Natural Coral Reefs Research Articles

那覇港内における網状人工基盤を用いたサンゴ群集の再生

The field observation was conducted to verify the technique using the mesh-type artificial base for restoring a coral community in the Naha port where its population is thin. This base is installed some distance from the seabed to avoid sedimentation of silts on it and can enhance habitation of coralline algae. Therefore settled coral larvae can survive easily. More than 75 % survival rate of the settled coral was confirmed one-year after the base installation. The observed data revealed that the appropriate flow velocity is necessary to keep the suitable habitat conditions for coral. The HSI (Habitat Suitability Index) model including flow velocity as a SI (Suitable Index) for natural coral reef by authors can evaluate also the coral on the artificial base.

High coral cover and subsequent high fish richness on mature breakwaters in Taiwan

Breakwaters are widely used in coastal development. Breakwaters can alter habitats by undermining shallow coastal ecosystems, especially coral reefs. However, recent studies indicate that mature breakwaters can have well-developed corals and coral-associated fishes. Breakwaters with colonized corals may act as surrogates of natural coral reefs against the global coral crisis. Here, we examined the composition of corals, fishes, and benthic biota/abiota between natural reefs and mature breakwaters to evaluate the possibility of breakwaters supplementing natural reefs. We found equal or higher coral cover, fish abundance, and species richness on breakwaters. Conversely, differential coral growth forms and fish assemblages on mature breakwaters suggested the irreplaceability of natural reefs. Corals and coral reef fishes on mature man-made structures, however, may improve the resistance and resilience of coral reefs. Conclusively, despite high coral cover on mature man-made structures appropriate management (e.g., marine reserves) is still necessary to sustain the coral reefs.

Contaminants assessment in the coral reefs of Virgin Islands National Park and Virgin Islands Coral Reef National Monument

Coral, fish, plankton, and detritus samples were collected from coral reefs in Virgin Islands National Park (VIIS) and Virgin Islands Coral Reef National Monument (VICR) to assess existing contamination levels. Passive water sampling using polar organic chemical integrative samplers (POCIS) and semi-permeable membrane devices found a few emerging pollutants of concern (DEET and galaxolide) and polynuclear aromatic hydrocarbons. Very little persistent organic chemical contamination was detected in the tissue or detritus samples. Detected contaminants were at concentrations below those reported to be harmful to aquatic organisms. Extracts from the POCIS were subjected to the yeast estrogen screen (YES) to assess potential estrogenicity of the contaminant mixture. Results of the YES (estrogen equivalency of 0.17–0.31ng/L 17-β-estradiol) indicated a low estrogenicity likelihood for contaminants extracted from water. Findings point to low levels of polar and non-polar organic contaminants in the bays sampled within VICR and VIIS.

The Sanya Coral Reef National Marine Nature Reserve, China: A governance analysis

This paper examines the governance of the Sanya Coral Reef National Marine Nature Reserve (SCR-NMNR) in China in the context of a rapidly growing local economy, driven mainly by recent growth in the tourism sector. The governance approach adopted in the SCR-NMNR is characterised by significant decentralisation, i.e. many roles have been devolved to the local government. However, this has led to the undermining of strategic conservation objectives by local economic development priorities, through the rapid development of mass tourism involving both the private sector and the local government. This reliance on economic incentives has provided alternative livelihoods and resources for the management of the MPA, but has also incurred environmental and social costs. Overall, it can be argued that the current governance approach cannot effectively address the full spectrum of challenges encountered, in that these costs appear to outweigh the benefits. In order to improve the governance of the SCR-NMNR towards more effective and equitable outcomes, strengthened leadership from the central state will be needed, as well as a sense of community stewardship towards the MPA.

A new species of the genus Rhopalaea (Class: Ascidiacea) from the Red Sea

During regular surveys and collection of ascidians along the Red Sea coast of Israel, several specimens of an undescribed species of Rhopalaea were collected. Samples were collected by SCUBA from the natural coral reef and man-made structures at depths between 10 to 40m. This is the first species of the genus Rhopalaea described from the Red Sea, which is characterized by a transparent, uncolored gelatinous tunic with elongated attachment extensions, and is distinguished by its eight atrial lobes, thoracic muscle arrangement, and branchial sac structure.

