phlorotannin
s which may protect larger plants from grazing by periwinkles
though young plants are susceptible.
and diploid
generations. The haploid
thalli form isogamous
, anisogamous
or oogamous
gamete
s and the diploid
thalli form zoospore
s by meiosis
. Reproduction is seasonal, and receptacles start being formed in late autumn in response to short days. The gametes are of both sexes and when released, ova
can survive and disperse for several days. It is thought that self-fertilisation often occurs in this species and once a zygote
is formed it can only be dispersed over a limited distance. The plant dies back after reproducing and gets washed from its rock substrate by waves during the following winter.
A study was undertaken to see what factors influenced natural gamete release and the rate of fertilisation
success in Fucus distichus. The study sites were rock pools on the coast of Maine
. It was found that the release and settlement of eggs and zygotes occurred during daytime low tide periods, particularly when these fell between 10am and 2pm. Few gametes were released during the night time low tide period nor during the daytime period around noon when there was not a low tide. There was no correlation between the temperature or salinity of the water and gamete release and only a weak association with the lunar phase
, few gametes being released around the times of full and new moons. The study showed that fertilisation was successful and in the range 80 to 100% in F. distichus due to the avoidance of gamete release when the water velocity is high under the turbulent conditions of high tide.
It has been found that this species grows more abundantly on sloped than on vertical rock faces. Its presence increases species richness as it forms canopies in the mid to high intertidal zone
that provide protection, shelter and food for a variety of small invertebrate
s including many gastropods and crustacean
s.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of brown alga in the family Fucaceae
Fucaceae
Fucaceae are a family of brown algae. There are seven genera in the family, most notably Fucus, which includes several common seaweeds....
to be found in the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
s of rocky seashore
Seashore
-Landform:* Coast* Intertidal zone, between high and low water lines* National seashore, a special designation in the United States* Shore-Other:* Seashore , an open source image editor, based on GIMP written in Cocoa for Mac OS X...
s in the northern hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
, mostly in rock pools
Tide pool
Tide pools are rocky pools by oceans that are filled with seawater. Many of these pools exist as separate entities only at low tide.Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists, as well as philosophical...
. The genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
has been sequenced.
Distribution
In Great Britain, rockweed is found on northern coasts of ScotlandScotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
and the north and west coasts of Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
where it is found on rock faces and in rock pools
Tide pool
Tide pools are rocky pools by oceans that are filled with seawater. Many of these pools exist as separate entities only at low tide.Tide pools are habitats of uniquely adaptable animals that have engaged the special attention of naturalists and marine biologists, as well as philosophical...
in the upper littoral zone. It also occurs on the eastern coast of North America. and on the west coast from Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
Description
This is a small tufted brown alga. The fronds are narrow and grow up to thirty centimetres long. They do not include airbladders as in some other species of FucusFucus
Fucus is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world.-Description and life cycle:...
. The fronds are fairly rigid and cartilaginous, partially flattened, and olive green to yellowish green in colour. The plant is branched and has a basal discoid holdfast
Holdfast
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. ...
. The midrib is conspicuous and near the holdfast the stalk is narrowed because of the thickening of the midrib and the erosion of the margins. The apices of the frond are rounded and the swollen receptacles at the tips are yellowish and up to six centimetres long.
The brown colour is due to the xanthophyll
Xanthophyll
Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. The name is from Greek xanthos + phyllon , due to their formation of the yellow band seen in early chromatography of leaf pigments...
, fucoxanthin
Fucoxanthin
Fucoxanthin is a xanthophyll, with formula C42H58O6. It is found as an accessory pigment in the chloroplasts of brown algae and most other heterokonts, giving them a brown or olive-green color...
which masks the colour of the other pigments, beta-carotene
Beta-carotene
β-Carotene is a strongly-coloured red-orange pigment abundant in plants and fruits. It is an organic compound and chemically is classified as a hydrocarbon and specifically as a terpenoid , reflecting its derivation from isoprene units...
, chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
a and c and other xanthophylls. Fucus distichus has a high content of phlorotannin
Phlorotannin
A phlorotannin is a type of tannin found in brown algae such as kelps and rockweeds or sargassacean species. Contrary to hydrolysable or condensed tannins, these compounds are oligomers of phloroglucinol...
s which may protect larger plants from grazing by periwinkles
Littorinidae
Littorinidae is a taxonomic family of over 200 species of sea snails, marine gastropod molluscs in the clade Littorinimorpha, commonly known as periwinkles and found world-wide.-Names:...
though young plants are susceptible.
Biology
Like other brown algae, there is an alternation of haploidPloidy
Ploidy is the number of sets of chromosomes in a biological cell.Human sex cells have one complete set of chromosomes from the male or female parent. Sex cells, also called gametes, combine to produce somatic cells. Somatic cells, therefore, have twice as many chromosomes. The haploid number is...
and diploid
Ploidy
Ploidy is the number of sets of chromosomes in a biological cell.Human sex cells have one complete set of chromosomes from the male or female parent. Sex cells, also called gametes, combine to produce somatic cells. Somatic cells, therefore, have twice as many chromosomes. The haploid number is...
generations. The haploid
Ploidy
Ploidy is the number of sets of chromosomes in a biological cell.Human sex cells have one complete set of chromosomes from the male or female parent. Sex cells, also called gametes, combine to produce somatic cells. Somatic cells, therefore, have twice as many chromosomes. The haploid number is...
thalli form isogamous
Isogamy
Isogamy is a form of sexual reproduction that involves gametes of similar morphology , differing only in allele expression in one or more mating-type regions...
, anisogamous
Anisogamy
Anisogamy refers to a form of sexual reproduction involving the union or fusion of two dissimilar gametes — anisogamous, anisogamic,...
or oogamous
Oogamy
Oogamy is the familiar form of sexual reproduction. It is a form of anisogamy in which the female gamete is significantly larger than the male gamete and is non-motile. The male gametes are typically highly motile spermatozoa competing for the fertilization of the immotile egg.By contrast to...
gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s and the diploid
Ploidy
Ploidy is the number of sets of chromosomes in a biological cell.Human sex cells have one complete set of chromosomes from the male or female parent. Sex cells, also called gametes, combine to produce somatic cells. Somatic cells, therefore, have twice as many chromosomes. The haploid number is...
thalli form zoospore
Zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some algae, bacteria and fungi to propagate themselves.-Flagella:...
s by meiosis
Meiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
. Reproduction is seasonal, and receptacles start being formed in late autumn in response to short days. The gametes are of both sexes and when released, ova
Ovum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
can survive and disperse for several days. It is thought that self-fertilisation often occurs in this species and once a zygote
Zygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
is formed it can only be dispersed over a limited distance. The plant dies back after reproducing and gets washed from its rock substrate by waves during the following winter.
A study was undertaken to see what factors influenced natural gamete release and the rate of fertilisation
Fertilisation
Fertilisation is the fusion of gametes to produce a new organism. In animals, the process involves the fusion of an ovum with a sperm, which eventually leads to the development of an embryo...
success in Fucus distichus. The study sites were rock pools on the coast of Maine
Maine
Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
. It was found that the release and settlement of eggs and zygotes occurred during daytime low tide periods, particularly when these fell between 10am and 2pm. Few gametes were released during the night time low tide period nor during the daytime period around noon when there was not a low tide. There was no correlation between the temperature or salinity of the water and gamete release and only a weak association with the lunar phase
Lunar phase
A lunar phase or phase of the moon is the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. The lunar phases change cyclically as the Moon orbits the Earth, according to the changing relative positions of the Earth, Moon, and Sun...
, few gametes being released around the times of full and new moons. The study showed that fertilisation was successful and in the range 80 to 100% in F. distichus due to the avoidance of gamete release when the water velocity is high under the turbulent conditions of high tide.
It has been found that this species grows more abundantly on sloped than on vertical rock faces. Its presence increases species richness as it forms canopies in the mid to high intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
that provide protection, shelter and food for a variety of small invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s including many gastropods and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s.