Lake Matano (Indonesian: Danau Matano), also known as Matana, is a tropical lake in East Luwu Regency, South Sulawesi province, Indonesia, that is noteworthy for the unique environment in its deeper layers.
| Matano | |
|---|---|
| Danau Matano (Indonesian) | |
 Lake Matano at sunset | |
  Matano  Matano | |
| Location | South Sulawesi, Indonesia |
| Coordinates | 2°29′7″S 121°20′0″E / 2.48528°S 121.33333°E |
| Type | Tectonic |
| Primary outflows | Penten River |
| Basin countries | Indonesia |
| Max. length | 28 km (17 mi)[1] |
| Max. width | 8 km (5.0 mi)[1] |
| Surface area | 164.1 km2 (63.4 sq mi) |
| Average depth | 240 m (790 ft) |
| Max. depth | 590 m (1,940 ft)[1] |
| Water volume | 39.38 km3 (9.45 cu mi) |
| Surface elevation | 382 m (1,253 ft)[1] |
With a depth of 590 m (1,940 ft), it is the deepest lake in Indonesia (ranked by maximum depth), the 11th deepest lake in the world and the deepest lake on an island by maximum depth. The surface elevation from mean sea level is only 382 m (1,253 ft), which means that the deepest portion of the lake is below sea level (cryptodepression). It is one of the two major lakes (the other being Lake Towuti) in the Malili Lake system.[1] Lake Matano is considered an ancient lake, and it formed in a tectonic graben around 1 to 2 million years ago.[2]
Lake Matano and its catchment area have a large amount of endemic flora and fauna. The catchment area's soils and rocks make it have a relatively high amount of iron. Because the temperature on Sulawesi Island does not change much during the year, the epilimnion never gets cold enough to mix with the hypolimnion. The environment in the hypolimnion is noteworthy for its possible similarity to oceans in the Archean and Paleoproterozoic Eons, before the Great Oxidation Event (GOE). The biogeochemical activity in the hypolimnion has been studied as a model for these oceans.
Environment
editCatchment
editThe catchment of Lake Matano is around 436 square kilometers, or around 2.7 times the surface area of the lake. The catchment consists of soils with an iron oxide/hydroxide content that can exceed 20%, explaining the high iron content of Lake Matano. A noteworthy amount of carbonate rocks are present south of the lake.[1] Every decade, around 2% of the catchment area of Lake Matano is deforested to generate new farmland. Farmland in the catchment could serve as a source of nutrients, possibly causing eutrophication. This could eventually disturb the unique environment of the lake and diminish endemic species. Lake Matano is already prone to receiving anthropogenic nitrogen from the atmosphere because of its geographic location.[2]
Climate and water cycling
editLake Matano is located in a tropical climate zone, and experiences two seasons, a wet and a dry season, with an approximately constant temperature year-round. Because of the constant environmental temperature, the water in the epilimnion cannot cool sufficiently for exchange with the hypolimnion. The relatively high concentration of total dissolved solids in the deeper layers increases their density, further preventing mixing of the layers. The density of the epilimnion, which extends to around 100 m below the surface, has been observed to increase during the dry season (though not to a sufficient extent for mixing), and increase during the wet season. Beneath the epilimnion, density is generally constant year-round.[1] Because the hypolimnion does not receive water from the epilimnion, the physical and chemical environment in the hypolimnion differs greatly from the environment in the epilimnion.[1][3]
Flora and fauna
editFlora
editFern
editA wide variety of fern species are present in the basin of Lake Matano. These species come from several families, such as Adiantaceae, Davalliaceae, Dennstaedtiaceae, and Schizaeaceae. Some, such as Schizaeaceae, are usually only found below the Wallace Line in places such as New Guinea. Others, including Adiantaceae, are usually only found above the Wallace Line in places like Borneo. Some species, such as Lindsea pellaeiformis, are likely endemic to Sulawesi Island, where Lake Matano is located.[4]
Diatoms
editRoughly a fifth of taxa of diatoms in Lake Matano are endemic; the greatest number of diatom species in the Malali Lake System belongs to the genus Surirella. While water from Lake Matano does flow via rivers to Lake Mahalona and Lake Towuti, such flow does not appear to spread diatoms from Lake Matano to these lakes, as the proportion of taxa each of these two lakes that are also in Lake Matano (roughly half) is the same as it is for Lake Masapi, another lake on Sulawesi disconnected from Lake Matano.[5] A few examples of taxa of diatom that are only in Lake Matano are Surirellla biseriata heteropolis, Surirella celebesiana matanensis,[6] and Gomphonema matanensis, which serves as an example of gigantism of diatoms.[7] Another endemic species is Cymbells distinguenda; it has been argued that this species may constitute a separate genus of diatoms.[8]