Fish settlement on reefballs artificial reef and natural coral reef at Buyat Bay and surrounding areas, North Sulawesi, Indonesia

Reefballs are internationally patented (1995) and/or copyrighted technologies that allow nearly all natural reef features to be mimicked (Barber, 2000). It is used in over 56 countries for a range of applications including fishing reefs (recreational and commercial), diving reefs, mitigation of dredging and blast fishing, enhancement of coastal develop-ments and multipurpose breakwaters. The rehabilitation of coral reef ecosystem have been broadly acted in Indonesia and even worldwide. Various models and structures of artificial reefs have been made in many countries from different materials. Many of those artificial reefs do not get good attention on their condition after locating them on the sea basin. In 1999, the gold mine operator PT Newmont Minahasa Raya initiated an artificial reef program to provide an incentive to protect local marine resources from bomb fishing, cyaniding and other unsustainable practices. Monitoring program was conducted annually from 2001 to 2009 in 3 locations both in reefball area and adjacent natural reef in 3m and 10m depth at Buyat Bay and surroundings, North Sulawesi, Indonesia. Monitoring was conducted specific for Target and Indicator species with ‘visual census’ method. The survey in 2009 identified 13 families, 29 genera, 81 species and 2,025 individuals inhabiting the reefballs at 3m depth whereas at 10m depth, 14 families, 36 genera, 106 species and 3883 individuals were found. After 9 years monitoring, it was found that one location of Reefball have better fish settlement compared to the adjacent natural reef. One location was in progress to recovery and the location still under the natural reef.

Impacts of artificial reefs and diving tourism

Coral reefs are currently endangered throughout the world. One of the main activities responsible for this is scuba-diving. Scuba-diving on coral reefs was not problematic in the begging, but due to popularization of the new sport, more and more tourists desired to participate in the activity. Mass tourism, direct contact of the tourists with the coral reefs and unprofessional behavior underwater has a negative effect on the coral reefs. The conflict between nature preservation and economy benefits related to scuba-diving tourism resulted in the creation of artificial reefs, used both to promote marine life and as tourists attractions, thereby taking the pressure off the natural coral reefs. Ships, vehicles and other large structures can be found on the coastal sea floor in North America, Australia, Japan and Europe. The concept of artificial reefs as a scuba-diving attraction was developed in Florida. The main goal was to promote aquaculture, with the popularization of scuba-diving attractions being a secondary effect. The aim of this paper is to determine the effects of artificial reefs on scuba-diving tourism, while taking into account the questionnaire carried out among 18 divers. .

Assessment of Seagrass Floral Community Structure from Two Caribbean Marine Protected Areas

Seagrass communities represent spatially complex and biomass producing systems comprised of intermixed seagrass and algal species. We investigated shallow water communities from two Marine Protected Areas (MPAs) in the Caribbean: St. John, United States Virgin Islands and Cayos Cochinos, Honduras. St. John sites (4) lie within the Virgin Islands National Park and the Coral Reef National Monument and are designated within an UNESCO Biosphere Reserve. Honduran sites (4) lie within the designated Marine National Monument. Our results indi- cate that both MPAs were dominated by Thalassia testudinum with spatial coverage and shoot density significantly greater in Honduras. Many sites also showed substantial cover of Syringodium filiforme , which was significantly greater in St. John. Most major algal groups showed signifi - cant differences between MPAs and among sites within locations. Specifically, Halimeda, Penicillus, Udotea, Galaxaura, and Dictyosphaeria were significantly more abundant in Honduras, while Padina and Avrainvillea were significantly greater from St. John. Additionally, only Honduran sites showed the presence of coral colonies (Montastrea and Porites) within their seagrass beds. Floral community level analyses demonstrated significant differences among almost all site comparisons suggesting relatively distinct floral communities exist within each of these regions, but both MPAs maintain high spatial coverage of seagrasses providing critical ecosystem services.

Object-oriented simulation of coral competition in a coral reef community

A 3-dimensional individual-based model, the ReefModel, was developed to simulate the dynamical structure of coral reef community using object-oriented techniques and Smalltalk/V language. Interactions among six functional groups of reef organisms: tabular coral, foliaceous coral, massive coral, macroalga, corallivorous gastropod and herbivorous fish were examined. Results from the simulation of interaction among the three coral groups are presented here. The behaviours of the coral groups were described with simple mechanistic rules that were derived from their general behaviours (e.g. growing habits, competitive mechanisms) observed in natural coral reef communities. All corals were allowed to grow in a 3-dimensional spatial environment. The model was implemented to explore the competitive mechanisms governing coral community structure. Simulation results suggest that a fast-growing habit with overtopping competitive mechanism is probably the most effective strategy for corals to gain spatial dominance in a coral community under stable environmental conditions. In addition, multimodality exists in the final states of individual coral group as a result of small random spatial events that occurred during the early stages of interactions among the corals in the community. This suggests that alternative stable states may exist in a coral community as a result of inter-specific coral competition.

