The Pamet River is a 4.2-mile-long (6.8 km) river in Truro, Massachusetts on Cape Cod . It is named for the Paomet tribe.
97-497: The river is primarily salt marsh , flows west nearly all the way across Cape Cod from its eastern beaches, and empties into Cape Cod Bay . It lies a few miles south of the Little Pamet River . The upper Pamet River is made up of a freshwater marsh . The marsh occupies the broad floor of the upper Pamet River valley. Originally, 12,000–13,000 years ago, this was the glacial outwash channel that drained water away from
194-640: A Geographic Information Systems polygon shapefile. This estimate is at the relatively low end of previous estimates (2.2–40 Mha). A later study conservatively estimated global saltmarsh extent as 90,800 km (9,080,000 hectares). The most extensive saltmarshes worldwide are found outside the tropics, notably including the low-lying, ice-free coasts, bays and estuaries of the North Atlantic which are well represented in their global polygon dataset. The formation begins as tidal flats gain elevation relative to sea level by sediment accretion , and subsequently
291-423: A coastal 'wasteland' has since changed, acknowledging that they are one of the most biologically productive habitats on earth, rivalling tropical rainforests . Salt marshes are ecologically important, providing habitats for native migratory fish and acting as sheltered feeding and nursery grounds. They are now protected by legislation in many countries to prevent the loss of these ecologically important habitats. In
388-522: A favorable habitat for them due to the low oxygen content and high levels of light present, optimizing their photosynthesis. In anoxic environments, like salt marshes, many microbes have to use sulfate as an electron acceptor during cellular respiration instead of oxygen, producing lots of hydrogen sulfide as a byproduct. While hydrogen sulfide is toxic to most organisms, purple bacteria require it to grow and will metabolize it to either sulfate or sulfur, and by doing so allowing other organisms to inhabit
485-435: A large amount of organic matter and are full of decomposition, which feeds a broad food chain of organisms from bacteria to mammals. Many of the halophytic plants such as cordgrass are not grazed at all by higher animals but die off and decompose to become food for micro-organisms, which in turn become food for fish and birds. The factors and processes that influence the rate and spatial distribution of sediment accretion within
582-426: A large role in the aquatic food web and the delivery of nutrients to coastal waters. They also support terrestrial animals and provide coastal protection . Salt marshes have historically been endangered by poorly implemented coastal management practices, with land reclaimed for human uses or polluted by upstream agriculture or other industrial coastal uses. Additionally, sea level rise caused by climate change
679-465: A larger area, being less concentrated, and also travels a longer distance through the Earth's atmosphere in which it may be absorbed, scattered or reflected, which is the same thing that causes winters to be colder than the rest of the year except in tropical regions. The axial tilt of the Earth has the most effect on climate of the polar regions due to its latitude. However, since the polar regions are
776-433: A likely response to the increased nutrient value of the leaves of fertilised Spartina densiflora plots, compared to non-fertilised plots. Regardless of whether the plots were fertilised or not, grazing by Neohelice granulata also reduced the length specific leaf growth rates of the leaves in summer, while increasing their length-specific senescence rates. This may have been assisted by the increased fungal effectiveness on
873-671: A major role in the salt marsh area. Salt marshes can suffer from dieback in the high marsh and die-off in the low marsh. A study published in 2022 estimates that 22% of saltmarsh loss from 1999-2019 was due to direct human drivers, defined as observable activities occurring at the location of the detected change, such as conversion to aquaculture, agriculture, coastal development, or other physical structures. Additionally, 30% of saltmarsh gain over this same time period were also due to direct drivers, such as restoration activities or coastal modifications to promote tidal exchange. Reclamation of land for agriculture by converting marshland to upland
970-407: A monoculture of the smooth cordgrass , Spartina alterniflora dominate, then heading landwards, zones of the salt hay, Spartina patens , black rush, Juncus gerardii and the shrub Iva frutescens are seen respectively. These species all have different tolerances that make the different zones along the marsh best suited for each individual. Plant species diversity is relatively low, since
1067-421: A pinnacle point where accommodation space was necessary for continued survival. The presence of accommodation space allows for new mid/high habitats to form, and for marshes to escape complete inundation. Earlier in the 20th century, it was believed that draining salt marshes would help reduce mosquito populations, such as Aedes taeniorhynchus , the black salt marsh mosquito. In many locations, particularly in
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#17327833447401164-527: A refuge for animals. Many marine fish use salt marshes as nursery grounds for their young before they move to open waters. Birds may raise their young among the high grasses, because the marsh provides both sanctuary from predators and abundant food sources which include fish trapped in pools, insects, shellfish, and worms. Saltmarshes across 99 countries (essentially worldwide) were mapped by Mcowen et al. 2017. A total of 5,495,089 hectares of mapped saltmarsh across 43 countries and territories are represented in
