Whitewater river (river type)
A whitewater river is classified based on its chemistry and water colour. Whitewater rivers have high levels of suspended sediments, giving the water a pH, near-neutral, a high electric conductivity and a pale muddy, café au lait-like colour. Whitewater rivers are important to local fisheries; the major seasonal Amazonian floodplains known as várzea receive their water from them. The best-known whitewater rivers are Amazonian and have their source in the Andes, but there are whitewater rivers elsewhere in South America and in other continents. Amazonian rivers fall into three main categories: whitewater and clearwater; this classification system was first proposed by Alfred Russel Wallace in 1853 based on water colour, but the types were more defined according to chemistry and physics by Harald Sioli from the 1950s to the 1980s. Although many Amazonian rivers fall into one of these categories, others show a mix of characteristics and may vary depending on season and flood levels; the best-known whitewater rivers have their source in the Andes.
The main rivers that are considered whitewater are Solimões–Amazon, Caquetá–Japurá, Marañón, Javary, Juruá, Purus, Madre de Dios, Madeira. Although the Branco River traditionally is considered whitewater, it has a number of characteristics that do not fit into the classification and some refer to it as clearwater. Outside the Amazon, a small number of South American rivers are considered whitewater, most notably certain tributaries of the Orinoco such as the Guaviare and Apure Rivers, of the Paraná—Paraguay such as the Bermejo and Salado Rivers, which have their source in the Andes. Outside South America, this system of classification is not used, but there are several rivers with whitewater characteristics. In Africa, these include the Niger main stem and its floodplain, Nile, the middle and lower Zambezi, the Cross, Mungo and Wouri rivers. In Asia, examples are the Mekong mainstream, several upland streams in large river basins in the southern and southeastern part of the continent. In Europe, sections of the Danube have whitewater characteristics.
In South America, most whitewater rivers originate in the Andes where they collect high levels of nutrient-rich sediments, notably illite and montmorillonite. They have a near-neutral pH, high levels of dissolved solids, high electric conductivity; the water is turbid, with a low visibility, between 20 and 60 cm. In the main stem of the Amazon River, about 82% of the total suspended solids and 90–95% of the suspended load of sediments originate from the Andes. Along their course, whitewater rivers become diluted due to the inflow of black- and clearwater tributaries. For example, the Rio Negro, the largest blackwater tributary, accounts for 14% of the total Amazon basin water and Tapajós, the largest clearwater tributary, accounts for 6%. Although the Amazon River is whitewater throughout its course, the electric conductivity is 120–200 μS/cm in the Andes, but by the time it reaches Santarém, it has fallen to 40-70 μS/cm. At high elevations in the Andes near the headwater, the pH of whitewater rivers can be above 8.
In some parts of the Amazon where the rivers are not whitewater, "pseudo-whitewater" exists because of soil erosion from human activities. The difference in chemistry and visibility between the various black and clearwater rivers result in distinct differences in flora and fauna. Although there is considerable overlap in the fauna found in the different river types, there are many species found only in one of them. Many blackwater and clearwater species are restricted to small parts of the Amazon, as different blackwater and clearwater systems are separated by large whitewater sections; these "barriers" are considered a main force in allopatric speciation in the Amazon basin. As in South America, distinct differences between species in black- and whitewater can be seen in Asia and Africa. For example, the fish fauna in African whitewater rivers tend to be dominated by cyprinids and elephantfish, whereas blackwater rivers have more characiforms and cichlids; the high nutrient levels in whitewater rivers allow high levels of periphyton, but the water turbidity restricts light, thereby limiting photosynthetic processes, which are necessary to algae and submerged macrophytes, to the uppermost part of the water column.
The periphyton equals the production level in temperate eutrophic lakes. Bacterial abundance and production rates are equal in whitewater and blackwater rivers, but both vary with water level and productions are higher during the high-water season; the major seasonal Amazonian floodplains known as várzea receive their water from whitewater rivers and are home to many animals and plants. In the Brazilian Amazon, várzea covers 200,000 km2, equalling 4% of the entire area. In addition to forests and woodlands with trees and other plants that are seasonally covered by water, about one-third of this floodplain's area is covered by large floating meadows; these floating meadows are home to the richest Amazonian community of aquatic invertebrates and important to fish species that visit during the flood season for feeding or breeding (a lower number of fish species live in the habita
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Lobotes is a genus of perciform fishes known as the tripletails native to subtropical and tropical waters in all oceans. This is the sole genus in the family Lobotidae; the recognized species in this genus are: Lobotes pacificus C. H. Gilbert, 1898 Lobotes surinamensis Froese and Daniel Pauly, eds.. "Lobotidae" in FishBase. December 2013 version
Xanthochromism is an unusually yellow pigmentation in an animal. It is associated with the lack of usual red pigmentation and its replacement with yellow; the cause is genetic but may be related to the animal's diet. A Cornell University survey of unusual-looking birds visiting feeders reported that 4% of such birds were described as xanthochromistic; the opposite of xanthochromism, a deficiency in or complete absence of yellow pigment, is known as axanthism. Birds exhibiting genetic xanthochromism deliberately bred mutations of several species of parrot in aviculture, are termed "lutinos". Wild birds in which xanthochromism has been recorded include yellow wagtail, wood warbler, Cape May warbler, rose-breasted grosbeak, evening grosbeak, red-bellied woodpecker, scarlet tanager, northern cardinal, great spotted woodpecker, common tailorbird, crimson-breasted shrike and kea. Cornell University Project Feeder Watch 2002-2003 Accessed 19 March 2007. Helleiner CW. "Xanthochroism in the Evening Grosbeak".
