Seashore wildlife

Seashore wildlife habitats exist from the Tropics to the Arctic and Antarctic. Seashores and beaches provide varied habitats in different parts of the world, and even within the same beach. Phytoplankton is at the bottom of some food chains, while zooplankton and other organisms eat phytoplankton. Kelp is also autotrophic and at the bottom of many food chains. Coastal areas are stressed through rapid changes, for example due to tides.

Iguana on the beach at Tortuga Bay Galapagos photo by Alvaro Sevilla Design
A marine iguana, Amblyrhynchus cristatus, on the beach at Tortuga Bay on Santa Cruz Island, Galapagos

British seashores

The coasts round Britain and the sea nearby is of international significance. Animal life varies from large whales, dolphins and porpoises, grey seals and common seals, through to microscopic animals. There are more than 200 species of fish, ranging from small fish like blennies through to basking sharks that are the second largest shark in the world.

Habitats include areas of landslips, beaches with sand, shingle and rock, cliffs, coastal lagoons, isolated sea stacks and islands, muddy estuaries, salt marshes, submaritime zones (i.e. land influenced by sea spray) and the sea itself. British coasts are affected by strong winds and in some areas large waves. British tidal ranges are large compared to some other parts of the world. Sheltered shores support different life from exposed shores.[1][2]

Non-flowering plants range from microscopic plants through to seaweed or kelp up to 5 meters in height. Many animals feed on kelp and kelp provides sheltered habitats for yet others. Sea grass is the only type of flowering plant that grows in British seas, but it nonetheless forms vast beds.

Invertebrates in coastal Britain are very diverse and include brittle stars, hermit crabs, mussels, prawns, sponges, sea anemones and sea squirts. Efforts are made to conserve rare plants and animals in Nature reserves.

Cliffs, islands and sea stacks are a habitat for breeding sea birds such as guillemots, kittiwakes and razor bills, as well as rock doves which can live inland as well. Peregrine falcons hunt the doves. Estuaries provide a habitat for waders and ducks, especially in winter.

West African seashores

The coastline of West Africa extends from Senegal to Gabon and like many other coastlines worldwide, it is characterized by a variety of ecosystems (Yankson and Kendall, 2001). Common on this coast are sandy shores interspersed with rocky shores and several rivers, which empty into the Gulf of Guinea. Well-known rocky beaches on the West African coast include Cape Verde in Senegal, Cape Three Points in Ghana and Mount Cameroun. There are other smaller rocky beaches and between them are sandy beaches, which may be small, or extensive (Yankson and Kendall, 2001). On the coast of Ghana for instance, the greatest extent of almost continuous rock shore is on either side of Cape Three Points and stretches from the Ankobra River in the west to Sekondi in the east, a distance of about 45 miles. The west of the Ankobra is characterized by sandy beaches extending through Ivory Coast. Also, between Takoradi and Prampram, 150 miles to the east, sandy shores dominate but rocky shores of limited extent occur in several places, notably in the region of Cape Coast and Elmina and in the Accra area. At the east of Prampram, sandy beaches stretch almost continuously along the eastern coast of Ghana and throughout Nigeria until a rocky shore is met with again in the Cameroons (Gauld and Buchanan, 1959).

Various surveys of the West African seashore have found barnacles and gastropods dominating the invertebrate community (Gauld and Buchanan, 1959; Yankson and Akpabey, 2001; Yankson and Kendall, 2001; Lamptey, Armah and Allotey, 2009).

Three species of barnacles, namely Cthamalus dentatus, Megabalanus tintinnabulum and Tetraclita squamata are found on the West African rocky shores. C. dentatus is the common barnacle of open coasts. They have a kite shaped opening to the shell. Six plates are clearly visible in isolated individuals. The plates have projecting ribs giving the animal a star-shaped outline. Recently settled animals are a pale brown color but as they age, they quickly become dirty white. C. dentatus have no calcareous base between the body of the animal and the rock surface (Edmunds, 1978; Yankson and Kendall, 2001).

Tetraclita squamata tends to be conical in shape and can reach a large size (25mm or more in length). Unlike Chthamalus species, it does not occur in vast sheets of interlocking animals. The plates making up the shell become fused as the animal grows and in large specimens can be difficult to distinguish. The plates are perforated by rows of fine holes. This species is often heavily overgrown by algae (Yankson and Kendall, 2001).

Megabalanus tintinnabulum is found worldwide and has been described on this site.

