|Scientific Name:||Lucifuga simile Nalbant, 1981|
|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 genus Lucifuga is known as one of the most diverse stygiobiotic genera 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.)|
|Red List Category & Criteria:||Critically Endangered B2ab(iii) ver 3.1|
|Assessor(s):||Dooley, J., Collette, B., Aiken, K.A., Marechal, J. & Pina Amargos, F.|
Lucifuga simile has a highly restricted distribution. It is only known to occur in two closely located caves in the Northwest Matanzas province of Cuba. Caves are frequently connected underground by water, and both of these caves are exposed to similar threats, therefore, a single location is suspected for this species. Its estimated extent of occurrence (EOO) is 816 km² and area of occupancy (AOO) is less than 10 km², which meets the thresholds for Endangered under criterion B1 and Critically Endangered under criterion B2.
Although data are limited, the population size of L. simile is potentially small and it may have a long generation length. The characteristic low levels of oxygen within these caves is another significant limiting factor.
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. The main threat to L. simile is habitat degradation by human activities (continuing decline in habitat quality for this species is suspected). In particular, the Grieta Punta de Guana, which has historically had a larger abundance of L. simile, is at risk due to negative impacts from an oil well operation that is blocking its entrance.
The widespread introduction of alien species into these cave systems are likely negatively impacting the populations of L. simile through competition or predation. Both Cueva La Pluma and Grieta Punta de Guana are located within Ecological Reserve Bacunayagua, which is listed by the IUCN as a National Park (category II). Additionally, Cueva La Pluma is a Relevan Natural Site and is listed as a natural outstanding element. The level of protection these conservation measures specifically offer L. simile is questionable.
The Cuban Red List (2012) listed L. simile as Critically Endangered (CR A2ce; B1+B2ab), based on its low reproductive rate, possible longevity, declines in habitat quality, effects from introduced species, and small EOO and AOO. Further research on population size is needed. Lucifuga simile is assessed for The IUCN Red List as Critically Endangered under criterion B (CR B2ab(iii)).
|Previously published Red List assessments:|
|Range Description:||The distributions of Lucifuga species are highly patchy, as they are only found in inland karst caves located near coastal margins (Garcia-Machado et al. 2011). Lucifuga simile is restricted to two cave systems in the Northwest Matanzas province of Cuba on the exposed karstic plains of the west part of the island: Cueva La Pluma and Grieta Punta de Guana, which are located approximately 2 km apart from each other (Garcia-Machado et al. 2011). Caves are frequently connected underground by water, and both caves are exposed to similar threats. Therefore, it is suspected that this species occurs at a single location. Within the caves, L. simile have been found from 0 to 22 m depth (Garrido-Linares and Acero 2006).|
There is also an unverified report of this species from a third location known as Cueva del Tnel in Quivico Mayabeque Province (Garcia-Machado and Hernandez 2012). There are six regions in Cuba that have not yet been exhaustively explored for the possible extent of this species, though a thorough search of Isla de La Juventud returned no Lucifuga species. These regions are as follows: Caibari Remedios-Yagajay, Nuevitas- Manati, Bahia de Malagueta, Bahia de Puerto Padre-Bahia de Gibara, Banes, Amancio- Manzanillo- Media Luna, and Las Coloradas- Punta Pesquero de la Alegria (Garcia-Debras et al. 1999).
The species' estimated EOO is 816 km² (based on a minimum convex polygon drawn around the extent of its range). Its AOO was calculated in the Red Book of Cuban Vertebrates as less than 10 km² (Garcia-Machado and Hernandez 2012).
