Fish

Black spot disease of Ocean surgeonfish (Acanthurus bahianus) population in Bonaire, Dutch Caribbean

Diseases of oceanic species are difficult to research due to the ocean‟s vast size and the overall logistics involved in studying disease in organisms that live in aquatic environments. Disease in marine organisms may go undetected even when an outbreak occurs. A healthy organism‟s immune system can fight an infection, but if it is weakened due to stress the ability of the immune system diminishes. Increasing human impacts in the world‟s oceans stress organisms through exposure to pollution and global climate change, which can increase the number of diseases in marine organisms. In the last year an unidentified disease has been reported on the Ocean surgeonfish, Acanthurus bahianus. The disease causes black spots on the epidermis of the fish and the deterioration of the fins. This disease has only been observed in Bonaire, Curacao, and the Turks and Caicos, all in the Caribbean. The purpose of this study was to generate a disease scale to facilitate the quantification of the progression of the disease and to compare the results conducted during the warmer months to those of the cooler months. Additionally, timed swims were used to determine the frequency of disease at various depths on the reef. Ocean surgeonfish play an essential role as herbivores in the coral reef ecosystems and since this disease is affecting 82% of ocean surgeonfish in Bonaire; it is crucial to study the distribution of

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 52-58 from CIEE Bonaire.

Date
2012
Data type
Other resources
Theme
Research and monitoring
Tags
Geographic location
Bonaire
Author

Utilization of smaller grouper species (Cephalopholis cruentata, Cephalopholis fulva, Epinephelus guttatus, Epinephelus adscensionis) densities as a coral reef health indicator

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.

Date
2013
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Effects of shore proximity and depth on the distribution of fish larvae in Bonaire, Dutch Caribbean

A vast majority of marine fish species, both reef and pelagic, are bipartite, meaning that they have a pelagic larval stage distinctly separate from their juvenile and adult stages. The survival of larval fish recruits results in the number of fish that make it to adulthood, which directly correlates to reef and pelagic fish population sizes and diversities that have significant biological and commercial importance. In response to being highly vulnerable to predation in the photic zone of open waters or reefs, fish larvae swim to deeper, darker pelagic waters where they can remain relatively unseen. This study examined whether a greater abundance and diversity of fish larvae would be found further from shore and at deeper depths off the island of Bonaire, Dutch Caribbean. To investigate this, research was conducted at a site close to the fringing reef in front of Kralendijk and a site roughly a kilometer offshore, between Klein Bonaire and Flamingo Airport. At each site, oblique plankton tows were conducted at three depths (≈1.83 m, ≈1.52 m, ≈0.61 m). Samples were analyzed for fish larvae abundance and individual fish larvae were identified to family in order to determine fish larval diversity using Simpson’s Diversity Index. Proximity to shore and depth were shown to have statistical significance on fish larval density. However, the same variables were not shown to have statistical significance on fish larval diversity. This study gives insight into the nocturnal vertical distribution of reef and pelagic fish larvae, which had not been previously studied on Bonaire.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 49-60 from CIEE Bonaire.

Date
2013
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Client choice, competition, and cleaner dependence pressure cleaner fish to cooperate in mutualistic symbiosis

Mutualistic symbiosis is a finely tuned relationship between two species in which each receives a service that increases its own fitness in exchange for providing service to another. The evolutionary stability of such a relationship is dependent on all species performing in an honest manner. However, many species that participate in mutualistic symbiosis have been observed cheating, or taking benefits beyond those evolutionarily agreed upon. This study attempted to identify factors that contribute to the frequency of cheating at cleaning stations on coral reefs. In these relationships, small fish and crustaceans clean parasites from larger host organisms. Client abundance and proximity of cleaning stations were examined as indicators for competition between cleaners and client choice. These factors put pressure on cleaners to cooperate by creating competition for clients. It was found that there was a greater abundance of clients at stations where cheating occurred less frequently, suggesting that clients may have chosen those stations for the higher quality service demonstrated. Proximity of cleaning stations did not seem to influence the frequency of cheating. Finally, obligate cleaners spent more time cleaning individual clients and cheated less frequently than facultative cleaners, demonstrating their higher dependence on the relationship. Understanding the factors that motivate cleaners and clients to cooperate at cleaning stations is an important component to comprehending community dynamics on reefs, but it is not as clear of a relationship as is commonly described.

