nomes no trilho de navegação
Die Socorro-Assel (Thermosphaeroma thermophilum) ist eine nordamerikanische Süßwasserassel, die nur an einer warmen Quelle in Neumexiko vorkam und inzwischen im ursprünglichen Wildbestand ausgestorben ist. Es bestehen aber mehrere Populationen in künstlichen Habitaten und in Gefangenschaft. Die Hauptbedrohung für die Art stellt inzwischen Vandalismus an ebendiesen Anlagen dar.
Socorro-Asseln sind abgeflachte Asseln, deren Körper etwa doppelt so lang wie breit ist. Der Kopf ist relativ kurz und gerundet und besitzen Augen und zwei Paar etwa gleich langer Fühler. Die Tiere sind graubraun mit schwarzen Punkten und Streifen, die zusammen ein breites dunkles Band in der Mitte der Thoraxsegmente bilden. Alle Kanten des Körpers sind leuchtend orange gefärbt. Während die Weibchen durchschnittlich 5,1 und maximal 21 Millimeter Länge erreichen, werden die Männchen mit durchschnittlich 7,8 und maximal 60 Millimetern Länge deutlich größer.[1] Das Peraeon mit den sieben Laufbeinpaaren ist wenig dicht behaart und wird nach hinten etwas breiter. Das Abdomen ist breit und gleichmäßig gerundet und weist zwei ruderähnliche Uropoden auf, wodurch die Art von allen anderen Asseln Neumexikos unterscheidbar ist.[2] Von den anderen Arten der Gattung kann die Socorro-Assel durch ihr abgerundetes Abdomen ohne zentralen Grat und die kurzen Exopoditen der Uropoden unterschieden werden.[3]
Socorro-Asseln kommen in warmem Quellwasser mit Temperaturen zwischen 27 und 34 °C vor. Die Tiere sind nachtaktiv und verbringen den Tag im Substrat vergraben. Sie ernähren sich vorwiegend von in Matten wachsenden Cyanobakterien, nehmen aber auch Detritus auf und erbeuten Tubifex-Würmer und Insektenlarven. Auch verletzte Artgenossen werden gefressen, wobei verletzte Tiere schnell von Gruppen aus 10 bis 30 Tieren angegriffen und innerhalb einer Stunde komplett aufgefressen werden. Die Lebensdauer wird auf acht Monate bis ein Jahr geschätzt.[1][4]
Die Fortpflanzung findet über das ganze Jahr statt und erreicht ihren Höhepunkt im April und nimmt dann bis zum Minimum im Spätsommer ab. Bei guter Ernährung sind die Weibchen alle zwei Monate fortpflanzungsfähig. Sie werden von den Männchen bewacht, die mit ihnen mehrere Tage ein Paar bilden und gemeinsam durch das Habitat schwimmen. Im Labor legen die Weibchen 3 bis 57, durchschnittlich 16 Eier, die im Marsupium getragen werden, bis die Jungtiere nach etwa 30 Tagen schlüpfen und davonschwimmen.[2]
Das einzige bekannte Vorkommen der Art beschränkte sich auf einen warmen Abfluss der Sedillo-Quelle etwa drei Kilometer westlich der Stadt Socorro im Socorro County (Neumexiko). Möglicherweise besiedelte sie früher auch die nahegelegene Cook- und die Socorro-Quelle, an denen sie aber nie nachgewiesen wurde. Im späten Pleistozän und frühen Holozän speisten diese drei Quellen ein inzwischen ausgetrocknetes Marschland, welches das ursprüngliche Verbreitungsgebiet der Art darstellen könnte.[1]
Das ursprüngliche Habitat der Socorro-Assel wurde in den 1970er Jahren durch Einfassung der Quelle für den Bau eines Thermalbads zerstört. Der Art gelang es aber, in zwei Becken und etwa 50 Metern Leitungssystem zu überleben, wo sie, möglicherweise auf Grund des Fehlens von Fressfeinden, hohe Bestandsdichten von bis zu 210 Tieren pro 100 Quadratzentimetern erreichten. In den späten 1970er Jahren blieb die Population stabil bei etwa 2500 Tieren.[1]
1988 brach das Vorkommen zusammen, als der Wasserzufluss durch Wurzelwachstum fast unterbunden wurde, erholte sich aber nach Wiederöffnung des Zuflusses einen Monat später und der Ansiedlung von Tieren, die zuvor an der University of New Mexico gehalten worden waren. 1990 wurde als Reaktion auf dieses Fast-Aussterben die Socorro Isopod Propagation Facility gegründet, die aus zwei unabhängigen Systemen mit vier Becken besteht. 1998 wurde eine dritte Population in Gefangenschaft im Albuquerque Biological Park und in der Folge eine weitere am Department of Game and Fish in Santa Fe etabliert.[5][6]
Die Art ist weiterhin durch Veränderungen des Wasserzuflusses, unterirdische Sprengversuche des Verteidigungsministeriums und vor allem durch Vandalismus an den Anlagen bedroht. So wurden zwischen 1995 und 2003 Ventile und Rohre abmontiert, der Wasserfluss blockiert, Becken beschädigt, ein Auto direkt neben der Quelle entsorgt und Pflanzen aus den Zuchtbecken entfernt. Außerdem unterscheidet sich die Population in der Socorro Isopod Propagation Facility inzwischen morphologisch und genetisch von der Wildpopulation, was auf andere Selektionsbedingungen zurückzuführen sein könnte.[5] Die Socorro-Assel wird in der Roten Liste der IUCN als Extinct in the Wild (in freier Wildbahn ausgestorben) geführt und ist in den Vereinigten Staaten als bedrohte Tierart geschützt.[6]
