Horn Pond is a 227-acre (92 ha) water body located on the border of Acton, Maine , and Wakefield, New Hampshire , in the United States. The lake is both spring-fed and fed by the outflows of Great East Lake to the north and Wilson Lake to the east. Horn Pond's outlet is the Salmon Falls River which forms a natural border between Maine and New Hampshire and empties into the Piscataqua River east of Dover, New Hampshire , and ultimately the Gulf of Maine .
41-534: Horn Pond is classified as "Potentially Non-supporting" under the New Hampshire Department of Environmental Services' revised water quality standards for oligotrophic lakes. The Horn Pond watershed covers 1,139 acres (461 ha) that is primarily forested (70%). Only 6% of the watershed is developed, with 34% buildable area. The shoreline of Horn Pond is composed primarily of low density houses and camps (51%) and undeveloped shoreline (44%). 70% of
82-548: A tropical rainforest and produces some of the most spectacular wildflowers in the world. It is however, severely threatened by climate change which has moved the winter rain belt south, and also by clearing for agriculture and through use of fertilizers , which is primarily driven by low land costs which make farming economic even with yields a fraction of those in Europe or North America. An example of oligotrophic soils are those on white-sands, with soil pH lower than 5.0, on
123-476: A large abundance of psychrophiles that are well adapted to living in an Antarctic biome. Most oligotrophs live in lakes where water helps support biochemical processes for growth and survival. Below are some documented examples of oligotrophic environments in Antarctica: Lake Vostok , a freshwater lake which has been isolated from the world beneath 4 km (2.5 mi) of Antarctic ice
164-475: A large fraction of the planetary surface experiences temperatures lower than 10 °C. They are present in permafrost , polar ice, glaciers , snowfields and deep ocean waters. These organisms can also be found in pockets of sea ice with high salinity content. Microbial activity has been measured in soils frozen below −39 °C. In addition to their temperature limit, psychrophiles must also adapt to other extreme environmental constraints that may arise as
205-443: A method for adapting to the cold; the flexibility of their enzyme structure will increase as a way to compensate for the freezing effect of their environment. Certain cryophiles, such as Gram-negative bacteria Vibrio and Aeromonas spp., can transition into a viable but nonculturable (VBNC) state. During VBNC, a micro-organism can respire and use substrates for metabolism – however, it cannot replicate. An advantage of this state
246-512: A result of their habitat. These constraints include high pressure in the deep sea, and high salt concentration on some sea ice. Psychrophiles are protected from freezing and the expansion of ice by ice-induced desiccation and vitrification (glass transition), as long as they cool slowly. Free living cells desiccate and vitrify between −10 °C and −26 °C. Cells of multicellular organisms may vitrify at temperatures below −50 °C. The cells may continue to have some metabolic activity in
287-844: A supercooled state, but die at their supercooling point. Freeze tolerant insects can survive ice crystal formation within their body at sub-freezing temperatures. Freeze tolerance within insects is argued to be on a continuum, with some insect species exhibiting partial (e.g., Tipula paludosa , Hemideina thoracica ), moderate (e.g., Cryptocercus punctulatus ), and strong freezing tolerance (e.g., Eurosta solidaginis and Syrphus ribesii ) , and other insect species exhibiting freezing tolerance with low supercooling point (e.g., Pytho deplanatus ). In 1940, ZoBell and Conn stated that they had never encountered "true psychrophiles" or organisms that grow best at relatively low temperatures. In 1958, J. L. Ingraham supported this by concluding that there are very few or possibly no bacteria that fit
328-590: A wide range of low temperature. In addition, the DNA repairing machinery in Actinomycetota protects them from lethal DNA mutation at low temperature. Psychrophile Psychrophiles or cryophiles (adj. psychrophilic or cryophilic ) are extremophilic organisms that are capable of growth and reproduction in low temperatures, ranging from −20 °C (−4 °F) to 20 °C (68 °F). They are found in places that are permanently cold, such as
369-474: Is 8.0 parts per billion (ppb) and the mean transparency is 6.6 m (21.7 ft). The Horn Pond Association has been recently redeveloped and aims to protect and improve the water quality of Horn Pond. The lake is classified as a warm- and coldwater fishery and contains brook trout , rainbow trout , brown trout , largemouth and smallmouth bass , Eastern chain pickerel , brown bullhead , white perch and bluegill . Oligotroph An oligotroph
410-505: Is a genus of fungi found in a wide range of environments including extreme cold. Among the psychrophile insects, the Grylloblattidae or ice crawlers, found on mountaintops, have optimal temperatures between 1–4 °C. The wingless midge (Chironomidae) Belgica antarctica can tolerate salt, being frozen and strong ultraviolet, and has the smallest known genome of any insect. The small genome , of 99 million base pairs ,
