Lionfish

Lionfish are an invasive species that are now well established throughout the Atlantic. Originally from the Indo-Pacific, they have decimated local shes’ populations due to their rapid reproduction, broad environmental tolerance, voracious appetite, and lack of predators. Through the examination of otoliths paired with morphometric data, this study investigates the age and growth of lionfish (sp. P. volitans) from two locations: North Carolina, USA and Bonaire, Dutch Caribbean. Otoliths were extracted from lionfish samples, embedded in resin, and then sectioned so that age could be determined with microscopic analysis. These age estimates along with the corresponding total lengths were used to calculate growth rates via the von Bertalanffy growth equation. Results returned a K and L-in nity value of 0.32 cm and 42.5 cm for lionfish from NC and 0.39 cm and 38.7 cm for Bonaire, respectively. These findings suggest that lionfish from NC have slower growth but grow older and larger than that of lionfish from Bonaire. This likely attributes to location as well as convenience and strength of removal efforts. In Bonaire, lionfish are hunted often and are easily accessible to the public, whereas in North Carolina, lionfish are found miles off the coast and their harvesting is not as popular. 

Bioinvasions are defined as the establishment of a species in an area where it has not existed previously. Usually the result of an anthropogenic introduction, bioinvasions pose a great threat to coral reef ecosystems. One example of an anthropogenically-induced bioinvasion is that of the lionfish (Pterois spp.) to the Atlantic basin. First reported in Bonaire, N.A. in 2009, the Indo-Pacific lionfish has spread rapidly, with 177 fish reported as of 31 March, 2010. One of the purposes of this study was to document interspecific interactions of lionfish with prey and non-prey fish species at twilight, when lionfish are reported to be active. Interactions were video recorded for further analysis. Additionally, stomach contents of lionfish on Bonaire were analyzed and compared to lionfish from a similar study in the Bahamas, which determined that as lionfish size increases, so does the % volume of fish in their diet. Lionfish, collected by the Bonaire National Marine Park and volunteers, were categorized according to total length for use in this study. Prey items found in the stomach contents were identified to the lowest possible taxon. It was hypothesized that as the size classes of lionfish increased, an increase in the % volume of fish and a decrease in the % volume of shrimp in their diet would be observed. Lionfish were observed interacting more with potential prey items than non-prey items based on video analysis. Data analysis of stomach content found that as lionfish size increased, the amount of fish by % volume increased from 60% volume in the smallest size class to 93% volume in the largest size class. This study showed that as lionfish size increases, they rely more heavily on fish as a part of their overall diet, and the fish they are consuming are those they are observed interacting with most.

This student research was retrieved from Physis: Journal of Marine Science VII (Spring 2010)19: 27-33 from CIEE Bonaire.

The Indo-Pacific lionfish Pterois volitans is an invasive species that was released along the U.S. Atlantic coast and spread to the Caribbean. Lionfish can inhabit a wide range of depths and they lack predation in their invasive range, leading to a successful invasion into their introduced range. Their large appetite combined with having no predators may pose an ecological threat to the Caribbean coral-reef ecosystem. Pterois volitans invaded Bonaire, Dutch Caribbean in 2009, and the extent of their presence and the impact they have upon the reefs surrounding Bonaire has yet to be investigated. Basic components to managing an invasive species are monitoring their occurrence and controlling their abundance. Around Bonaire, managers and diver volunteers catch and kill P. volitans to control their numbers in an attempt to reduce their negative impacts on the ecosystem. This study investigated the effectiveness of the current management strategy, P. volitans removal, by comparing their densities at frequented hunting sites with no-hunting sites. To achieve this, the densities of P. volitans at eight hunted and less frequented sites were calculated by searching for their presence in 50 x 4 m belt transects at five different depths (6 m, 12 m, 18 m, 24 m, 30 m) at selected sites along the west coast of the island. All P. volitans recorded were categorized into three size classes (small: 0-10 cm, medium: 11-30 cm, large: ≥ 30 cm). The results of this study show no significant differences between the densities of lionfish found at hunted sites (10/ha) compared to less frequented sites (16/ha). This study is the only known effort that attempts to determine the effectiveness of P. volitans removal from invaded areas in Bonaire.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 64-69 from CIEE Bonaire.

