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Deep Chlorophyll Maximum
The deep chlorophyll maximum (DCM), also called the subsurface chlorophyll maximum, is the region below the surface of water with the maximum concentration of chlorophyll. The DCM generally exists at the same depth as the nutricline, the region of the ocean where the greatest change in the nutrient concentration occurs with depth. A DCM is not always present - sometimes there is more chlorophyll at the surface than at any greater depth - but it is a common feature of most aquatic ecosystems, especially in regions of strong thermal stratification. The depth, thickness, intensity, composition, and persistence of DCMs vary widely. A common way of determining the DCM is through the use of a CTD rosette, an underwater instrument that measures various parameters of water at specific depths. The location and formation of the DCM depends on multiple factors, such as the resident organisms' nutritional needs and light availability. Some organisms have adapted to lower levels of light thro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorophyll
Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to absorb energy from light. Chlorophylls absorb light most strongly in the blue portion of the electromagnetic spectrum as well as the red portion. Conversely, it is a poor absorber of green and near-green portions of the spectrum. Hence chlorophyll-containing tissues appear green because green light, diffusively reflected by structures like cell walls, is less absorbed. Two types of chlorophyll exist in the photosystems of green plants: chlorophyll ''a'' and ''b''. History Chlorophyll was first isolated and named by Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817. The presence of magnesium in chlorophyll was discovered in 1906, and was that element's first detection in living tissue. After initial work done by German chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinoflagellate
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy and myzocytosis). In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, ''Oodinium'' and ''Pfiesteria''). Some dinoflagellates pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Superior
Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh water. The northern and westernmost of the Great Lakes of North America, it straddles the Canada–United States border with the province of Ontario to the north and east, and the states of Minnesota to the northwest and Wisconsin and Michigan to the south. It drains into Lake Huron via St. Marys River, then through the lower Great Lakes to the St. Lawrence River and the Atlantic Ocean. Name The Ojibwe name for the lake is ''gichi-gami'' (in syllabics: , pronounced ''gitchi-gami'' or ''kitchi-gami'' in different dialects), meaning "great sea". Henry Wadsworth Longfellow wrote this name as "Gitche Gumee" in the poem ''The Song of Hiawatha'', as did Gordon Lightfoot in his song " The Wreck of the ''Edmund Fitzgerald''". According to oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pycnocline
A pycnocline is the Cline (hydrology), cline or layer where the density gradient () is greatest within a body of water. An ocean current is generated by the forces such as breaking waves, temperature and salinity differences, wind, Coriolis effect, and tides caused by the gravitational pull of celestial bodies. In addition, the physical properties in a pycnocline driven by density gradients also affect the flows and vertical profiles in the ocean. These changes can be connected to the transport of heat, salt, and nutrients through the ocean, and the pycnocline diffusion controls upwelling. Below the mixed layer, a stable density gradient (or pycnocline) separates the upper and lower water, hindering vertical transport. This separation has important biological effects on the ocean and the marine living organisms. However, vertical mixing across a pycnocline is a regular phenomenon in oceans, and occurs through shear-produced turbulence. Such mixing plays a key role in the transport ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Sea in the north. It is more than long and wide, covering . It hosts key north European shipping lanes and is a major fishery. The coast is a popular destination for recreation and tourism in bordering countries, and a rich source of energy resources, including wind and wave power. The North Sea has featured prominently in geopolitical and military affairs, particularly in Northern Europe, from the Middle Ages to the modern era. It was also important globally through the power northern Europeans projected worldwide during much of the Middle Ages and into the modern era. The North Sea was the centre of the Vikings' rise. The Hanseatic League, the Dutch Republic, and the British each sought to gain command of the North Sea and access t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prochlorophyta
Prochlorophyta is a group of photosynthetic bacteria, an important component of picoplankton. These oligotrophic organisms are abundant in nutrient poor tropical waters and use a unique photosynthetic pigment, divinyl-chlorophyll, to absorb light and acquire energy. Prochlorophyta lack red and blue phycobilin pigments and have stacked thylakoids, making them distinctly different from Cyanobacteria (or Cyanophyta), but some authors consider them as part of the Cyanobacteria, as the group Prochlorales. Discovery and naming This unique group of phytoplankton, with no phycobilin pigments, were initially found in 1975 near the Great Barrier Reef and off the coast of Mexico (''Prochloron''). Prochlorophyta was soon assigned as a new algal sub-class in 1976 by Ralph A. Lewin of the Scripps Institution of Oceanography. Other phytoplankton that lacked phycobilin pigments were later found in freshwater lakes in the Netherlands by Tineke Burger-Wiersma