|
Lake Sturgeon
The lake sturgeon (''Huso fulvescens''), also known as the rock sturgeon, is a North American temperate freshwater fish, one of 27 species of sturgeon. Like other sturgeons, this species is a bottom feeder and has a partly cartilaginous skeleton, an overall streamlined shape, and skin bearing rows of bony plates on the sides and back. The lake sturgeon uses its elongated, spade-like snout to stir up the substrate and sediments on the beds of rivers and lakes to feed. Four sensory organs ( barbels) hang near its mouth to help the sturgeon locate bottom-dwelling prey. Lake sturgeons can grow to a large size for freshwater fish, topping 7.25 ft (2.2 m) long and 240 lbs (108 kg). Taxonomy Prior to 2025, it was placed in the genus ''Acipenser'', but this placement was found to be paraphyletic, and it is more accurately placed in the genus ''Huso''. It is one of two species of ''Huso'' found in North America alongside the shortnose sturgeon (''H. brevirostrum''). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek () 'most' and (; Latinized as ) 'new'. The aridification and cooling trends of the preceding Neogene were continued in the Pleistocene. The climate was strongly variable depending on the glacial cycle, oscillating between cold Glacial period, glacial periods and warmer Interglacial, int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage Basin
A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the drainage divide, made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern. Other terms for a drainage basin are catchment area, catchment basin, drainage area, river basin, water basin, and impluvium. In North America, they are commonly called a watershed, though in other English-speaking places, " watershed" is used only in its original sense, that of the drainage divide line. A drainage basin's boundaries are determined by watershed delineation, a common task in environmental engineering and science. In a closed drainage basin, or endorheic basin, rather than flowing to the ocean, water converges toward the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NatureServe
NatureServe, Inc. is a non-profit organization based in Arlington County, Virginia, United States, US, that provides proprietary wildlife conservation-related data, tools, and services to private and government clients, partner organizations, and the public. NatureServe reports being "headquartered in Arlington, Virginia, with regional offices in four U.S. locations and in Canada." In calendar year 2011 they reported having 86 employees, 6 volunteers, and 15 independent officers. History The Nature Conservancy reports that in 2000 it spun off its 85-center Natural Heritage Network "into a new independent organization, the Association for Biodiversity Information (later renamed NatureServe)." NatureServe reports that it was established in 1994 as the Association for Biodiversity Information. In 2001 the IRS approved a name change to NatureServe that was requested in 1999, while maintaining the organization's 501(c)(3) tax-exempt status granted in July 1995. NatureServe's website dec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benthic Zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". Organisms living in this zone are called benthos and include microorganisms (e.g., bacteria and Fungus, fungi) as well as larger invertebrates, such as crustaceans and polychaetes. Organisms here, known as bottom dwellers, generally live in close relationship with the substrate and many are permanently attached to the bottom. The benthic boundary layer, which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud. Description Oceans The benthic region of the ocean begins at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phototactic
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus (physiology), stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive light for photosynthesis. Phototaxis is called positive if the movement is in the direction of increasing light intensity and negative if the direction is opposite. Phototaxis has been described in microorganisms and algea, insects and other invertebrates, and vertebrates. Typically nocturnal insects can show positive phototaxis, while nocturnal mammals often show negative phototaxis. Phototaxis in bacteria and archea Phototaxis can be advantageous for phototrophic bacteria as they can orient themselves most efficiently to receive light for photosynthesis. Phototaxis is called positive if the movement is in the direction of increasing light intensity and negative if the direction is opposite. Two types of positive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagic Zone
The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the surface of the sea and the bottom. Conditions in the water column change with depth: pressure increases; temperature and light decrease; salinity, oxygen, micronutrients (such as iron, magnesium and calcium) all change. In a manner analogous to stratification in the Earth's atmosphere, the water column can be divided vertically into up to five different layers (illustrated in the diagram), with the number of layers depending on the depth of the water. Marine life is affected by bathymetry (underwater topography) such as the seafloor, shoreline, or a submarine seamount, as well as by proximity to the boundary between the ocean and the atmosphere at the ocean surface, which brings light for photosynthesis, predation from above, and wind sti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Lake Iroquois
