''Antrolana lira'', also known as The Madison Cave

isopod Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as woodlice. All have rigid, segmented exoskeletons ...

, is a freshwater, cave-dwelling

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

species. It is in the family

Cirolanidae Cirolanidae is a family of aquatic isopods Isopoda is an Order (biology), order of crustaceans. Members of this group are called isopods and include both Aquatic animal, aquatic species and Terrestrial animal, terrestrial species such as wo ...

and it is the only species of its genus ''Antrolana''. This isopod can be found in flooded limestone caves and

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

s throughout the

Great Appalachian Valley The Great Appalachian Valley, also called The Great Valley or Great Valley Region, is one of the major landform features of eastern North America. It is a gigantic trough, including a chain of valley lowlands, and the central feature of the Appal ...

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

and

West Virginia West Virginia is a mountainous U.S. state, state in the Southern United States, Southern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States.The United States Census Bureau, Census Bureau and the Association of American ...

."Madison Cave Isopod, ''Antrolana lira''" (PDF). United States Fish and Wildlife Service. October 2010. Retrieved 2022-04-11. The Madison Cave isopod has been listed as a

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

since 1983 and as a

threatened species A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

under the United States

Endangered Species Act The Endangered Species Act of 1973 (ESA; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...

since 1982.“Listing the Madison Cave Isopod as Threatened Species” (PDF). United States Fish and Wildlife Service. October 1982. Retrieved 2022-04-12. The species was named after the cave in which it was first discovered, Madison Saltpetre Cave.“Madison Cave Isopod (''Antrolana lira'') Recovery Plan” (PDF). United States Fish and Wildlife Service. September 1996. Retrieved 2022-04-13. Very little is known about the life history and

behavior Behavior (American English) or behaviour (British English) is the range of actions of Individual, individuals, organisms, systems or Artificial intelligence, artificial entities in some environment. These systems can include other systems or or ...

of the Madison Cave isopod.

Description

Madison Cave isopods are the largest subterranean isopods in the

eastern United States The Eastern United States, often abbreviated as simply the East, is a macroregion of the United States located to the east of the Mississippi River. It includes 17–26 states and Washington, D.C., the national capital. As of 2011, the Eastern ...

. Adult males reach a length of and a width of . Adult females reach a length of and a width of . Their bodies are flat with 7 pairs of legs, the first pair being modified to grab objects. They have two pairs of antennae, one short and one long. They are completely unpigmented and have no eyes.

Life History

The Madison Cave isopod's reproduction mechanism is currently unknown. In related isopod species, females incubate fertilized eggs in a

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

marsupium after mating, though this has never been observed in any captured Madison Cave isopod. It is inferred that the species has a low reproductive potential, as the majority of samples consist of very few to no juveniles and no egg-bearing females. Based on sampling data, populations of Madison Cave isopods tend to skew towards a female-biased

sex ratio A sex ratio is the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. However, many species deviate from an even sex ratio, ei ...

, ranging from 2.2 to 3.7 females per male. However, it has been suggested that this sex ratio may be due to differential responses of females and males to

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

bait.

Ecology

Diet

The feeding habits of Madison Cave isopods are unknown, but they are believed to be

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

as they readily consume shrimp bait. Insect parts were found in the stomachs of several individuals from Steger's Fissure.

Behavior

Most other Madison Cave isopods spend much of their time walking along the bottoms of pools. However, the Madison Cave isopod swims freely through

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

-rich-waters in the caves it occupies. There is no information available on its

mating In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually repr ...

foraging Foraging is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavi ...

, and

territorial A territory is an area of land, sea, or space, belonging or connected to a particular country, person, or animal. In international politics, a territory is usually a geographic area which has not been granted the powers of self-government, ...

behaviors.

Habitat

The Madison Cave isopod lives in water that ranges in temperature from . Plates of calcite are often found floating on the surface of the aquifers it occupies, which indicates that the water is

supersaturated In physical chemistry, supersaturation occurs with a solution when the concentration of a solute exceeds the concentration specified by the value of solubility at equilibrium. Most commonly the term is applied to a solution of a solid in a ...

with calcium carbonates. The levels of water in the karst aquifers it occupies can vary by tens of meters in certain areas.

Range

The Madison Cave isopod is found within a

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

that extends from Lexington, Virginia to Charles Town, West Virginia. All population sites are found within a 15 mile wide belt, with known population centers in the Waynesboro-Grottoes area ( Augusta County, VA), the Harrisonburg area ( Rockingham County, VA), and the valley of the main stem of the

Shenandoah River The Shenandoah River is the principal tributary of the Potomac River, long with two River fork, forks approximately long each,U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed August ...

(

Warren Warren most commonly refers to: * Warren (burrow), a network dug by rabbits * Warren (name), a given name and a surname, including lists of persons so named Warren may also refer to: Places Australia * Warren (biogeographic region) * War ...

and

Clarke Clarke is a surname which means "clerk". The surname is of English and Irish origin and comes from the Latin . Variants include Clerk and Clark. Clarke is also uncommonly chosen as a given name. Irish surname origin Clarke is a common surname ...

counties, VA, and Jefferson County, WV).

