Corals

Space-filling and benthic competition on coral reefs

Abstract

 

Reef-building corals are ecosystem engineers that compete with other benthic organisms for space and resources. Corals harvest energy through their surface by photosynthesis and heterotrophic feeding, and they divert part of this energy to defend their outer colony perimeter against competitors. Here, we hypothesized that corals with a larger space-filling surface and smaller perimeters increase energy gain while reducing the exposure to competitors. This predicted an association between these two geometric properties of corals and the competitive outcome against other benthic organisms. To test the prediction, fifty coral colonies from the Caribbean island of Curaçao were rendered using digital 3D and 2D reconstructions. The surface areas, perimeters, box-counting dimensions (as a proxy of surface and perimeter space-filling), and other geometric properties were extracted and analyzed with respect to the percentage of the perimeter losing or winning against competitors based on the coral tissue apparent growth or damage. The increase in surface space-filling dimension was the only significant single indicator of coral winning outcomes, but the combination of surface space-filling dimension with perimeter length increased the statistical prediction of coral competition outcomes. Corals with larger surface space-filling dimensions (Ds > 2) and smaller perimeters displayed more winning outcomes, confirming the initial hypothesis. We propose that the space-filling property of coral surfaces complemented with other proxies of coral competitiveness, such as life history traits, will provide a more accurate quantitative characterization of coral competition outcomes on coral reefs. This framework also applies to other organisms or ecological systems that rely on complex surfaces to obtain energy for competition.

Date
2021
Data type
Scientific article
Theme
Research and monitoring
Document
Journal
Geographic location
Curacao

Size Distribution of Spirobranchus gianteus in Bonaire: Is There a Benefit of Recruitment to Live Coral?

Spirobranchus giganteus is a tube-dwelling polychaete more commonly known as the Christmas tree worm. S. giganteus larvae are planktonic, which is followed by benthic settlement and development into a sessile adult. It has been shown that chemical and physical cues produced by live coral and adult S. giganteus attract larvae to settlement sites. In fact, it has been postulated that there may be a mutualistic relationship between S. giganteus and live coral. However, settlement of S. giganteus on coral rubble has been noted in the field. The aim of this study is to investigate whether there is a relationship between size of S. giganteus and substratum settlement type on the coral reefs of Bonaire. The hypothesis under examination in this study states that S. giganteus settled on live coral will be larger than S. giganteus settled on rubble. The measurement chosen for this study was the diameter of the orifice of the calcareous tube, since it has been shown that this is a good estimate for overall size of the polychaete. The diameter of the orifice of S. giganteus was significantly greater for individuals living on rubble (0.510 cm) than individuals living on live coral (0.457 cm). The species of coral that S. giganteus settled on also appeared to affect the orifice diameter. Individuals on Agaricia agaricites were significantly smaller than individuals settled on both Montastrea annularis and Siderastrea siderea. These results may indicate that the interactions between S. giganteus and live coral, such as extracoelenteric digestion and sweeper tentacles, may be disruptive enough to cause a lower size distribution of polychaetes on that substrate when compared to rubble.

This student research was retrieved from Physis: Journal of Marine Science III (Spring 2008)19: 25-30 from CIEE Bonaire.

Date
2008
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Can native sessile species resist the settlement of the orange cup coral, Tubastraea coccinea, on hard substrate communities of Bonaire, Netherlands Antilles?

Tubastrea coccinea is an invasive coral species found on the reefs of Bonaire. These corals are typically seen at various densities (up to 80% m-2) on hard, vertical substrata suggesting that biotic resistance could be one possible biological factor preventing settlement of T. coccinea elsewhere (e.g.,,, horizontal substrata). The impact potential competitors have on the successful invasion, recruitment and growth of T. coccinea was experimentally assessed by establishing replicated 15 x 15 cm plots of substrata already inhabited by single species or combinations of native species (0-3 and 3 seeded with adult T. coccinea) at the Harbor Village jetty, Kralendijk, Bonaire, which had the necessary vertical substrata. Monitoring occurred over a period of three weeks to assess percent cover change of the studied organisms. Additionally 15 vertical, 5 m transects were run to evaluate mean percent cover of all sessile species that inhabited the surveyed locations for a general representation of species diversity at the jetty. T. coccinea was not observed to settle in any of the experimental plots nor did the seeded adult conspecifics show any evidence of growth or recruitment. Observational data indicated that an algal turf had the highest mean percent cover, but in areas around T. coccinea, algal turf percent cover decreased by almost 20%, suggesting competition between the two organisms. No firm conclusions could be drawn about T. coccinea recruitment or growth, but results suggested that the presence of an invasive species may negatively affect the growth of native species when they are found in close proximity to it.

This student research was retrieved from Physis: Journal of Marine Science IV (Fall 2008)19: 2-6 from CIEE Bonaire.