1261-405: A result of the degradation of the coastal food web in the region. The bare areas left by the intense grazing of cordgrass by Sesarma reticulatum at Cape Cod are suitable for occupation by another burrowing crab, Uca pugnax , which are not known to consume live macrophytes. The intense bioturbation of salt marsh sediments from this crab's burrowing activity has been shown to dramatically reduce
1358-447: A result, there are microhabitats populated by different species of flora and fauna dependent on their physiological abilities. The flora of a salt marsh is differentiated into levels according to the plants' individual tolerance of salinity and water table levels. Vegetation found at the water must be able to survive high salt concentrations, periodical submersion , and a certain amount of water movement, while plants further inland in
1455-411: Is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated by dense stands of salt-tolerant plants such as herbs , grasses , or low shrubs . These plants are terrestrial in origin and are essential to the stability of the salt marsh in trapping and binding sediments . Salt marshes play
1552-472: Is a common elevation (above the sea level) limit for these plants to survive, where anywhere below the optimal line would lead to anoxic soils due to constant submergence and too high above this line would mean harmful soil salinity levels due to the high rate of evapotranspiration as a result of decreased submergence. Along with the vertical accretion of sediment and biomass, the accommodation space for marsh land growth must also be considered. Accommodation space
1649-464: Is also dependent on other factors like productivity of the vegetation, sediment supply, land subsidence, biomass accumulation, and magnitude and frequency of storms. In a study published by Ü. S. N. Best in 2018, they found that bioaccumulation was the number one factor in a salt marsh's ability to keep up with SLR rates. The salt marsh's resilience depends upon its increase in bed level rate being greater than that of sea levels' increasing rate, otherwise
1746-542: Is correlated with sediment size: coarser sediments will deposit at higher elevations (closer to the creek) than finer sediments (further from the creek). Sediment size is also often correlated with particular trace metals, and thus tidal creeks can affect metal distributions and concentrations in salt marshes, in turn affecting the biota. Salt marshes do not however require tidal creeks to facilitate sediment flux over their surface although salt marshes with this morphology seem to be rarely studied. The elevation of marsh species
1843-541: Is endangering other marshes, through erosion and submersion of otherwise tidal marshes. However, recent acknowledgment by both environmentalists and larger society for the importance of saltwater marshes for biodiversity, ecological productivity and other ecosystem services , such as carbon sequestration , have led to an increase in salt marsh restoration and management since the 1980s. Salt marshes occur on low-energy shorelines in temperate and high-latitudes which can be stable, emerging, or submerging depending if
1940-498: Is important; those species at lower elevations experience longer and more frequent tidal floods and therefore have the opportunity for more sediment deposition to occur. Species at higher elevations can benefit from a greater chance of inundation at the highest tides when increased water depths and marsh surface flows can penetrate into the marsh interior. The coast is a highly attractive natural feature to humans through its beauty, resources, and accessibility. As of 2002, over half of
2037-416: Is in the fall. Thus seasonally, the abundance of chemolithotrophs in salt marshes is highest in autumn. Salt marshes are the ideal environment for sulfate-reducing bacteria. The sulfate-reducing bacteria tend to live in anoxic conditions, such as in salt marshes, because they require reduced compounds to produce their energy. Since there is a high sedimentation rate and a high amount of organic matter ,
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#17327833447402134-533: Is largely determined by the composition of plant species in the salt marsh ecosystem. Each type of salt-marsh plant has varying lengths of growing seasons , varying photosynthetic rates, and they all lose varying amounts of organic matter to the ocean, resulting in varying carbon-inputs to the ecosystem. The results from an experiment that was done in a salt marsh in the Yangtze estuary in China, suggested that both
2231-420: Is made accessible to the salt marsh food web largely through these bacterial communities which are then consumed by bacterivores . Bacteria are responsible for the degradation of up to 88% of lignocellulotic material in salt marshes. However, fungal populations have been found to dominate over bacterial populations in winter months. The fungi that make up the decomposition community in salt marshes come from
2328-464: Is measured in g m yr they are equalled only by tropical rainforests. Additionally, they can help reduce wave erosion on sea walls designed to protect low-lying areas of land from wave erosion. De-naturalisation of the landward boundaries of salt marshes from urban or industrial encroachment can have negative effects. In the Avon-Heathcote estuary/Ihutai, New Zealand, species abundance and
2425-423: Is microbial decomposition activity. Nutrient cycling in salt marshes is highly promoted by the resident community of bacteria and fungi involved in remineralizing organic matter. Studies on the decomposition of a salt marsh cordgrass, Spartina alterniflora , have shown that fungal colonization begins the degradation process, which is then finished by the bacterial community. The carbon from Spartina alterniflora
