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53-646: Sheshnag Lake ( Urdu pronunciation: [ʃeːʃnɑːɡ]  ; Kashmiri pronunciation: [ʃiːʃinaːɡ] ) is an alpine high elevation oligotrophic lake located in Anantnag district of Kashmir Valley in Jammu and Kashmir , India at an elevation of 3590 meters. It is situated on the track leading to the Amarnath cave , about 23 km from Pahalgam . It has a maximum length of 1.1 km and maximum width of 0.7 km. In ancient times, cloud bursts at

106-734: A comprehensive overview of alien aquatic plants in 46 European countries found 96 alien aquatic species. The aliens were primarily native to North America, Asia, and South America. The most spread alien plant in Europe was Elodea canadensis (Found in 41 European countries) followed by Azolla filiculoides in 25 countries and Vallisneria spiralis in 22 countries. The countries with the most recorded alien aquatic plant species were France and Italy with 30 species followed by Germany with 27 species, and Belgium and Hungary with 26 species. The European and Mediterranean Plant Protection Organization has published recommendations to European nations advocating

159-417: A food source. Examples include wild rice ( Zizania ), water caltrop ( Trapa natans ), Chinese water chestnut ( Eleocharis dulcis ), Indian lotus ( Nelumbo nucifera ), water spinach ( Ipomoea aquatica ), prickly waterlily ( Euryale ferox ), and watercress ( Rorippa nasturtium-aquaticum ). A decline in a macrophyte community may indicate water quality problems and changes in the ecological status of

212-457: A holomictic lake, during the fall, the cooling of the epilimnion reduces lake stratification, thereby allowing for mixing to occur. Winds aid in this process. Thus it is the deep mixing of lakes (which occurs most often during the fall and early winter, in holomictic lakes of the monomictic subtype) that allows oxygen to be transported from the epilimnion to the hypolimnion. In this way, oligotrophic lakes can have significant oxygen down to

265-503: A lack of pressure that terrestrial plants experience. Green algae are also known to have extremely thin cell walls due to their aquatic surroundings, and research has shown that green algae is the closest ancestor to living terrestrial and aquatic plants. Terrestrial plants have rigid cell walls meant for withstanding harsh weather, as well as keeping the plant upright as the plant resists gravity. Gravitropism, along with phototropism and hydrotropism, are traits believed to have evolved during

318-468: A nutrient-rich region with high net primary productivity may be naturally eutrophic. Nutrients carried into water bodies from non-point sources such as agricultural runoff, residential fertilisers, and sewage will all increase the algal biomass , and can easily cause an oligotrophic lake to become hypereutrophic. Although there is no absolute consensus as to which nutrients contribute the most to increasing primary productivity, phosphorus concentration

371-563: A rough estimate of biological condition of water bodies. Carlson's index was proposed by Robert Carlson in his 1977 seminal paper, "A trophic state index for lakes". It is one of the more commonly used trophic indices and is the trophic index used by the United States Environmental Protection Agency . The trophic state is defined as the total weight of biomass in a given water body at the time of measurement. Because they are of public concern,

424-818: A trek of 7  km upslope to reach the Sheshnag Lake. Amarnath Temple is situated 20 kilometers north of this lake. Oligotrophic lake The TSI of a water body is rated on a scale from zero to one hundred. Under the TSI scale, water bodies may be defined as: The quantities of nitrogen , phosphorus , and other biologically useful nutrients are the primary determinants of a water body's TSI. Nutrients such as nitrogen and phosphorus tend to be limiting resources in standing water bodies, so increased concentrations tend to result in increased plant growth, followed by corollary increases in subsequent trophic levels . Consequently, trophic index may sometimes be used to make

477-1002: A water body's trophic index should be. Aquatic plant Aquatic plants are vascular plants that have adapted to live in aquatic environments ( saltwater or freshwater ). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes ( phytoplanktons ). In lakes , rivers and wetlands , aquatic vegetations provide cover for aquatic animals such as fish , amphibians and aquatic insects , create substrate for benthic invertebrates , produce oxygen via photosynthesis , and serve as food for some herbivorous wildlife. Familiar examples of aquatic plants include waterlily , lotus , duckweeds , mosquito fern , floating heart , water milfoils , mare's tail , water lettuce and water hyacinth . Although seaweeds , which are large multicellular marine algae , have similar ecological functions to aquatic plants such as seagrass , they are not typically referred to as macrophytes as they lack

