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Lucifuga spelaeotes 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Ophidiiformes Bythitidae

Scientific Name: Lucifuga spelaeotes Cohen & Robins, 1970
Common Name(s):
English Bahama Cavefish, New Providence Cusk-eel
Taxonomic Source(s): Eschmeyer, W.N. and Fricke, R. (eds). 2015. Catalog of Fishes: genera, species, references. Updated 1 October 2015. Available at: http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp. (Accessed: 1 October 2015).
Taxonomic Notes: The Lucifuga genus is known as one of the most diverse stygiobiotic fishes to have been described. The taxonomy of Lucifuga species may still be incomplete due to relatively common discoveries of new species. Garcia-Machado et al. (2011) concluded that Lucifuga spp. are genetically divergent, but morphologically indistinguishable and recommends revisiting the taxonomy of the genus. Since the distribution of certain morphological characters among these species are disjointed, they possibly may not be used for classification in the future. A revision of the Lucifuga spp. of Cuba with the description of a new species is currently in preparation by Hernández et al. (Hernández, D., Casane, D., García, A., Chevalier-Monteagudo, P., Møller, P. R. and García-Machado, E.)

Assessment Information [top]

Red List Category & Criteria: Vulnerable B1ab(iii) ver 3.1
Year Published: 2015
Date Assessed: 2013-01-29
Assessor(s): Dooley, J., Collette, B., Aiken, K.A., Marechal, J. & Pina Amargos, F.
Reviewer(s): Cox, N.A.
Facilitator/Compiler(s): Harwell, H.
Justification:
Lucifuga spelaeotes has a patchy and restricted distribution. It has been collected or reported from 12 marine blue holes, inland caves, and deep fracture oriented chasms on eight different islands (eight locations) throughout the Little and Great Bahama Bank Islands from 0-28 m depth. It is understood that the taxonomy of the Lucifuga genus is not yet complete, but is currently being researched. The species' extent of occurrence (EOO) is estimated to be 323 km². Although data are limited, the population size of L. spelaeotes is potentially small. The characteristic low levels of oxygen within these caves is another significant limiting factor. Data on the life history of L. spelaeotes are limited. Spawning may occur infrequently with a relatively low fecundity and long gestation period. It has been inferred that Lucifuga species have a long generation length.

Threats to cave-dwelling species in the Caribbean include habitat degradation through rock removal or siltation, hydrological manipulations caused by water removal, environmental pollution, and the introduction of alien species. Typically, a cave that is near high densities of human populations is more threatened. Since an illegal sewage dump within the type locality of L. spelaeotes, Mermaid's Pool on New Providence Island, no fish have been observed and threats are likely ongoing due to encroaching housing developments. Shortly after this incident, L. spelaeotes was sighted in the nearby R.M. Bailey School Cave despite the observed presence of large trash items such as entire motor vehicles. Currently, Lucayan Caverns is protected within the Lucayan National Park, which is managed by the Bahamas National Trust and restricts recreational scuba diving to special permission only. The status of conservation in the other cave systems is unknown. A proposal for cave conservation of 17 blue holes on Great Abaco Island was submitted in 2010, but an updated status is not available. Lucifuga spelaeotes is listed as Vulnerable under criterion B (VU B1ab(iii)).

Previously published Red List assessments:

Geographic Range [top]

Range Description:The distributions of Lucifuga spp. are highly patchy, as they are only found in inland karst caves located near coastal margins (Garcia-Machado et al. 2011).