2522-614: Is not very marked; the Venetian Lagoon in Italy , for example, is made up of these sorts of animals and or living organisms belonging to this ecosystem. They have a big impact on the biodiversity of the area. Salt marsh ecology involves complex food webs which include primary producers (vascular plants, macroalgae, diatoms, epiphytes, and phytoplankton), primary consumers (zooplankton, macrozoa, molluscs, insects), and secondary consumers. The low physical energy and high grasses provide
2619-458: Is the land available for additional sediments to accumulate and marsh vegetation to colonize laterally. This lateral accommodation space is often limited by anthropogenic structures such as coastal roads, sea walls and other forms of development of coastal lands. A study by Lisa M. Schile, published in 2014, found that across a range of sea level rise rates, marshlands with high plant productivity were resistant against sea level rises but all reached
2716-605: Is the largest research station in Antarctica , run by the United States. Other notable stations include Palmer Station and Amundsen–Scott South Pole Station (United States), Esperanza Base and Marambio Base ( Argentina ), Scott Base ( New Zealand ), and Vostok Station (Russia). While there are no indigenous human cultures, there is a complex ecosystem, especially along Antarctica's coastal zones. Coastal upwelling provides abundant nutrients that feed krill ,
2813-480: Is the meandering, slow-flowing stream that flows from the Atlantic dunes at Ballston Beach west to the bay, with low, flat banks that lie just above the water table. The entire valley, fresh and salt, is underlain by a thick mat of peat derived from the original salt marshes. All plant species growing in this upper portion were brought in as seeds, mostly by birds and mammals. All are indigenous, and virtually none
2910-399: Is tolerant of seawater. MassWildlife has stocked the river with trout. U.S. Geological Survey Geographic Names Information System: Pamet River 41°59′30.82″N 70°4′46.21″W / 41.9918944°N 70.0795028°W / 41.9918944; -70.0795028 Salt marsh A salt marsh , saltmarsh or salting , also known as a coastal salt marsh or a tidal marsh ,
3007-757: The Arctic Ocean in the north, and by the Antarctic ice sheet on the continent of Antarctica and the Southern Ocean in the south. The Arctic has various definitions, including the region north of the Arctic Circle (currently Epoch 2010 at 66°33'44" N), or just the region north of 60° north latitude, or the region from the North Pole south to the timberline . The Antarctic is usually defined simply as south of 60° south latitude, or
Pamet River - Misplaced Pages Continue
3104-1157: The Camargue , France in the Rhône delta or the Ebro delta in Spain. They are also extensive within the rivers of the Mississippi River Delta in the United States . In New Zealand, most salt marshes occur at the head of estuaries in areas where there is little wave action and high sedimentation. Such marshes are located in Awhitu Regional Park in Auckland , the Manawatū Estuary , and the Avon Heathcote Estuary / Ihutai in Christchurch . Back-barrier marshes are sensitive to
3201-508: The Crenarchaeota group, AOB play a critical role within the salt marsh environment too. Increases in marsh salinity tend to favor AOB, while higher oxygen levels and lower carbon-to-nitrogen ratios favor AOA. These AOB are important in catalyzing the rate-limiting step within the nitrification process, by using ammonium monooxygenase (AMO), produced from amoA , to convert ammonium (NH4+) into nitrite (NO2-). Specifically, within
3298-570: The United States ( Alaska ), Canada ( Yukon , the Northwest Territories and Nunavut ), Denmark ( Greenland ), Norway , Finland , Sweden , Iceland , and Russia . Arctic circumpolar populations, though small, often share more in common with each other than with other populations within their national boundaries. As such, the northern polar region is diverse in human settlements and cultures. The southern polar region has no permanent human habitation as of now. McMurdo Station
3395-676: The mineralization of organic nitrogen compounds, to the process of nitrogen oxidation. Further, nitrogen oxidation is important for the downstream removal of nitrates into nitrogen gas, catalyzed by denitrifiers , from the marsh environment. Hence, AOB play an indirect role in nitrogen removal into the atmosphere. The bacterial photoautotroph community of salt marshes primarily consists of cyanobacteria , purple bacteria , and green sulfur bacteria . Cyanobacteria are important nitrogen fixers in salt marshes, and provide nitrogen to organisms like diatoms and microalgae. Oxygen inhibits photosynthesis in purple bacteria, which makes estuaries
3492-408: The sedimentation is greater, equal to, or lower than relative sea level rise ( subsidence rate plus sea level change), respectively. Commonly these shorelines consist of mud or sand flats (known also as tidal flats or abbreviated to mudflats ) which are nourished with sediment from inflowing rivers and streams. These typically include sheltered environments such as embankments, estuaries and
3589-641: The species richness and total abundance of sulfate-reducing bacterial communities increased when a new plant, S. alterniflora , with a higher C-input to the ecosystem was introduced. Although chemolithotrophs produce their own carbon, they still depend on the C-input from salt marshes because of the indirect impact it has on the amount of viable electron donors , such as reduced sulfur compounds. The concentration of reduced sulfur compounds, as well as other possible electron donors , increases with more organic-matter decomposition (by other organisms). Therefore if
