''Cymodocea nodosa'' is a species of

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

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Cymodoceaceae Cymodoceaceae is a family of flowering plants, sometimes known as the "manatee-grass family", which includes only marine species. The 2016 APG IV does recognize Cymodoceaceae and places it in the order Alismatales, in the clade monocots. The ...

and is sometimes known as little Neptune grass.Lesser Neptune Grass (''Cymodocea nodosa'')
''Archipelagos Wildlife Library''. Retrieved 2011-08-17 As a seagrass, it is restricted to growing underwater and is found in shallow parts of the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

and certain adjoining areas of the

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

Description

''C. nodosa'' has light green or greyish-green leaves. They are very narrow but may be up to forty centimetres long. Each leaf has seven to nine veins running along its length. The plant produces

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

s which are only 1 mm in diameter and have leaf scars at intervals. Inconspicuous grass-like flowers are sometimes produced at the end of long stems in the spring when water temperatures begin to rise after their winter minimum. The pollen is liberated into the sea and the seeds remain dormant until the following spring.

Distribution and habitat

This seagrass is found in shallow parts of the

and the adjoining parts of the Atlantic Ocean, the coasts of

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

Mauritania Mauritania, officially the Islamic Republic of Mauritania, is a sovereign country in Maghreb, Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to Mauritania–Western Sahara border, the north and northwest, ...

and

Senegal Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...

and round the

Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...

and

Madeira Madeira ( ; ), officially the Autonomous Region of Madeira (), is an autonomous Regions of Portugal, autonomous region of Portugal. It is an archipelago situated in the North Atlantic Ocean, in the region of Macaronesia, just under north of ...

. It grows at depths of down to nineteen metres in sandy sediments in sheltered locations and needs clear waters for

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

. Off the Catalan coast in the western Mediterranean, a single meadow of this grass covering at least has been discovered.

Ecology

''Cymodocea nodosa'' grows in meadows on the seabed and is sometimes associated with the other seagrasses, '' Zostera noltii'' and '' Posidonia oceanica'' and the seaweeds '' Caulerpa prolifera'' and '' Caulerpa racemosa''. Although it is adversely affected by mechanical disturbance such as trawling and by pollution, and although it is in competition with other seagrass species, ''C. nodosa'' is not considered to be threatened. In the

, fifty-three species of

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

were found to grow on the leaves and rhizomes of ''C. nodosa''. Many of these were encrusting species of Corallinaceae.

Seagrass meadow A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...

s have high biological productivity and are rich,

biodiverse Biodiversity is the variability of life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and phylogenetic diversity. Diversity is not distributed evenly on Earth ...

habitats. Fish species associated with ''C. nodosa'' in a coastal lagoon in south east Spain include '' Atherina boyeri'', ''

Pomatoschistus marmoratus ''Pomatoschistus marmoratus'', the marbled goby, is a species of goby native to the eastern Atlantic from the Bay of Biscay down around the Iberian Peninsula through the Mediterranean Sea, the Black Sea and the Sea of Azov. It is also found in ...

'', '' Liza aurata'', '' Liza saliens'', '' Syngnathus abaster'' and '' Aphanius iberus''. The meadows are an important rearing ground for juvenile fish. Invertebrates associated with seagrass meadows include

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

worms,

amphipods Amphipoda () is an order (biology), 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 10,700 amphip ...

isopods Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

decapods The Decapoda or decapods, from Ancient Greek δεκάς (''dekás''), meaning "ten", and πούς (''poús''), meaning "foot", is a large order (biology), order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfis ...

and

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

s. ''C. nodosa'' tends to grow in patches. This is because it favours unstable sandy sediments and subaqueous

dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...

s tend to move over time. If the sand accretion is not too fast, the stolons can grow vertically through it, but the seagrass can be overwhelmed by rapid accretion. Patch death was mostly caused by erosion as roots were uncovered, encrusting and drilling organisms increased and plants were swept away. The dune movement cycle tended to take two to six years, which gives the seagrass time to recolonise bare areas. Sand accretion also stimulates flowering and dormant seeds can enable recolonisation when conditions allow it. The fact that the pattern of ''C. nodosa'' growth changes as sand is deposited provides a means of measuring the travel of subaqueous dunes. In the Alfacs Bay in the northwest

, it was found that the rate of dune advance averaged 13 metres per year, and that the seagrasses could be used to monitor movement rates ranging from 0.15 metres to 980 metres per year. The invasive

alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

'' Caulerpa taxifolia'' is often associated with ''C. nodosa''. It has an extensive

rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be un ...

al system that anchors it to a sandy substrate. The alga is better able to extract nutrients from the substrate than can the seagrass. A study was undertaken near the island of

Elba Elba (, ; ) is a Mediterranean Sea, Mediterranean island in Tuscany, Italy, from the coastal town of Piombino on the Italian mainland, and the largest island of the Tuscan Archipelago. It is also part of the Arcipelago Toscano National Park, a ...

, Italy, in which slow release fertiliser sticks were added to test plots of the seabed where the seagrass and alga both grew. It was found that although both species responded with increased growth rates, the seagrass was relatively disadvantaged in that increased growth of the alga restricted the amount of sunlight reaching the seagrass whereas the alga was less constrained by limited light.

References

External links

* Fotos of Cymodocea nodosa i
iNaturalist
{{Taxonbar, from=Q2294077 Cymodoceaceae Biota of the Atlantic Ocean Biota of the Mediterranean Sea Biota of the Adriatic Sea Biota of the Canary Islands Flora of Madeira Biota of Mauritania Flora of Portugal Flora of Senegal Taxa named by Bernardino da Ucria Taxa named by Paul Friedrich August Ascherson Flora of Malta