Canadian Field-Naturalist. 93: 66–7. Isted, Deloris. "A xanthochroistic male Purple Finch". Bulletin of the Oklahoma Ornithological Society. 18: 31. Schnell, Gary D. Auk. 83: 667–8. Doi:10.2307/4083162. Schwartz FJ. "Xanthochromism in Epinephelus drummondhayi caught off North Carolina". Northeast Gulf Science. 2: 62–4. Birders’ World Magazine, August 2003 Strange birds at your feeder Yellow-breasted Crimson-breasted Shrike
Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, along with the wrasses, in the order Perciformes but molecular studies have contradicted this grouping; the closest living relatives of cichlids are the convict blennies and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is both diverse. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, many species remain undescribed; the actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000. Many cichlids tilapia, are important food fishes, while others, such as the Cichla species, are valued game fish; the family includes many popular freshwater aquarium fish kept by hobbyists, including the angelfish and discus. Cichlids have the largest number of endangered species among vertebrate families, most in the haplochromine group.
Cichlids are well known for having evolved into a large number of related but morphologically diverse species within large lakes Tanganyika, Victoria and Edward. Their diversity in the African Great Lakes is important for the study of speciation in evolution. Many cichlids introduced into waters outside of their natural range have become nuisances. All cichlids have some form of parental care for their eggs and fry; that parental care may come in the form of guarding the eggs and fry or it may come in the form of mouthbrooding. Cichlids span a wide range of body sizes, from species as small as 2.5 cm in length to much larger species approaching 1 m in length. As a group, cichlids exhibit a similar diversity of body shapes, ranging from laterally compressed species to species that are cylindrical and elongated. However, cichlids tend to be of medium size, ovate in shape, laterally compressed, similar to the North American sunfishes in morphology and ecology. Cichlids share a single key trait: the fusion of the lower pharyngeal bones into a single tooth-bearing structure.
A complex set of muscles allows the upper and lower pharyngeal bones to be used as a second set of jaws for processing food, allowing a division of labor between the "true jaws" and the "pharyngeal jaws". Cichlids are efficient and highly specialized feeders that capture and process a wide variety of food items; this is assumed to be one reason. The features that distinguish them from the other families in Labroidei include: A single nostril on each side of the forehead, instead of two No bony shelf below the orbit of the eye Division of the lateral line organ into two sections, one on the upper half of the flank and a second along the midline of the flank from about halfway along the body to the base of the tail A distinctively shaped otolith The small intestine's left-side exit from the stomach instead of its right side as in other Labroidei Kullander recognizes eight subfamilies of cichlids: the Astronotinae, Cichlinae, Geophaginae, Heterochromidinae, Pseudocrenilabrinae, Retroculinae.
A ninth subfamily, was recognized by Sparks and Smith. Cichlid taxonomy is still debated, classification of genera cannot yet be definitively given. A comprehensive system of assigning species to monophyletic genera is still lacking, there is not complete agreement on what genera should be recognized in this family; as an example of the classification problems, Kullander placed the African genus Heterochromis phylogenetically within Neotropical cichlids, although papers concluded otherwise. Other problems center upon the identity of the putative common ancestor for the Lake Victoria superflock, the ancestral lineages of Tanganyikan cichlids. Comparisons between a morphologically-based phylogeny and analyses of gene loci produce differences at the genus level. There remains a consensus. In cichlid taxonomy, dentition was used as a classifying characteristic. However, this was complicated by the fact that in many cichlids, tooth shape changes with age, due to wear, cannot be relied upon. Genome sequencing and other technologies transformed cichlid taxonomy.
