Kelp forest
A kelp forest, and kelp forest (after eng. Kelp forest ) or algae forest called, is a occurring in the riparian zones of temperate oceans ecosystem. The name derives from the kelp, in particular some large multicellular algae growing from the order of Laminariales. The home in the kelp forest algae are predominantly brown and red algae. They provide habitat for a variety of fish and invertebrates and also play for the survival of bird species involved. Predators, such as sea urchins, Fisheries and heating the water including in the context of the El Niño - Southern Oscillation endanger the existence of Tangwälder.
Features
The macroalgae that dominate the kelp forest, consist of three main parts: the claw-like holdfast on the floor ( rhizoid ), this agrees with the flexible stems ( Cauloid ) and on the water surface, leaf-like fronds are ( Phylloid ). These parts form at the same time typical for normal forest stratification in several habitats: Top - sometimes even at the water surface - form the fronds of larger Tangen the tree crown. In between, the central building of the stem is in the shadowy light in which that have many species of fish. Amongst them is the dark ocean floor. Similar to the coral reefs is the struggle for the light or the shadow casting an important mechanism in the competition between different species, but also different creatures of the same kind
Individual Tanggewächse reach a great height, the giant kelp ( Macrocystis pyrifera ) can be up to 45 meters long and it achieved growth of 30 to 50 cm per day. The rapid growth leads to a very changing vegetation and a frequent change of forest between the seasons. Storms in autumn and winter tear old fronds from the crown, so that more light reaches the ground. It may also happen that the holdfast from the ground and solves the Tang begins to float around freely. The plant then floats to the surface and continues to grow until it reached on stranded or warm water. They can form a rallying point for many marine animals.
Ecology
The Tangwälder deemed submarine counterparts of the rain forests, because they also have a large diversity of species and a similar vertical structure. The molecular biologist J. Craig Venter calculated from newly found genes over 1000 undiscovered species alone in the Sargasso Sea. Consequently, could in kelp beds world still several thousand so far are undescribed species. These primarily include many microorganisms of phytoplankton.
Different Tangwälder
The Tangwälder usually have a complex spatial structure with many coexisting species, to which the term "forest" best describes. In the east and north Pacific often dominates the annual Nereocystis luetkeana ( Bullkelp ) that defies even stronger currents. In the kelp forest occurring algae such as giant kelp ( Macrocystis ) and Nereocystis have floats that keep their fronds at the water surface in order to operate effectively photosynthesis can. The algae start to grow further in the width. There may be more pronounced vertical layers in addition to the costs associated with the fronds crowns.
In the northern hemisphere lower Tangwälder dominate from Laminaria species in the North Sea and Baltic Sea, these are Palmentang ( Laminaria hyperborea ), kelp ( Laminaria digitata ) and sugar kelp ( Saccharina latissima, Laminaria saccharina Syn ). Before Alaska it may, when the Tang of sea urchins is undisturbed, happen that the perennial algae Laminaria groenlandica gains the upper hand and other types takes the light.
Tangwälder on the Atlantic coast of North America do not occur at such a high diversity of species, but are lush and support rich communities of benthic invertebrates. They range then due south to Cape Cod and dive only sporadically at the eastern end of Long Iceland.
In the Sargasso Sea, in the Atlantic, not a forest of giant Tangen occurs, but instead floating in the water brown algae of the genus Golf algae ( Sargassum, of the order Fucales ). So here is the general term " algae forest " or " Sargassumwald " true. The Sargasso Sea is a special habitat for small crabs, worms and other marine animals represents the plankton production here is significant: it is estimated that one third of plankton production of the Atlantic takes place in the Sargasso Sea.
Habitat algae forest
The kelp forest provides a habitat for many creatures, such as chordates, arthropods, annelids, echinoderms, bryozoans, cnidarians, mollusks, flatworms, brachiopods and sponges.
Algae are vitamin suppliers and beyond rich in protein and trace elements. Tang is the same for both people (especially in Japan) as well as for many animals an important food. Especially is dead Tang freely dissolved organic solids. May have the woods. During photosynthesis analogous to the tropical rain forests even have an impact on the global climate
The for Tangwälder characteristic, usually slow-flowing water makes for great collections of plankton and other benthic invertebrates and microorganisms. In the Tang itself, preferably on the large fronds, often live Epizoen, so Aufsitzertiere as sea anemones and bryozoans, on the stems settle numerous species of algae ( epiphytes ). The bottom is lined with sponges and bryozoans.