|FAO Marine Fishing Areas:|
Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Cave-diving expeditions can be logistically challenging and dangerous to undertake, therefore population data for L. simile are limited. In the 1980s, four specimens were collected from Cueva La Pluma and at least 55 from Grieta Punta de Guana. Due to its uncommon occurrence, the population size may be small (Nielsen et al. 1999), although it has been observed that populations of Lucifuga spp. tend to remain stable throughout the year (Garcia-Machado and Hernandez 2012).|
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). Moller et al. (2006) calculated the population size of L. spelaeotes, a closely related Bahamian species with a wider distribution, as less than 1,000 individuals.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Lucifuga simile is a small, viviparous, eel-like fish that shies away from direct light where it lives in landlocked cave systems. It has been collected to a maximum size of 8 cm standard length (SL) (Nielsen 2002). It has greatly reduced eyes, a characteristic that is considered advanced within the genus (Moller et al. 2006).|
The species is known from two anchialine, relatively stable cave/crevice systems in the Northwest Matanzas province of Cuba named Cueva La Pluma and Grieta Punta de Guana, which have water temperatures that fluctuate around 25°C and salinities that range from fresh to 22 ppm (Nielsen et al. 1999, Garcia-Machado and Hernandez 2012). This species has been collected and observed from both the fresh and salty layers of these caves, indicating that it is euryhaline in nature. In a report from 1973, Cueva la Pluma contained a phreatic lake covered with thick organic detritus composed mostly of guano that is at the same level as the ocean, and that Grieta Punta de Guana was described as a 25 m length fissure situated along the ocean bordered by a rocky ledge with two main openings (Kornicker and Yager 1996). 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, Garcia-Machado and Hernandez 2012).
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). The highest densities of Lucifuga spp. are usually observed hiding under ledges and in dark alcoves near the entrance where prey items tend to congregate (Trajano 2001). 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). Vegetable matter was found in the digestive tract of the holotype of L. simile. 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). A species of the genus Eleotris (Sleeper Goby) has been observed to coexist with L. simile. The level of competition for resources with these small fish is not yet known (Garcia-Machado and Hernandez 2012). Danielopolina orghidani, a species of troglobitic ostracod, is also found in Grieta Punta de Guana (Kornicker and Yager 1996). Both L. subterranea and L. teresinarum (freshwater cave-fish) co-occur with L. simile (Nielsen et al. 1999).
Data on the reproductive strategy of L. simile 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. simile 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. simile 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).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Use and Trade:||Lucifuga simile is not utilized.|
The main threat to L. simile is habitat degradation by human activities. Garcia-Machado and Hernandez (2012) reported that an oil well established near Grieta Punta de Guana may be leaching hydrocarbon residuals from the exploitation of petroleum. It has been impossible to observe the recent state of this crevice since this industrial activity has apparently made the entrance inaccessible. There have been multiple reports of introduced species of fish in the cave systems of Cuba. Most are freshwater species, but due to the anchialine nature of these caves, it is entirely likely that they inhabit the fresh layer even if a salty layer exists beneath.
The North African Catfish (Clarias gariepinus), which is an important aquaculture species throughout the world, have been found as adults introduced into these caves. It is likely that this catfish would prey on small fish such as Lucifuga spp. given the opportunity. Erik Garcia-Machado (personal communication) also mentioned that native Girardinus microdactylus (Smallfinger Topminnow), Nandopsis tetracanthus (Cuban Cichlid), Rivulus cylindraceus (Green Rivulus Killifish), Eleotris spp. (Sleeper Gobies), and non-native guppies and swordtail fishes are relatively frequently introduced into these caves, sometimes by natural stochastic events, but definitely by intentional human introduction. These small fishes likely compete with Lucifuga spp. for the limited food sources in these caves.
Lucifuga spp. 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 harbour populations (Garcia-Machado et al. 2011). 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). Both Cueva La Pluma and Grieta Punta de Guana are located within Ecological Reserve Bacunayagua, which is listed by the IUCN as a National Park (category II). Additionally, Cueva La Pluma is a Relevan Natural Site and is listed as a natural outstanding element on Protected Planet (Garcia-Machado pers. comm).
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 L. simile has been raised successfully on a diet of Troglocubanus sp. (cave shrimp) (Garcia-Debras and Gonzalez 1999). Further research on rearing L. simile should be explored.
|Citation:||Dooley, J., Collette, B., Aiken, K.A., Marechal, J. & Pina Amargos, F. 2015. Lucifuga simile. The IUCN Red List of Threatened Species 2015: e.T12399A19929441.Downloaded on 16 January 2018.|
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