The most common hermit crabs on this shore are Clibernarius chapini and Clibernarius senegalensis. Identification of species is complex but the common rule is C. chapini occurs mostly in long turreted gastropod shells while C. senegalensis in short, more rounded shells (Yankson and Kendall, 2001).

Three types of keyhole limpets, family Fissurellidae are encountered on the West African seashore.

Diodora menkeana (Dunker) has an aperture length between 6–15 mm; height about half its length and a small apical hole markedly anterior. It has sculpture of intersecting radiating and concentric ridges, color may be cream, pale pink or brown. This species occurs throughout West Africa in shallow and low on rocky shores though rare (Yankson and Kendall, 2001).

The genus Fissurella is distinguished from Diodora by its flatter shell, a larger more central apical hole, sculpture of only radiating ridges and height about a third of its length. Species of this genus are found low on the shore attached to rocks from which they scrape minute algae. They rest on open rock and do not seek crevices (Yankson and Kendall, 2001). Two species has been recorded.

Fissurella coarctata has a large apical hole and of characteristic shape, color pale pink or brown. It has a length of about 25–35 mm. This species is fairly common in Senegal and Sierra Leone, rare in Ghana and has not been recorded further east (Yankson and Kendall, 2001).

Fissurella nubecula has an aperture length of 15–25 mm, medium sized apical hole and color pink or violet often with radiating white bands. This species is common from Ghana eastwards and in Senegal though it seems to be rarer in between. It is commoner in sheltered rather than in exposed areas (Yankson and Kendall, 2001).

Siphonaria pectinata (Family: Siphonariidae, described on another page) has an aperture length of 20–30 mm long, slightly less wide, height about half its length or more, sculpture of fine radiating ridges, often worn smooth at apex. This species has a color that is externally dark brown or grey, paler at worn apex, internally shining black at edges, paler at center. It is common at all levels on the West African rocky shores and it rests on exposed shores (Edmunds, 1978).

Patella safiana (see Cymbula safiana, family Patellidae) has an oval aperture height about 40–60 mm or more. It is sculptured by radiating ridges, colored grey externally, and blue-grey and white internally, with a horseshoe shaped paler scar, which is interrupted anteriorly to make room for the head. It is found throughout West Africa usually common on open rocks from low to mid shore or sometimes higher on exposed shores. It is often found in damp hollows, but does not particularly seek crevices. It feeds by scraping minute algae and grasping pieces of seaweeds. Each individual rests in the same place and wears a slight depression in the rock into which the shell fits exactly. It is hard to remove when attached to the rock with its foot (Edmunds, 1978).

Nerita senegalensis (Family Neritiidae) has shell height and width almost the same length, 15–20 mm, with teeth occurring on the outer lip of aperture. It has a pleated collumella with irregular tubercles and very fine spiral ridges on shell. This species has a dark grey color with small paler markings and sometimes uniformly yellow color. This is one of the commonest gastropod species on West African rocky shores, occurring from low tide level to the upper shore. It usually rests in crevices when the tide is out, and may also be found on the open rock and in rocky pools. In Senegal, it extends into rocky estuaries (Yankson and Kendall, 2001).

Three species of the gastropod family Littorinidae are common on the West Africa shore. Littorina punctata has a shell height of about 8–15 mm, color brown or grey with white markings in spiral rows often giving a checked appearance. This species is usually common on all rocky West African shores, occurring from the middle to upper parts, though young specimen occur lower down and in rock pools (Yankson and Kendall, 2001).

Littorina cinguilifera has a shell height of about 8–12 mm, color alternating brown or grey and white bands, the darker bands sometimes interrupted with white dots especially near the top of the whorl. This species occurs from the middle to upper parts of rocky shores and extends into rocky estuaries. It is usually rarer than the previous species though common in Sierra Leone, it is rare in Senegal and probably Nigeria but extends to Cameroun (Yankson and Kendall, 2001).

Littorina angulifera (Littoraria angulifera) Thais species (Muricidae) have wide oval aperture, notched at base; columella callosity smooth and arched; operculum is horny thin, nucleus at outside edge; sculpture of rounded or pointed tubercles. This genus is distributed worldwide. The species found on the West Africa shore are Thais forbesi, Thais nodosa, Thais callifera and Thais haemostoma.

Thais nodosa shell height is about 40–55 mm, width somewhat less; body whorl large, spire short and blunt; outer lip is spreading outwards; columella callosity broad, almost flat, white with usually two purple spots on it, sculpture of five spiral rows or rounded tubercles, the two upper ones being the most prominent; color pale fawn. This is a fairly common species low on rocky shores especially in crevices under overhanging rocks, etc (Yankson and Kendall, 2001).

