Back Reef Research Articles

Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat-forming biota on a tropical coral reef.

Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large‐scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large‐scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy‐forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO‐influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids (r = .9), siganids (r = .9), and mullids (r = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña‐related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat‐forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.

CORAL COMMUNITIES, ZONATION AND PALEOECOLOGY OF AN UPPER JURASSIC REEF COMPLEX (ELLIPSACTINIA LIMESTONES, CENTRAL APENNINES, ITALY)

This work describes and analyzes an original collection of fossil corals from the Ellipsactinia Limestones (Kimmeridgian-Tithonian), exposed in the Marsica area (central Apennines, Italy), focusing on taxonomy and paleoecology. 43 species grouped into 32 genera, 16 families and 9 suborders were identified. Astreoidogyra giadae nov. gen. nov. sp. (Rhipidogyridae) and Clausastrea eliasovae nov. sp. (Montlivaltiidae) are new taxa. Corals occur from the back reef to the reef crest, showing a marked zonation, expressed by a variation of coral cover and type, although the reef front and slope facies could not be sampled. The back reef is characterised by scattered medium-to-small colonies, with a relative high variety of colony shape, corallite arrangement types and high taxonomic diversity. Stylosmilia, Calamophylliopsis, Intersmilia, Pleurophyllia, Bracthelia, Heliocoenia, Ogilvinella occur here among others. The inner reef flat records the highest coral cover, with large robust branching, such as “Pseudocoenia”, Heliocoenia, Calamophylliopsis, and large dome-shaped meandroid, such as Psammogyra, Pruvostrastraea, Eugyriopsis) colonies. Within the external reef flat and the reef crest the coral cover is low and the stromatoporoid-bearing mounds dominate on the isolated coral bioconstructions. Controlling factors as bathymetry, hydrodynamic disturbances, abrasive currents, background sedimentation and morphological irregularities of the depositional profile are considered to explain the observed coral zonation. High diversity and low dominance indices are interpreted to result from reef complex heterogeneity, which should have influenced the formation of different ecological niches and consequently the proliferation of a greater number of taxa in a relatively small area.

Have the Algae-Grazing Fish in the Back Reefs of Jamaica and Grand Cayman Changed in Size? A View across 36 Years

The island of Jamaica is often cited as an example of how overfishing has dramatically reduced the sizes of coral reef fishes. To examine the change in fish sizes over a 36-year period, we analyzed data from systematic surveys conducted in 1977 and 2013/14 of the sizes and relative abundances of four common algae-grazing fishes in the shallow backreef habitats of Jamaica and Grand Cayman. The four species are: striped parrotfish (Scarus iseri), stoplight parrotfish (Sparisoma viride), ocean surgeon (Acanthurus tractus) and the blue tang (Acanthurus coeruleus). We predicted that all four species would be larger in Grand Cayman than in Jamaica in 1977 as well as in 2013/14, because Grand Cayman has been cited as having less fishing pressure than Jamaica. For the same reason, we expected all four species would have declined in size over the 36 years in Jamaica but not in Grand Cayman. Furthermore, we predicted that the compressed body shape of the ocean surgeon and the blue tang would have made them especially vulnerable to net and trap fishing compared to the two parrotfishes, and that accordingly the effects of overfishing would be greater in these two species. We rejected this hypothesis. The size distributions of the laterally compressed species changed significantly on both islands over the 36-year time span, although not as predicted. At both islands, the blue tangs shifted toward smaller sizes and the ocean surgeons shifted toward larger sizes. There were no size distribution changes detected in the two fusiform species. There was also no support for the prediction that the sizes of these four species were larger in Grand Cayman than in Jamaica during either time period.