530-416: Is also applied to terrestrial habitats. Mesotrophic soils have moderate nutrient levels. A eutrophic water body, commonly a lake or pond, has high biological productivity. Due to excessive nutrients, especially nitrogen and phosphorus, these water bodies are able to support an abundance of aquatic plants. Usually, the water body will be dominated either by aquatic plants or algae. When aquatic plants dominate,

583-410: Is complete, the plant descends through the water column and the roots atrophy. In floating aquatic angiosperms, the leaves have evolved to only have stomata on the top surface to make use of atmospheric carbon dioxide. Gas exchange primarily occurs through the top surface of the leaf due to the position of the stomata, and the stomata are in a permanently open state. Due to their aquatic surroundings,

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636-667: Is frequently saturated , and are therefore a common component of swamps and marshlands . One of the largest aquatic plants in the world is the Bolivian waterlily , which holds the Guinness World Record of having the largest undivided leaf at 3.2 m (10 ft 6 in) diameter; the smallest is the rootless duckweed , which is only 1 mm (0.039 in) across. Many small animals use aquatic plants such as duckweeds and lily pads for spawning or as protective shelters against predators both from above and below

689-470: Is one of the famous tourist destinations in Kashmir Valley . It is mostly fed by melting of snow and streams coming down from mountaintops. It drains out through a stream that joins Lidder River at Pahalgam . Sheshnag Lake is situated 120 kilometers east from Srinagar and 23 km from Pahalgam . It can be accessed 113  km by road up to Chandanwari from which ponies can be hired to cover

742-443: Is sufficient for their needs. Anoxia is more common in the hypolimnion during the summer when mixing does not occur. In the absence of oxygen from the epilimnion, decomposition can cause hypoxia in the hypolimnion. Mesotrophic lakes are lakes with an intermediate level of productivity. These lakes are commonly clear water lakes and ponds with beds of submerged aquatic plants and medium levels of nutrients. The term mesotrophic

795-482: Is supported by the evidence that several of the earliest known fossil angiosperms were aquatic. Aquatic plants are phylogenetically well dispersed across the angiosperms , with at least 50 independent origins, although they comprise less than 2% of the angiosperm species. Archaefructus represents one of the oldest, most complete angiosperm fossils which is around 125 million years old. These plants require special adaptations for living submerged in water or floating at

848-456: Is thought to be the main limiting factor in freshwater lakes. This is likely due to the prevalence of nitrogen-fixing microorganisms in these systems, which can compensate for a lack of readily available fixed nitrogen. In some coastal marine ecosystems, research has found nitrogen to be the key limiting nutrient, driving primary production independently of phosphorus. Nitrogen fixation cannot adequately supply these marine ecosystems, because

901-590: Is usually classified as being in one of three possible classes: oligotrophic , mesotrophic or eutrophic . Lakes with extreme trophic indices may also be considered hyperoligotrophic or hypereutrophic (also "hypertrophic"). The table below demonstrates how the index values translate into trophic classes. Oligotrophic lakes generally host very little or no aquatic vegetation and are relatively clear, while eutrophic lakes tend to host large quantities of organisms, including algal blooms. Each trophic class supports different types of fish and other organisms, as well. If

954-718: The Carlson index uses the algal biomass as an objective classifier of a lake or other water body's trophic status. According to the US EPA, the Carlson Index should only be used with lakes that have relatively few rooted plants and non-algal turbidity sources. Because they tend to correlate, three independent variables can be used to calculate the Carlson Index: chlorophyll pigments , total phosphorus and Secchi depth . Of these three, chlorophyll will probably yield

1007-473: The Secchi depth. By translating the Secchi transparency values to a log base 2 scale, each successive doubling of biomass is represented as a whole integer index number. The Secchi depth, which measures water transparency, indicates the concentration of dissolved and particulate material in the water, which in turn can be used to derive the biomass. This relationship is expressed in the following equation: A lake

1060-493: The algal biomass in a lake or other water body reaches too high a concentration (say >80 TSI), massive fish die-offs may occur as decomposing biomass deoxygenates the water. Limnologists use the term " oligotrophic " or "hipotrophic" to describe lakes that have low primary productivity due to nutrient deficiency. (This contrasts against eutrophic lakes, which are highly productive due to an ample supply of nutrients, as can arise from human activities such as agriculture in

1113-432: The depth to which the aforementioned seasonal mixing occurs, but they will be oxygen deficient below this depth. Therefore, oligotrophic lakes often support fish species such as lake trout , which require cold, well- oxygenated waters. The oxygen content of these lakes is a function of their seasonally mixed hypolimnetic volume. Hypolimnetic volumes that are anoxic will result in fish congregating in areas where oxygen