Threshold of carbonate saturation state determined by CO<sub>2</sub> control experiment

Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies have suggested that carbonate dissolution will occur in polar regions and in the deep sea where saturation state with respect to carbonate minerals (Ω) will be <1 by 2100. Recent reports demonstrate nocturnal carbonate dissolution of reefs, despite a Ωa (aragonite saturation state) value of >1. This is probably related to the dissolution of reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined. We designed an experimental dissolution system with conditions mimicking those of a natural coral reef, and measured the dissolution rates of aragonite in corals, and of Mg-calcite excreted by other marine organisms, under conditions of Ωa > 1, with controlled seawater pCO2. The experimental data show that dissolution of bulk carbonate sediments sampled from a coral reef occurs at Ωa values of 3.7 to 3.8. Mg-calcite derived from foraminifera and coralline algae dissolves at Ωa values between 3.0 and 3.2, and coralline aragonite starts to dissolve when Ωa = 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminiferans and coralline algae in reef sediments.

Impacts of ocean acidification in naturally variable coral reef flat ecosystems

Ocean acidification leads to changes in marine carbonate chemistry that are predicted to cause a decline in future coral reef calcification. Several laboratory and mesocosm experiments have described calcification responses of species and communities to increasing CO2. The few in situ studies on natural coral reefs that have been carried out to date have shown a direct relationship between aragonite saturation state (Ωarag) and net community calcification (Gnet). However, these studies have been performed over a limited range of Ωarag values, where extrapolation outside the observational range is required to predict future changes in coral reef calcification. We measured extreme diurnal variability in carbonate chemistry within a reef flat in the southern Great Barrier Reef, Australia. Ωarag varied between 1.1 and 6.5, thus exceeding the magnitude of change expected this century in open ocean subtropical/tropical waters. The observed variability comes about through biological activity on the reef, where changes to the carbonate chemistry are enhanced at low tide when reef flat waters are isolated from open ocean water. We define a relationship between net community calcification and Ωarag, using our in situ measurements. We find net community calcification to be linearly related to Ωarag, while temperature and nutrients had no significant effect on Gnet. Using our relationship between Gnet and Ωarag, we predict that net community calcification will decline by 55% of its preindustrial value by the end of the century. It is not known at this stage whether exposure to large variability in carbonate chemistry will make reef flat organisms more or less vulnerable to the non‐calcifying physiological effects of increasing ocean CO2 and future laboratory studies will need to incorporate this natural variability to address this question.

Dissipation of wave energy and turbulence in a shallow coral reef lagoon

Simultaneous in situ measurements of waves, currents and turbulence are presented to describe dissipation rates of wave energy and turbulent kinetic energy in the windward coral reef‐lagoon system at Lady Elliot Island (LEI), Australia. The dissipation of wave energy in the lagoon is tidally modulated and strongly correlates with frictional dissipation due to the presence of the extremely rough bottom boundary. The observed turbulent kinetic energy (TKE) dissipation rate, ε, in this wave‐dominated lagoon is much larger than recently reported values for unidirectional flows over natural fringing coral reefs. The correlation between the wave dissipation and ε is examined. The average rate of dissipation induced by the rough turbulent flow was estimated directly from the observed ε coupled with both a depth‐integrated approach and with a bottom boundary layer scaling. Rates of TKE dissipation estimated using the two approaches approximate well, within a factor of 1.5 to 2.4, to the surface‐wave energy dissipation rate. The wave dissipation and friction factor in the lagoon can be described by a spectral wave‐frictional model with a bottom roughness length scale that is approximately constant across the lagoon. We also present estimates of dissipation induced by the canopy drag force of the coral heads. The dissipation in this case is enhanced and becomes more significant for the total energy dissipation when the water depth in the lagoon is comparable to the height of the coral heads.

Selective mortality associated with variation in CO2 tolerance in a marine fish

Predicted future CO2 levels can affect reproduction, growth, and behaviour of many marine organisms. However, the capacity of species to adapt to predicted changes in ocean chemistry is largely unknown. We used a unique field-based experiment to test for differential survival associated with variation in CO2 tolerance in a wild population of coral-reef fishes. Juvenile damselfish exhibited variation in their response to elevated (700 μatm) CO2 when tested in the laboratory and this influenced their behaviour and risk of mortality in the wild. Individuals that were sensitive to elevated CO2 were more active and move further from shelter in natural coral reef habitat and, as a result, mortality from predation was significantly higher compared with individuals from the same treatment that were tolerant of elevated CO2. If individual variation in CO2 tolerance is heritable, this selection of phenotypes tolerant to elevated CO2 could potentially help mitigate the effects of ocean acidification.

