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27-519: White Brook begins near the edge of a plateau in North Branch Township. It flows south-southwest for a few tenths of a mile, heading into a valley. The stream then turns south-southeast for several tenths of a mile before entering Forkston Township and reaching the valley floor, where it receives an unnamed tributary from the right . It then turns east-southeast for several tenths of a mile before turning east-northeast for several tenths of

54-462: A barrier island or a submerged plateau , such as an ocean bank . A barrier island is a long narrow island composed of sand and forming a barrier between an island lagoon or sound and the ocean. A submerged plateau is a relatively flat topped elevation of the sea floor at shallow depth — generally less than 200 metres (660 ft) — typically on the continental shelf or near an island . Freshwater ecosystem Freshwater ecosystems are

81-439: A canopy derive the majority of their food base from algae. Anadromous fish are also an important source of nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution and introduced species . A dam produces negative effects that continue down the watershed. The most important negative effects are the reduction of spring flooding, which damages wetlands, and the retention of sediment, which leads to

108-454: A river , creek, or stream . The bank consists of the sides of the channel , between which the flow is confined. Stream banks are of particular interest in fluvial geography, which studies the processes associated with rivers and streams and the deposits and landforms created by them. Bankfull discharge is a discharge great enough to fill the channel and overtop the banks. The descriptive terms left bank and right bank refer to

135-511: A mile and exiting the valley. Here, the stream flows east for several tenths of a mile in the Mehoopany Creek valley before reaching its confluence with Mehoopany Creek. White Brook joins Mehoopany Creek 8.88 miles (14.29 km) upstream of its mouth. The elevation near the mouth of White Brook is 879 feet (268 m) above sea level . The elevation near the source of the stream is 2,043 feet (623 m) above sea level. There

162-407: A shallow slope. In freshwater ecology , banks are of interest as the location of riparian habitats . Riparian zones occur along upland and lowland river and stream beds. The ecology around and depending on a marsh , swamp , slough , or estuary , sometimes called a bank, is likewise studied in freshwater ecology. Banks are also of interest in navigation , where the term can refer either to

189-564: A subset of Earth's aquatic ecosystems . They include lakes , ponds , rivers , streams , springs , bogs , and wetlands . They can be contrasted with marine ecosystems , which have a larger salt content. Freshwater habitats can be classified by different factors, including temperature, light penetration, nutrients, and vegetation. There are three basic types of freshwater ecosystems: Lentic (slow moving water, including pools , ponds , and lakes ), lotic (faster moving water, for example streams and rivers ) and wetlands (areas where

216-458: Is a waterfall on White Brook. It is approximately 15 feet (4.6 m) high and is in a rugged glen with many cascades, ledges, boulders, and white cobbles. However, it is only accessible by bushwhacking . One person has received an encroachment permit to build and maintain a 26-foot (7.9 m) private footbridge across White Brook near State Route 3001. The watershed on White Brook has an area of 1.75 square miles (4.5 km). The mouth of

243-701: Is common when defining the idealized " health" of a freshwater ecosystem. Reference sites can be selected spatially by choosing sites with minimal impacts from human disturbance and influence. However, reference conditions may also be established temporally by using preserved indicators such as diatom valves, macrophyte pollen, insect chitin and fish scales can be used to determine conditions prior to large scale human disturbance. These temporal reference conditions are often easier to reconstruct in standing water than moving water because stable sediments can better preserve biological indicator materials. The effects of climate change greatly complicate and frequently exacerbate

270-856: Is commonly monitored because of the diverse taxonomy, ease of collection, sensitivity to a range of stressors, and overall value to the ecosystem. Additionally, algal community structure (often using diatoms) is measured in biomonitoring programs. Algae are also taxonomically diverse, easily collected, sensitive to a range of stressors, and overall valuable to the ecosystem. Algae grow very quickly and communities may represent fast changes in environmental conditions. In addition to community structure, responses to freshwater stressors are investigated by experimental studies that measure organism behavioural changes, altered rates of growth, reproduction or mortality. Experimental results on single species under controlled conditions may not always reflect natural conditions and multi-species communities. The use of reference sites

297-747: The Asian carp competing with the paddlefish in the Mississippi river . Common causes of invasive species in freshwater ecosystems include aquarium releases, introduction for sport fishing , and introduction for use as a food fish. Over 123 freshwater fauna species have gone extinct in North America since 1900. Of North American freshwater species, an estimated 48.5% of mussels, 22.8% of gastropods , 32.7% of crayfishes, 25.9% of amphibians, and 21.2% of fish are either endangered or threatened. Extinction rates of many species may increase severely into

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324-463: The Latin lentus , which means "sluggish"), which include ponds , lakes and 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 ecosystems are examples of freshwater ecosystems. River ecosystems are flowing waters that drain

351-1107: The dominant plants and the source of the water. For example, marshes are wetlands dominated by emergent herbaceous vegetation such as reeds , cattails and sedges . Swamps are dominated by woody vegetation such as trees and shrubs (although reed swamps in Europe are dominated by reeds, not trees). Mangrove forest are wetlands with mangroves , halophytic woody plants that have evolved to tolerate salty water . Five broad threats to freshwater biodiversity include overexploitation , water pollution , flow modification, destruction or degradation of habitat , and invasion by exotic species . Recent extinction trends can be attributed largely to sedimentation, stream fragmentation, chemical and organic pollutants, dams, and invasive species. Common chemical stresses on freshwater ecosystem health include acidification, eutrophication and copper and pesticide contamination. Freshwater biodiversity faces many threats. The World Wide Fund for Nature's Living Planet Index noted an 83% decline in