Glacial Lake Iroquois was a prehistoric proglacial lake that existed at the end of the last ice age approximately 13,000 years ago. Description The lake was essentially an enlargement of the present Lake Ontario that formed because the St. Lawrence River downstream from the lake was blocked by the ice sheet near the present Thousand Islands. The level of the lake was approximately 30 m (~100 ft) above the present level of Lake Ontario. The work of Anderson and Lewis (1985) is the basis for these authors' views on the history of the postglacial water levels. The lake drained to the southeast, through a channel passing near present day Rome, New York. The Rome Sand Plains has several sand ridges that geologists think were formed at this time. The channel then followed the valley of the Mohawk River to the Hudson River. The lake was fed by Early Lake Erie, as well as Glacial Lake Algonquin, an early partial manifestation of Lake Huron, that drained directly to Lak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Agassiz
Lake Agassiz ( ) was a large proglacial lake that existed in central North America during the late Pleistocene, fed by meltwater from the retreating Laurentide Ice Sheet at the end of the last glacial period. At its peak, the lake's area was larger than all of the modern Great Lakes combined. It eventually drained into what is now Hudson Bay, leaving behind Lake Winnipeg, Lake Winnipegosis, Lake Manitoba, and Lake of the Woods. First postulated in 1823 by William H. Keating, it was named by Warren Upham in 1879 after Louis Agassiz, the then recently deceased (1873) founder of glaciology, when Upham recognized that the lake was formed by glacial action. Geological progression During the last glacial maximum, northern North America was covered by an ice sheet, which alternately advanced and retreated with variations in the climate. This continental ice sheet formed during the period now known as the Wisconsin glaciation, and covered much of central North America betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Champlain
Lake Champlain ( ; , ) is a natural freshwater lake in North America. It mostly lies between the U.S. states of New York (state), New York and Vermont, but also extends north into the Canadian province of Quebec. The cities of Burlington, Vermont and Plattsburgh, New York are the largest settlements on the lake, and towards the south lies the historic Fort Ticonderoga in New York. The Quebec portion is in the Regional county municipality, regional county municipalities of Le Haut-Richelieu Regional County Municipality, Quebec, Le Haut-Richelieu and Brome-Missisquoi Regional County Municipality, Brome-Missisquoi. There are a number of islands in the lake; the largest include Grand Isle (island), Grand Isle, Isle La Motte and North Hero: all part of Grand Isle County, Vermont. Because of Lake Champlain's connections both to the St. Lawrence Seaway via the Richelieu River, and to the Hudson River via the Champlain Canal, Lake Champlain is sometimes referred to as "The Sixth Great ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hudson Bay Lowland
The Hudson Bay Lowlands is a vast wetland located between the Canadian Shield and southern shores of Hudson Bay and James Bay. Most of the area lies within the province of Ontario, with smaller portions reaching into Manitoba and Quebec. Many wide and slow-moving rivers flow through this area toward the saltwater of Hudson Bay: these include the Churchill, Nelson and Hayes in Manitoba, Severn, Fawn, Winisk, Asheweig, Ekwan, Attawapiskat, and Albany in Ontario, and the Harricana, Rupert and Eastmain in Quebec. This is the largest wetland in Canada, and one of the largest in the world.Abraham, K.F. and C.J. Keddy. The Hudson Bay Lowland. Pages 118–148 in L.H. Fraser and P.A. Keddy (eds.). 2005. The World's Largest Wetlands: Ecology and Conservation. Cambridge University Press, Cambridge, UK. 488 p. The region can be subdivided into three bands running roughly northwest to southeast: the Coastal Hudson Bay Lowland (a narrow band along the northern coast), Hudson Bay Lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Saskatchewan
The South Saskatchewan River is a major river in the Canadian provinces of Alberta and Saskatchewan. The river begins at the confluence of the Bow and Oldman Rivers in southern Alberta and ends at the Saskatchewan River Forks in central Saskatchewan. The Saskatchewan River Forks is the confluence of the South and North Saskatchewan Rivers and is the beginning of the Saskatchewan River. For the first half of the 20th century, the South Saskatchewan would completely freeze over during winter, creating spectacular ice breaks and dangerous conditions in Saskatoon, Medicine Hat, and elsewhere. At least one bridge in Saskatoon was destroyed by ice carried by the river. The construction of the Gardiner Dam in the 1960s, however, lessened the power of the river by diverting a substantial portion of the South Saskatchewan's natural flow into the Qu'Appelle River. By the 1980s many permanent sandbars had formed due to the lowering of the level of the river. From the headwaters of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Saskatchewan
The North Saskatchewan River is a glacier-fed river that flows from the Canadian Rockies continental divide east to central Saskatchewan, where it joins with the South Saskatchewan River to make up the Saskatchewan River. Its water flows eventually into the Hudson Bay. The Saskatchewan River system is the largest shared between the Canadian provinces of Alberta and Saskatchewan. Its watershed includes most of southern and central Alberta and Saskatchewan. Course The North Saskatchewan River has a length of , and a drainage area of . At its end point at Saskatchewan River Forks it has a mean discharge of . The yearly discharge at the Alberta–Saskatchewan border is more than . The river begins above at the toe of the Saskatchewan Glacier in the Columbia Icefield, and flows southeast through Banff National Park alongside the Icefields Parkway. At the junction of the David Thompson Highway (Highway 11), it initially turns northeast for before switching to a more d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