This student research was retrieved from Physis: Journal of Marine Science XIV (Fall 2013)19: 33-40 from CIEE Bonaire.

Date
2013
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Impacts of cleaner shrimp, Ancylomenes pedersoni, density at cleaning stations on cleaner and client behavior

Mutualisms and symbiotic relationships are common in the marine environment. Relationships between cleaner species, their hosts, and their client species are prime examples of these types of relationships. Cleaner shrimp, which are typically found in association with sea anemones, exhibit mutualistic behavior through the removal and consumption of parasites, injured tissue and various other particles from their client fish. The shrimp may inhabit their host anemone alone, or in groups ranging up to more than ten individuals. This study focused on the cleaner shrimp species Ancylomenes pedersoni and examined the relationship between the number of shrimp present at cleaning stations and the number of client fish visiting that station. The relationship between the number of shrimp present and the size of the host anemone was also investigated; the data collected did not support any significant relationships between the variables tested. All data was collected through observational studies and video analysis of specimens in the field. Because cleaner species are crucial to the heath of their clients and therefore to the overall heath of the reef, enhanced understanding of the behavior of A. pedersoni will contribute to better conservation of the species and consequently their client fish.

This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 1-8 from CIEE Bonaire.

Date
2014
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Comparison of foraging strategies and feeding rates of the Atlantic Trumpetfish, Aulostomus maculatus

Coral reef fish exhibit remarkably diverse hunting techniques such as solitary hunting, shadow stalking, nuclear hunting, and hunting in schools of fish. This study examines the differences in feeding rates of the Atlantic Trumpetfish, Aulostomus maculatus, while it utilizes four dissimilar foraging strategies. Observations were completed in Bonaire, Dutch Caribbean while SCUBA diving to record A. maculatus striking at its prey. Feeding rates were calculated from the number of bites at prey during an observation period, in order to rank the strategies. Although consumption of prey was not determined, it is expected that feeding rate will track the number of bites at prey items and is used as a proxy for feeding rate in this study. Solitary foraging was hypothesized to exhibit the highest feeding rate due to its high prevalence on the reef, followed by shadow stalking, nuclear hunting, and hunting in schools. Competition for prey during associations with other fish and rarity of dense aggregations of schooling fish was thought to support the hypothesis. In this study, the feeding rate during solitary foraging was found to be significantly lower than shadow stalking, nuclear hunting, and hunting in schools, which were not significantly different from each other. The results indicate that A. maculatus forage more successfully in groups and exhibit multiple foraging strategies to exploit prey most efficiently. The hunting behavior of A. maculatus affects prey and other associated species, thus understanding this behavior may lead to further knowledge of other predatory fish and interspecific interactions.

This student research was retrieved from Physis: Journal of Marine Science XVI (Fall 2014)19: 1-5 from CIEE Bonaire.

Date
2014
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire

Distribution and abundance of spatial competition between scleractinian corals and sessile aggressive invertebrates on the west coast of Bonaire

Processes affecting reef ecosystems have three levels of organization: macroscale, mesoscale and microscale. These processes are conducive to interspecific competition amongst various coral and aggressive invertebrate species. Surveys of these organisms’ distribution, abundance and ecological description of their intra/interspecific competition have been conducted throughout the Caribbean. Previous research has found that scleractinian corals in reef slope ecosystems are frequently outcompeted by sessile aggressive invertebrates, such as Clionid sponges, encrusting bryozoans, encrusting gorgonians and overgrowing mat tunicates. Furthermore, interspecific spatial competition between corals and aggressive invertebrates has been observed to increase in frequency with depth. This project analyzed the distribution and abundance of coral-aggressive invertebrate spatial competition along a fringing reef ecosystem on the west coast of Bonaire. Belt transects were laid out between 200 m north and south of the GPS coordinates N 12°09.6 12’ W 068° 16.9 15’, at two depths (10 and 15 m) along the reef slope. Instances of spatial competition involving individuals at least 10 cm in length were photographed for further analysis. Five coral species and 25 aggressive invertebrate species were encountered in a total of 216 coral-aggressive invertebrate interactions. Quantitative data analysis showed that the orange lumpy encrusting sponge (Scopalina ruetzleri) was the most abundant aggressor at 15 and 10 m, although mean total area covered by coralaggressive invertebrate interactions and their frequency did not increase with depth. Findings could be used as a baseline for future scientific marine research, potentially on growth rate of competing species and the underlying mechanisms responsible for their interspecific spatial competition.