3686-505: The Pamet, which is now only four miles long, compared to 30 miles (48 km) long thousands of years ago. This upper freshwater marsh dates from the middle 19th century, when, to promote agriculture, the saltwater tides were prevented from entering by means of a dike that traverses the valley where Truro Center Road (a former routing of US Route 6 ) now passes. A one-way clapper valve permitted fresh water to leave at low tide. The result
3783-589: The Plum Island estuary, Massachusetts (U.S.), stratigraphic cores revealed that during the 18th and 19th century the marsh prograded over subtidal and mudflat environments to increase in area from 6 km to 9 km after European settlers deforested the land upstream and increased the rate of sediment supply. The conversion of marshland to upland for agriculture has in the past century been overshadowed by conversion for urban development. Coastal cities worldwide have encroached onto former salt marshes and in
3880-554: The U.S. the growth of cities looked to salt marshes for waste disposal sites. Estuarine pollution from organic, inorganic, and toxic substances from urban development or industrialisation is a worldwide problem and the sediment in salt marshes may entrain this pollution with toxic effects on floral and faunal species. Urban development of salt marshes has slowed since about 1970 owing to growing awareness by environmental groups that they provide beneficial ecosystem services . They are highly productive ecosystems , and when net productivity
3977-535: The United States and Europe, they are now accorded a high level of protection by the Clean Water Act and the Habitats Directive respectively. With the impacts of this habitats and their importance now realised, a growing interest in restoring salt marshes through managed retreat or the reclamation of land has been established. However, many Asian countries such as China still need to recognise
Pamet River - Misplaced Pages Continue
4074-583: The abundance of fixed-nitrogen in these environments critically influences the distribution of the betaproteobacteria within the salt marsh: Nitrosomonas are more found to be in greater abundance within high N and C environments, whereas Nitrosospira are found to be more abundant in lower N and C regions. Further, factors such as temperature, pH, net primary productivity, and regions of anoxia may limit nitrification , and thus critically influence nitrifier distribution. The role of nitrification by AOB in salt marshes critically links ammonia , produced from
4171-419: The access of nutrients to other species. Their burrows provide an avenue for the transport of dissolved oxygen in the burrow water through the oxic sediment of the burrow walls and into the surrounding anoxic sediment, which creates the perfect habitat for special nitrogen cycling bacteria. These nitrate reducing (denitrifying) bacteria quickly consume the dissolved oxygen entering into the burrow walls to create
4268-420: The area expanding to lower marshes and becoming a dominant species. P. australis is an aggressive halophyte that can invade disturbed areas in large numbers outcompeting native plants. This loss in biodiversity is not only seen in flora assemblages but also in many animals such as insects and birds as their habitat and food resources are altered. Due to the melting of Arctic sea ice and thermal expansion of
4365-580: The bacteria can break down chitin into available carbon and nitrogen for plants to use. Actinobacteria have also been found in plant rhizosphere in costal salt marshes and help plants grow through helping plants absorb more nutrients and secreting antimicrobial compounds. In Jiangsu, China, Actinobacteria from the suborders Pseudonocardineae , Corynebacterineae , Propionibacterineae , Streptomycineae , Micromonosporineae , Streptosporangineae and Micrococcineae were cultured and isolated from rhizosphere soil. Another key process among microbial salt marshes
4462-585: The capability to keep pace with a rising sea level, by 2100, mean sea level could see increases between 0.6m to 1.1m. Marshes are susceptible to both erosion and accretion, which play a role in a what is called a bio-geomorphic feedback. Salt marsh vegetation captures sediment to stay in the system which in turn allows for the plants to grow better and thus the plants are better at trapping sediment and accumulate more organic matter. This positive feedback loop potentially allows for salt marsh bed level rates to keep pace with rising sea level rates. However, this feedback
4559-558: The class of Betaproteobacteria , Nitrosomonas aestuarii , Nitrosomonas marina , and Nitrosospira ureae are highly prevalent within the salt marsh environment; similarly, within the class of Gammaproteobacteria , Nitrosococcus spp. are key AOB in the marshes. The abundance of these chemolithoautotrophs varies along the salinity gradients present within salt marshes: Nitrosomonas are more prevalent within lower salinity or freshwater regions, while Nitrosospira are found to dominate in higher saline environments. In addition,
4656-419: The common inundation of marshlands. These types of plants are called halophytes. Halophytes are a crucial part of salt marsh biodiversity and their potential to adjust to elevated sea levels. With elevated sea levels, salt marsh vegetation would likely be more exposed to more frequent inundation rates and it must be adaptable or tolerant to the consequential increased salinity levels and anaerobic conditions. There
4753-515: The compacted agricultural soils acting as an aquiclude . Terrestrial soils of this nature need to adjust from fresh to saline interstitial water by a change in the chemistry and the structure of the soil, accompanied with fresh deposition of estuarine sediment, before salt marsh vegetation can establish. The vegetation structure, species richness, and plant community composition of salt marshes naturally regenerated on reclaimed agricultural land can be compared to adjacent reference salt marshes to assess