Die Socorro-Assel (Thermosphaeroma thermophilum) ist eine nordamerikanische Süßwasserassel, die nur an einer warmen Quelle in Neumexiko vorkam und inzwischen im ursprünglichen Wildbestand ausgestorben ist. Es bestehen aber mehrere Populationen in künstlichen Habitaten und in Gefangenschaft. Die Hauptbedrohung für die Art stellt inzwischen Vandalismus an ebendiesen Anlagen dar.
Thermosphaeroma thermophilum is a crustacean in the family Sphaeromatidae. It is commonly known as the Socorro isopod or Socorro sowbug. It was endemic to the thermal water of Sedillo Spring. This was located in Socorro County in the state of New Mexico, United States.[2]
Harriet Richardson first described the Socorro isopod in 1897.[3] As of 2006, it resides in captive populations at the Socorro Isopod Propagation Facility (SIPF), Albuquerque Biological Park (ABP), the Minnesota Zoo, the New Mexico Department of Game and Fish Laboratory in Santa Fe, and by the Department of Biology at New Mexico Tech.[2] It was reintroduced following a near-extinction incident in 1988. The wild population became extinct when a tree root burst the pipe and cut off water flow to the concrete pools.[2]
The body size of the Socorro isopod is sexually dimorphic, varying noticeably depending on gender. Males tend to reach 7.1 millimeters in length on average (4-13 millimeter range). Meanwhile, females tend to reach 5.1 millimeters in length on average (4.5-6 millimeter range).[2] Both sexes are gray to reddish-brown in color, with the edges of their bodies being tinted bright orange.[4] Their body is flattened and segmented, with the last body segment possessing uropods. They have seven pairs of legs and a pair of antennae on their head.[2]
The Socorro isopod has a lifespan of 1 year. During the timespan between March and October, the mean body size for both males and females increases. It then rapidly decreases from October to February. They reach sexual maturity between 4-11 weeks, with males maturing faster than females. Some females won’t sexually mature at all because they will reabsorb their ovaries, the reason this might happen is unknown. Females are iteroparous and are capable of reproducing multiple times throughout their lives.[4][5] Given adequate food and proper temperature conditions they can give birth every two months.[6][7] They are receptive to mating during their molting process. They store sperm at this time to use it later when they ovulate. Their ovaries will mature after mating, an adaptation that evolved in response to male isopods being very aggressive during mating.[4][5] Females will carry their offspring for about 30 days, after which they will give birth to between 3 and 57 offspring under laboratory conditions, with an average of 16 offspring.[7] After giving birth, their ovaries will need about 30 days to recover before they can mate again. Their brood is skewed towards males.[7] Sometimes pregnant females won’t give birth because they reabsorb their unborn offspring.[5] April sees the largest number of pregnant females before declining to a minimum number around late summer.[7]
The Socorro isopod is omnivorous, eating both plant material and other aquatic invertebrates.[6] They feed on blue-green algae and leaves or detritus from cottonwood. They also eat juniper, or mesquite trees, and dragonfly nymphs.[6] A large part of their diet is also made up by cannibalism. Healthy and uninjured isopods are sometimes cannibalized by larger individuals. Victims of cannibalism are always smaller than their attackers. The individuals that are either injured or dying are often eaten by other isopods.[4][5] This cannibalistic behavior helps to structure the population demographics of the species.[8] Aside from cannibalism, the Socorro isopod appears to lack any natural predators. The water is too deep (15-26 cm) for birds to reach them. They eat other carnivorous invertebrates themselves.[6]