Can a small artificial reef reduce diving pressure from a natural coral reef? Lessons learned from Eilat, Red Sea

Part of the decline of coral reefs is attributed to the physical damage caused by divers. Consequently, active efforts are being invested to mitigate the diving pressure on and around natural reefs. We measured the effect of artificial reef (AR) placement on the diving behaviors of divers in training in the Red Sea’s Gulf of Eilat on the southern tip of Israel. Dive groups were followed, and their diving times in an adjacent marine protected area (MPA) and surrounding natural coral outcrops were recorded. Time spent inside the MPA did not change. However, in-training divers reduced their times in the MPA and at two adjacent coral outcrops following AR deployment, but they did not alter other elements of their dives; coral transplantation did not affect diving behavior. A dive entry point located at least 90-m from the border of the MPA was sufficient to reduce dive time in the MPA. The AR had only a partial impact on diver behavior. Accordingly, future projects should take into account location, size, aesthetics, and the target visitors of the ARs.

The biology and economics of coral growth.

To protect natural coral reefs, it is of utmost importance to understand how the growth of the main reef-building organisms—the zooxanthellate scleractinian corals—is controlled. Understanding coral growth is also relevant for coral aquaculture, which is a rapidly developing business. This review paper provides a comprehensive overview of factors that can influence the growth of zooxanthellate scleractinian corals, with particular emphasis on interactions between these factors. Furthermore, the kinetic principles underlying coral growth are discussed. The reviewed information is put into an economic perspective by making an estimation of the costs of coral aquaculture.

The Influence of Wave Exposure on Coral Community Development on Man-Made Breakwater Reefs, with a Comparison to a Natural Reef

Breakwaters dominate shorelines in many coastal urban areas, providing substantial hard-bottom habitat upon which diverse and abundant reef communities develop. In recognition of their potential ecological and economic importance, there is increasing interest in understanding how design features can influence community development. We investigated the influence of wave exposure on breakwater coral communities in Dubai, United Arab Emirates. Coral community composition, cover, size structure, recruitment, mortality, and growth rates were compared quarterly between two windward and two leeward breakwater sites for 1 yr to explore the influence of wave exposure on coral community development. Comparisons also were made with a natural coral reef to gain an understanding of how community structure and dynamics compare between these habitats. Benthic and water column sediment particle sizes were also analyzed. Leeward breakwaters contained a low-cover coral community dominated by small colonies with high mortality compared with windward breakwaters and the natural reef. Windward breakwater coral communities had comparable recruitment, mortality, and growth rates as the natural reef. Fine sediments ( 125 μm), likely as a result of differences in wave action among reef types. Overall, these results suggest that leeward breakwaters represent sub-optimal habitats for coral community development. However, with appropriate design, breakwaters can develop diverse and abundant coral communities with comparable coral cover, demographics, and growth rates to those on the natural reef in Dubai.

High diversity and abundance of scleractinian corals growing on and near mangrove prop roots, St. John, US Virgin Islands