4850-595: The conditions of the sediment are usually dependably anoxic. However, the conditions all across the salt marsh (above the sediment) are not completely anoxic, which means the organisms living here must have some level of tolerance to oxygen. Many of the chemolithoautotrophs living outside or at the surface of the sediment also exhibit this characteristic. Sulfate-reducing bacteria play a significant role in nutrient recycling and in reducing nitrate pollution levels. Since humans have been adding disproportionate amounts of nitrates to coastal waters, salt marshes are one of
4947-507: The continent of Antarctica. The 1959 Antarctic Treaty uses the former definition. The two polar regions are distinguished from the other two climatic and biometric belts of Earth, a tropics belt near the equator, and two middle latitude regions located between the tropics and polar regions . Polar regions receive less intense solar radiation than the other parts of Earth because the Sun's energy arrives at an oblique angle , spreading over
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#17327833447405044-521: The cordgrass Spartina anglica was introduced from England into the Manawatū River mouth in 1913 to try and reclaim the estuary land for farming. A shift in structure from bare tidal flat to pastureland resulted from increased sedimentation and the cordgrass extended out into other estuaries around New Zealand. Native plants and animals struggled to survive as non-natives out competed them. Efforts are now being made to remove these cordgrass species, as
5141-600: The damages are slowly being recognized. In the Blyth estuary in Suffolk in eastern England, the mid-estuary reclamations (Angel and Bulcamp marshes) that were abandoned in the 1940s have been replaced by tidal flats with compacted soils from agricultural use overlain with a thin veneer of mud. Little vegetation colonisation has occurred in the last 60–75 years and has been attributed to a combination of surface elevations too low for pioneer species to develop, and poor drainage from
5238-435: The depth and duration of tidal flooding. As a result, competitive species that prefer higher elevations relative to sea level can inhabit the area and often a succession of plant communities develops. Coastal salt marshes can be distinguished from terrestrial habitats by the daily tidal flow that occurs and continuously floods the area. It is an important process in delivering sediments, nutrients and plant water supply to
5335-503: The ditches. Increased nitrogen uptake by marsh species into their leaves can prompt greater rates of length-specific leaf growth, and increase the herbivory rates of crabs. The burrowing crab Neohelice granulata frequents SW Atlantic salt marshes where high density populations can be found among populations of the marsh species Spartina densiflora and Sarcocornia perennis . In Mar Chiquita lagoon , north of Mar del Plata , Argentina , Neohelice granulata herbivory increased as
5432-436: The ecosystem contains more decomposing organic matter, as with plants with high photosynthetic and littering rates, there will be more electron donors available to the bacteria, and thus more sulfate reduction is possible. As a result, the abundance of sulfate-reducing bacteria increases. The high-photosynthetic-rate, high-litter-rate salt marsh plant, S. alterniflora, was discovered to withstand high sulfur concentrations in
5529-517: The ecosystems where nitrate pollution remains an issue. The enrichment of nitrates in the water increases denitrification , as well as microbial decomposition and primary productivity . Sulfate-reducing and oxidizing bacteria, however, play a role in removing the excess nitrates from the water to prevent eutrophication . Since the sulfate-reducing bacteria is in the water and sediment , reduced sulfur molecules are usually in abundance. These reduced sulfates then react with excess nitrate in
5626-462: The farthest from the equator , they receive the weakest solar radiation and are therefore generally frigid year round due to the earth's axial tilt of 23.5° not being enough to create a high maximum midday declination to sufficiently compensate the Sun's rays for the high latitude even in summer, except for relatively brief periods in peripheral areas near the polar circles. The large amount of ice and snow also reflects and weakens of what weak sunlight
5723-403: The flora must be tolerant of salt, complete or partial submersion, and anoxic mud substrate. The most common salt marsh plants are glassworts ( Salicornia spp.) and the cordgrass ( Spartina spp.), which have worldwide distribution. They are often the first plants to take hold in a mudflat and begin its ecological succession into a salt marsh. Their shoots lift the main flow of the tide above
5820-541: The glacier westward, northward and finally eastward into the Atlantic some distance from where Provincetown now lies. Sea level was then 300 to 400 feet (91 to 122 m) lower than it is today. There was no Cape Cod Bay, and Stellwagen Bank and the Grand Banks were hills well above the ocean. The subsequent rise of the Atlantic Ocean, which continues to this day, nearly drowned the outer Cape, including
5917-446: The human population as human-induced nitrogen enrichment enters these habitats. Nitrogen loading through human-use indirectly affects salt marshes causing shifts in vegetation structure and the invasion of non-native species. Human impacts such as sewage, urban run-off, agricultural and industrial wastes are running into the marshes from nearby sources. Salt marshes are nitrogen limited and with an increasing level of nutrients entering
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#17327833447406014-517: The land. It is important to note that restoration can often be sped up through the replanting of native vegetation. Polar region The polar regions , also called the frigid zones or polar zones , of Earth are Earth's polar ice caps , the regions of the planet that surround its geographical poles (the North and South Poles ), lying within the polar circles . These high latitudes are dominated by floating sea ice covering much of