Thais haemostoma (see Stramonita haemastoma described on this site).

Thais forbesi shell height is about 25–35 mm, width somewhat less and aperture about half height of shell. It is not usually toothed; spire somewhat pointed; two or three spiral rows of pointed tubercles. This species is grey to brown in color, often overgrown; and inside of the aperture is grey(Yankson and Kendall, 2001).

Thais callifera has a shell height of 30 – 70 mm, with width slightly less, aperture notched near suture as well as below; body whorl large, spire short and blunt, sculpture two or four rows or rounded tubercles, color pale fawn, inside of aperture pale orange. This species has been recorded in Nigeria and Cameroun. Shells may sometimes be confused with Thais haemostoma, but are paler and fatter (Yankson and Kendall, 2001).

Rotula sp. (Echinodermata: West African sand dollar) have the appearance of flattened sea urchin. They are circular to heart shaped in outline and little more than the thickness of a coin in depth. A mat of flat lying spines covers them. Sand dollars bury into intertidal sand leaving a characteristic mark at the sediment surface. This species had been recorded in Ghana though rare (Yankson and Kendall, 2001).

Other species found on the West Africa shore such as sea anemone, Perna perna, Ocypode cursor, Diadema antillarum have already been described on this site.

See also

References

  1. ^ "Sea & seashore". When to Watch Wildlife. Retrieved 2015-08-11.
  2. ^ "Marine Life". Wildlifetrust.org.uk. Retrieved 2015-08-11.

Edmunds, J. (1978). Sea shells and other molluscs found on West African coast and estuaries. Arakan Press Ltd. Accra. 146pp.

Gauld, D. T. and Buchanan, J. B. (1959). The principal features of the rock shore fauna in Ghana. Fasc. Oikos 1 (10): 121-132.

Lamptey, E., Armah,A.K and Allotey, L.C. (2000). Spatial Assemblages of Tropical Intertidal Rocky Shore Communities in Ghana, West Africa. Environmental Science, Engineering and Technology.

Yankson, K. and Akpabey, F.J. 2001. A preliminary survey of the macro-invertebrate fauna at Iture Rocky Beach, Cape Coast, Ghana. Journal of Natural Sciences, 1: 11-22.

Yankson, K. and Kendall, M. (2001). A student's Guide to the Fauna of Seashores in West Africa. Darwin Initiative. Newcastle. 132pp.

Aquatic ecosystem

An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.

Aquatic toxicology

Aquatic toxicology is the study of the effects of manufactured chemicals and other anthropogenic and natural materials and activities on aquatic organisms at various levels of organization, from subcellular through individual organisms to communities and ecosystems. Aquatic toxicology is a multidisciplinary field which integrates toxicology, aquatic ecology and aquatic chemistry.This field of study includes freshwater, marine water and sediment environments. Common tests include standardized acute and chronic toxicity tests lasting 24–96 hours (acute test) to 7 days or more (chronic tests). These tests measure endpoints such as survival, growth, reproduction, that are measured at each concentration in a gradient, along with a control test. Typically using selected organisms with ecologically relevant sensitivity to toxicants and a well-established literature background. These organisms can be easily acquired or cultured in lab and are easy to handle.

Benthos

Benthos is the community of organisms that live on, in, or near the seabed, river, lake, or stream bottom, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

Many organisms adapted to deep-water pressure cannot survive in the upperparts of the water column. The pressure difference can be very significant (approximately one atmosphere for each 10 metres of water depth).Because light is absorbed before it can reach deep ocean-water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain; most organisms in the benthic zone are scavengers or detritivores.

The term benthos, coined by Haeckel in 1891, comes from the Greek noun βένθος "depth of the sea". Benthos is used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams. There is also a redundant synonym, benthon.

Bioluminescence

Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria and terrestrial invertebrates such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic organisms such as Vibrio bacteria; in others, it is autogenic, produced by the animals themselves.

In a general sense, the principal chemical reaction in bioluminescence involves some light-emitting molecule and an enzyme, generally called the luciferin and the luciferase, respectively. Because these are generic names, the luciferins and luciferases are often distinguished by including the species or group, i.e. Firefly luciferin. In all characterized cases, the enzyme catalyzes the oxidation of the luciferin.