Invasive species have a history of damaging their invaded ecosystems and in the case of the Pterois volitans invasion to the waters of many Caribbean Island nations, there has been no exception. Pterois volitans has caused negative impacts to the coal reef ecosystems such as reduced juvenile coral reef fish recruitment and, consequently damage to the associated fisheries. Management strategies of multiple nations are currently centered upon the reduction of populations via hunting. This strategy requires substantial effort and thus long term management solutions may include biotic controls. Parasitism is an important facet of population dynamics and could be important to the population dynamics for Pterois volitans around Bonaire. Pterois volitans is rarely a victim of parasitism in its native range and has similarly low rates of parasitism reported in its invasive range. The prevalence or lack of parasitic interactions between Pterois volitans and native parasites could be important in planning management strategies and controlling populations in the future. This study examined 200 Pterois volitans captured in the coastal waters of Bonaire for parasites in the mouth and gill structure, as well as over the entirety of the skin, to investigate possible interactions occurring between local parasites and Pterois volitans. Only one of the 200 investigated specimens was found to have an isopod attached to its gill structure.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 44-49 from CIEE Bonaire.

Invasive species are often a detriment to the environment due to the lack of parasites, disease and natural predators in the invaded environment, which allows the population to explode. Pterois volitans were introduced into the eastern part of the Atlantic in 1980’s, and migrated to the southern Caribbean and in October 2009, lionfish were first documented on the island of Bonaire, Dutch Caribbean. The purpose of this study was to document the feeding ecology of lionfish by identifying and quantifying stomach contents of different size classes of lionfish found on the island using four different metrics- frequency of occurrence, percent by volume, percent by number and Index of Relative Importance (IRI). Of the 70 lionfish stomachs analyzed, there was a positive correlation between lionfish size and amount of fish consumed. Similarly, there was a negative trend seen with size class and the amount of shrimp found in the stomach contents. When IRI was used to compare feeding ecology of Bonaire lionfish to a Bahamas study, the top five ranked families of preyed differed. This study identifies major dietary trends of lionfish on Bonaire, and can be used to better understand the feeding ecology and diet habits.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 38-43 from CIEE Bonaire.

Circadian rhythms are common in many organisms and provide an organism synchrony with its environment, which is vital for survival. Entraining factors, called Zeitgebers, can modulate and synchronize the internal clock. Prey availability can change circadian rhythms and has been modeled in the laboratory with the presentation of food. The anticipation of the presentation of food, called food-anticipatory activity (FAA), has been studied extensively in mammals but is poorly understood in fish. The aim of the present study was to examine circadian rhythms and FAA of the Indo-Pacific lionfish, Pterois volitans. P. volitans is an invasive species of fish that may alter the composition of coral reefs. Lionfish have become established from the southeastern coast of the United States through the Caribbean Islands and parts of South America. In the wild, lionfish are most active around the crepuscular periods, dawn and dusk, and least active at midday. Lionfish maintained under constant conditions (CC) for two weeks did not demonstrate the same patterns of activity observed in the wild. The pattern that emerged was similar overall but much less distinct, suggesting that the pattern observed in the wild requires a specific Zeitgeber to persist. When fed consistently at 1300 hrs for two weeks under CC, a significant change in activity levels occurred. Lionfish demonstrated clear evidence of FAA through a significant increase in time spent active during the hour preceding prey availability. This study adds to the literature on fish chronobiology and provides insight into the adaptive nature of lionfish.

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 75-82 from CIEE Bonaire.

Indo-Pacific lionfish (Pterois spp.) have spread to and established sufficient numbers throughout the Caribbean. They are extreme generalists that feed on ecologically and economically important species, they can reduce recruitment of native fishes by up to 79%, and can occur in densities in orders of magnitude greater than in their home range. Because prey do not recognize lionfish as predators (prey naiveté), lionfish prey on fish and invertebrates using little energy. The purpose of this study was to test if lionfish in Bonaire were obese and if obesity was more pronounced in males over females. Because of limited research on invasive species obesity, the presence of interstitial fat and fat in the liver was used to determine if a lionfish was obese or not. A total of 161 lionfish for interstitial fat and 74 lionfish for liver fat were analyzed. All males in this study were obese (they all had both interstitial and liver fat) however, not all females had interstitial and liver fat. Females also possessed interstitial and liver fat in lesser quantities than males probably because of allocation of energy towards reproduction. This study highlights the importance of studying obesity on invasive species, an open topic in marine science that has not been addressed thoroughly.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 89-95 from CIEE Bonaire.