Received: 20 April 2009/Accepted: 10 June 2009/Published online: 12 July 2009 Springer-Verlag 2009A narrow zone of red mangroves fringes the shorelines of four small bays inHurricane Hole, within Virgin Islands Coral Reef National Monument (VICRNM)on St. John. In two of these bays, Otter Creek and Water Creek, a particularlyhigh abundance and diversity of corals are growing directly on or near the proproots (Fig. 1a,b,c). To date, 28 coral species have been found: Stephanocoeniaintersepta, Agaricia sp., Agaricia agaricites, Siderastrea siderea, S. radians,Porites porites, P. astreoides, P. furcata, P. divaricata, Favia fragum, Diploriastrigosa, D. labyrinthiformis, D. clivosa, Manicina areolata, Colpophyllia natans,C. amaranthus, Montastraea annularis, M. faveolata, M. franksi, M. cavernosa,Oculina diffusa, Meandrina meandrites, Dendrogyra cylindrus, Scolymia cubensis,Mycetophyllia sp., Eusmilia fastigiata, Cladocora arbuscula, and Tubastreacoccinea. The size of many of the colonies, including some M. faveolata andC. natans colonies over 1 m across (Fig. 1b), indicate that they survived the2005/2006 bleaching and disease event that caused losses of over 60% of the coralcover on St. John reefs (Rogers et al. 2008). Shading by the mangroves possiblyreduced the thermal and photic stress on these corals. The coral diversity in thesemangroves may be higher than for other Caribbean mangrove systems. Few pub-lished papers include data on corals in these habitats. Two comprehensive reviewsof the biology of mangroves make no reference to corals on or near prop roots(Kathiresan and Bingham 2001; Nagelkerken et al. 2008). The number of corals inHurricane Hole, particularly the new recruits on the prop roots (Fig. 1c), may haveincreased since the establishment of the VICRNM in 2001, as boaters are notpermitted to overnight in these bays or to tie their boats to the mangrove trees as wasdone in the past.Acknowledgments Thanks to J. Miller, R. Boulon, E. Weil and J. Lang for livelydiscussions about the corals in these bays, and to K. and R. Vahling for researchsupport.

Catastrophic regime shifts in coral communities exposed to physical disturbances: Simulation results from object-oriented 3-dimensional coral reef model

A 3-dimensional individual-based model, the ReefModel, was developed to simulate the dynamical structure of coral reef community using object-oriented techniques. Interactions among functional groups of reef organisms were simulated in the model. The behaviours of these organisms were described with simple mechanistic rules that were derived from their general behaviours (e.g. growing habits, competitive mechanisms, response to physical disturbance) observed in natural coral reef communities. The model was implemented to explore the effects of physical disturbance on the dynamical structure of a 3-coral community that was characterized with three functional coral groups: tabular coral, foliaceous coral and massive coral. Simulation results suggest that (i) the integration of physical disturbance and differential responses (disturbance sensitivity and growing habit) of corals plays an important role in structuring coral communities; (ii) diversity of coral communities can be maximal under intermediate level of acute physical disturbance; (iii) multimodality exists in the final states and dynamic regimes of individual coral group as well as coral community structure, which results from the influence of small random spatial events occurring during the interactions among the corals in the community, under acute and repeated physical disturbances. These results suggest that alternative stable states and catastrophic regime shifts may exist in a coral community under unstable physical environment.

Mapping ecosystem functions to the valuation of ecosystem services: implications of species–habitat associations for coastal land-use decisions

Habitats and the ecosystem services they provide are part of the world’s portfolio of natural capital assets. Like many components of this portfolio, it is difficult to assess the full economic value of these services, which tends to over-emphasize the value of extractive activities such as coastal development. Building on recent ecological studies of species–habitat linkages, we use a bioeconomic model to value multiple types of habitats as natural capital, using mangroves, sea grass, and coral reefs as our model system. We show how key ecological variables and processes, including obligate and facultative behaviors map into habitat values and how the valuation of these ecological processes can inform decisions regarding coastal development (habitat clearing). Our stylized modeling framework also provides a clear and concise road map for researchers interested in understanding how to make the link between ecosystem function, ecosystem service, and conservation policy decisions. Our findings also highlight the importance of additional ecological research into how species utilize habitats and that this research is not just important for ecological science, but it can and will influence ecosystem service values that, in turn, will impact coastal land-use decisions. While refining valuation methods is not necessarily going to lead to more rational coastal land-use decisions, it will improve our understanding on the ecological–economic mechanisms that contribute to the value of our natural capital assets.

Long-term monitoring of habitats and reef fish found inside and outside the U.S. Virgin Islands Coral Reef National Monument: A comparative assessment

The primary objective of this study was to assess the efficacy of the Virgin Islands Coral Reef National Monument (VICR), a marine protected area in St John, US Virgin Islands. Surveys of habitat and fishes inside and outside of VICR were conducted in 2003–2008. Areas outside the VICR had significantly more scleractinian corals, greater habitat complexity, and greater species richness and density of reef fishes than areas inside., Areas inside and outside the VICR exhibited significant decreases in percent scleractinian coral coverage over the study period. A contrasting trend of increasing macroalgal cover was also observed. No clear effect of the severe 2005 coral bleaching event was observed suggesting other causal factors. No obvious trends in the fish community were observed across the study period. The significant decline in habitat condition, coupled with the initial incorporation of some of the more degraded reefs into the marine protected area may result in a longer time period necessary to detect positive changes in the St. John coral reef ecosystem and associated reef fish abundance and community structure.