Fauna
editLake Matano is home to many species of endemic fish and other animals (e.g. Caridina shrimps,[9] Parathelphusid crabs[10] and Tylomelania snails[11]). The endemic fishes of Matano have been compared to the species swarms of the Rift Valley Lakes of Africa. While not as diverse, they are thought to have all arisen from a single ancestor species and diversified into numerous different species, which now fill many of the previously vacant ecological niches, as can be seen in the family Telmatherinidae.[12] Endemic and near-endemic fishes from other families include Glossogobius matanensis, Mugilogobius adeia, Nomorhamphus weberi and Oryzias matanensis. Many of the endemics are seriously threatened due to pollution and predation/competition from a wide range of introduced fishes, including flowerhorn cichlids.[13] The water snake Enhydris matannensis is only known from the vicinity of Lake Matano and on Muna Island.[14]
Microbial and biochemical activity
editBanded iron formations
edit
The environment in Lake Matano in the hypolimnion is considered comparable to the environment in the ocean in the Archean Eon, as well as in the beginning of the Proterozoic Eon, before the Great Oxidation Event (GOE). This is because these oceans, like Lake Matano, probably lacked sulfate and oxygen, and likely had a relatively high amount of Fe(II). Banded iron formations (BIFs), which have both Fe(II) and Fe(III), were deposited in such environments. The method of formation of Fe(III) in such environments is unclear; one possibility is photoferrotrophy. As in the pre-GOE oceans, there was low phosphate availability, limiting the amount of life the epilimnion can support. Because of this, there is sufficient radiation from the Sun for photosynthesis by green sulfur bacteria with Bacteriochlorophyll e, even at depths greater than 100 m. In an environment like Lake Matano, the photoferrotrophy of such bacteria is described by this equation:
![{\displaystyle {\ce {{HCO3^{-}}+{4Fe^{II}}+{10H2O}->[{light}][{}]{CH2O}+{4Fe(OH)3}+7H+}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/bc72f0b467153244b25c6cd7f7eb4440eace6c81)
The iron in the product would have an oxidation state of +3, potentially explaining the Fe(III) in BIFs.[15] Most Fe(III) is thought to be covered with Fe(II) rather than exposed to organisms for use.[3] However, a small amount of Fe(III), enough to consume a thirtieth of organic carbon, is reduced by microorganisms for respiration.[16]
Methane cycling
editMethane is virtually absent above roughly 105 m; its concentration then rises steadily until around 200 m before stabilizing at around 1.25 mmol/L. The amount of Carbon-14 in methane sampled from the lake suggests that the methane is only around 2 millennia old, and could not have been formed due to hydrothermal activity. The δ13C-CH4 in Lake Matano is around -70 permil, suggesting that the carbon in the methane likely came from an organism. Methanogenesis in Lake Matano under 110 m is anaerobic, and likely occurs from acetate metabolism, or from carbon dioxide reduction with H2. Any oxygen that would reach the anoxic zone would likely abiotically oxidize Fe(II), rather than methane. It is unclear how methane oxidation is able to occur at 122 m, as there is virtually no sulfate or nitrate. Coupling with catalyzed iron and manganese hydroxide reduction is one possibility.[3]
δ13C-CO2 is at around -8 permil below the epilimnion.The CO2 could be depleted to this extent because the carbon in this CO2 is coming from oxidation of the depleted CH4,[3] or because it has a hitherto unknown source.[16] It is more depleted at 104 m and 122 m, possibly suggesting biotic methane oxidation. An area of less depleted δ13C-CO2 at around 110 m may be due to CO2 metabolism by green sulfur bacteria.[3]
In oxic environments, such as those present in most modern ecosystems, methanogens are outcompeted for organic carbon to metabolize such that, each year, over 99% of organic carbon is not metabolized to methane. Because most of these competing organisms are aerobic, it is likely that such competition did not exist in the anoxic environments that were present before the GOE, and that are present in places like the hypolimnion in Lake Matano, to the same extent. Because of this relative lack of competition, more organic carbon is metabolized to methane. The percent metabolized to methane is unclear; amounts from 5-10%[17][16] to 80%[3] have been suggested.