Facies Development of Carbonate Rock and System Tract Influence Based on Fullbore Formation Microimager (FMI) and Well Log Analysis on Carbonate Reservoir Tuban Formation, North East Java Basin

The North East Java Basin is known to be one of the basins that consist of Miocene carbonate rocks, like the reef carbonate of Tuban Formation. It has the potential hydrocarbons that can be explored. Therefore, the FMI log analysis is very important to identify carbonate rocks of Tuban Formation to know facies and characteristics of that carbonate rocks. The method used descriptive and analysis process of FMI and Gamma Ray log to determine facies of the carbonate rock and the system tract. Based on the result of FMI log analysis, there are variations lithofasies include mudstone, wackestone, packstone, grainstone, floatstone, rudstone and claystone. A collection of rock associations can interpret the reef facies. It involves back reef facies, reef core facies, and fore reef facies. The changes of lithofasies and reef facies are caused by sea level fluctuations and subsidence resulting in the system tract. The system tracts generated in the research area include transgressive and highstand system tract.

High-frequency temperature variability mirrors fixed differences in thermal limits of the massive coral Porites lobata.

Spatial heterogeneity in environmental characteristics can drive adaptive differentiation when contrasting environments exert divergent selection pressures. This environmental and genetic heterogeneity can substantially influence population and community resilience to disturbance events. Here, we investigated corals from the highly variable back-reef habitats of Ofu Island in American Samoa that thrive in thermal conditions known to elicit widespread bleaching and mortality elsewhere. To investigate the relative importance of acclimation versus site of origin in shaping previously observed differences in coral tolerance limits at Ofu Island, specimens of the common Indo-Pacific coral Porites lobata from locations with differing levels of thermal variability were acclimated to low and high thermal variation in controlled common garden aquaria. Overall, there were minimal effects of the acclimation exposure. Corals native to the site with the highest level of daily variability grew fastest, regardless of acclimation treatment. When exposed to lethal thermal stress, corals native to both variable sites contained elevated levels of heat shock proteins and maintained photosynthetic performance for 1-2 days longer than corals from the stable environment. Despite being separated by <5 km, there was significant genetic differentiation among coral colonies (FST=0.206, P<0.0001; nuclear ribosomal DNA), whereas Symbiodiniaceae were all Cladocopium sp. (ITS type C15). Our study demonstrates consistent signatures of adaptation in growth and stress resistance in corals from naturally thermally variable habitats, suggesting that differences in the amount of thermal variability may be an important contributor to adaptive differentiation in reef-building corals.

Unusually high coral recruitment during the 2016 El Niño in Mo'orea, French Polynesia.

The negative implications of the thermal sensitivity of reef corals became clear with coral bleaching throughout the Caribbean in the 1980’s, and later globally, with the severe El Niño of 1998 and extensive seawater warming in 2005. These events have substantially contributed to declines in coral cover, and therefore the El Niño of 2016 raised concerns over the implications for coral reefs; on the Great Barrier Reef these concerns have been realized. A different outcome developed in Mo’orea, French Polynesia, where in situ seawater temperature from 15 March 2016 to 15 April 2016 was an average of 0.4°C above the upper 95% CI of the decadal mean temperature, and the NOAA Degree Heating Weeks (DHW) metric supported a Level 1 bleaching alert (DHW ≥ 4.0). Starting 1 September 2016 and for the rest of the year (122 d), in situ seawater temperature was an average of 0.4°C above the 95% CI of long-term values, although DHW remained at zero. Minor coral bleaching (0.2–2.6% of the coral) occurred on the outer reef (10-m and 17-m depth) in April 2016, by May 2016 it had intensified to affect 1.3–16.8% of the coral, but by August 2016, only 1.4–3.0% of the coral was bleached. Relative to the previous decade, recruitment of scleractinians to settlement tiles on the outer- (10 m) and back- (2 m) reef over 2016/17 was high, both from January 2016 to August 2016, and from August 2016 to January 2017, with increased relative abundances of pocilloporids on the outer reef, and acroporids in the back reef. The 2016 El Niño created a distinctive signature in seawater temperature for Mo’orea, but it did not cause widespread coral bleaching or mortality, rather, it was associated with high coral recruitment. While the 2016 El Niño has negatively affected other coral reefs in the Indo-Pacific, the coral communities of Mo’orea continue to show signs of resilience, thus cautioning against general statements regarding the effects of the 2015/16 El Niño on coral reefs in the region.