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1166-412: The desired trophic index differs between stakeholders. Water-fowl enthusiasts (e.g. duck hunters) may want a lake to be eutrophic so that it will support a large population of waterfowl. Residents, though, may want the same lake to be oligotrophic, as this is more pleasant for swimming and boating. Natural resource agencies are generally responsible for reconciling these conflicting uses and determining what

1219-507: The distribution of aquatic plants is the availability of water. However, other abiotic factors may also control their distribution including nutrient availability, availability of carbon dioxide and oxygen, water temperature, characteristics of the substrate, water transparency, water movement, and salinity. Some aquatic plants are able to thrive in brackish, saline, and salt water . Also biotic factors like grazing, competition for light, colonization by fungi, and allelopathy are influencing

1272-698: The environment . Eutrophic comes from the Greek eutrophos meaning "well-nourished", from eu meaning good and trephein meaning "to nourish". Hypertrophic or hypereutrophic lakes are very nutrient-rich lakes characterized by frequent and severe nuisance algal blooms and low transparency. Hypereutrophic lakes have a visibility depth of less than 3 feet (90 cm), they have greater than 40 micrograms/litre total chlorophyll and greater than 100 micrograms/litre phosphorus . The excessive algal blooms can also significantly reduce oxygen levels and prevent life from functioning at lower depths creating dead zones beneath

1325-479: The important functions performed by macrophyte is uptake of dissolved nutrients including nitrogen and phosphorus. Macrophytes are widely used in constructed wetlands around the world to remove excess N and P from polluted water. Beside direct nutrient uptake, macrophytes indirectly influence nutrient cycling , especially N cycling through influencing the denitrifying bacterial functional groups that are inhabiting on roots and shoots of macrophytes. Macrophytes promote

1378-647: The leaves can photosynthesize more efficiently in air and competition from submerged plants but often, the main aerial feature is the flower and the related reproductive process. The emergent habit permits pollination by wind or by flying insects . There are many species of emergent plants, among them, the reed ( Phragmites ), Cyperus papyrus , Typha species, flowering rush and wild rice species. Some species, such as purple loosestrife , may grow in water as emergent plants but they are capable of flourishing in fens or simply in damp ground. Submerged macrophytes completely grow under water with roots attached to

1431-429: The leaves on the plant that grew while above water, along with oxygen levels being higher in the portion of the plant grown underwater versus the sections that grew in their terrestrial environment. This is considered a form of phenotypic plasticity as the plant, once submerged, experiences changes in morphology better suited to their new aquatic environment. However, while some terrestrial plants may be able to adapt in

1484-430: The leaves' thickness, shape and density and are the main factor responsible for the greatly reduced rate of gaseous transport across the leaf/water boundary and therefore greatly inhibit transport of carbon dioxide. To overcome this limitation, many aquatic plants have evolved to metabolise bicarbonate ions as a source of carbon. Environmental variables affect the instantaneous photosynthetic rates of aquatic plants and

1537-453: The lore and with it, the original, aboriginals inhabitants of Kashmir, the Nagas. The protagonist of this story was Nagrai, a Naga, the serpent king. Sheshnag Lake is home to many types of fish among which is the brown trout . It freezes during winter, and is inaccessible during this season due to heavy snowfall. It is surrounded by green lush meadows and mountains covered by snow. Sheshnag Lake

1590-440: The most accurate measures, as it is the most accurate predictor of biomass. Phosphorus may be a more accurate estimation of a water body's summer trophic status than chlorophyll if the measurements are made during the winter. Finally, the Secchi depth is probably the least accurate measure, but also the most affordable and expedient one. Consequently, citizen monitoring programs and other volunteer or large-scale surveys will often use

1643-438: The nitrogen fixing microbes are themselves limited by the availability of various abiotic factors like sunlight and dissolved oxygen. However, marine ecosystems are too broad a range of environments for one nutrient to limit all marine primary productivity. The limiting nutrient may vary in different marine environments according to a variety of factors like depth, distance from shore, or availability of organic matter. Often,

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1696-474: The occurrence of macrophytes. Aquatic plants have adapted to live in either freshwater or saltwater. Aquatic vascular plants have originated on multiple occasions in different plant families; they can be ferns or angiosperms (including both monocots and dicots ). The only angiosperms capable of growing completely submerged in seawater are the seagrasses . Examples are found in genera such as Thalassia and Zostera . An aquatic origin of angiosperms