See also
editReferences
edit- ^ a b c d e f g h Crowe, Sean A.; O’Neill, Andrew H.; Katsev, Sergei; Hehanussa, Peter; Haffner, G. Douglas; Sundby, Bjørn; Mucci, Alfonso; Fowle, David A. (January 2008). "The biogeochemistry of tropical lakes: A case study from Lake Matano, Indonesia". Limnology and Oceanography. 53 (1): 319–331. doi:10.4319/lo.2008.53.1.0319. hdl:1808/16958. ISSN 0024-3590.
- ^ a b Hampton, Stephanie E.; McGowan, Suzanne; Ozersky, Ted; Virdis, Salvatore G. P.; Vu, Tuong Thuy; Spanbauer, Trisha L.; Kraemer, Benjamin M.; Swann, George; Mackay, Anson W.; Powers, Stephen M.; Meyer, Michael F.; Labou, Stephanie G.; O'Reilly, Catherine M.; DiCarlo, Morgan; Galloway, Aaron W. E. (September 2018). "Recent ecological change in ancient lakes". Limnology and Oceanography. 63 (5): 2277–2304. doi:10.1002/lno.10938. ISSN 0024-3590.
- ^ a b c d e f Crowe, S. A.; Katsev, S.; Leslie, K.; Sturm, A.; Magen, C.; Nomosatryo, S.; Pack, M. A.; Kessler, J. D.; Reeburgh, W. S.; Roberts, J. A.; González, L.; Douglas Haffner, G.; Mucci, A.; Sundby, B.; Fowle, D. A. (January 2011). "The methane cycle in ferruginous Lake Matano". Geobiology. 9 (1): 61–78. doi:10.1111/j.1472-4669.2010.00257.x. PMID 20854329.
- ^ Hovenkamp, P.; De Joncheere, G. J. (1988). "Additions to the fern flora of Sulawesi". Blumea: Biodiversity, Evolution and Biogeography of Plants. 33 (2): 395–409.
- ^ Bramburger, Andrew J.; Hamilton, Paul B.; Hehanussa, Peter E.; Haffner, G. Douglas (2008). "Processes regulating the community composition and relative abundance of taxa in the diatom communities of the Malili Lakes, Sulawesi Island, Indonesia". Hydrobiologia. 615 (1): 215–224. doi:10.1007/s10750-008-9562-2. ISSN 0018-8158. S2CID 44194423.
- ^ Bramburger, Andrew J.; Haffner, G. Douglas; Hamilton, Paul B.; Hinz, Friedel; Hehanussa, Peter E. (2006). "AN EXAMINATION OF SPECIES WITHIN THE GENUS SURIRELLA FROM THE MALILI LAKES, SULAWESI ISLAND, INDONESIA, WITH DESCRIPTIONS OF 11 NEW TAXA". Diatom Research. 21 (1): 1–56. doi:10.1080/0269249X.2006.9705650. ISSN 0269-249X. S2CID 85145241.