Lucifuga spelaeotes has been collected or reported from 12 marine blue holes, inland caves, and deep fracture oriented chasms on eight different islands throughout the Little and Great Bahama Bank Islands from 0-28 m depth (Smith 1997, Moller et al. 2006, Proudlove 2006). Moller et al. (2006) breaks down the known localities as such: Grand Bahama Island: Lucayan Caverns and Zodiac Caverns, Abaco Island: Inland sink hole, Berry Islands, Andros Island: ocean blue holes and Uncle Charlie’s Blue Hole, New Providence Island: Mermaid’s Pool and R.M. Bailey School Cave, Eleuthera Island: Nixon’s Blue Hole and Sink Hole, Great Exuma Island: Angelfish Blue Hole, and Long Island. The range of L. spelaeotes is separated from that of L. lucayana by the deep waters of the Providence Channels. The EOO is estimated at 323 km². When L. spelaeotes was listed as Vulnerable on The IUCN Red List in 1996 (World Conservation Monitoring Centre 1996), the AOO was calculated as less than 100 km² with the number of recorded locations as less than five (Moller et al. 2006).
Countries occurrence:
Native:
Bahamas
FAO Marine Fishing Areas:
Native:
Atlantic – western central
Additional data:
Number of Locations:8
Lower depth limit (metres):28
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Cave-diving expeditions can be logistically challenging and dangerous to undertake, therefore population data for Lucifuga spelaeotes are limited. The Lucifuga genus continues to evolve due to the discovery of new species in previously unexplored caves throughout the Caribbean. It will be difficult to grasp a complete understanding of the populations of Lucifuga spp. until a more detailed picture of their diversity and distribution is realized (Moller et al. 2006, Garcia-Machado et al. 2011). Garcia-Machado and Hernandez (2012) reported that populations of Lucifuga spp. tend to remain stable throughout the year. It was originally described from two specimens collected from a brackish sinkhole in 1970. The species description was updated in 2006 from a collection of 44 specimens. The population size was calculated as less than 1,000 individuals (Moller et al. 2006).
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Lucifuga spelaeotes is a small, viviparous, eel-like fish with reduced eyes that shies away from direct light. It is considered to be the most ancestral of the Lucifuga spp. due to its relatively developed eyes (Moller et al. 2006). It has been collected to a maximum size of 18.2 cm TL. It is known from at least eight islands and 12 different anchialine holes/caves in the Bahamas, where the top layer of water is fresh and the bottom is salty due to a subterranean connection to the sea. This species has been collected and observed from both the fresh layer and the salty layer, indicating that it is euryhaline in nature (Moller et al. 2006). Caribbean anchialine caves have very low levels of oxygen in the water and sediments, often with a boundary layer of hydrogen sulfide separating the fresh and salty (Hutchinson 1999, Bishop et al. 2004). The biogeochemistry of individual holes/caves vary widely, with particular sensitivity to solar insolation, water flow velocities, and organic matter inputs (Hutchinson 1999, Gonzalez et al. 2011). Due to the already harsh nature of this environment, even slight changes in cave water quality can negatively affect troglobitic organisms, which have already adapted with very low metabolic rates and small size so as to efficiently use energy when oxygen and food supply are lacking (Hutchinson 1999, Bishop et al. 2004, Gonzalez et al. 2011). 

Food availability is a significant limiting factor for these cave fishes. Gonzalez et al. (2011) reported that food webs in these caves may be dependent on indigenous bacterial primary production. Populations of Lucifuga spp. seem to remain stable throughout the year, but the populations of the invertebrates that constitute their diet fluctuate significantly (Garcia-Machado and Hernandez 2012). Lucifuga spp. are opportunistic, passive foragers that primarily prey on troglobitic amphipods and mysids, but will also eat crustaceans and shrimp (Garcia-Debras and Gonzalez 1999, Trajano 2001, Moller et al. 2006). The highest densities of L. spelaeotes are usually observed hiding under ledges and in dark alcoves near the entrance where prey items such as the hypogean shrimp, Barbouria cubensis tend to congregate (Trajano 2001, Moller et al. 2006). It has also been reported together with the grapsid crab, Sesarma angustipes, in Uncle Charlie's Blue Hole on Andros Island (Proudlove 2006). Vegetable matter was found in the digestive tract of the holotype of Lucifuga simile, a closely related species endemic to Cuba. Populations of Lucifuga spp. are significantly more abundant in caves that bats also inhabit because their guano fertilizes the water and promotes growth of food sources for the fish (Garcia-Debras and Gonzalez 1999).  

Data on the reproductive strategy of L. spelaeotes are limited, however, two other species of Lucifuga that are endemic to freshwater caves in Cuba have a breeding peak in March, with females carrying 2-15 embryos that are approximately 2.5 cm SL at birth (Eigenmann 1909). The ovaries in female fishes of the Lucifuga and Ogilbia genera are very similar, however, sexual structures of the male, though both intromittent, are different. Male fishes are characterized by the presence of an external reproductive organ anterior to the anal fin, which it uses to facilitate internal fertilization of females (Nielsen et al. 1999). It is thought that mating begins as soon as the female reaches maturity, when the female is able to carry and even nourish the delivered spermatozoa within their body for long periods of time. Throughout their five stages of development, the embryos of Ogilbia spp. obtain nutrients from yolk and ovigerous tissue produced within the female. Fecundity levels among bythitids vary greatly (Wourms 1981). The significantly smaller brood size of L. spelaeotes compared to other bythitid species, is probably due to a longer gestation of the embryos, which allow them to reach a more advanced stage of development, and consequently, allow for a greater chance of survival after birth (Suarez 1975). Reproduction may be infrequent and fecundity relatively low, but further research is needed (Trajano 2001, Garcia-Machado and Hernandez 2012). Definitive data on the longevity of L. lucayana are unknown, but it may be inferred that Lucifuga spp. have a long generation length because their populations are small and there have been very few captures of juveniles or pregnant females (Garcia-Machado and Hernandez 2012).   


Systems:Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: Lucifuga spelaeotes is not utilized.