Aerial images can detect 3D small patch reefs that are potential habitats for anemonefish Amphiprion frenatus

Patchy habitats often enhance species coexistence and, consequently, abundance of each species. The present study examined two indicators of potential habitats for anemonefish Amphiprion frenatus: total area of dark-colored patch reefs that are detectable on an aerial image with image analysis software, and total area of tall patch reefs (>1.5 m in height) that are detectable on stereoscopic aerial images with a stereoscope. Relationships between patch reef area and anemonefish abundance, as estimated by number of host anemone Entacmaea quadricolor, were investigated at Shiraho Reef, Ishigaki Island, Japan. Total number of anemones was not correlated with total area of tall patch reefs but was highly correlated with total area of dark-colored patch reefs. Underwater observations confirmed that upper surface of tall patch reefs often involved bare substratum, whereas dark-colored patch reefs did not include this substratum. Because reef area approximately reflected reef volume within shallow back reefs, total area of dark-colored patch reefs that are detectable by aerial photography will reflect total volume of reef fish habitat. The present study suggests that aerial photography with a drone can provide a useful predictor of reef fish abundance.

Daily variation in net primary production and net calcification in coral reef communities exposed to elevated &amp;lt;i&amp;gt;p&amp;lt;/i&amp;gt;CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;

Abstract. The threat represented by ocean acidification (OA) for coral reefs has received considerable attention because of the sensitivity of calcifiers to changing seawater carbonate chemistry. However, most studies have focused on the organismic response of calcification to OA, and only a few have addressed community-level effects, or investigated parameters other than calcification, such as photosynthesis. Light (photosynthetically active radiation, PAR) is a driver of biological processes on coral reefs, and the possibility that these processes might be perturbed by OA has important implications for community function. Here we investigate how CO2 enrichment affects the relationships between PAR and community net O2 production (Pnet), and between PAR and community net calcification (Gnet), using experiments on three coral communities constructed to match (i) the back reef of Mo'orea, French Polynesia, (ii) the fore reef of Mo'orea, and (iii) the back reef of O'ahu, Hawaii. The results were used to test the hypothesis that OA affects the relationship between Pnet and Gnet. For the three communities tested, pCO2 did not affect the Pnet–PAR relationship, but it affected the intercept of the hyperbolic tangent curve fitting the Gnet–PAR relationship for both reef communities in Mo'orea (but not in O'ahu). For the three communities, the slopes of the linear relationships between Pnet and Gnet were not affected by OA, although the intercepts were depressed by the inhibitory effect of high pCO2 on Gnet. Our result indicates that OA can modify the balance between net calcification and net photosynthesis of reef communities by depressing community calcification, but without affecting community photosynthesis.

Seaweed beds support more juvenile reef fish than seagrass beds in a south-western Atlantic tropical seascape