Cichlids are one of the largest vertebrate families in the world. They are most diverse in South America. Africa alone is estimated to host at least 1,600 species. Central America and Mexico have about 120 species, as far north as the Rio Grande in southern Texas. Madagascar has its own distinctive species, only distantly related to those on the African mainland. Native cichlids are absent in Asia, except for 9 species in Israel and Syria, two in Iran, three in India and Sri Lanka. If disregarding Trinidad and Tobago, the three species from the genus Nandopsis are the only cichlids from the Antilles in the Caribbean Cuba and Hispaniola. Europe, Australia and North
Rineloricaria is a genus of freshwater tropical catfish belonging to the Loricariidae family. They are called whiptail catfish because of the long filament that grows out of the tip of the caudal fin, characteristic of the genus. With the exception of R. altipinnis from Panama, they are native to the rivers of northern and central South America. Some species are seen in the aquarium trade; this genus was described with R. lima as the type species. This genus is by far one of the most speciose of the subfamily Loricariinae, containing about 30 species. On the other hand, it is one of the least resolved genera. In 2008, 14 new species were added to this genus. Hemiloricaria and Leliella been variably considered synonyms of Rineloricaria. However, the traits used to diagnose these genera have been thought to be insufficient. There are 64 recognized species in this genus: Rineloricaria aequalicuspis R. E. dos Reis & A. R. Cardoso, 2001 Rineloricaria altipinnis Rineloricaria anhanguapitan Ghazzi, 2008 Rineloricaria anitae Ghazzi, 2008 Rineloricaria aurata Rineloricaria baliola M. S. Rodriguez & R. E. dos Reis, 2008 Rineloricaria beni Rineloricaria cacerensis Rineloricaria cadeae Rineloricaria capitonia Ghazzi, 2008 Rineloricaria caracasensis Rineloricaria castroi Isbrücker & Nijssen, 1984 Rineloricaria catamarcensis Rineloricaria cubataonis Rineloricaria daraha Rapp Py-Daniel & Fichberg, 2008 Rineloricaria eigenmanni Rineloricaria fallax Rineloricaria felipponei Rineloricaria formosa Isbrücker & Nijssen, 1979 Rineloricaria hasemani Isbrücker & Nijssen, 1979 Rineloricaria henselii Rineloricaria heteroptera Isbrücker & Nijssen, 1976 Rineloricaria hoehnei Rineloricaria isaaci M. S. Rodriguez & Miquelarena, 2008 Rineloricaria jaraguensis Rineloricaria jubata Rineloricaria jurupari Rineloricaria konopickyi Rineloricaria kronei Rineloricaria lanceolata Rineloricaria langei Ingenito, Duboc & Abilhoa, 2008 Rineloricaria latirostris Rineloricaria lima Rineloricaria longicauda R. E. dos Reis, 1983 Rineloricaria maacki Ingenito, Duboc & Abilhoa, 2008 Rineloricaria magdalenae Rineloricaria malabarbai M. S. Rodriguez & R. E. dos Reis, 2008 Rineloricaria maquinensis R. E. dos Reis & A. R. Cardoso, 2001 Rineloricaria melini Rineloricaria microlepidogaster Rineloricaria microlepidota Rineloricaria misionera M. S. Rodriguez & Miquelarena, 2005 Rineloricaria morrowi Fowler, 1940 Rineloricaria nigricauda Rineloricaria osvaldoi Fichberg & Chamon, 2008 Rineloricaria pareiacantha Rineloricaria parva Rineloricaria pentamaculata Langeani & R. B. de Araujo, 1994 Rineloricaria phoxocephala Rineloricaria platyura Rineloricaria quadrensis R. E. dos Reis, 1983 Rineloricaria reisi Ghazzi, 2008 Rineloricaria sanga Ghazzi, 2008 Rineloricaria setepovos Ghazzi, 2008 Rineloricaria sneiderni Rineloricaria steindachneri Rineloricaria stellata Ghazzi, 2008 Rineloricaria stewarti Rineloricaria strigilata Rineloricaria teffeana Rineloricaria thrissoceps Rineloricaria tropeira Ghazzi, 2008 Rineloricaria wolfei Fowler, 1940 Rineloricaria zaina Ghazzi, 2008 The genus is distributed on nearly the entire subcontinent, from Costa Rica to Argentina, on both slopes of the Andes.
Rineloricaria species are found in a large variety of habitats, including large rivers and lagoons, associated with bottoms consisting of sand or rocks, sometimes found in marginal vegetation. They are found to tolerate environments with a wide temperature gradient. Rineloricaria have an adaptive capacity enabling many species to exploit the most varied habitats; the average length of a Rineloricaria catfish is about 13 cm long. The fish are long, have no visible barbels, an erect dorsal fin, a thin caudal peduncle, a narrow face. Coloration of the fishes are light brown with darker blotches, have a dark dorsal fin, they are covered with bony plates and have a sucker disk mouth, as is common with most fish in the Loricariidae family. Sexual dimorphism includes hypertrophied development of the odontodes along the sides of the head, on the pectoral spines and rays, predorsal area of mature males. Several species show hypertrophied development of the odontodes on the entire caudal peduncle. In males, the pectoral fin spine is thick and curved when compared to the female.
Rineloricaria are cavity brooders. Numerous eggs are laid attached to one another in single layer masses on the cavity floor, are brooded by males. Rineloricaria exhibit high levels of karyotypic diversity with chromosome numbers ranging from 36 to 70. List of freshwater aquarium fish species
The Approuague river is a major river in French Guiana. It runs north from the Tumuk Humak Mountains to the Atlantic Ocean parallel with the Oiapoque, with its mouth by the Pointe Béhague cape; the Approuague Bridge is 2 kilometres south of Régina