In some species, the luciferase requires other cofactors, such as calcium or magnesium ions, and sometimes also the energy-carrying molecule adenosine triphosphate (ATP). In evolution, luciferins vary little: one in particular, coelenterazine, is found in eleven different animal (phyla), though in some of these, the animals obtain it through their diet. Conversely, luciferases vary widely between different species, and consequently bioluminescence has arisen over forty times in evolutionary history.

Both Aristotle and Pliny the Elder mentioned that damp wood sometimes gives off a glow and many centuries later Robert Boyle showed that oxygen was involved in the process, both in wood and in glow-worms. It was not until the late nineteenth century that bioluminescence was properly investigated. The phenomenon is widely distributed among animal groups, especially in marine environments where dinoflagellates cause phosphorescence in the surface layers of water. On land it occurs in fungi, bacteria and some groups of invertebrates, including insects.

The uses of bioluminescence by animals include counter-illumination camouflage, mimicry of other animals, for example to lure prey, and signalling to other individuals of the same species, such as to attract mates. In the laboratory, luciferase-based systems are used in genetic engineering and for biomedical research. Other researchers are investigating the possibility of using bioluminescent systems for street and decorative lighting, and a bioluminescent plant has been created.

Dead zone (ecology)

Dead zones are hypoxic (low-oxygen) areas in the world's oceans and large lakes, caused by "excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water. (NOAA)". Historically, many of these sites were naturally occurring. However, in the 1970s, oceanographers began noting increased instances and expanses of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated. (The vast middle portions of the oceans, which naturally have little life, are not considered "dead zones".)

In March 2004, when the recently established UN Environment Programme published its first Global Environment Outlook Year Book (GEO Year Book 2003), it reported 146 dead zones in the world's oceans where marine life could not be supported due to depleted oxygen levels. Some of these were as small as a square kilometre (0.4 mi²), but the largest dead zone covered 70,000 square kilometres (27,000 mi²). A 2008 study counted 405 dead zones worldwide.

Ecosystem of the North Pacific Subtropical Gyre

The North Pacific Subtropical Gyre (NPSG) is the largest contiguous ecosystem on earth. In oceanography, a subtropical gyre is a ring-like system of ocean currents rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere caused by the Coriolis Effect. They generally form in large open ocean areas that lie between land masses.

The NPSG is the largest of the gyres as well as the largest ecosystem on our planet. Like other subtropical gyres, it has a high-pressure zone in its center. Circulation around the center is clockwise around this high-pressure zone. Subtropical gyres make up 40% of the Earth’s surface and play critical roles in carbon fixation and nutrient cycling. This particular gyre covers most of the Pacific Ocean and comprises four prevailing ocean currents: the North Pacific Current to the north, the California Current to the east, the North Equatorial Current to the south, and the Kuroshio Current to the west. Its large size and distance from shore has caused the NPSG to be poorly sampled and thus poorly understood.

The life processes in open-ocean ecosystems are a sink for the atmosphere’s increasing CO2. Gyres make up a large proportion, approximately 75%, of what we refer to as the open ocean, or the area of the ocean that does not consist of coastal areas. They are considered oligotrophic, or nutrient poor because they are far from terrestrial runoff. These regions were once thought to be homogenous and static habitats. However, there is increasing evidence that the NPSG exhibits substantial physical, chemical, and biological variability on a variety of time scales. Specifically, the NPSG exhibits seasonal and interannual variations in primary productivity (simply defined as the production of new plant material), which is important for the uptake of CO2.

The NPSG is not only a sink for CO2 in the atmosphere, but also other pollutants. As a direct result of this circular pattern, gyres act like giant whirlpools and become traps for anthropogenic pollutants, such as marine debris. The NPSG has become recognized for the large quantity of plastic debris floating just below the surface in the center of the gyre. This area has recently received a lot of media attention and is commonly referred to as the Great Pacific Garbage Patch.

Floodplain restoration

Floodplain restoration is the process of fully or partially restoring a river's floodplain to its original conditions before having been affected by the construction of levees (dikes) and the draining of wetlands and marshes.

The objectives of restoring floodplains include the reduction of the incidence of floods, the provision of habitats for aquatic species, the improvement of water quality and the increased recharge of groundwater.

GIS and aquatic science

Geographic Information Systems (GIS) has become an integral part of aquatic science and limnology. Water by its very nature is dynamic. Features associated with water are thus ever-changing. To be able to keep up with these changes, technological advancements have given scientists methods to enhance all aspects of scientific investigation, from satellite tracking of wildlife to computer mapping of habitats. Agencies like the US Geological Survey, US Fish and Wildlife Service as well as other federal and state agencies are utilizing GIS to aid in their conservation efforts.