Threats [top]

Major Threat(s): Lucifuga spelaeotes may be experiencing direct threats from habitat degradation and introduced alien species. Repeated efforts to contact the Bahamas National Trust to determine an update on the status of these cave systems in which L. spelaeotes and Lucifuga lucayana have occurred has not yet been answered, though it could be inferred that the Lucayan Caverns have a low level of impact due to their protected status. Proudlove (2001) described five main threats to cave-dwelling species: habitat degradation through rock removal or siltation, hydrological manipulations caused by water removal, environmental pollution, overexploitation, and the introduction of alien species. On multiple occasions, people have reported evidence of trash, sewage, industrial pollution, and competition from introduced species in caves throughout the range of all Caribbean Lucifuga spp. (Hutchinson 1999, Proudlove 2001, Proudlove 2006, Moller et al. 2006, Garcia-Machado et al. 2011). The level of impact and rate of occurrence of these disturbances directly correlates to the location of the cave/hole in relation to human population density. A hole/cave that is distantly located and difficult to access will remain more pristine and unaltered (Proudlove 2001). In contrast, increasing human population density around a subterranean habitat is a threat. There is concern that caves that are proximal to dense human populations could be exposed to insecticide spraying (Hutchinson 1999). In 2005, an expedition to Alphonso Dean's Blue Hole on Southern Long Island, where L. spelaeotes was collected in 1985, did not find fish, but did report the presence of shrimp and a large amount of trash such as tires and rusted metal, which may have negatively impacted the water quality (Moller et al. 2006). This species has not been observed at its type locality (Mermaid's Pool on New Providence Island) following reports of an illegal sewage dump into the hole and encroaching housing developments. It was found in the R.M. Bailey School Cave on the same island coexisting with mosquitofish and various rubbish such as two sunken automobiles, of which there was a subsequent cleanup (Proudlove 2001, Moller et al. 2006).
Scuba divers can be detrimental to these caves when they disturb the stratification of bacterial mats that lie near the halocline, enrich the levels of oxygen in the water, and perhaps introduce flora and fauna to the system. Though some opinions are that any information gained from further exploration of these environments may overcome the possible negative effects especially because a small proportion of these holes are likely to be affected by such activity (Hutchinson 1999, Proudlove 2001).

Conservation Actions [top]

Conservation Actions: Lucifuga species play an important ecological role in the balance of caves that they inhabit (Garcia-Debras and Gonzalez 1999). The threats of ongoing habitat degradation by human activities within the extremely limited distribution and the more recent widespread introduction of alien species that deplete the limited food supply of Lucifuga spp. require the attention of conservationists. Since species diversity for the Lucifuga genus is likely underestimated due to the incomplete exploration of their highly fragmented distribution, implementing conservation could be difficult without a more complete list of specific holes/caves that currently harbor populations (Garcia-Machado et al. 2011).
The Lucayan Caves are contained within the Lucayan National Park, which is managed by the Bahamas National Trust, an organization tasked with the conservation of the country's natural resources. Diving in the Lucayan Caves is regulated to certain areas and is allowed only by special permission from the Underwater Explorers Society to experienced and trained divers. Details on diving in the Zodiac Caverns and holes on Abaco Island are not available at this time. The Bahamas Caves Research Foundation, drafted a proposal in the year 2010 that would protect 17 blue holes on Great Abaco Island and create awareness about cave conservation (Kakuk and Patterson 2010). Efforts to contact both the BNT and BCRF via email to request further information on conservation measures specific to these cave environments were largely unanswered. Proudlove (2001) reported that most Lucifuga species listed as threatened or more are not receiving necessary conservation attention. Habitat management, monitoring, education, and economic activities surrounding subterranean cave systems should be considered during the planning process (Garcia-Machado et al. 2011, Garcia-Machado and Hernandez 2012).
Exploring captive breeding of this species would be useful if populations became depleted enough to require restocking (Proudlove 2001). It is important to note that Lucifuga simile has been raised successfully on a diet of Troglocubanus sp. (cave shrimp) (Garcia-Debras and Gonzalez 1999). Further research on rearing L. spelaeotes should be explored.
In 1996 and 2000, L. spelaeotes was listed by the IUCN as VU (A1ce, B1 + 2bc, D2) based on decline in area, habitat quality, and pollution. The population was estimated as less than 1,000, the AOO as less than 100 km2, and the number of locations as less than 5. Proudlove (2001, 2006) concluded that the population and number of locations were underestimated because other populations known from Grand Bahama, Abaco, Andros, Long, and Berry Islands were not included. He also maintains that there are threats to the populations on New Providence due to pollution and introductions of alien species, but that those on other islands are under less pressure due to their seclusion from human activities. If these criteria were to be accepted, Proudlove states that L. spelaeotes would be down-listed to Least Concern. Moller et al. (2006) replied with the argument that L. spelaeotes is now known from only 5 confirmed islands after a revision of the species description where Lucifuga lucayana, a new Bahamian species, was also included. Therefore, he strongly recommends maintaining the current D2 status until the diversity and distribution of these two species are further explored.

Citation: Dooley, J., Collette, B., Aiken, K.A., Marechal, J. & Pina Amargos, F. 2015. Lucifuga spelaeotes. The IUCN Red List of Threatened Species 2015: e.T12398A19929465. . Downloaded on 19 September 2018.
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