378-440: The landscape, and include the biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions of its many parts. River ecosystems are part of larger watershed networks or catchments, where smaller headwater streams drain into mid-size streams, which progressively drain into larger river networks. The major zones in river ecosystems are determined by

405-561: The loss of deltaic wetlands. A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water , either permanently, for years or decades, or only seasonally. Flooding results in oxygen -poor ( anoxic ) processes taking place, especially in the soils . Wetlands form a transitional zone between waterbodies and dry lands , and are different from other terrestrial or aquatic ecosystems due to their vegetation 's roots having adapted to oxygen-poor waterlogged soils . They are considered among

432-438: The most biologically diverse of all ecosystems, serving as habitats to a wide range of aquatic and semi-aquatic plants and animals , with often improved water quality due to plant removal of excess nutrients such as nitrates and phosphorus . Wetlands exist on every continent , except Antarctica . The water in wetlands is either freshwater , brackish or saltwater . The main types of wetland are defined based on

459-455: The next century because of invasive species, loss of keystone species, and species which are already functionally extinct (e.g., species which are not reproducing). Even using conservative estimates, freshwater fish extinction rates in North America are 877 times higher than background extinction rates (1 in 3,000,000 years). Projected extinction rates for freshwater animals are around five times greater than for land animals, and are comparable to

486-411: The perspective of an observer looking downstream ; a well-known example of this being the southern left bank and the northern right bank of the river Seine defining parts of Paris . The shoreline of ponds , swamps , estuaries , reservoirs , or lakes are also of interest in limnology and are sometimes referred to as banks. The grade of all these banks or shorelines can vary from vertical to

513-481: The populations of freshwater vertebrates between 1970 and 2014. These declines continue to outpace contemporaneous declines in marine or terrestrial systems. The causes of these declines are related to: Invasive plants and animals are a major issue to freshwater ecosystems, in many cases outcompeting native species and altering water conditions. Introduced species are especially devastating to ecosystems that are home to endangered species. An example of this being

540-503: The rates for rainforest communities. Given the dire state of freshwater biodiversity, a team of scientists and practitioners from around the globe recently drafted an Emergency Action plan to try and restore freshwater biodiversity. Current freshwater biomonitoring techniques focus primarily on community structure, but some programs measure functional indicators like biochemical (or biological) oxygen demand, sediment oxygen demand, and dissolved oxygen. Macroinvertebrate community structure

567-445: The river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen , which supports greater biodiversity than the slow-moving water of pools. These distinctions form the basis for the division of rivers into upland and lowland rivers. The food base of streams within riparian forests is mostly derived from the trees, but wider streams and those that lack

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594-696: The soil is saturated or inundated for at least part of the time). Freshwater ecosystems contain 41% of the world's known fish species. Freshwater ecosystems have undergone substantial transformations over time, which has impacted various characteristics of the ecosystems. Original attempts to understand and monitor freshwater ecosystems were spurred on by threats to human health (for example cholera outbreaks due to sewage contamination). Early monitoring focused on chemical indicators, then bacteria, and finally algae, fungi and protozoa. A new type of monitoring involves quantifying differing groups of organisms ( macroinvertebrates , macrophytes and fish ) and measuring

621-471: The soil is saturated or inundated for at least part of the time). Limnology (and its branch freshwater biology ) is a study about freshwater ecosystems. A lake ecosystem or lacustrine ecosystem includes biotic (living) plants , animals and micro-organisms , as well as abiotic (non-living) physical and chemical interactions. Lake ecosystems are a prime example of lentic ecosystems ( lentic refers to stationary or relatively still freshwater , from

648-690: The stream conditions associated with them. Threats to freshwater biodiversity include overexploitation , water pollution , flow modification, destruction or degradation of habitat , and invasion by exotic species . Climate change is putting further pressure on these ecosystems because water temperatures have already increased by about 1 °C, and there have been significant declines in ice coverage which have caused subsequent ecosystem stresses. There are three basic types of freshwater ecosystems: Lentic (slow moving water, including pools , ponds , and lakes ), lotic (faster moving water, for example streams and rivers ) and wetlands (areas where

675-515: The stream is in the United States Geological Survey quadrangle of Dutch Mountain. However, its source is in the quadrangle of Jenningsville. The stream's mouth is located near Kasson Brook. There are a few cottages along the lower reaches of the stream. White Brook is classified as a High-Quality Coldwater Fishery. Wild trout naturally reproduce in the stream from its headwaters downstream to its mouth. White Brook

702-410: The upper reaches of the stream's watershed. These are maintained via flagging and removal of brush and trees. right bank In geography , a bank is the land alongside a body of water . Different structures are referred to as banks in different fields of geography, as follows. In limnology (the study of inland waters), a stream bank or river bank is the terrain alongside the bed of

729-700: Was entered into the Geographic Names Information System on August 2, 1979. Its identifier in the Geographic Names Information System is 1199780. Since 2000, a streambank stabilization project has been done on White Brook. White Brook is in Pennsylvania State Game Lands Number 57 . An old, unmarked steep trail follows the stream up to a "beautiful" vista at Flat Top. Some all-terrain vehicle trails are present in

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