Serranidae, the grouper family, are common carnivorous fish that inhabit Bonaire’s coral reefs. Smaller grouper species are commonly spotted along the lower layers and crevices under the complex coral reef structure. These carnivores control population levels of lower trophic level omnivores (e.g. damselfish). Four smaller grouper species (Cephalopholis cruentata, Cephalopholis fulva, Epinephelus guttatus, and Epinephelus adscensionis) densities were used as indicator to evaluate current coral reef health on Bonaire. Maximum reef relief was estimated to evaluate for consistency in reef complexity across box transects. AGGRA fish methodology was used to survey densities of targeted Serranidae species. Recorded densities were compared to previously reported grouper densities from 2003 to 2011. A significant increase in density for C. cruentata (9.58 individuals/100 m2 ) and E. guttatus density (4.17 individuals/100 m2 ) was found since 2011. E. adscensionis and C. fulva densities were found to be consistent since 2003. Overall, a healthy coral reef was supported by the evidences of an increase in C. cruentata and E. guttatus since 2011. This increase in Serranidae density is controversial to commonly proposed competition between lionfish and native carnivores. Lionfish removal efforts are hypothesized to positively affect smaller Serranidae density, leading to a higher density in 2013. A biocontrol mechanism is proposed as a long-term solution following lionfish invasion. Future directions are discussed in regards to maintaining a resilient Serranidae population on Bonaire’s coral reef by establishing marine reserves and continued removal of Pterois spp. individuals.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 69-78 from CIEE Bonaire.

Since the invasion of red lionfish, Pterois spp., in the Western Atlantic and Caribbean, many studies have evaluated the predatory behavior of the species both in the field and in the laboratory. There is still relatively little knowledge regarding the intraspecific behaviors of the species, which could be successfully studied with the use of visual models. However, information is lacking regarding visual ability of the species. One study has confirmed that the lens of the eye of the lionfish eye is adapted to transmit visible light, but further anatomical evidence is required to confirm the use of color vision in the species. Color vision has recently been assessed in reef fish using stimulus-reward methods. Similar methods were repeated with lionfish in this study. Preference tests were performed following a week-long rewardstimulus training regime. The difference between time spent with the “training color” and the “distraction color” was not significant, but the group as a whole spent more time on the correct side than the incorrect side of the aquarium. Although there was no significant data to support color vision in the species, the behaviors of each individual are discussed in detail. The study, however, does not rule out nor confirm color vision in lionfish. It can be concluded that lionfish do not learn to associate colors with food rewards as readily as other reef fish species.

This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 52-57 from CIEE Bonaire.

Since their introduction into the western Atlantic, lionfish (Pterois volitans) have become a major threat to the coral-reef ecosystems. Lionfish have proven to be formidable predators and it has been demonstrated that they have to potential to reduce recruitment of native fishes and even contribute to phase shifts. It is known that lionfish are capable of hunting and catching many species of native fishes, however little is known about the anti- predator responses of those prey fish. This study examined the antipredator responses of herbivorous ocean surgeonfish to lionfish. The ocean surgeonfish were visually exposed to a lionfish and their resulting behaviors were analyzed to determine if the fish exhibited an anti-predator response to an invasive predator. The naïve prey hypothesis predicts that prey will not react to predators if they do not share an evolutionary history with those predators, therefore it was predicted that juvenile ocean surgeonfish would not exhibit anti-predator behaviors in response to lionfish. The results of this study were inconclusive due to the absence of a positive control, but they indicate that ocean surgeonfish do not exhibit an anti-predator response to lionfish. If this study were to be successfully repeated with a positive control, the results may help to enhance our understanding of the ecological effects lionfish are having on the coral-reef ecosystem and will help us to mitigate those effects.

This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 21-29 from CIEE Bonaire.