6111-771: The leeward side of barrier islands and spits . In the tropics and sub-tropics they are replaced by mangroves ; an area that differs from a salt marsh in that instead of herbaceous plants , they are dominated by salt-tolerant trees. Most salt marshes have a low topography with low elevations but a vast wide area, making them hugely popular for human populations. Salt marshes are located among different landforms based on their physical and geomorphological settings. Such marsh landforms include deltaic marshes, estuarine, back-barrier, open coast, embayments and drowned-valley marshes. Deltaic marshes are associated with large rivers where many occur in Southern Europe such as
6208-766: The main role in nutrient cycling and biogeochemical processing. To date, the microbial community of salt marshes has not been found to change drastically due to human impacts, but the research is still ongoing. Because of the major role of microbes in these environments, it is critical to understand the different processes performed and different microbial players present in salt marshes. Salt marshes provide habitat for chemo(litho)autotrophs , heterotrophs , and photoautotrophs alike. These organisms contribute diverse environmental services such as sulfate reduction , nitrification , decomposition and rhizosphere interactions. Chemoautotrophs , also known as chemolithoautotrophs, are organisms capable of creating their own energy, from
6305-500: The marsh can sometimes experience dry, low-nutrient conditions. It has been found that the upper marsh zones limit species through competition and the lack of habitat protection, while lower marsh zones are determined through the ability of plants to tolerate physiological stresses such as salinity, water submergence and low oxygen levels. The New England salt marsh is subject to strong tidal influences and shows distinct patterns of zonation. In low marsh areas with high tidal flooding,
6402-424: The marsh canopy. Inundation and sediment deposition on the marsh surface is also assisted by tidal creeks which are a common feature of salt marshes. Their typically dendritic and meandering forms provide avenues for the tide to rise and flood the marsh surface, as well as to drain water, and they may facilitate higher amounts of sediment deposition than salt marsh bordering open ocean. Sediment deposition
6499-489: The marsh will be overtaken and drowned. Biomass accumulation can be measured in the form of above-ground organic biomass accumulation, and below-ground inorganic accumulation by means of sediment trapping and sediment settling from suspension. Salt marsh vegetation helps to increase sediment settling because it slows current velocities, disrupts turbulent eddies, and helps to dissipate wave energy. Marsh plant species are known for their tolerance to increased salt exposure due to
6596-449: The marsh. At higher elevations in the upper marsh zone, there is much less tidal inflow, resulting in lower salinity levels. Soil salinity in the lower marsh zone is fairly constant due to everyday annual tidal flow. However, in the upper marsh, variability in salinity is shown as a result of less frequent flooding and climate variations. Rainfall can reduce salinity and evapotranspiration can increase levels during dry periods. As
6693-466: The mud surface while their roots spread into the substrate and stabilize the sticky mud and carry oxygen into it so that other plants can establish themselves as well. Plants such as sea lavenders ( Limonium spp.), plantains ( Plantago spp.), and varied sedges and rushes grow once the mud has been vegetated by the pioneer species . Salt marshes are quite photosynthetically active and are extremely productive habitats. They serve as depositories for
6790-523: The mudflats); decreased with those species at the highest elevations, which experienced the lowest frequency and depth of tidal inundations; and increased with increasing plant biomass. Spartina alterniflora , which had the most sediment adhering to it, may contribute >10% of the total marsh surface sediment accretion by this process. Salt marsh species also facilitate sediment accretion by decreasing current velocities and encouraging sediment to settle out of suspension. Current velocities can be reduced as
6887-542: The natural tidal cycles are shifted due to land changes. The second option suggested by Bakker et al. (1997) is to restore the destroyed habitat into its natural state either at the original site or as a replacement at a different site. Under natural conditions, recovery can take 2–10 years or even longer depending on the nature and degree of the disturbance and the relative maturity of the marsh involved. Marshes in their pioneer stages of development will recover more rapidly than mature marshes as they are often first to colonize
6984-431: The northeastern United States, residents and local and state agencies dug straight-lined ditches deep into the marsh flats. The end result, however, was a depletion of killifish habitat. The killifish is a mosquito predator , so the loss of habitat actually led to higher mosquito populations, and adversely affected wading birds that preyed on the killifish. These ditches can still be seen, despite some efforts to refill
7081-558: The oceans, as a result of global warming, sea levels have begun to rise. As with all coastlines, this rise in water levels is predicted to negatively affect salt marshes, by flooding and eroding them. The sea level rise causes more open water zones within the salt marsh. These zones cause erosion along their edges, further eroding the marsh into open water until the whole marsh disintegrates. While salt marshes are susceptible to threats concerning sea level rise, they are also an extremely dynamic coastal ecosystem. Salt marshes may in fact have