GIS is being used in multiple fields of aquatic science from limnology, hydrology, aquatic botany, stream ecology, oceanography and marine biology. Applications include using satellite imagery to identify, monitor and mitigate habitat loss. Imagery can also show the condition of inaccessible areas. Scientists can track movements and develop a strategy to locate locations of concern. GIS can be used to track invasive species, endangered species, and population changes.

One of the advantages of the system is the availability for the information to be shared and updated at any time through the use of web-based data collection.

Lake ecosystem

A lake ecosystem includes biotic (living) plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions.Lake ecosystems are a prime example of lentic ecosystems. Lentic refers to stationary or relatively still water, from the Latin lentus, which means sluggish. Lentic waters range from ponds to lakes to wetlands, and much of this article applies to lentic ecosystems in general. Lentic ecosystems can be compared with lotic ecosystems, which involve flowing terrestrial waters such as rivers and streams. Together, these two fields form the more general study area of freshwater or aquatic ecology.

Lentic systems are diverse, ranging from a small, temporary rainwater pool a few inches deep to Lake Baikal, which has a maximum depth of 1642 m. The general distinction between pools/ponds and lakes is vague, but Brown states that ponds and pools have their entire bottom surfaces exposed to light, while lakes do not. In addition, some lakes become seasonally stratified (discussed in more detail below.) Ponds and pools have two regions: the pelagic open water zone, and the benthic zone, which comprises the bottom and shore regions. Since lakes have deep bottom regions not exposed to light, these systems have an additional zone, the profundal. These three areas can have very different abiotic conditions and, hence, host species that are specifically adapted to live there.

Limnology

Limnology ( lim-NOL-ə-jee; from Greek λίμνη, limne, "lake" and λόγος, logos, "knowledge"), is the study of inland aquatic ecosystems.

The study of limnology includes aspects of the biological, chemical, physical, and geological characteristics and functions of inland waters (running and standing waters, fresh and saline, natural or man-made). This includes the study of lakes, reservoirs, ponds, rivers, springs, streams, wetlands, and groundwater. A more recent sub-discipline of limnology, termed landscape limnology, studies, manages, and seeks to conserve these ecosystems using a landscape perspective, by explicitly examining connections between an aquatic ecosystem and its watershed. Recently, the need to understand global inland waters as part of the Earth System created a sub-discipline called global limnology. This approach considers processes in inland waters on a global scale, like the role of inland aquatic ecosystems in global biogeochemical cycles.Limnology is closely related to aquatic ecology and hydrobiology, which study aquatic organisms and their interactions with the abiotic (non-living) environment. While limnology has substantial overlap with freshwater-focused disciplines (e.g., freshwater biology), it also includes the study of inland salt lakes.

List of watershed topics

This list embraces topographical watersheds and drainage basins and other topics focused on them.

Marine habitats

Marine habitats are habitats that support marine life. Marine life depends in some way on the saltwater that is in the sea (the term marine comes from the Latin mare, meaning sea or ocean). A habitat is an ecological or environmental area inhabited by one or more living species. The marine environment supports many kinds of these habitats.

Marine habitats can be divided into coastal and open ocean habitats. Coastal habitats are found in the area that extends from as far as the tide comes in on the shoreline out to the edge of the continental shelf. Most marine life is found in coastal habitats, even though the shelf area occupies only seven percent of the total ocean area. Open ocean habitats are found in the deep ocean beyond the edge of the continental shelf.

Alternatively, marine habitats can be divided into pelagic and demersal zones. Pelagic habitats are found near the surface or in the open water column, away from the bottom of the ocean. Demersal habitats are near or on the bottom of the ocean. An organism living in a pelagic habitat is said to be a pelagic organism, as in pelagic fish. Similarly, an organism living in a demersal habitat is said to be a demersal organism, as in demersal fish. Pelagic habitats are intrinsically shifting and ephemeral, depending on what ocean currents are doing.

Marine habitats can be modified by their inhabitants. Some marine organisms, like corals, kelp, mangroves and seagrasses, are ecosystem engineers which reshape the marine environment to the point where they create further habitat for other organisms. By volume, oceans provide about 99 percent of the living space on the planet.

Outline of fishing

The following outline is provided as an overview of and topical guide to fishing:

Fishing – activity of trying to catch fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping.