Date
2008
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Is the introduced cup coral Tubastraea coccinea an invasive species in Bonaire, Dutch Caribbean?

The orange cup coral Tubastraea coccinea has expanded its range from the Indo-Pacific into the western Atlantic region. It grows on a wide variety of natural and man-made substrates, including rock ledges, docks, and shipwrecks. Its early reproductive age, fast growth rate, and ability to thrive where other species cannot could potentially make T. coccinea a valid threat to native species. The goal of this study is to provide baseline data on the size, depth, and range of T. coccinea on the island of Bonaire in the Dutch Caribbean. Substrate and light intensity preferences were also investigated by estimating percent cover on a variety of substrates and light conditions. A clear preference was observed for concrete substrates and low light conditions. Interactions between T. coccinea and a variety of other coral and sponge species were also investigated for potential harmful effects, but despite documentation of harmful coral-coral interactions in Brazil, no evidence of T. coccinea exhibiting harmful effects on native coral species was found in the study area of Bonaire. While T. coccinea does not currently appear to exhibit negative effects on native species in Bonaire, it may simply be in the early stages of expansion and this expansion needs to be monitored for future development of harmful effects on native species.

This student research was retrieved from Physis: Journal of Marine Science IX (Spring 2011)19: 70-78 from CIEE Bonaire.

Date
2011
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

Potential for transmission of yellow band disease between colonies of Montastrea annularis through common research techniques

This study investigates the relationship between yellow band disease (YBD) infected Montastrea annularis coral colonies and its potential to spread by contact with transect tapes, as commonly used in research. M. annularis plays an important role in maintaining reef complexity and diversity in Bonaire as it is a structural reef-building coral, yet the recent spread of YBD has created an degrading the reefs (Bruckner 2006). The study has two primary goals, to investigate whether the use of transect lines had the potential to transfer YBD from one coral to another, and whether a simple cleaning protocol can reduce this transfer. Transects placed on the YBD infected colonies of M. annularis had the most percent bacterial growth, though not statistically significant. It also showed that even though specific species of bacteria were unable to be identified, the transect lines are indeed capable of carrying bacteria. Although the difference was not significant in this study, cleansing treatments may have an effect on lessening the growth of bacteria.

This student research was retrieved from Physis: Journal of Marine Science X (Fall 2011)19: 11-15 from CIEE Bonaire.

Date
2011
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Author

The effects of Stegastes planifrons gardening on the prevalence of yellow band disease in the Montastrea annularis species complex

Yellow band disease (YBD) is a bacterial infection affecting corals of the Montastrea annularis species complex. Recent mortality rates of M. annularis spp. on Bonaire have risen due to YBD and other biotic and abiotic factors. The loss of staghorn coral, Acropora cervicornis, the preferred habitat of the threespot damselfish, Stegastes planifrons, has caused the damselfish to inhabit M. annularis spp. Unfortunately, M. annularis spp. are slower growing corals that take longer to reach reproductive maturity and are thus less able to withstand S. planifrons biting their tissues and creating algal gardens on exposed skeleton. This weakens the coral and makes it more susceptible to diseases like YBD. The objective of this study was to examine the relationship between S. planifrons gardening and YBD. Sample sites of healthy and diseased colonies of M. annularis spp. were established across depths at Yellow Sub dive site in Kralendijk, Bonaire. Sites were monitored for damselfish inhabitants and signs of coral biting. Pictures were taken of each site to chart the progress of the disease over the course of the study, and ImageJ was used to determine percent cover of healthy versus unhealthy coral. No significant relationship was found between S. planifrons activity and YBD, although S. planifrons seemed to select healthy colonies. The increase of damselfish populations and their detrimental effects on Bonaire’s reef calls attention to the need for fishing regulations of predatory species and a heavier focus on the conservation of A. cervicornis thickets.

This student research was retrieved from Physis: Journal of Marine Science XI (Fall 2012)19: 83-87 from CIEE Bonaire.

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

Vibrio communities associated with the azooxanthellate coral Tubastraea coccinea as compared to zooxanthellate shallow sea corals

A coral is made up of key associations between endosymbiotic zooxanthellae, protists, bacteria, archaea, viruses, and fungi. These microbe-coral interactions can be very beneficial, some associations providing key functions in reproduction, nutrition, and antimicrobial protection. However, as a coral becomes thermally stressed, the ability to regulate microbe growth in its surface mucus layer becomes diminished and opportunistic pathogens are able to colonize. Corals may be able to adapt for the changing reef ecosystem by selecting for more beneficial associations: one of the facets of the coral probiotic hypothesis. The invasive azooxanthellate coral Tubastraea coccinea is able to colonize very shallow, hot and turbid areas that are not favorable for settlement by other species. However, not much is known about T. coccinea other than its invasive nature in the Caribbean. The purpose of this investigation was to determine if the surface microbial communities of T. coccinea are one of the factors aiding its survival. Culturing on Thiosulfate Citrate Bile Salt plates was used to visualize and compare the overall culturable Vibrio spp. communities present in T. coccinea and other widespread shallow corals. At each site, the numbers of Vibrio spp. were not significantly different between the three species, but numbers of a gram-positive bacteria, Enterococcus spp., were found to be significantly higher in T. coccinea.

