''Zostera marina'' is a flowering

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They al ...

species as one of many kinds of

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

, with this species known primarily by the English name of eelgrass with seawrack much less used, and refers to the plant after breaking loose from the submerged wetland soil, and drifting free with ocean current and waves to a coast seashore. It is a saline soft-sediment submerged plant native to marine environments on the coastlines of northern latitudes from subtropical to subpolar regions of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

Distribution

This species is the most wide-ranging marine

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the Northern Hemisphere. It lives in cooler ocean waters in the

North Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe and ...

and

North Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, and in the warmer southern parts of its range it dies off during warmer seasons.Flora of North America
/ref> It grows in the

Arctic The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...

region and endures several months of ice cover per year.Borum J., et al., (Eds.) (2004.
European seagrasses: an introduction to monitoring and management.
European Union: Monitoring & Managing of European Seagrasses. It is the only seagrass known from

Iceland Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...

. It can be found in bays,

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

, on

beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from rock, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc shel ...

es, and in other coastal habitat. The several ecotypes each have specific habitat requirements. It occurs in calmer waters in the

sublittoral The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal area ...

zone, where it is rarely exposed to air. It anchors via

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

s in sandy or muddy substrates and its leaves catch particulate debris in the water which then collects around the bases of the plants, building up the top layer of the seabed.

Description and reproduction

This flowering plant is a rhizomatous herb which produces a long stem with hairlike green leaves that measure up to 1.2 cm wide and may reach over 1.0 m long. It is a perennial plant, but it may grow as an annual. The rhizome grows horizontally through the substrate, anchoring via clusters of roots at nodes. The plant is

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...

, with an individual bearing both male and female flowers in separate alternating clusters. The inflorescence is about 10 cm long.Parnell, J. and Curtis, T. 2012. ''Webb's An Irish Flora.'' Cork University Press The fruit is a nutlet with a transparent coat containing the seed. The plant can also undergo

vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...

, sprouting repeatedly from its rhizome and spreading into a meadow-like colony on the seabed known as a genet.Fonseca, M., et al. (2003)
NOAA joint pilot project on eelgrass (''Zostera marina'' L.) recovery in San Francisco Bay.
NOAA National Centers for Coastal Ocean Science. One meadow of cloned eelgrass was determined to be 3000 years old, genetically. When undergoing

sexual reproduction Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote tha ...

, the plant produces large quantities of seeds, at times numbering several thousand seeds per square meter of plants. The plant disperses large distances when its stems break away and carry the fertile seeds to new areas, eventually dropping to the seabed. The seagrass is a favorite food of several species of

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...

, which may also distribute the seeds.

Ecology

This Zostera grows in muddy and sandy shores only at and below spring tides. This plant is an important member of the coastal ecosystem in many areas because it helps to physically form the habitat and it plays a crucial role for many other species.Wyllie-Echeverria, S. and M. Fonseca. (2003)
Eelgrass (''Zostera marina'' L.) in San Francisco Bay, California from 1920 to the present.
NOAA National Centers for Coastal Ocean Science. For example, it provides a sheltered

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...

ground for the

Pacific herring The Pacific herring (''Clupea pallasii'') is a species of the herring family associated with the Pacific Ocean environment of North America and northeast Asia. It is a silvery fish with unspined fins and a deeply forked caudal fin. The distribut ...

(''Clupea pallasii''). Juvenile

Atlantic cod The Atlantic cod (''Gadus morhua'') is a benthopelagic fish of the family Gadidae, widely consumed by humans. It is also commercially known as cod or codling.Status and conservation of eelgrass (''Zostera marina'') in eastern Canada.
Canadian Wildlife Service Technical Report Series #412. The

blue mussel The blue mussel (''Mytilus edulis''), also known as the common mussel, is a medium-sized edible marine bivalve mollusc in the family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. A species with a l ...

(''Mytilus edulis'') attaches to its leaves. The

green alga The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

'' Entocladia perforans'', an

endophyte An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; h ...

, depends on this eelgrass. A great many animals use the plant for food, including the

isopod Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...

'' Idotea chelipes'' and the purple sea urchin ''

Paracentrotus lividus ''Paracentrotus lividus'' is a species of sea urchin in the family Parechinidae commonly known as the purple sea urchin. It is the type species of the genus and occurs in the Mediterranean Sea and eastern Atlantic Ocean. Description ''Paracentr ...