451-548: Is an organism that can live in an environment that offers very low levels of nutrients . They may be contrasted with copiotrophs , which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates of metabolism, and generally low population density. Oligotrophic environments are those that offer little to sustain life. These environments include deep oceanic sediments, caves, glacial and polar ice, deep subsurface soil, aquifers, ocean waters, and leached soils. Examples of oligotrophic organisms are
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#1732793091468492-467: Is frequently held to be a primary example of an oligotrophic environment. Analysis of ice samples showed ecologically separated microenvironments. Isolation of microorganisms from each microenvironment led to the discovery of a wide range of different microorganisms present within the ice sheet. Traces of fungi have also been observed which suggests potential for unique symbiotic interactions. The lake’s extensive oligotrophy has led some to believe parts of
533-520: Is low, and remobilise them when demand increases. Oligotrophs occupy environments where the available nutrients offer little to sustain life. The term “ oligotrophic ” is commonly used to describe terrestrial and aquatic environments with very low concentrations of nitrates, iron, phosphates, and carbon sources. Oligotrophs have acquired survival mechanisms that involve the expression of genes during periods of low nutrient conditions, which has allowed them to find success in various environments. Despite
574-443: Is reduced by very slow growth rates, and by efficient use of low-availability nutrients; for example, the use of highly available ions to maintain turgor pressure , with low-availability nutrients reserved for the building of tissues. Despite these adaptations, nutrient requirement typically exceed uptake during the growing season, so many oligotrophic plants have the ability to store nutrients, for example, in trunk tissues, when demand
615-476: Is that it is highly reversible. It has been debated whether VBNC is an active survival strategy or if eventually the organism's cells will no longer be able to be revived. There is proof however it may be very effective – Gram positive bacteria Actinobacteria have been shown to have lived about 500,000 years in the permafrost conditions of Antarctica, Canada, and Siberia. Psychrophiles include bacteria, lichens, snow algae, phytoplankton, fungi, and insects. Among
656-476: Is the presence of fungi, because Collimonas have the ability of not only hydrolyzing the chitin produced by fungi for nutrients, but also producing materials (e.g., P. fluorescens 2-79) to protect themselves from fungal infection. The mutual relationship is common in the oligotrophic environments. Additionally, Collimonas can also obtain electron sources from rocks and minerals by weathering . In terms of polar areas, such as Antarctic and Arctic region,
697-399: Is thought to be adaptive to extreme environments. Psychrotrophic microbes are able to grow at temperatures below 7 °C (44.6 °F), but have better growth rates at higher temperatures. Psychrotrophic bacteria and fungi are able to grow at refrigeration temperatures, and can be responsible for food spoilage and as foodborne pathogens such as Yersinia . They provide an estimation of
738-704: The Chironomidae family are still active at −16 °C. Microalgae that live in snow and ice include green, brown, and red algae. Snow algae species such as Chloromonas sp. , Chlamydomonas sp. , and Chlorella sp. are found in polar environments. Some phytoplankton can tolerate extremely cold temperatures and high salinities that occur in brine channels when sea ice forms in polar oceans. Some examples are diatoms like Fragilariopsis cylindrus , Nitzchia lecointeii , Entomoneis kjellmanii , Nitzchia stellata , Thalassiosira australis , Berkelaya adeliense , and Navicula glaciei . Penicillium
779-518: The Cambrian and there has been no glaciation to renew soils since the Carboniferous . Thus, soils are extremely nutrient-poor and most vegetation must use strategies such as cluster roots to gain even the smallest quantities of such nutrients as phosphorus and sulfur . The vegetation in these regions, however, is remarkable for its biodiversity , which in places is as great as that of
820-582: The Rio Negro basin on northern Amazonia that house very low-diversity, extremely fragile forests and savannahs drained by blackwater rivers ; dark water colour due to high concentration of tannins , humic acids and other organic compounds derived from the very slow decomposition of plant matter. Similar forests are found in the oligotrophic waters of the Patía River delta on the Pacific side of
861-639: The Andes. In the ocean , the subtropical gyres north and south of the equator are regions in which the nutrients required for phytoplankton growth (for instance, nitrate , phosphate and silicic acid ) are strongly depleted all year round. These areas are described as oligotrophic and exhibit low surface chlorophyll . They are occasionally described as "ocean deserts". The oligotrophic soil environments include agricultural soil, frozen soil, et cetera . Various factors, such as decomposition , soil structure, fertilization and temperature , can affect