- ^ Kociolek, John Patrick; Kapustin, Dmitry; Kulikovskiy, Maxim (3 April 2018). "A new, large species of Gomphonema Ehrenberg from ancient Lake Matano, Indonesia". Diatom Research. 33 (2): 241–250. doi:10.1080/0269249X.2018.1513868. ISSN 0269-249X. S2CID 91377564.
- ^ Kapustin, D.A.; Kulikovskiy, M.; Kociolek, J.P. (3 January 2018). "Celebesia gen. nov., a new cymbelloid diatom genus from the ancient Lake Matano (Sulawesi Island, Indonesia)". Nova Hedwigia, Beihefte. 146: 147–155. doi:10.1127/1438-9134/2017/147. ISSN 1438-9134.
- ^ von Rintelen, K., and Y. Cai (2009). Radiation of endemic species flocks in ancient lakes: systematic revision of the freshwater shrimp Caridina H. Milne Edwards, 1837 (Crustacea: Decapoda: Atyidae) from the ancient lakes Of Sulawesi, Indonesia, with the description of eight new species. Raffles Bulletin of Zoology 57: 343-452.
- ^ Chia, O. C. K. and Ng, P. K. L. (2006). The freshwater crabs of Sulawesi, with descriptions of two new genera and four new species (Crustacea: Decapoda: Brachyura: Parathelphusidae). Raffles Bulletin of Zoology Singapore 54: 381–428.
- ^ von Rintelen , T., K. von Rintelen, and M. Glaubrecht (2010). The species flock of the viviparous freshwater gastropod Tylomelania (Mollusca: Cerithioidea: Pachychilidae) in the ancient lakes of Sulawesi, Indonesia: the role of geography, trophic morphology and colour as driving forces in adaptive radiation. pp. 485-512 in: Glaubrecht, M., and H. Schneider, eds. (2010). Evolution in Action: Adaptive Radiations and the Origins of Biodiversity. Springer Verlag, Heidelberg, Germany.
- ^ Herder, F., J. Pfaender, and U.K. Schliewen (2008). Adaptive sympatric speciation of polychromatic "roundfin" sailfin silverside fish in Lake Matano (Sulawesi). Evolution 62(9): 2178-95
- ^ Herder, F., U.K. Schliewen, M.F. Geiger, R.K. Hadiaty, S.M. Gray, J.S. McKinnon, R.P. Walter and J. Pfaender (2012) Alien invasion in Wallace's Dreamponds: records of the hybridogenic “flowerhorn” cichlid in Lake Matano, with an annotated checklist of fish species introduced to the Malili Lakes system in Sulawesi. Aquatic Invasions 7(4): 521–535
- ^ Murphy, J. (2010). "Enhydris matannensis". IUCN Red List of Threatened Species. 2010: e.T176696A7285471. doi:10.2305/IUCN.UK.2010-4.RLTS.T176696A7285471.en.
- ^ a b Crowe, Sean A.; Jones, CarriAyne; Katsev, Sergei; Magen, Cédric; O'Neill, Andrew H.; Sturm, Arne; Canfield, Donald E.; Haffner, G. Douglas; Mucci, Alfonso; Sundby, Bjørn; Fowle, David A. (14 October 2008). "Photoferrotrophs thrive in an Archean Ocean analogue". Proceedings of the National Academy of Sciences. 105 (41): 15938–15943. doi:10.1073/pnas.0805313105. ISSN 0027-8424. PMC 2572968. PMID 18838679.
- ^ a b c Kuntz, L. B.; Laakso, T. A.; Schrag, D. P.; Crowe, S. A. (2015). "Modeling the carbon cycle in Lake Matano". Geobiology. 13 (5): 454–461. doi:10.1111/gbi.12141. PMID 25923883. S2CID 12350538.
- ^ Laakso, Thomas A.; Schrag, Daniel P. (15 September 2019). "Methane in the Precambrian atmosphere". Earth and Planetary Science Letters. 522: 48–54. doi:10.1016/j.epsl.2019.06.022. ISSN 0012-821X. S2CID 198414785.