Conservation

Population size

The exact number of populations of Madison Cave isopods is unknown. Heavy

folding Fold, folding or foldable may refer to: Arts, entertainment, and media * ''Fold'' (album), the debut release by Australian rock band Epicure * Fold (poker), in the game of poker, to discard one's hand and forfeit interest in the current pot *Abov ...

and

faulting In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

in the

Shenandoah Valley The Shenandoah Valley () is a geographic valley and cultural region of western Virginia and the eastern panhandle of West Virginia in the United States. The Valley is bounded to the east by the Blue Ridge Mountains, to the west by the east ...

area suggests limited connectivity between the aquifers in which the Madison Cave isopod is found. The isopods from all seven sites most likely make up between 1 and 7 distinct genetic populations, despite being morphologically identical. At most sites, the population size of the Madison Cave isopod is unknown, although rough estimates for Madison Saltpetre Cave and Steger's Fissure exist. Sampling done at Madison Saltpetre Cave and Steger's Fissure found 1972 (± 851) and 6678 (± 3782) isopods per two hours, respectively. These are huge populations compared to the other five sites, where a total of 33 individuals had been collected from 1990 to 1996.

Past and current geographical distribution

Prior to 1990, Madison Cave isopods had only been found in Madison Saltpetre Cave and in Steger's Fissure, which is located about 100 meters north-northeast of the cave. Since then, they have been identified and collected from five more sites. Front Royal Caverns is the most isolated and northernmost site. All seven sites are found within the Shenandoah Valley.

Major threats

Madison Cave isopod populations are very small and reproduce at low rates. They are therefore very sensitive to disturbances.

Urban development Urban means "related to a city". In that sense, the term may refer to: * Urban area, geographical area distinct from rural areas * Urban culture, the culture of towns and cities Urban may also refer to: General * Urban (name), a list of peop ...

in the northern part of Madison Cave isopod's range and agricultural runoff in the Shenandoah Valley increases the probability of pollutants entering the groundwater. Front Royal Caverns are especially vulnerable to urban development because of its proximity to U.S. Highway 340. Fourteen new homes and a large church were built in the recharge area of the Front Royal Caverns aquifer. The exact recharge zones of the aquifers at any location with Madison Cave isopods are unknown, so the total impact of pollution into

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

is difficult to predict. When Madison Saltpetre cave was open to the public for commercial tours, it was subject to

vandalism Vandalism is the action involving deliberate destruction of or damage to public or private property. The term includes property damage, such as graffiti and defacement directed towards any property without permission of the owner. The t ...

. The cave is currently managed by the Cave Conservancy of the Virginias and protected by a gate.

Listing under the ESA

The Madison Cave isopod was first proposed as a

in January 1977, after it was found in only three small pools of water; two of which were in Madison Saltpetre Cave. The proposal was withdrawn after the listing procedures changed by the 1978 amendment to the

. A report by Bolgiano found that the isopod were threatened by human vandalism and mercury pollution in the South River. The South River is connected underground to the pools where Madison Cave isopods are found. It was officially listed as a threatened species in November 1982.

5-year review

A 5-year review was initiated twice: for the first time in December 2008, and again in November 2021,“Initiation of 5- Year Reviews of Eight Northeastern Species; request for information” (PDF). United States Fish and Wildlife Service. November 2021. Retrieved 2022-04-12 although the formal review has not been completed as of April 2022.

Species status assessment

The Species Status Assessment is not yet available for the Madison Cave isopod.

Recovery plan

The recovery plan for the Madison Cave isopod was first established in September 1996, and is still ongoing as of April 2022. The plan focuses on six major action items, some of which were initiated before 1995, and others initiated in 2007. There is still no estimated completion date for these items. The six main points of the recovery plan are: # Determine the number of genetic populations #*

Random Amplification of Polymorphic DNA Random amplified polymorphic DNA (RAPD), pronounced "rapid", is a type of polymerase chain reaction (PCR), but the segments of DNA that are amplified are random. The scientist performing RAPD creates several arbitrary, short primers (10–12 nuc ...

(RAPD) will be used to analyze the genetic distance between individuals at all seven sites to determine the number of genetic populations. RAPD will be used because not much is known about the genetic information of the Madison Cave isopod and a small amount of DNA is needed to analyze a large set of polymorphisms. # Search for additional populations #* The large gap between the population of Madison Cave isopods at Front Royal caverns and the other sites indicates that additional populations are possible. Search efforts should focus on well samples in this gap, along with searches in caves within the deep karst aquifer habitat. # Identify potential sources and entry points of contamination of the deep karst aquifer habitat #* Outline the recharge zone of deep karst aquifers #* Monitor the effects of land use patterns on potential and identified recharge zones of deep karst aquifers # Protect known populations and habitats, taking a watershed perspective #* Enforce existing regulations to protect Madison Cave isopod and its deep aquifer habitat #* Encourage cooperation among landowners and governmental and nongovernmental agencies in achieving long-term protection of Madison Cave isopod habitat # Collect baseline ecological data for management and recovery #* Characterize the habitat requirements of Madison Cave isopod and monitor the habitat conditions #* Estimate population size and monitor population trends #* Develop methods for and conduct life history and population viability studies # Implement recovery progress program #* The U.S. Fish and Wildlife Service will be responsible for arranging an informal recovery group to meet when needed to make sure the recovery plan is being implemented effectively and with complete cooperation.

References

{{Taxonbar, from=Q3318923, from2=Q202352 Cymothoida Cave crustaceans Endemic crustaceans of the United States Freshwater crustaceans of North America Fauna of the Southeastern United States Monotypic isopod genera Taxonomy articles created by Polbot ESA threatened species Endemic fauna of the Southeastern United States