7178-405: The oxic mud layer that is thinner than that at the mud surface. This allows a more direct diffusion path for the export of nitrogen (in the form of gaseous nitrogen (N 2 )) into the flushing tidal water. The variable salinity, climate, nutrient levels and anaerobic conditions of salt marshes provide strong selective pressures on the microorganisms inhabiting them. In salt marshes, microbes play
7275-467: The phylum ascomycota , the two most prevalent species being Phaeosphaeria spartinicola and Mycosphaerella sp. strain 2. In terms of bacteria, the alphaproteobacteria class is the most prevalent class within the salt marsh environment involved in decomposition activity. The propagation of Phaeosphaeria spartinicola is through ascospores that are released when the host plant is wetted by high tides or rain. The perception of bay salt marshes as
7372-459: The physical properties of the surrounding margins were strongly linked, and the majority of salt marsh was found to be living along areas with natural margins in the Avon / Ōtākaro and Ōpāwaho / Heathcote river outlets; conversely, artificial margins contained little marsh vegetation and restricted landward retreat. The remaining marshes surrounding these urban areas are also under immense pressure from
7469-505: The plant, although the exact mechanism has yet to be determined. Examining 16S ribosomal DNA found in Yangtze River Estuary, the most common bacteria in the rhizosphere were Proteobacteria such as Betaproteobacteria , Gammaproteobacteria , Deltaproteobacteria , and Epsilonproteobacteria . One such widespread species had a similar ribotype to the animal pathogen S. marcescens , and may be beneficial for plants as
7566-479: The polar regions receive further, contributing to the cold. Polar regions are characterized by extremely cold temperatures, heavy glaciation wherever there is sufficient precipitation to form permanent ice , short and still cold summers, and extreme variations in daylight hours, with twenty-four hours of daylight in summer, and complete darkness at mid-winter . There are many settlements in Earth's north polar region. Countries with claims to Arctic regions are:
7663-548: The process. They are very adapted to photosynthesizing in low light environments with bacteriochlorophyll pigments a, c, d, and e, to help them absorb wavelengths of light that other organisms cannot. When co-existing with purple bacteria, they often occupy lower depths as they are less tolerant to oxygen, but more photosynthetically adept. Some mycorrhizal fungi , like arbuscular mycorrhiza are widely associated with salt marsh plants and may even help plants grow in salt marsh soil rich in heavy metals by reducing their uptake into
7760-463: The rate and duration of tidal flooding decreases so that vegetation can colonize on the exposed surface. The arrival of propagules of pioneer species such as seeds or rhizome portions are combined with the development of suitable conditions for their germination and establishment in the process of colonisation. When rivers and streams arrive at the low gradient of the tidal flats, the discharge rate reduces and suspended sediment settles onto
7857-641: The reshaping of barriers in the landward side of which they have been formed. They are common along much of the eastern coast of the United States and the Frisian Islands . Large, shallow coastal embayments can hold salt marshes with examples including Morecambe Bay and Portsmouth in Britain and the Bay of Fundy in North America. Salt marshes are sometimes included in lagoons, and the difference
7954-412: The rising tide around their stems and leaves and form low muddy mounds which eventually coalesce to form depositional terraces, whose upward growth is aided by a sub-surface root network which binds the sediment. Once vegetation is established on depositional terraces further sediment trapping and accretion can allow rapid upward growth of the marsh surface such that there is an associated rapid decrease in
8051-415: The salt marsh are numerous. Sediment deposition can occur when marsh species provide a surface for the sediment to adhere to, followed by deposition onto the marsh surface when the sediment flakes off at low tide. The amount of sediment adhering to salt marsh species is dependent on the type of marsh species, the proximity of the species to the sediment supply, the amount of plant biomass, and the elevation of
8148-401: The soil, which would normally be somewhat toxic to plants. The abundance of chemolithoautotrophs in salt marshes also varies temporally as a result of being somewhat dependent on the organic C-input from plants in the ecosystem. Since plants grow most throughout the summer, and usually begin to lose biomass around fall during their late stage, the highest input of decomposing organic matter
8245-555: The species. For example, in a study of the Eastern Chongming Island and Jiuduansha Island tidal marshes at the mouth of the Yangtze River , China, the amount of sediment adhering to the species Spartina alterniflora , Phragmites australis , and Scirpus mariqueter decreased with distance from the highest levels of suspended sediment concentrations (found at the marsh edge bordering tidal creeks or
8342-406: The stems of tall marsh species induce hydraulic drag, with the effect of minimising re-suspension of sediment and encouraging deposition. Measured concentrations of suspended sediment in the water column have been shown to decrease from the open water or tidal creeks adjacent to the marsh edge, to the marsh interior, probably as a result of direct settling to the marsh surface by the influence of