''. The Atlantic brant (''Branta bernicula hrota'') subsists almost entirely on the plant. When the eelgrass dies, detaches, and washes up on the beach, a whole new

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

is founded; many species of insects and other invertebrates begin to inhabit the dead plant, including the

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

Talitrus saltator ''Talitrus saltator'', a species of sand hopper, is a common amphipod crustacean of sandy coasts around Europe. The animal's typical "hopping" movement gives it its common name, and is produced by a flexion of the abdomen. In order to do this, ...

'', the

fly Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwing ...

'' Fucellia tergina'', and the

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s '' Stenus biguttatus'', ''

Paederus littoralis ''Paederus'' is a genus of small beetles of the family Staphylinidae ("rove beetles"). With 622 valid species assigned by 1987 to the subtribe Paederina (''Paederus'' and its close allies), and with all but 148 within ''Paederus'' itself, the g ...

'', and ''

Coccinella septempunctata ''Coccinella septempunctata'', the seven-spot ladybird (or, in North America, seven-spotted ladybug or "C-7"), is the most common ladybird in Europe. Its elytra are of a red colour, but punctuated with three black spots each, with one further spot ...

''. The

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

l species '' Granulosicoccus coccoides'' was first isolated from the leaves of the plant.Kurilenko, V. V., et al. (2010). ''Granulosicoccus coccoides'' sp. nov., isolated from leaves of seagrass (''Zostera marina''). ''Int J Syst Evol Microbiol'' 60 972-76.

Threats

Populations of the plant have been damaged by a number of processes, especially increased

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids can ...

in the water; like most other plants, eelgrass requires sunlight to grow. One plant may adapt to light level by growing longer leaves to reach the sun in low-light areas; individuals in clear or shallow water may have leaves a few centimeters long, while individuals in deeper spots may have leaves over a meter long. Human activities such as

dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing da ...

and

trawling Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different spec ...

damage eelgrass meadows; practices used in

scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related families ...

and

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...

harvesting in the

Wadden Sea The Wadden Sea ( nl, Waddenzee ; german: Wattenmeer; nds, Wattensee or ; da, Vadehavet; fy, Waadsee, longname=yes; frr, di Heef) is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern conti ...

have cleared much eelgrass from the sea bottom there.

Aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. lot ...

operations and coastal development destroy colonies.

Pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

from many sources, including riverside

farm A farm (also called an agricultural holding) is an area of land that is devoted primarily to agricultural processes with the primary objective of producing food and other crops; it is the basic facility in food production. The name is used fo ...

sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...

lines, fish processing plants, and

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

s, damage eelgrass meadows. Conservation and restoration efforts of ''Zostera marina'' habitats have been plenty since their rapid decline started several decades ago.

Invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

have been shown to have a negative effect on eelgrass and associated ecosystems. In

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

, the invasive exotic

green crab ''Carcinus maenas'' is a common littoral crab. It is known by different names around the world. In the British Isles, it is generally referred to as the shore crab, or green shore crab. In North America and South Africa, it bears the name europ ...

(''Carcinus maenas'') destroys eelgrass when it digs in the substrate for prey items, or by directly eating eelgrass seeds. The decline of eelgrass in

Antigonish Harbour Antigonish Harbour is a community and harbour in the Canadian province of Nova Scotia, located in Antigonish County , nickname = , settlement_type = List of counties of Nova Scotia, County , motto ...

has resulted in fewer

Canada geese The Canada goose (''Branta canadensis''), or Canadian goose, is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is o ...

, which feed on the rhizome, and fewer

common goldeneye The common goldeneye or simply goldeneye (''Bucephala clangula'') is a medium-sized sea duck of the genus ''Bucephala'', the goldeneyes. Its closest relative is the similar Barrow's goldeneye. The genus name is derived from the Ancient Greek ' ...

, which eat

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s that live in eelgrass meadows. The

slime mold Slime mold or slime mould is an informal name given to several kinds of unrelated eukaryotic organisms with a life cycle that includes a free-living single-celled stage and the formation of spores. Spores are often produced in macroscopic mu ...

Labyrinthula zosterae The genus ''Labyrinthula'' is part of the protist group Labyrinthulomycetes and contains thirteen species. The major feature of this genus is the formation of an ectoplasmic net secreted by specialized organelles called bothrosomes which surrou ...