This student research was retrieved from Physis: Journal of Marine Science XII (Fall 2012)19: 73-79 from CIEE Bonaire.

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

Tubastraea coccinea: Distribution and substratum preference of an exotic coral in Bonaire, Dutch Caribbean

The study of introduced species has gained popularity in recent years. A species introduced to a new area can have negative effects on the native ecosystems, as well as positive interactions with local fauna. The success of an exotic species depends on many factors. Those that are most successful at expanding possess mechanisms of reproduction, settlement, and distribution that aid in competing for space and resources. Tubastraea coccinea, also known as orange cup coral, is native to the Indo-Pacific and was introduced in Bonaire in the 1940s. Little is known about the effects T. coccinea has on the local marine community. It has a very opportunistic nature and has become a dominant scleractinian coral in the subtidal zones occupying shallow, heavy surged waters. T. coccinea is an azooxanthellate coral, which explains its ability to occupy habitats not desirable by other corals requiring sufficient nutrients and sunlight for photosynthesis. The purpose of this investigation was to determine the distribution and abundance of T. coccinea along various sites in Bonaire and observe its habitat preferences. Six sites in Kralendijk, Bonaire were surveyed by snorkelers, who counted various sized colonies and substratum occupancy. T. coccinea was found at all six surveyed sites, being most abundant at sites with very shallow shores and heavy surge. It preferred man-made pilings underneath docks as its habitat. This confirms that T. coccinea is established in Bonaire. By observing the distribution and preferences, the successful nature of T. coccinea throughout the Caribbean can be better understood.

This student research was retrieved from Physis: Journal of Marine Science XIII (Spring 2013)19: 10-16 from CIEE Bonaire.

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

Spatial distribution and severity of dark spots disease in Bonaire, Dutch Caribbean

Corals are the building blocks of coral reefs as they provide countless marine organisms with protection and habitat. However, coral diseases are currently threatening coastal environments by causing tissue loss and, in some cases, death of corals. This destroys the habitats utilized by marine organisms and the biodiversity of given areas. Many factors contribute to the prevalence of coral diseases, but very little is known about the overall impact of anthropogenic stressors on diseases. Dark spots disease (DSD) is a common coral disease found in the Caribbean and was the subject of this study. Dark spots disease prevalence and severity was quantified utilizing video transects and a severity index approximately one kilometer north of downtown Kralendijk on the west coast of Bonaire, Dutch Caribbean. This data was then analyzed for any trends with regards to spatial location and depth. It was observed that DSD is typically more common and severe at deeper depths of 15 m than at shallower depths of 8 m, although no trends were observed in regards to spatial location and DSD distribution. Gaining a better understanding of DSD distribution paves the way for future studies to potentially understand causative agents of DSD; therefore, allowing for more preventative measures and mitigation processes to conserve the health of coral reefs.

This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 79-85 from CIEE Bonaire.

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

Does nutrient pollution affect the prevalence of dark spots disease in corals on Bonaire, Dutch Caribbean?

Environmental changes and deterioration have increased coral disease outbreaks, creating a Caribbean hot spot of high disease prevalence and virulence. Dark spots disease (DSD) has an unknown causative agent, although it is suspected to be a result of a biotic pathogen. Variation with anthropogenic stressors and DSD has been limited in research; therefore, the purpose of this study was to determine if a correlation existed between DSD prevalence and nutrient enrichment, in the form of nitrogen concentration. It was hypothesized that DSD prevalence and nitrogen concentration would be highest at shallower depths and that there would be a positive correlation between DSD prevalence and nitrogen concentration. In Kralendijk, Bonaire, sites were surveyed for DSD to calculate the prevalence and water samples were collected to determine the concentration of nitrogen. The results indicated no significant effect of depth and site on DSD prevalence as well as no significant effect of depth on nitrogen concentration. There was a significant effect of site on nutrient concentration as indicated by the significantly higher nitrogen concentration. The pooled data illustrated a weak positive relationship and correlation between DSD prevalence and nitrogen concentration with insignificant results, but one site illustrated a moderately strong positive relationship and correlation with statistical significance. The significant results at that site suggest some correlation between DSD prevalence and nitrogen concentration which requires further investigation ex situ to establish a stronger correlation or possible causation.

This student research was retrieved from Physis: Journal of Marine Science XV (Spring 2014)19: 36-44 from CIEE Bonaire.

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