To determine if mating is worthwhile, male isopods engage in mate-guarding behavior. There are four main forms of mate guarding behavior: encounter, assessment, rejection, and guarding. During encounter, the male acknowledges a female but does not attempt to guard her. During assessment, the male grabs onto a female and moves his legs across her body for less than 15 seconds. Males will assess females on their backs by lifting them up with their legs. This allows them to better determine female body size. During rejection, a male will grab a female for longer than 15 seconds, but less than 5 minutes. During guarding, a male grabs onto a female for longer than 5 minutes.[5] Both isopod genders attempt to mate with large-bodied members of the opposite sex. For females, a large-bodied male is more likely to pass his survival genes on to offspring. This could help females to increase reproductive success, making large males more attractive.[5] Mate-guarding can inhibit female fecundity, so females have evolved counter-adaptations against male mate-guarding. These include resistance against guarding, hiding from suitors, and sperm storage.[5]
The Socorro isopod lives in warm aquatic habitats.[5] They like environmental temperatures ranging from 26–33 °C (79–91 °F). They are endemic to the thermal waters of Socorro Spring in Socorro County in New Mexico, United States.[2] The smaller juveniles and adult females are commonly found residing on vegetation. This serves as a hiding place from the larger males that could cannibalize them. Meanwhile, adult males are commonly found living directly on the bottom sediments. They often burrow beneath the substrate during the day and emerge again later on at dusk.[5]
The Socorro isopod was formerly endemic to the Sedillo Spring near Socorro County, New Mexico, USA. In 1947, the spring waters were diverted to provide the city of Socorro with drinking water. This forced the isopods to only live in a single old water pipeline in the city. In 1988, a tree root caused the pipeline to burst, resulting in the extinction of the wild population. The only surviving isopods were from captive communities. These have since been reintroduced back into the pipeline, where a wild population still resides today. There are also captive populations in the SIPF, ABP, the Minnesota Zoo, the New Mexico Department of Game and Fish Laboratory in Santa Fe, and the Department of Biology at New Mexico Tech.[2]
The historical population size of the Socorro isopod is unknown. Their current population size of the wild population is about 2,500 isopods. The ABP also houses 300 individuals in 5 large tanks that continually reproduce and are self-sustaining.[2]
The Socorro isopod used to be endemic to the Sedillo Spring near Socorro County, New Mexico, USA. It now resides on a pipeline constructed in 1947 to provide the city with water. There are also various captive populations residing in the SIPF, ABP, the Minnesota Zoo, the New Mexico Department of Game and Fish (NMDGF) Laboratory in Santa Fe, and the Department of Biology at New Mexico Tech.[2] The city of Socorro, in collaboration with the United States Fish and Wildlife Service (USFWS) and the NMDGF, constructed the SIPF. This artificial habitat was constructed near the isopod’s native habitat. It attempts to best replicate its natural environmental conditions. It consists of 8 artificial pools connected by pipes. Controlled propagation of isopods began at the facility in 1990. 600 isopods were introduced to the facility, with 75 isopods per pool.[9]
The main threat to the Socorro isopod is disruption of thermal groundwater discharge. This disruption results from woody root growth, surface mining, explosive tests on nearby Department of Defense lands, and human vandalism.[10][11] Vandalism in particular has become a worsening threat to the species.[10] From 1995 to 2002, this vandalism included damaging, diverting or blocking the spring’s water flow, removal of vegetation, destruction of protective concrete walls around the spring, and pollution from the abandonment of a junk car near the spring.[11]
The IUCN Red List lists the Socorro isopod as extinct in the wild (EW).[12] This listing is likely out of date since the isopod was last assessed on August 1, 1996. Based on the five-year review from the USFWS the isopod is likely Vulnerable (VU).[2] It was the first crustacean ever listed on the endangered species list.[13]
The Socorro isopod was native to a spring in Socorro, New Mexico. This spring was converted to a bathhouse in the early 1900s. Some isopods still live in the bathhouse remains, but the natural habitat no longer exists. Little is known about the conditions in which the isopod evolved. In 1988, a drought destroyed the wild population, but a captive population at the University of New Mexico was present and was reintroduced to the bathhouse. To protect against future drought harming the isopod, water was diverted to the SIPF outside the city. ABP also houses 300 individuals in 5 large tanks that continually reproduce and are self-sustaining.[2]
Not available at this point.