8439-436: The success of Spartina alterniflora and Suaeda maritima seed germination and established seedling survival, either by burial or exposure of seeds, or uprooting or burial of established seedlings. However, bioturbation by crabs may also have a positive effect. In New Zealand, the tunnelling mud crab Helice crassa has been given the stately name of an 'ecosystem engineer' for its ability to construct new habitats and alter
8536-410: The success of marsh regeneration. Cultivation of land upstream from the salt marsh can introduce increased silt inputs and raise the rate of primary sediment accretion on the tidal flats, so that pioneer species can spread further onto the flats and grow rapidly upwards out of the level of tidal inundation. As a result, marsh surfaces in this regime may have an extensive cliff at their seaward edge. At
8633-497: The system from anthropogenic effects , the plant species associated with salt marshes are being restructured through change in competition. For example, the New England salt marsh is experiencing a shift in vegetation structure where S. alterniflora is spreading from the lower marsh where it predominately resides up into the upper marsh zone. Additionally, in the same marshes, the reed Phragmites australis has been invading
8730-423: The tidal flat surface, helped by the backwater effect of the rising tide. Mats of filamentous blue-green algae can fix silt and clay sized sediment particles to their sticky sheaths on contact which can also increase the erosion resistance of the sediments. This assists the process of sediment accretion to allow colonising species (e.g., Salicornia spp.) to grow. These species retain sediment washed in from
8827-450: The toxic environment. Purple bacteria can be further classified as either purple sulphur bacteria , or purple non-sulfur bacteria. Purple sulphur bacteria are more tolerant to sulfide and store the sulfur they create intracellularly, while purple non-sulfur bacteria excrete any sulfur they produce. Green sulfur bacteria ( Chlorobiaceae ) are photoautotrophic bacteria that utilize sulfide and thiosulfate for their growth, producing sulfate in
8924-1043: The use of inorganic molecules , and are able to thrive in harsh environments, such as deep sea vents or salt marshes, due to not depending upon external organic carbon sources for their growth and survival. Some Chemoautotrophic bacterial microorganisms found in salt marshes include Betaproteobacteria and Gammaproteobacteria , both classes including sulfate-reducing bacteria (SRB), sulfur-oxidizing bacteria (SOB), and ammonia-oxidizing bacteria (AOB) which play crucial roles in nutrient cycling and ecosystem functioning. Bacterial chemolithoautotrophs in salt marshes include sulfate-reducing bacteria. In these ecosystems, up to 50% of sedimentary remineralization can be attributed to sulfate reduction. The dominant class of sulfate-reducing bacteria in salt marshes tends to be Deltaproteobacteria. Some examples of deltaproteobacteria that are found in salt marshes are species of genera Desulfobulbus , Desulfuromonas , and Desulfovibrio . The abundance and diversity of chemolithoautotrophs in salt marshes
9021-511: The value of marshlands. With their ever-growing populations and intense development along the coast, the value of salt marshes tends to be ignored and the land continues to be reclaimed. Bakker et al. (1997) suggests two options available for restoring salt marshes. The first is to abandon all human interference and leave the salt marsh to complete its natural development. These types of restoration projects are often unsuccessful as vegetation tends to struggle to revert to its original structure and
9118-603: The water, reducing nitrate and oxidizing the reduced sulfur. As a result of human nitrate enrichment, it is predicted that sulfur-oxidizing bacteria which also reduce nitrates will increase in relative abundance to sulfur-reducing bacteria. Within salt marshes, chemolithoautotrophic nitrifying bacteria are also frequently identified, including Betaproteobacteria ammonia oxidizers such as Nitrosomonas and Nitrosospira . Although ammonia-oxidizing Archaea (AOA) are found to be more prevalent than ammonium-oxidizing Bacteria (AOB) within salt marsh environments, predominantly from
9215-536: The world's population was estimated to being living within 60 km of the coastal shoreline, making coastlines highly vulnerable to human impacts from daily activities that put pressure on these surrounding natural environments. In the past, salt marshes were perceived as coastal 'wastelands,' causing considerable loss and change of these ecosystems through land reclamation for agriculture, urban development, salt production and recreation. The indirect effects of human activities such as nitrogen loading also play
9312-475: The wounds left by the crabs. The salt marshes of Cape Cod , Massachusetts (US), are experiencing creek bank die-offs of Spartina spp. (cordgrass) that has been attributed to herbivory by the crab Sesarma reticulatum . At 12 surveyed Cape Cod salt marsh sites, 10% – 90% of creek banks experienced die-off of cordgrass in association with a highly denuded substrate and high density of crab burrows. Populations of Sesarma reticulatum are increasing, possibly as
9409-645: Was historically a common practice. Dikes were often built to allow for this shift in land change and to provide flood protection further inland. In recent times intertidal flats have also been reclaimed. For centuries, livestock such as sheep and cattle grazed on the highly fertile salt marsh land. Land reclamation for agriculture has resulted in many changes such as shifts in vegetation structure, sedimentation, salinity, water flow, biodiversity loss and high nutrient inputs. There have been many attempts made to eradicate these problems for example, in New Zealand,
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