Among the dependent kelp forest animals, herbivores and filtrations are as mussels, bryozoans, polychaetes, sea snails and crabs, one of which can feed larger animals in the food chain. In the forests falling off the coast of South Africa in particular, the abalones. The herbivores feed on seaweed and other algae that grow in the kelp forest.
In the central building of the Tangwalds numerous species of fish of all sizes, most of which are carnivores and predators, such as seahorses and sea dragons, wrasse and file fish frolic. Among other consequences associated with the Blacksmith damselfish ( Chromis punctipinnis ) feeds on parasites of Tangs. Lobsters are also to be found there. Such species migrate hunters like the blue shark, the Great Amberjack ( Seriola lalandei ) and sunfish on. There are whales that feed on plankton, spotted rays, such as the eagle rays or electric ray, looking between the Tang for prey. But the giant kelp also provides hiding places and breeding grounds for many marine species: To find, for example, juvenile fish and flying fish refuge - even in the midst freely drifting seaweed. Dolphins, like the white -sided dolphin, it has been observed while playing with pieces about driving Tangs. Also they use the forests as hideouts. Sea otters feed on, among other things from the sea urchin, who is a great enemy of the Tangs. The abundant starfish eat also sea urchins. In addition, seabirds such as cormorants hunt fish in the kelp beds.
Dissemination
An important prerequisite for the Tangwälder are the local properties of the sea: Most multicellular algae species require calm waters, because they would find no support in strong currents. It must be rich in nutrients. Since light is needed for photosynthesis, the water must be very clear, for the same reason are the seaweed forests in shallow water, which is rarely deeper than 15 to 40 meters. Most often they are found on rocky soil on which the plants easily find support. In contrast to the coral they require a low water temperature. The larger forests are located in cold waters, an average temperature of 20 ° C is considered the upper limit.
They grow on the entire west coast of America, from the Aleutian Islands in Alaska to the Strait of Magellan, but never consistently because they depend on a rather quiet flow. Are especially marked Tangwälder off California, between San Diego and Santa Cruz and there especially in the Monterey Bay. These are also best explored because, among other things, the universities of the two cities to carry out investigations there.
In the Atlantic, they are found off the coast of Argentina. Off the west coast of South Africa, partly in the Indian Ocean, off the southern coast of Australia, in New Zealand and partly off Antarctica are more Tangwälder.
In Europe Tangwälder of Iceland and Norway to the south are common to the north-west coast of Africa. Before Norway they covered an area of several thousand square kilometers. In the North Sea and Baltic Sea they are confined to coasts with rocky seabed. The only occurrence in the German Bight is at Helgoland ( Helgoland nature reserve rock base ). ( See also list of marine algae from Helgoland ). The underwater forests rich in Heligoland up to 10 m water depth down, the clearer the Mediterranean to 120 m. In the Baltic Sea Tangwälder can be found for example in the Southeast Rügen Biosphere Reserve.
Threat of Tangwälder
The fragile ecosystem of the submarine forests is exposed to numerous threats. Polluted water from the rivers carries pesticides, herbicides and other chemicals into the sea and in the Tangwälder. This can be messed up the natural balance, biodiversity and ultimately the entire ecosystem are threatened. This increasing wastewater that can be used by sea urchins as food, particularly in the Pacific led to her heaping occurrence. Also, it comes to over-fishing and the threat of further predators such as the sea otter or cod. The natural enemies of herbivores sea urchins and also the scavengers such as sea cucumbers and brittle stars occurr as often. This is a serious threat to the kelp forest, because of this, among other storm damage in the many predators can hardly recover.
Due to the growing Seetangmarktes exists in some places the risk of overexploitation. Among other things, before California and Tasmania Tang is harvested with large ships since the 1950s, which cut off the top fronds with scissors. When harvesting the petals, the phenomenon can occur that the brown alga Desmarestia ligulata occurs amplified and below the water surface forms a new dense crown, which hinders the amount of light in the depth and so damage the kelp forest. The targeted application of seaweed in an aquaculture conserves natural Tangwälder and is also economically efficient.
Also, global warming is said to have an important role, since the Tang needed cool water. Changes in ocean currents are found off Tasmania, which also result in the erosion of Tangwälder by itself.