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#1732793091468902-596: The RecBCD enzyme are essential for physiological activities of the enzyme in the Antarctic Pseudomonas syringae , namely, repairing of DNA damage and supporting the growth at low temperature. The RecBCD enzymes are exchangeable between the psychrophilic P. syringae and the mesophilic E. coli when provided with the entire protein complex from same species. However, the RecBC proteins (RecBCPs and RecBCEc) of
943-623: The bacteria that can tolerate extreme cold are Arthrobacter sp., Psychrobacter sp. and members of the genera Halomonas , Pseudomonas , Hyphomonas , and Sphingomonas . Another example is Chryseobacterium greenlandensis , a psychrophile that was found in 120,000-year-old ice. Umbilicaria antarctica and Xanthoria elegans are lichens that have been recorded photosynthesizing at temperatures ranging down to −24 °C, and they can grow down to around −10 °C. Some multicellular eukaryotes can also be metabolically active at sub-zero temperatures, such as some conifers; those in
984-607: The capability to live in low nutrient concentrations, oligotrophs may find difficulty surviving in nutrient-rich environments. The presence of excess nutrients overwhelm oligotroph's metabolic systems, which cause them to struggle to regulate nutrient uptake. For example, oligotroph's enzymes function well in low nutrient environments, but struggle in high nutrient environments. Antarctic environments offer very little to sustain life as most organisms are not well adapted to live under nutrient-limiting conditions and cold temperatures (lower than 5 °C). As such, these environments display
1025-401: The cardinal temperatures for their isolates. The similarity between these two is that they are both capable of growing at zero, but optimum and upper temperature limits for the growth are lower for psychrophiles compared to psychrotrophs. Psychrophiles are also more often isolated from permanently cold habitats compared to psychrotrophs. Although psychrophilic enzymes remain under-used because
1066-781: The cave-dwelling olm ; the bacterium " Candidatus Pelagibacter communis ", which is the most abundant organism in the ocean (with an estimated 2 × 10 individuals in total); and lichens , with their extremely low metabolic rate . Etymologically , the word "oligotroph" is a combination of the Greek adjective oligos (ὀλίγος) meaning "few" and the adjective trophikos (τροφικός) meaning "feeding". Plant adaptations to oligotrophic soils provide for greater and more efficient nutrient uptake, reduced nutrient consumption, and efficient nutrient storage. Improvements in nutrient uptake are facilitated by root adaptations such as nitrogen-fixing root nodules , mycorrhizae and cluster roots . Consumption
1107-606: The cold ocean waters near Antarctica often have very high protein content, containing some of the highest concentrations ever measured of enzymes like Rubisco . Insects that are psychrotrophic can survive cold temperatures through several general mechanisms (unlike opportunistic and chill susceptible insects): (1) chill tolerance, (2) freeze avoidance, and (3) freeze tolerance. Chill tolerant insects succumb to freezing temperatures after prolonged exposure to mild or moderate freezing temperatures. Freeze avoiding insects can survive extended periods of time at sub-freezing temperatures in
1148-479: The extracellular fluid down to these temperatures, and they remain viable once restored to normal temperatures. They must also overcome the stiffening of their lipid cell membrane, as this is important for the survival and functionality of these organisms. To accomplish this, psychrophiles adapt lipid membrane structures that have a high content of short, unsaturated fatty acids . Compared to longer saturated fatty acids, incorporating this type of fatty acid allows for
1189-527: The lake are completely sterile. This lake is a helpful tool for simulating studies regarding extraterrestrial life on frozen planets and other celestial bodies. Crooked Lake is an ultra-oligotrophic glacial lake with a thin distribution of heterotrophic and autotrophic microorganisms. The microbial loop plays a big role in cycling nutrients and energy within this lake, despite particularly low bacterial abundance and productivity in these environments. The little ecological diversity can be attributed to
1230-536: The lake's low annual temperatures. Species discovered in this lake include Ochromonas , Chlamydomonas , Scourfeldia , Cryptomonas , Akistrodesmus falcatus , and Daphniopsis studeri (a microcrustacean). It is proposed that low competitive selection against Daphniopsis studeri has allowed the species to survive long enough to reproduce in nutrient limiting environments. The sandplains and lateritic soils of southern Western Australia , where an extremely thick craton has precluded any geological activity since
