Laminaria hyperborea
Encyclopedia
Laminaria hyperborea is a species
of large brown alga, a kelp
in the family
Laminariaceae
, also known by the common names of tangle and cuvie. It is found in the sublittoral zone of the northern Atlantic Ocean
. A variety, Laminaria hyperborea f. cucullata (P.Svensden & J.M.Kain, 1971) is known from Scandinavia
.
. The holdfast
is large and cone-shaped, with branched rhizoids, looking rather like a bird's foot. The stipe
is circular in cross section, rough, thick at the base and tapering upwards. Older stipes are often covered with epiphytic
red algae
. The laminate blade is yellowish brown with large digitate segments. It is a long-lived species and has been recorded as surviving for 15 years.
Laminaria hyperborea can be distinguished from the rather similar L. digitata
by being paler in colour and having a longer stipe which snaps when it is bent sharply.
, from Scandinavia south to Spain
and the Canary Islands
, the Baltic Sea
and the North Sea
.
Laminaria hyperborea grows on rocks in the sublittoral zone at depths down to about 10 m (35 ft) in turbid waters and down to 30 m (100 ft) where the water is clear. It tends to be the dominant species in a narrow zone near low-water at spring tides. It also predominates in deeper waters on stable substrates in exposed areas while Saccharina latissima tends to be dominant in sheltered areas or those with less stable substrates. Down to about 15 m (50 ft) the growth may be very dense and may be referred to as a "kelp forest" but at greater depths there is a more open community and these areas have been referred to as "parks".
opportunity while the plant's low stature causes it to be overshadowed. In later years, more growth takes place in the stipe and holdfast. A new frond grows annually in the spring from the top of the stipe. The old frond is sloughed off later after much of its nutrient content has been transferred to the new growth.
Laminaria hyperborea can liberate upward of a million zoospore
s from sori on the surface of the blade during the course of a few weeks during the winter. These have flagella and settle after about 24 hours before developing into microscopic gametophyte
s which become fertile in about 10 days. Male gametophytes release large quantities of motile sperm, apparently stimulated to do so by the release of female gametes by the female gametophytes in the vicinity. The fertilised zygotes germinate into young sporophyte
s which will grow into the mature seaweed. Sexual reproduction is dependant on a minimum quantity of blue light; under less than optimal conditions, the gametophytes may develop vegetatively instead.
habitat. The grazing behaviour of sea urchins, particularly the green sea urchin, Strongylocentrotus droebachiensis
, restricts the development of new growth of L. hyperborea. If the urchins become too numerous, whole areas normally dominated by kelp may become "urchin barrens", denuded of kelp and supporting a much less biodiverse community based on encrusting coralline algae
.
Laminaria hyperborea is host to a large and diverse community of invertebrate
s. In one study in Norway
, up to 238 species of benthic
macrofauna were found associated with it, with a density of 8000 individuals per kelp plant. The blades were the part of the plant least populated by invertebrates. They were however covered by a bacteria
l biofilm
in which Planctomycetes
and Alphaproteobacteria
were found all year long and other bacteria occurred seasonally. The stipes, being rough, provided good anchor points for Palmaria palmata and several other species of red algae
. The resulting epiphytic growth was home to a range of species of gastropods
, amphipods and other invertebrates. Depending upon the season and density of the L. hyperborea bed, the total number of these animals varied; at one location, it ranged from a small number to over 80,000 individuals living on a single stipe. The holdfasts offered a sheltered refuge and housed a large number of mobile macrofauna, a community that was quite different from that on the stipes.
In a study undertaken on the north east coast of Britain, 61 different species of nematode were found living in the holdfasts of L. hyperborea. The majority of these were omnivore
s feeding on deposits or herbivore
s feeding on the epiphytic algae growing on the kelp.
In another study comparing the macrofauna resident in the holfasts of L. hyperborea round the coasts of Britain, it was found that, except for the suspension feeders, there was an inverse relationship between the richness of the flora and the pollution, as measured by the heavy metal content of the water, and its clarity.
of L. hyperborea have been studied with regard to its possible use as a fuel. A study found that it could produce annual increases in biomass of 16.5 and 8.0 metric tons of organic matter per hectare
at depths of 3 and 9 metres respectively.
Alginates can be extracted from L. hyperborea. In France, Ireland, Scotland and Norway, stipes cast up on beaches are collected for this purpose and in Norway some kelp is harvested by trawling.
Because of its ability to absorb and retain water, L. hyperborea has been used in wound dressings to prevent adhesions. It has also been used to help dilate the cervix
during childbirth
.
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 large brown alga, a kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Laminariaceae
Laminariaceae
Laminariaceae are a family of seaweeds, classified as brown algae. The table indicates the genera within this family. The family includes the largest known seaweeds: Nereocystis and Macrocystis....
, also known by the common names of tangle and cuvie. It is found in the sublittoral zone of the northern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
. A variety, Laminaria hyperborea f. cucullata (P.Svensden & J.M.Kain, 1971) is known from Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
.
Description
Laminaria hyperborea is a massive, leathery seaweedSeaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
. The 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. ...
is large and cone-shaped, with branched rhizoids, looking rather like a bird's foot. The stipe
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
is circular in cross section, rough, thick at the base and tapering upwards. Older stipes are often covered with epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
red algae
Red algae
The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds...
. The laminate blade is yellowish brown with large digitate segments. It is a long-lived species and has been recorded as surviving for 15 years.
