Coral reefs

The effect of land-based pollution on Bonaire’s coral reef ecosystem has not been well-quantified. Observations of the coral reefs of Bonaire show a great abundance of the polychaete Spirobranchus giganteus. This study investigated whether S. giganteus is sensitive to the environmental stress caused by wastewater pollution and therefore could be used as a bioindicator species of pollution in coral reef health assessments. Pollution indicators were assessed through the analysis of water samples, concentrating on the levels of ammonia, nitrate, nitrite and phosphate, sediment levels, and fecal contamination. To allow for comparison between differing levels of water pollution, six different sites were chosen with various levels of expected pollution impact by their proximity to resorts. Abundance of S. giganteus and coral reef cover at these sites were analyzed through transects at different depths. No significance was found between S. giganteus density and nutrient levels or fecal contamination. This study found a significant positive correlation (r² = 0.936) between S. giganteus density and sedimentation rates, suggesting the possible use of S. giganteus as a bioindicator of sedimentation_stress_on_coral_reefs.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 20-30 from CIEE Bonaire.

The creation of harbours through dredging combined with boat maintenance and waste is known to increase nutrients and sedimentation within coastal waters causing the degradation of nearby coral reefs. Winds and currents play a large role in the transportation of nutrients and sediments. This study investigated the distribution of nutrients in water surrounding Harbour Village Marina in Bonaire, Dutch Caribbean, as well as the extent to which the harbour affects adjacent coral reefs. Water samples were collected at increasing distances from the entrance to the harbour and were tested for nutrients. Percent coral cover was estimated using 10 m line-intercept transects. By noting the wind direction and currents when collecting data, it was determined that both the surface and bottom currents flow predominantly north. Results show that current plays a large role in nutrient distribution, but the effects on coral cover are unknown. Coral cover was also much lower north of the harbour in the direction of current flow compared to the south. This study increases the knowledge on nutrient distribution and coral cover as well as the impact harbours have on surrounding reefs. The results can be used for management efforts to help maintain coral reef health, and to keep nutrient levels low during the creation and upkeep of small harbours.

This student research was retrieved from Physis: Journal of Marine Science X (Fall 2011)19: 16-20 from CIEE Bonaire.

The biodiversity of coral reefs will decline as the global degradation of reefs continues, pushing the science of restoration techniques such as the utilization of artificial reefs, to the forefront of coral reef ecology. Artificial reefs provide shelter and habitat through design features such as topographic complexity, substrate diversity, refuge hole size, vertical relief, and percentage live coral cover. These elements have been manipulated to study the relationship between design and fish community response. This study examines the relationship between hole size in artificial reef units (ARUs) and species richness and abundance of coral reef fish at a study site on Bonaire, Dutch Caribbean. Four types of ARUs were constructed including units with no holes, small holes, large holes and a combination of small and large holes. Various fish and invertebrate species utilized ARUs for grazing, benthic egg laying, protection and hunting. There was no difference in fish density or species richness among the four ARU types. However, differences in species composition among the four ARU types were found. The smaller, benthic fish were more prevalent at the small hole ARU, while the larger, territorial fish were found utilizing the large hole and no hole ARUs more often. Mixed hole ARUs exhibited a compilation of both small and large fish. Since there are differences in community composition, specialized artificial reef designs could possibly be used to enhance particular species that are important to maintain community structure of degraded reefs.

This student research was retrieved from Physis: Journal of Marine Science X (Fall 2011)19: 1-10 from CIEE Bonaire.