Particle (ecology)

In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater. However, they eventually settle (rate determined by Stokes' law) and accumulate as sediment. Some can enter the atmosphere through wave action where they can act as cloud condensation nuclei (CCN). Many organisms filter particles out of the water with unique filtration mechanisms (filter feeders). Particles are often associated with high loads of toxins which attach to the surface. As these toxins are passed up the food chain they accumulate in fatty tissue and become increasingly concentrated in predators (see bioaccumulation). Very little is known about the dynamics of particles, especially when they are re-suspended by dredging. They can remain floating in the water and drift over long distances. The decomposition of some particles by bacteria consumes a lot of oxygen and can cause the water to become hypoxic.

Photic zone

The photic zone, euphotic zone (Greek for "well lit": εὖ "well" + φῶς "light"), or sunlight (or sunlit) zone is the uppermost layer of water in a lake or ocean that is exposed to intense sunlight. It corresponds roughly to the layer above the compensation point, i.e. depth where the rate of carbon dioxide uptake, or equivalently, the rate of photosynthetic oxygen production, is equal to the rate of carbon dioxide production, equivalent to the rate of respiratory oxygen consumption, i.e. the depth where net carbon dioxide assimilation is zero.

It extends from the surface down to a depth where light intensity falls to one percent of that at the surface, called the euphotic depth. Accordingly, its thickness depends on the extent of light attenuation in the water column. Typical euphotic depths vary from only a few centimetres in highly turbid eutrophic lakes, to around 200 meters in the open ocean. It also varies with seasonal changes in turbidity.

Since the photic zone is where almost all of the photosynthesis occurs, the depth of the photic zone is generally proportional to the level of primary production that occurs in that area of the ocean. About 90% of all marine life lives in the photic zone. A small amount of primary production is generated deep in the abyssal zone around the hydrothermal vents which exist along some mid-oceanic ridges.

The zone which extends from the base of the euphotic zone to about 200 metres is sometimes called the disphotic zone. While there is some light, it is insufficient for photosynthesis, or at least insufficient for photosynthesis at a rate greater than respiration. The euphotic zone together with the disphotic zone coincides with the epipelagic zone. The bottommost zone, below the euphotic zone, is called the aphotic zone. Most deep ocean waters belong to this zone.

The transparency of the water, which determines the depth of the photic zone, is measured simply with a Secchi disk. It may also be measured with a photometer lowered into the water.

Ramsar Convention

The Ramsar Convention on Wetlands of International Importance especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of wetlands. It is also known as the Convention on Wetlands. It is named after the city of Ramsar in Iran, where the Convention was signed in 1971.

Every three years, representatives of the Contracting Parties meet as the Conference of the Contracting Parties (COP), the policy-making organ of the Convention which adopts decisions (Resolutions and Recommendations) to administer the work of the Convention and improve the way in which the Parties are able to implement its objectives. COP12 was held in Punta del Este, Uruguay, in 2015. COP13 was held in Dubai, United Arab Emirates, in October 2018.

Ramsar site

A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention.The Convention on Wetlands, known as the Ramsar Convention, is an intergovernmental environmental treaty established in 1971 by UNESCO, which came into force in 1975. It provides for national action and international cooperation regarding the conservation of wetlands, and wise sustainable use of their resources.Ramsar identifies wetlands of international importance, especially those providing waterfowl habitat.

As of 2016, there were 2,231 Ramsar sites, protecting 214,936,005 hectares (531,118,440 acres), and 169 national governments are currently participating.

Rocky shore

A rocky shore is an intertidal area of seacoasts where solid rock predominates. Rocky shores are biologically rich environments, and are a useful "natural laboratory" for studying intertidal ecology and other biological processes. Due to their high accessibility, they have been well studied for a long time and their species are well known.

Sustainable gardening

Sustainable gardening includes the more specific sustainable landscapes, sustainable landscape design, sustainable landscaping, sustainable landscape architecture, resulting in sustainable sites. It comprises a disparate group of horticultural interests that can share the aims and objectives associated with the international post-1980s sustainable development and sustainability programs developed to address the fact that humans are now using natural biophysical resources faster than they can be replenished by nature.Included within this compass are those home gardeners, and members of the landscape and nursery industries, and municipal authorities, that integrate environmental, social, and economic factors to create a more sustainable future.

Organic gardening and the use of native plants are integral to sustainable gardening.

Aquatic ecosystems

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