The Socorro isopod is currently protected by the USFWS. Permits are being issued to protect this species.[2] A recovery plan was even written and approved in 1982, before they became extinct in the wild. Captive populations have been established to secure the future of the isopod. They are held in the SIPF, which was constructed as a collaboration between the city of Socorro, the USFWS, and the New Mexico Department of Game and Fish. This is an artificial habitat constructed outside the isopod’s native habitat in order to best replicate its natural environmental conditions. Controlled propagation of isopods began at the facility in 1990. Further captive populations are present in the ABP, New Mexico Tech, and the New Mexico Department of Game and Fish laboratory.[2]
Thermosphaeroma thermophilum is a crustacean in the family Sphaeromatidae. It is commonly known as the Socorro isopod or Socorro sowbug. It was endemic to the thermal water of Sedillo Spring. This was located in Socorro County in the state of New Mexico, United States.
Harriet Richardson first described the Socorro isopod in 1897. As of 2006, it resides in captive populations at the Socorro Isopod Propagation Facility (SIPF), Albuquerque Biological Park (ABP), the Minnesota Zoo, the New Mexico Department of Game and Fish Laboratory in Santa Fe, and by the Department of Biology at New Mexico Tech. It was reintroduced following a near-extinction incident in 1988. The wild population became extinct when a tree root burst the pipe and cut off water flow to the concrete pools.
Thermosphaeroma thermophilum es una especie de crustáceo isópodo de la familia Sphaeromatidae. Fue endémica de los Estados Unidos de América.
Su hábitat natural eran los ríos. Extinta en la naturaleza debido a la pérdida de hábitat. La especie todavía existe en pozos de hormigón en la localidad de Socorro, Nuevo México.
Thermosphaeroma thermophilum es una especie de crustáceo isópodo de la familia Sphaeromatidae. Fue endémica de los Estados Unidos de América.
Su hábitat natural eran los ríos. Extinta en la naturaleza debido a la pérdida de hábitat. La especie todavía existe en pozos de hormigón en la localidad de Socorro, Nuevo México.
Isopode de Socorro, Cloporte de Socorro
Thermosphaeroma thermophilum, communément appelé l'Isopode de Socorro ou le Cloporte de Socorro (Socorro sawbug en anglais), est une espèce de crustacés isopodes de la famille des Sphaeromatidae ayant disparu à l'état naturel.
Il était endémique de la source thermale de Sedillo Spring, dans le comté de Socorro, au Nouveau-Mexique dans le Sud des États-Unis.
Isopode de Socorro, Cloporte de Socorro
Thermosphaeroma thermophilum, communément appelé l'Isopode de Socorro ou le Cloporte de Socorro (Socorro sawbug en anglais), est une espèce de crustacés isopodes de la famille des Sphaeromatidae ayant disparu à l'état naturel.
Il était endémique de la source thermale de Sedillo Spring, dans le comté de Socorro, au Nouveau-Mexique dans le Sud des États-Unis.
Thermosphaeroma thermophilum is een pissebed uit de familie Sphaeromatidae. De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1897 door Richardson.[2]
Bronnen, noten en/of referenties
Thermosphaeroma thermophilum é uma espécie de crustáceo da família Sphaeromatidae. Foi endémica dos Estados Unidos da América.
O seu habitat natural eram rios.É classificada como Extinta na natureza pela IUCN devido à perda de habitat. A espécie ainda existe em poços de concreto na localidade de Socorro, Novo México.
Thermosphaeroma thermophilum é uma espécie de crustáceo da família Sphaeromatidae. Foi endémica dos Estados Unidos da América.
O seu habitat natural eram rios.É classificada como Extinta na natureza pela IUCN devido à perda de habitat. A espécie ainda existe em poços de concreto na localidade de Socorro, Novo México.