Coral reefs are important marine ecosystems with high biodiversity that provides food and socioeconomic benefits to people in tropical regions around the world. In the last thirty years coral cover has declined and has been wiped out in some areas. The coral loss affects all benthic organisms and fishes supported by these habitats. Artificial reefs have been used to enhance coral recruitment and to provide a habitat for reef fishes. In Bonaire, Dutch Caribbean, reef fish species richness, diversity, and density were measured at two types of artificial reefs, branching and block-style, at various times of the day. Field observations of reef-fish species richness and density were conducted at midday, dusk, and night. Branching artificial reefs supported higher species richness and diversity. Multiple herbivorous species utilized this habitat for grazing while other species used it for shelter. The block-style reefs supported a higher density (ind m -2 ) of reef fish. Fish density, species richness, and diversity decreased at night at the branching reef. The decrease in fish community complexity could be because the complexity of the block-style reef was not suitable for nighttime sheltering needs. Species richness and diversity also decreased at night at the block-style reefs; but density at night was no different than midday and dusk because the blocks supported a very high number of small individuals during nighttime. Two different artificial reef structures were found to support complex fish assemblages; however the species richness and fish abundance varied between the structures. This suggests that morphology of artificial reefs is a tool that can be utilized to attract specific reef fish communities. During a time of reef degradation and habitat loss, artificial reefs can be used to supply reef fish a habitat to live. 

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 35-45 from CIEE Bonaire.

Damselfish have a considerable effect on benthic composition and have been described as a keystone species because of their role in the maintenance of coral and algal assemblages within their communities. By looking at the different densities of damselfish at varying depths and locations, this study aims to see the effects of damselfish densities on coral reef benthic composition and if the presence of damselfish is beneficial to coral reef benthos. The abundance of all damselfish was recorded within 30 x 2 m belt transects. Random photographs within the belts were taken and still images were analyzed using Coral Point Count software to determine total percent coral cover, total percent algal cover, and coral species richness. A total of 702 damselfishes over 4 species were observed. Thirteen species of coral were identified. Contrary to the predictions, a higher density of damselfish was not correlated to increased coral cover and coral species richness. There was significantly more algae than coral cover throughout the study, but such a trend fits with the theory of phase shifts of coral reefs from coral dominated to algae dominated reefs.

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 29-34 from CIEE Bonaire.

The relationship that benthic organisms have on fish that live on the reef is well known. Some benthic organisms can be regarded as bio-indicators, acting as indicators of nutrient levels in an ecosystem. Benthic organisms are also an important food source for fish and other invertebrates. In this study, organisms from sediment cores at five different depths were analyzed. Meiofauna and macrofauna cores were collected at each depth and the organisms were identified to family level. This study provides information on where these organisms prefer to live, and if there are any depths that are more favorable or diverse. The abundance of species increased in macrofauna samples from depth 10 m to 20 m. This was after a decrease in density from 5 m, which had the highest density, to 10 m depths, which had the lowest density. This trend was also present in macrofauna species richness. The meiofauna samples also had the highest species richness and density of individuals at 5 m depth for species, but both variables decreased with increasing depths. The data shows an increase at the 5 m depth. With further testing we can better understand the relationship depth has on the diversity of the benthic zone in the southern Caribbean

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 9-14 from CIEE Bonaire.

Cleaning is a symbiotic behavior that has been observed in many animals, including both terrestrial and marine species. Cleaner species and their cleaning stations play a vital role in coral reef ecosystems by removing parasites, mucus, and diseased or dead tissues from their client fish. In this study, the depth distribution of cleaning stations and the interactions between cleaner and client species were observed with respect to three of the most prominent cleaner species in the Caribbean: juvenile Bodianus rufus (Spanish hogfish), Elacatinus evelynae (Sharknose goby), and Anclyomenes pedersoni (Pederson‟s cleaning shrimp). Research dives were conducted at Yellow Sub dive site on the leeward or west coast of Bonaire, D.C., a small island in the southern Caribbean off the coast of Venezuela. Two dives were conducted ad libitum, with observers recording all cleaning stations between 20 and 50 ft to determine the distribution of the three cleaning species. Observations on cleaner-client interactions were collected at several shallow stations on ten subsequent dives. Cleaner-client interactions at each station were categorized as inspected and cleaned, ignored, jolted, and scared away by another fish. Data analysis indicates that B. rufus, E. evelynae, and A. pedersoni do not have different depth distributions, but they all show the highest abundance of stations between 20 and 30 ft. The four cleaner-client interactions varied by both cleaner and client species. It is important to better understand the role of cleaning stations in coral reef ecosystems, as they are known to positively affect fish richness and diversity.