1749-412: The photosynthetic enzymes pigments. In water, light intensity rapidly decreases with depth. Respiration is also higher in the dark per the unit volume of the medium they live in. Fully submerged aquatic plants have little need for stiff or woody tissue as they are able to maintain their position in the water using buoyancy typically from gas filled lacunaa or turgid Aerenchyma cells. When removed from

1802-563: The plants are not at risk of losing water through the stomata and therefore face no risk of dehydration. For carbon fixation, some aquatic angiosperms are able to uptake CO 2 from bicarbonate in the water, a trait that does not exist in terrestrial plants. Angiosperms that use HCO 3 - can keep CO 2 levels satisfactory, even in basic environments with low carbon levels. Due to their environment, aquatic plants experience buoyancy which counteracts their weight. Because of this, their cell covering are far more flexible and soft, due to

1855-514: The sedimentation of suspended solids by reducing the current velocities, impede erosion by stabilising soil surfaces. Macrophytes also provide spatial heterogeneity in otherwise unstructured water column. Habitat complexity provided by macrophytes tends to increase diversity and density of both fish and invertebrates. The additional site-specific macrophytes' value provides wildlife habitat and makes treatment systems of wastewater aesthetically satisfactory. Some aquatic plants are used by humans as

1908-426: The short-term to an aquatic habitat, it may not be possible to reproduce underwater, especially if the plant usually relies on terrestrial pollinators . Based on growth form, macrophytes can be characterised as: An emergent plant is one which grows in water but pierces the surface so that it is partially exposed to air. Collectively, such plants are emergent vegetation . This habit may have developed because

1961-530: The site caused a deep groove lined by mountains. Those mountains are covered with snow and ice sheets which melt slowly so that water flows into the deep groove and forms a lake. It was named Sheshnag because Sheshanaga (Śeṣanāga) is the nagaraja or King of all Nāgas and one of the primal beings of creation in Hinduism. An hour's drive away from Srinagar city lies a fabled spring from a popular Kashmiri folk tale, “ Himal and Nagrai ”. A stone marker there commemorates

2014-492: The specialized root / rhizoid system of plants. Instead, seaweeds have holdfasts that only serve as anchors and have no absorptive functions . Aquatic plants require special adaptations for prolonged inundation in water, and for floating at the water surface. The most common adaptation is the presence of lightweight internal packing cells, aerenchyma , but floating leaves and finely dissected leaves are also common. Aquatic plants only thrive in water or in soil that

2067-607: The stem and root of Ludwigia adscendens , as well as those of the fruit, leaf and stem of Monochoria hastata were found to have lipoxygenase inhibitory activity. Hot water extract prepared from the leaf of Ludwigia adscendens exhibits alpha-glucosidase inhibitory activity more potent than that of acarbose . Macrophytes have an essential role in some forms of wastewater treatment, most commonly in small scale sewage treatment using constructed wetlands or in polishing lagoons for larger schemes. The introduction of non-native aquatic plants has resulted in numerous examples across

2120-616: The substrate (e.g. Myriophyllum spicatum ) or without any root system (e.g. Ceratophyllum demersum ). Helophytes are plants that grow partly submerged in marshes and regrow from buds below the water surface. Fringing stands of tall vegetation by water basins and rivers may include helophytes. Examples include stands of Equisetum fluviatile , Glyceria maxima , Hippuris vulgaris , Sagittaria , Carex , Schoenoplectus , Sparganium , Acorus , yellow flag ( Iris pseudacorus ), Typha and Phragmites australis . Floating-leaved macrophytes have root systems attached to

2173-769: The substrate or bottom of the body of water and with leaves that float on the water surface. Common floating leaved macrophytes are water lilies (family Nymphaeaceae ), pondweeds (family Potamogetonaceae ). Free-floating macrophytes are found suspended on water surface with their root not attached to the substrate, sediment , or bottom of the water body. They are easily blown by air and provide breeding ground for mosquitoes. Examples include Pistia spp. commonly called water lettuce, water cabbage or Nile cabbage. The many possible classifications of aquatic plants are based upon morphology. One example has six groups as follows: Macrophytes perform many ecosystem functions in aquatic ecosystems and provide services to human society. One of

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2226-459: The surface of the water. Some still-water plants can alter their position in the water column at different seasons. One notable example is Water soldier which rests as a rootless rosette on the bottom of the water body but slowly floats to the surface in late Spring so that its inflorescence can emerge into the air. While it is ascending through the water column it produces roots and vegetative daughter plants by means of rhizomes . When flowering