'' caused a "wasting disease" of eelgrass resulting in large-scale losses in the 1930s; localized populations are still affected by the slime mold today. During this time, populations of the eelgrass-eating Atlantic brant dropped. Remaining geese ate less-preferred food plants and algae, and hunters subsequently noticed that brant meat began to taste different. Even today, brants no longer migrate over the Nova Scotia area.

Genomics and evolutionary adaptations

The ''Zostera marina''

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

has been

sequenced In genetics and biochemistry, sequencing means to determine the primary structure (sometimes incorrectly called the primary sequence) of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which suc ...

and analyzed by Olsen ''et al.'' in 2016 and the resulting article has been published in

Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

. The approximate genome sequence of ''Z. marina'' is 202.3 Mb and encodes approximately 20450

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

-coding genes (of which 86,6% are supported by

transcriptome The transcriptome is the set of all RNA transcripts, including coding and non-coding, in an individual or a population of cells. The term can also sometimes be used to refer to all RNAs, or just mRNA, depending on the particular experiment. The t ...

data). The assembled genome was found to consist of large numbers of

repeat element Repeated sequences (also known as repetitive elements, repeating units or repeats) are short or long patterns of nucleic acids (DNA or RNA) that occur in multiple copies throughout the genome. In many organisms, a significant fraction of the genom ...

s accounting for 63% of the assembled genome. The researchers revealed key adaptations at the molecular biological level that have occurred during evolution of ''Z. marina'', an

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

that has adopted a marine lifestyle. Genome analysis revealed that ''Z. marina'' lost the entire repertoire of

stoma In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...

tal genes, genes involved in volatile compound biosynthesis and signaling (such as

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

and

terpenoid The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes" ...

s) as well as genes for

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...

protection and

phytochrome Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They are sensitive to light in the red and far-red region of the visible spectrum and can be classed as either Type I, which are activated by far-re ...

s used for far-red sensing. Besides these gene losses, also gene gain events have been described, mostly involving the adjustment to full salinity and ion

homeostasis In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...

. Also macro-algae like cell wall components (low-methylated polyanionic

pectin Pectin ( grc, πηκτικός ': "congealed" and "curdled") is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component of ...

s and sulfated galatans) have been described, unique for ''Z. marina'' compared to other angiosperms.

Human uses

People have long used this plant species as roof thatching in some areas. It has been used as

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

and

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...

fodder Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food g ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

for centuries.Alm, T. (2003)
On the uses of ''Zostera marina'', mainly in Norway.
''Economic Botany'' 57:4 640-45. It has also been dried and used as stuffing for mattresses and furniture. The

Seri Seri or SERI may refer to: People *Jean Michaël Seri, an Ivorian professional footballer Places *Seri Yek-e Zarruk, Iran *Seri, Bheri, Nepal *Seri, Karnali, Nepal *Seri, Mahakali, Nepal *Seri, Raebareli, a village in Uttar Pradesh, India Oth ...

hunter gatherers of Mexico eat eelgrass grains after toasting them and grinding into a paste. Ángel León, a Spanish chef, has planted meadows of ''Z. marina'' (described as "sea rice") in the

Bay of Cádiz The Bay of Cádiz is a body of water in the province of Cádiz, Spain, adjacent to the southwestern coast of the Iberian Peninsula. The Bay of Cádiz adjoins the Gulf of Cádiz, a larger body of water which is in the same area but further offsho ...

in order to harvest the grains. The texture is described as between rice and

quinoa Quinoa (''Chenopodium quinoa''; , from Quechua ' or ') is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins, and ...

, but with a more saline flavour. It is gluten-free and high in fibre.

References

External links

The IUCN Red List

Jepson Manual Treatment

USDA Plants Profile

Washington Burke Museum

Photo gallery
* {{Taxonbar, from=Q21128

marina A marina (from Spanish , Portuguese and Italian : ''marina'', "coast" or "shore") is a dock or basin with moorings and supplies for yachts and small boats. A marina differs from a port in that a marina does not handle large passenger ships o ...

Biota of the Adriatic Sea Biota of the Atlantic Ocean Biota of the Black Sea Biota of the Mediterranean Sea Biota of the Pacific Ocean Biota of the Sea of Azov Plants described in 1753 Salt marsh plants Taxa named by Carl Linnaeus