This student research was retrieved from Physis: Journal of Marine Science XVII (Spring 2015)19: 17-25 from CIEE Bonaire.

Date
2015
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Infection frequency and species identification of the black spot causing parasite found commonly on ocean surgeonfish (Acanthurus tractus) in Bonaire

Diseases, pathogens, and parasites in marine ecosystems are difficult to research and understand. Tracking the health of ecosystems, such as tropical coral reefs, is important for protecting these sensitive ecological areas. On the coral reefs surrounding Bonaire and other Caribbean islands, a dark spot ailment has been observed on ocean surgeonfish, Acanthurus tractus. This condition has been found to be a parasite, although its exact taxonomic identity is still unknown. The study of this parasite has become the point of interest for many researchers because dark spots have now been observed on other herbivorous fish in this region. The current frequency of the parasite on ocean surgeonfish and other species of surgeonfish is not known. These herbivorous fish are crucial to a healthy and sustainable coral reef ecosystem; a large change to the health of the population of these fishes could potentially affect the entire system. The purpose of this research was to find the prevalence of this parasite in species of surgeonfish through repetitive transects of counting infected individuals on the reefs of Bonaire. Additionally, collection and excision of parasites from their hosts allowed for a hypothesized genus of the infecting organism. The proportion of the density of ocean surgeonfish infected with this black spot causing parasite was 63% and it was found that the proportion of density for the degree of infection for ocean surgeonfish differed significantly among the population. Furthermore, through individual samplings of ocean surgeonfish, the lowest possible taxonomic description of this parasite was found to be the genus Paravortex.

This student research was retrieved from Physis: Journal of Marine Science XVII (Spring 2015)19: 1-9 from CIEE Bonaire.

Date
2015
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Cephalopholis cruentata (graysby) behavior and interspecific response to invasive Pterois volitans (lionfish) in Bonaire, Dutch Caribbean

The invasion of Pterois volitans (lionfish) is a serious concern for Caribbean coral reef health. The morphology and behavior of lionfish is novel to the reef in Bonaire, which allows lionfish to take advantage of resources at the expense of native reef fish. Cephalopholis cruentata (graysby) is a native grouper on a similar trophic level as lionfish. Other groupers show congeneric aggression, but documentation of graysby behavior is scarce. This study observed graysby behavior and investigated whether graysbys recognize lionfish as competitors. A model-bottle experiment was used to present lionfish to graysbys. Graysby responses, aggressive, neutral, and submissive, were observed. Behavior was quantified using a reactive index. No significant difference in the frequency distribution of behavior types was observed between treatments. A moderate correlation was observed between graysby size and reactive index, suggesting that graysby reactions may be size-dependent. Future studies should consider size when analyzing graysby behavior towards other species, native or invasive.

This student research was retrieved from Physis: Journal of Marine Science XIX (Spring 2016)19: 85-90 from CIEE Bonaire.

Date
2016
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Structure and substratum preference of a schooling fish: observing the habitat use and nutrient input of smallmouth grunts (Haemulon chrysargyreum) in Bonaire

Various marine organisms are known to consciously select specific types of habitat that provide maximum shelter from potential predators. Reef fish such as Haemulon chrysargyreum (smallmouth grunts) are commonly seen congregating in groups around the coral structures in Bonaire. Observing schooling fish can provide pertinent information on the refuge provided by structurally complex and diverse ecosystems. This study assessed the habitat preference of H. chrysargyreum based on species of coral, complexity of sites, and substrate type. Levels of phosphate, nitrate, and ammonia were also analyzed in the areas occupied by shoaling H. chrysargyreum to see if they provide a significant input of nutrients into the coral reef ecosystem. The results of this study demonstrate that H. chrysargyreum prefer areas of medium to high complexity accompanied with a soft substrate (sand, rubble) and an overhanging structure. Nutrient level analysis was inconclusive and, therefore, requires further studies. This research sought to identify certain species of coral and structures that are used by H. chrysargyreum for habitation. Such knowledge can aid conservation efforts by honing in on specific areas that schooling fish utilize for shoaling and feeding. Additionally, data from this study provided preliminary assessment for future studies on the potential nutrient input of H. chrysargyreum to the marine ecosystem.

This student research was retrieved from Physis: Journal of Marine Science XIX (Spring 2016)19: 52-63 from CIEE Bonaire.

Date
2016
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author