Laminaria hyperborea can be distinguished from the rather similar L. digitata
Laminaria digitata
Laminaria digitata is a large brown alga in the family Laminariaceae, also known by the common name Oarweed. It is found in the sublittoral zone of the northern Atlantic Ocean.-Description:...
by being paler in colour and having a longer stipe which snaps when it is bent sharply.
Distribution and habitat
The range is the northeast Atlantic OceanAtlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, from Scandinavia south to Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
, the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...
and the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
.
Laminaria hyperborea grows on rocks in the sublittoral zone at depths down to about 10 m (35 ft) in turbid waters and down to 30 m (100 ft) where the water is clear. It tends to be the dominant species in a narrow zone near low-water at spring tides. It also predominates in deeper waters on stable substrates in exposed areas while Saccharina latissima tends to be dominant in sheltered areas or those with less stable substrates. Down to about 15 m (50 ft) the growth may be very dense and may be referred to as a "kelp forest" but at greater depths there is a more open community and these areas have been referred to as "parks".
Biology
In young individuals of L. hyperborea, the annual growth consists mainly of the enlargement of the blade. This maximises the photosyntheticPhotosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
opportunity while the plant's low stature causes it to be overshadowed. In later years, more growth takes place in the stipe and holdfast. A new frond grows annually in the spring from the top of the stipe. The old frond is sloughed off later after much of its nutrient content has been transferred to the new growth.
Laminaria hyperborea can liberate upward of a million 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 from sori on the surface of the blade during the course of a few weeks during the winter. These have flagella and settle after about 24 hours before developing into microscopic gametophyte
Gametophyte
A gametophyte is the haploid, multicellular phase of plants and algae that undergo alternation of generations, with each of its cells containing only a single set of chromosomes....
s which become fertile in about 10 days. Male gametophytes release large quantities of motile sperm, apparently stimulated to do so by the release of female gametes by the female gametophytes in the vicinity. The fertilised zygotes germinate into young sporophyte
Sporophyte
All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...
s which will grow into the mature seaweed. Sexual reproduction is dependant on a minimum quantity of blue light; under less than optimal conditions, the gametophytes may develop vegetatively instead.
Ecology
Kelp beds provide a nursery area for many marine species and a biodiverseBiodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
habitat. The grazing behaviour of sea urchins, particularly the green sea urchin, Strongylocentrotus droebachiensis
Strongylocentrotus droebachiensis
Strongylocentrotus droebachiensis is commonly known as the green sea urchin because of its characteristic green color. It has the longest genus-species names in the animal kingdom...
, restricts the development of new growth of L. hyperborea. If the urchins become too numerous, whole areas normally dominated by kelp may become "urchin barrens", denuded of kelp and supporting a much less biodiverse community based on encrusting coralline algae
Coralline algae
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls...
.
Laminaria hyperborea is host to a large and diverse community of 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. In one study in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, up to 238 species of benthic
Benthos
Benthos is the community of organisms which live on, in, or near the seabed, also known as the benthic zone. This community lives in or near marine sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.Many organisms...
macrofauna were found associated with it, with a density of 8000 individuals per kelp plant. The blades were the part of the plant least populated by invertebrates. They were however covered by a bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l biofilm
Biofilm
A biofilm is an aggregate of microorganisms in which cells adhere to each other on a surface. These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance...
in which Planctomycetes
Planctomycetes
Planctomycetes are a phylum of aquatic bacteria and are found in samples of brackish, and marine and fresh water. They reproduce by budding. In structure, the organisms of this group are ovoid and have a holdfast, called the stalk, at the nonreproductive end that helps them to attach to each other...
and Alphaproteobacteria
Alphaproteobacteria
Alphaproteobacteria is a class of Proteobacteria. Like all Proteobacteria, they are Gram-negative.-Characteristics:The Alphaproteobacteria comprise most phototrophic genera, but also several genera metabolising C1-compounds , symbionts of plants and animals, and a group of pathogens, the...
were found all year long and other bacteria occurred seasonally. The stipes, being rough, provided good anchor points for Palmaria palmata and several other species of red algae
Red algae
The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species of mostly multicellular, marine algae, including many notable seaweeds...
. The resulting epiphytic growth was home to a range of species of gastropods
Gastropoda
The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large...
, amphipods and other invertebrates. Depending upon the season and density of the L. hyperborea bed, the total number of these animals varied; at one location, it ranged from a small number to over 80,000 individuals living on a single stipe. The holdfasts offered a sheltered refuge and housed a large number of mobile macrofauna, a community that was quite different from that on the stipes.
In a study undertaken on the north east coast of Britain, 61 different species of nematode were found living in the holdfasts of L. hyperborea. The majority of these were omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
s feeding on deposits or herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s feeding on the epiphytic algae growing on the kelp.
In another study comparing the macrofauna resident in the holfasts of L. hyperborea round the coasts of Britain, it was found that, except for the suspension feeders, there was an inverse relationship between the richness of the flora and the pollution, as measured by the heavy metal content of the water, and its clarity.
Uses
The calorific values and biomassBiomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
of L. hyperborea have been studied with regard to its possible use as a fuel. A study found that it could produce annual increases in biomass of 16.5 and 8.0 metric tons of organic matter per hectare
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...
at depths of 3 and 9 metres respectively.
Alginates can be extracted from L. hyperborea. In France, Ireland, Scotland and Norway, stipes cast up on beaches are collected for this purpose and in Norway some kelp is harvested by trawling.
Because of its ability to absorb and retain water, L. hyperborea has been used in wound dressings to prevent adhesions. It has also been used to help dilate the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
during childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
.