Seascape connectivity is regarded essential for healthy reef fish communities in tropical shallow systems. A number of reef fish species use separate adult and nursery habitats, and hence contribute to nutrient and energy transfer between habitats. Seagrass beds and mangroves often constitute important nursery habitats, with high structural complexity and protection from predation. Here, we investigated if reef fish assemblages in the tropical south-western Atlantic demonstrate ontogenetic habitat connectivity and identify possible nurseries on three reef systems along the eastern Brazilian coast. Fish were surveyed in fore reef, back reef, Halodule wrightii seagrass beds and seaweed beds. Seagrass beds contained lower abundances and species richness of fish than expected, while Sargassum-dominated seaweed beds contained significantly more juveniles than all other habitats (average juvenile fish densities: 32.6 per 40 m2 in Sargassum beds, 11.2 per 40 m2 in back reef, 10.1 per 40 m2 in fore reef, and 5.04 per 40 m2 in seagrass beds), including several species that are found in the reef habitats as adults. Species that in other regions worldwide (e.g. the Caribbean) utilise seagrass beds as nursery habitats were here instead observed in Sargassum beds or back reef habitats. Coral cover was not correlated to adult fish distribution patterns; instead, type of turf was an important variable. Connectivity, and thus pathways of nutrient transfer, seems to function differently in east Brazil compared to many tropical regions. Sargassum-dominated beds might be more important as nurseries for a larger number of fish species than seagrass beds. Due to the low abundance of structurally complex seagrass beds we suggest that seaweed beds might influence adult reef fish abundances, being essential for several keystone species of reef fish in the tropical south-western Atlantic.

AMS Carbon-14 dating of microbial carbonates in Holocene coral reefs, Western Luzon, Philippines

Microbial carbonates (microbialites) occurred in the Holocene coral reefs at Paraoir, the Philippines. These microbialites appeal grayish to buff in color with a stromatolitic to thrombolitic structures, and encrust on corals directly or on a thin layer of calcareous red algae or encrusting foraminifera that covered the corals first. The microbialites only occur in the lower (earlier) parts of the Holocene reef sequence where Heliopora coerulea dominated. No microbial carbonates were observed in the upper (younger) part of the Holocene reefs that is interpreted to grow in water depth shallower than 6 m on the basis of coral community. Samples of microbial carbonate and associated coral were dated by AMS 14C. The results show that the microbialites formed about 10 to 7.5 kyr BP, nearly coeval to or a few hundred years younger than the corals on which the microbialites encrusted. AMS 14C ages of samples recovered at reef margins are consistent to 230Th ages of corals associated with the microbialites, but those recovered in the back reef are much older that the previously published 230Th ages of corals and interpreted to be reworked into the backreef. It is proposed that the microbialites at Paraoir formed in early Holocene on reef slope when the deglacial sea level was rising rapidly. After 7.5 kyr BP when the sea-level rise slowed down and coral reefs caught up with sea level, the condition became favorable to corals prospered in shallow water, and no longer suitable for microbialite formation.

Calcium carbonate (CaCO3) sediment dissolution under elevated concentrations of carbon dioxide (CO2) and nitrate (NO3−)

Ocean acidification (OA), attributed to the sequestration of atmospheric carbon dioxide (CO2) into the surface ocean, and coastal eutrophication, attributed in part to land-use change and terrestrial runoff of fertilizers, have received recent attention in an experimental framework examining the effects of each on coral reef net ecosystem calcification (Gnet). However, OA and eutrophication in conjunction have yet to receive attention from the perspective of coral reef sediment dissolution. To address this omission, CO2 and nitrate (NO3−) addition experiments were performed in Mo'orea, French Polynesia. Incubation chambers were used to measure sediment Gnet during the day and night under three different [NO3−] (0, 9.8, and 19.7μM) that were nested within four separate constructed coral reef communities maintained at different PCO2 levels (417, 721, 1030, and 1333μatm, respectively). PCO2 negatively affected sediment Gnet during the day and night, resulting in a shift to diel net dissolution at a PCO2 of 1030μatm. Elevated NO3− alone, and the combination of NO3− and PCO2, both negatively affected sediment Gnet at night. However, the response of Gnet to NO3− was less clear during the day, where diurnal sediment Gnet was enhanced under the combined treatment of elevated NO3− and PCO2, resulting in no net effect of NO3− on sediment Gnet on diel timescales. Overall, these results show that ocean acidification represents a greater threat to the balance of calcification and dissolution in Mo'orea's back reef sediment communities than the potential impact of NO3− enrichment on relatively short timescales.