2279-500: The surface. Although most aquatic angiosperms can reproduce by flowering and setting seeds, many have also evolved to have extensive asexual reproduction by means of rhizomes , turions , and fragments in general. Submerged aquatic plants have more restricted access to carbon as carbon dioxide compared to terrestrial plants. They may also experience reduced light levels. In aquatic plants diffuse boundary layers (DBLs) around submerged leaves and photosynthetic stems vary based on

2332-403: The surface. Likewise, large algal blooms can cause biodilution to occur, which is a decrease in the concentration of a pollutant with an increase in trophic level . This is opposed to biomagnification and is due to a decreased concentration from increased algal uptake. Both natural and anthropogenic factors can influence a lake or other water body's trophic index. A water body situated in

2385-443: The transition from an aquatic to terrestrial habitat. Terrestrial plants no longer had unlimited access to water and had to evolve to search for nutrients in their new surroundings as well as develop cells with new sensory functions, such as statocytes . Terrestrial plants may undergo physiological changes when submerged due to flooding. When submerged, new leaf growth has been found to have thinner leaves and thinner cell walls than

2438-689: The water body. Such problems may be the result of excessive turbidity , herbicides , or salination . Conversely, overly high nutrient levels may create an overabundance of macrophytes, which may in turn interfere with lake processing . Macrophyte levels are easy to sample, do not require laboratory analysis, and are easily used for calculating simple abundance metrics. Phytochemical and pharmacological researches suggest that freshwater macrophytes, such as Centella asiatica , Nelumbo nucifera , Nasturtium officinale , Ipomoea aquatica and Ludwigia adscendens , are promising sources of anticancer and antioxidative natural products. Hot water extracts of

2491-564: The water flow, capture sediments and trap pollutants . Excess sediment will settle into the stream bed due to the reduced flow rates, and some aquatic plants also have symbiotic microbes capable of nitrogen fixation and breaking down the pollutants trapped and/or absorbed by the roots. Historically, aquatic plants have been less studied than terrestrial plants , and management of aquatic vegetation has become an increasingly interested field as means to reduce agricultural pollution of water bodies . The principal factor controlling

2544-437: The water surface. Aquatic plants are important primary producers and are the basis of food web for many aquatic fauna , especially wetland species. They compete with phytoplanktons for excess nutrients such as nitrogen and phosphorus , thus reducing the prevalence of eutrophication and harmful algal blooms , and have a significant effect on riparian soil chemistry as their leaves , stems and roots slow down

2597-409: The water tends to be clear. When algae dominate, the water tends to be darker. The algae engage in photosynthesis which supplies oxygen to the fish and biota which inhabit these waters. Occasionally, an excessive algal bloom will occur and can ultimately result in fish death, due to respiration by algae and bottom-living bacteria. The process of eutrophication can occur naturally and by human impact on

2650-618: The water, such plants are typically limp and lose turgor rapidly. Those living in rivers do, however, need sufficient structural xylem to avoid being damaged by fast flowing water and they also need strong mechanisms of attachment to avoid being uprooted by river flow. Many fully submerged plants have finely dissected leaves, probably to reduce drag in rivers and to provide a much increased surface area for interchange of minerals and gasses. Some species of plants such as Ranunculus aquatilis have two different leaf forms with finely dissected leaves that are fully submerged and entire leaves on

2703-499: The watershed.) Oligotrophic lakes are most common in cold, sparsely developed regions that are underlain by crystalline igneous , granitic bedrock. Due to their low algal production, these lakes consequently have very clear waters, with high drinking-water quality. Lakes that have intermixing of their layers are classified into the category of holomictic , whereas lakes that do not have interlayer mixing are permanently stratified and thus are termed meromictic . Generally, in

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2756-419: The whole body of many ponds to the almost total exclusion of other plants and wildlife Other notable invasive plant species include floating pennywort , Curly leaved pondweed , the fern ally Water fern and Parrot's feather . Many of these invasive plants have been sold as oxygenating plants for aquaria or decorative plants for garden ponds and have then been disposed of into the environment. In 2012,

2809-416: The world of such plants becoming invasive and frequently dominating the environments into which they have been introduced. Such species include Water hyacinth which is invasive in many tropical and sub-tropical locations including much of the southern US, many Asian countries and Australia. New Zealand stonecrop is a highly invasive plant in temperate climates spreading from a marginal plant to encompassing

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