and colleagues and were termed ''Proc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by the Southern Ocean or Antarctica, depending on the definition in use. Along its core, the Indian Ocean has some large marginal or regional seas such as the Arabian Sea, Laccadive Sea, Bay of Bengal, and Andaman Sea. Etymology The Indian Ocean has been known by its present name since at least 1515 when the Latin form ''Oceanus Orientalis Indicus'' ("Indian Eastern Ocean") is attested, named after Indian subcontinent, India, which projects into it. It was earlier known as the ''Eastern Ocean'', a term that was still in use during the mid-18th century (see map), as opposed to the ''Western Ocean'' (Atlantic Ocean, Atlantic) before the Pacific Ocean, Pacific was surmised. Conversely, Ming treasure voyages, Chinese explorers in the Indian Oce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Picoplankton
Picoplankton is the fraction of plankton composed by cells between 0.2 and 2 μm that can be either prokaryotic and eukaryotic phototrophs and heterotrophs: * photosynthetic * heterotrophic They are prevalent amongst microbial plankton communities of both freshwater and marine ecosystems. They have an important role in making up a significant portion of the total biomass of phytoplankton communities. Classification In general, plankton can be categorized on the basis of physiological, taxonomic, or dimensional characteristics. Subsequently, a generic classification of a plankton includes: * Bacterioplankton * Phytoplankton * Zooplankton However, there is a simpler scheme that categorizes plankton based on a logarithmic size scale: * Macroplankton (200–2000 μm) * Micro-plankton (20–200 μm) * Nanoplankton (2–20 μm) This was even further expanded to include picoplankton (0.2-2 μm) and fem-toplankton (0.02-0.2 μm), as well as net plankton, ultraplankton. Now that p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coccolithophore
Coccolithophores, or coccolithophorids, are single celled organisms which are part of the phytoplankton, the autotrophic (self-feeding) component of the plankton community. They form a group of about 200 species, and belong either to the kingdom Protista, according to Robert Whittaker's Five kingdom classification, or clade Hacrobia, according to a newer biological classification system. Within the Hacrobia, the coccolithophores are in the phylum or division Haptophyta, class Prymnesiophyceae (or Coccolithophyceae). Coccolithophores are almost exclusively marine, are photosynthetic, and exist in large numbers throughout the sunlight zone of the ocean. Coccolithophores are the most productive calcifying organisms on the planet, covering themselves with a calcium carbonate shell called a ''coccosphere''. However, the reasons they calcify remains elusive. One key function may be that the coccosphere offers protection against microzooplankton predation, which is one of the ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the east by the Levant. The Sea has played a central role in the history of Western civilization. Geological evidence indicates that around 5.9 million years ago, the Mediterranean was cut off from the Atlantic and was partly or completely desiccated over a period of some 600,000 years during the Messinian salinity crisis before being refilled by the Zanclean flood about 5.3 million years ago. The Mediterranean Sea covers an area of about , representing 0.7% of the global ocean surface, but its connection to the Atlantic via the Strait of Gibraltar—the narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates the Iberian Peninsula in Europe from Morocco in Africa—is only wide. The Mediterranean Sea e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cryptomonad
The cryptomonads (or cryptophytes) are a group of algae, most of which have plastids. They are common in freshwater, and also occur in marine and brackish habitats. Each cell is around 10–50 μm in size and flattened in shape, with an anterior groove or pocket. At the edge of the pocket there are typically two slightly unequal flagella. Some may exhibit mixotrophy. Characteristics Cryptomonads are distinguished by the presence of characteristic extrusomes called ejectosomes, which consist of two connected spiral ribbons held under tension. If the cells are irritated either by mechanical, chemical or light stress, they discharge, propelling the cell in a zig-zag course away from the disturbance. Large ejectosomes, visible under the light microscope, are associated with the pocket; smaller ones occur underneath the periplast, the cryptophyte-specific cell surrounding. Except for the class ''Goniomonadea'', which lacks plastids entirely, and ''Cryptomonas paramecium'' (previo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epilimnion
The epilimnion or surface layer is the top-most layer in a thermally stratified lake. It sits above the deeper metalimnion and hypolimnion. It is typically warmer and has a higher pH and higher dissolved oxygen concentration than the hypolimnion. Physical Structure Properties In the water column, the epilimnion sits above all other layers. The epilimnion is only present in stratified lakes. On the topside of the epilimnion it is in contact with air, which leaves it open to wind action, which allows the water to experience turbulence. Turbulence and convection work together to make waves which increases aeration. On the bottom side of the epilimnion is the metalimnion, which contains the thermocline. The thermocline is created because of the difference in temperature between the epilimnion and the metalimnion. This is due to the fact that since the epilimnion is in contact with air and is above everything, it interacts with the sun and heat more, making it warmer than the lay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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