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 91-100 from CIEE Bonaire.

Coral reefs are undergoing phase shifts becoming dominated by algae rather than live coral. Algae on reefs is greatly impacted by herbivores such as parrotfish that use both the reef and shallow intertidal zone to feed. These two habitats are unique with differences in algal cover and algal community composition. The shallow intertidal may have greater risk of predation from ospreys and the habitat is more extreme in terms of turbulence and constantly changing microenvironments. It is unknown if feeding in the shallow intertidal zone provides a benefit that offsets the risk of feeding there. This study observed initial and terminal phases Sparisoma viride and Scarus taeniopterus to determine if there are differences in feeding by parrotfish between the shallow intertidal and the reef crest. The main goals of the study were 1) to compare algae from the shallow (higher predation risk) habitat to algae from the deeper (lower predation risk) habitats and 2) to compare abundance of terminal phase and initial phase. Transects at two different depths of 0.5 m and 10 m were placed at 10 different sites on the leeward side of Bonaire, Dutch Caribbean. Point intercept surveys and dry weight of algae samples were used to compare algal cover and fish surveys were conducted to measure parrotfish. Although the shallow intertidal zone had greater algal cover there was not a significant difference in abundance of parrotfish during either developmental stage studied, which may be explained by greater

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 33-38 from CIEE Bonaire.

Cyanobacteria presence in the marine ecosystem is biologically significant due to its versatile nature. This phylum is responsible for destructive red tides and black band disease as well as building up the limestone in reefs. Nodularia cf. spumigena has been an indicator of groundwater off of the coast of Bahamas and may provide insight into where Bonaire‟s groundwater enters the marine ecosystem. Bonaire is a tropical oceanic island with a fringing coral reef located in the south Caribbean Sea and, although the population of the island is small (~16,000), it has developed a population center of residential and commercial use in Kralendijk, a coastal city. To compare how the benthic cyanobacteria mats off of Bonaire relate to this growing population, a three-fold study was conducted. A large scale pattern of cyanobacteria was studied at nine sites on the leeward side, a medium scale pattern was studied at four sites off the coast of Kralendijk in between two known nutrient outputs, and tests of mean levels of Escherichia coli and total coliforms inside and outside the cyanobacteria mats were completed. Video transects were used to determine percent cover of the large and medium scale patterns and IDEXX technology was used to test pore water inside and outside the mats for two types of bacteria associated with human waste. No definite patterns of groundwater or population center were directly linked to benthic cyanobacteria cover. The large scale did show a higher average cyanobacteria cover throughout the three-year study, indicating that there may be a relationship between the hydrology of the island and nutrient circulation. The medium scale showed an inverse relationship between turf algae and cyanobacteria.

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 9-15 from CIEE Bonaire.

Eels play an important role in coral reef ecosystems as part of nuclear hunting groups and as top predators. They are often underrepresented in fish population surveys due to their hiding behavior. There is consensus among the scientific community that most visual survey methods are not able to give an accurate measurement of the eels in the area surveyed. This study conducted surveys using the methods of two environmental and research organizations: the Reef Environmental Education Foundation (REEF) and the Atlantic and Gulf Rapid Reef Assessment (AGRRA). The surveys conducted in this study looked specifically for eels and the results were compared with historic data collected using both methods. This comparison indicates how accurate these methods are at representing eel populations in Bonaire. Using the same protocols but looking specifically for eels this study found eels more frequently and in greater numbers than the REEF surveys from the online database. The density of eels found using the AGRRA protocol was higher but not significantly different than the density reported in a similar study from 2011. The conclusions from this study are that the REEF methodology, while excellent at reporting species diversity, in not a very accurate method when it reports eel densities. The AGRRA method is about as accurate as a visual survey method can be for eels and allows the data to be reported in a much more usable manner.

This student research was retrieved from Physis: Journal of Marine Science XIII (Spring 2013)19: 39-44 from CIEE Bonaire.