1271-588: The lipid cell membrane to have a lower melting point, which increases the fluidity of the membranes. In addition, carotenoids are present in the membrane, which help modulate the fluidity of it. Antifreeze proteins are also synthesized to keep psychrophiles' internal space liquid, and to protect their DNA when temperatures drop below water's freezing point. By doing so, the protein prevents any ice formation or recrystallization process from occurring. The enzymes of these organisms have been hypothesized to engage in an activity-stability-flexibility relationship as
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1312-406: The nutrient-availability in the soil environments. Generally, the nutrient becomes less available along the depth of the soil environment, because on the surface, the organic compounds decomposed from the plant and animal debris are consumed quickly by other microbes, resulting in the lack of nutrient in the deeper level of soil. In addition, the metabolic waste produced by the microorganisms on
1353-582: The polar regions and the deep sea. They can be contrasted with thermophiles , which are organisms that thrive at unusually high temperatures, and mesophiles at intermediate temperatures. Psychrophile is Greek for 'cold-loving', from Ancient Greek ψυχρός ( psukhrós ) 'cold, frozen'. Many such organisms are bacteria or archaea , but some eukaryotes such as lichens , snow algae , phytoplankton , fungi, and wingless midges , are also classified as psychrophiles. The cold environments that psychrophiles inhabit are ubiquitous on Earth, as
1394-800: The product's shelf life, but also they can be found in soils, in surface and deep sea waters, in Antarctic ecosystems, and in foods. Psychrotrophic bacteria are of particular concern to the dairy industry . Most are killed by pasteurization ; however, they can be present in milk as post-pasteurization contaminants due to less than adequate sanitation practices. According to the Food Science Department at Cornell University , psychrotrophs are bacteria capable of growth at temperatures at or less than 7 °C (44.6 °F). At freezing temperatures, growth of psychrotrophic bacteria becomes negligible or virtually stops. All three subunits of
1435-430: The snow surface covering land, glaciers, or sea ice when there is sufficient light. These snow algae darken the surface of the snow and can contribute to snow melt. In seawater, phytoplankton that can tolerate both very high salinities and very cold temperatures are able to live in sea ice. One example of a psychrophilic phytoplankton species is the ice-associated diatom Fragilariopsis cylindrus . Phytoplankton living in
1476-403: The soil environment is considered as oligotrophic because the soil is frozen with low biological activities. The most abundant species in the frozen soil are Actinomycetota , Pseudomonadota , Acidobacteriota and Cyanobacteria , together with a small amount of archaea and fungi. Actinomycetota can maintain the activity of their metabolic enzymes and continue their biochemical reactions under
1517-430: The soil provides the alternative sources for the species living in the oligotrophic soil. In terms of the agricultural lands, the application of fertilizer has a complicated impact on the source of carbon, either increasing or decreasing the organic carbon in the soil. Collimonas is one of the genera that are capable of living in the oligotrophic soil. One common feature of the environments where Collimonas lives
1558-409: The structures along the shoreline are within 50 feet (15 m) of the water's edge. Horn Pond water quality monitoring has been collected since 1982. During this period, 11 years of secchi disk transparency data, 7 years of total phosphorus (TP) data, 2 years of chlorophyll -a (Chl-a) data, and 5 years of dissolved oxygen (DO) data has been collected. From this data, the median TP concentration
1599-410: The surface also causes the accumulation of toxic chemicals in the deeper area. Furthermore, oxygen and water are important for some metabolic pathways, but it is difficult for water and oxygen to diffuse as the depth increases. Some factors such as: soil aggregates, pores and extracellular enzymes, may help water, oxygen and other nutrients diffuse into the soil. Moreover, the presence of mineral under
1640-428: The textbook definitions of psychrophiles. Richard Y. Morita emphasizes this by using the term psychrotroph to describe organisms that do not meet the definition of psychrophiles. The confusion between the terms psychrotrophs and psychrophiles was started because investigators were unaware of the thermolability of psychrophilic organisms at the laboratory temperatures. Due to this, early investigators did not determine
1681-740: The two bacteria are not equivalent; the RecBCEc is proficient in DNA recombination and repair, and supports the growth of P. syringae at low temperature, while RecBCPs is insufficient for these functions. Finally, both helicase and nuclease activity of the RecBCDPs are although important for DNA repair and growth of P. syringae at low temperature, the RecB-nuclease activity is not essential in vivo. Microscopic algae that can tolerate extremely cold temperatures can survive in snow, ice, and very cold seawater. On snow, cold-tolerant algae can bloom on