Comparison of recruitment tile materials for monitoring coralline algae responses to a changing climate

Settlement plates are widely used in ecological studies as a simple and effective way to assess recruitment and growth of sessile benthic communities. Plate material and surface complexity, positioning, size, attachment method, placement within the reef and duration of deployment can all influence the communities that recruit. Using different plate types can affect study reproducibility and skew results, yet no standardised guidelines exist for monitoring crustose coralline algae (CCA), a key bioindicator of changing seawater carbonate chemistry. Here, we compare 6 experimental tile materials (including plastic, ceramic and glass tiles) at 2 orientations (horizontal and vertical) for CCA community recruitment and calcification across 3 habitats (back reef, fore reef crest and reef slope). CCA were 20% more abundant, calcified faster and were twice as speciose on fore reef habitats. Community composition also varied with tile material and orientation. Vertically oriented surfaces and plastic and limestone tiles produced the closest approximation of real-world communities. Horizontal surfaces appeared to encourage coralline recruitment, particularly in light-limited environments, but also attracted greater herbivory. PVC tiles were the optimal approach when all factors were considered, as they generated a percent cover representative of adjacent reef communities and produced more consistent calcification estimates (across space and time), as well as being cheaper and easier to work with. Selection of plate type and deployment methods will ultimately depend on the experimental question; here we describe the benefits and costs of each material and/or orientation and suggest the adoption of PVC tiles as an optimal overall approach for monitoring CCA.

Differential growth responses to water flow and reduced pH in tropical marine macroalgae

The physical environment plays a key role in facilitating the transfer of nutrients and dissolved gases to marine organisms and can alter the rate of delivery of dissolved inorganic carbon. For non-calcifying macroalgae, water motion can influence the physiological and ecological responses to various environmental changes such as ocean acidification (OA). We tested the effects of lowered pH under three different flow speeds on three dominant non-calcifying macroalgal species differing in their carbon-use and are commonly found in the back reefs of Moorea, French Polynesia. Relative growth rates (RGR) of two phaeophytes, Dictyota bartayresiana and Lobophora variegata (HCO3− users), and a rhodophyte, Amansia rhodantha (CO2 user) were measured to examine how the combined effects of OA and flow can affect algal growth. Growth rates were affected independently by pCO2 and flow treatments but there was no significant interactive effect. Additionally, growth rates among species varied within the different flow regimes. Of the three species, L. variegata had the overall greatest increase in RGR across all three flow speeds while A. rhodantha exhibited the greatest negative impact under elevated pCO2 at 0.1cm·s−1. These differential responses among algal species demonstrate the importance of flow when examining responses to a changing environment, and if the responses of macroalgae differ based on their carbon-use strategies, it may provide advantages to some macroalgal species in a future, more acidic ocean.

Facies development of the Middle Miocene reefal limestone in northwest Saudi Arabia

The Middle Miocene reefal limestone of Wadi Waqb Member (Jabal Kibrit Formation) in northwest Saudi Arabia is unconformably overlaying the Precambrian basement rocks and/or Early Miocene siliciclastics. On the basis of field observations, microfacies analyses and fossil content, particularly scleractinian corals, the reefal limestone is composed of three depositional facies. These depositional facies are from base to top: 1) fore-reef facies, consists of hard, massive, marly coralline limestone with low diverse, small isolated corals heads, 2) reef-core facies, which consists of very hard, bioturbated coralline limestone with exclusively huge coral colonies of Porites and Tarbellastraea spp. and, 3) back reef facies, consists of sandy to pebbly massive, bioturbated limestone with very low diverse, scattered, small dendroid and massive heads of corals. The studied reefal limestone was deposited in fore-reef framework in an open marine environment with moderate to high energy conditions and changed upward to shallow marine facies with accumulation of skeletal grains by storms during regression.

Stressors and Disturbance Regimes on Back Reef Systems: Scale and Scope from Natural and Anthropogenic Sources

Back reef environments present a particular challenge in terms of characterization and management. Shallow near shore and lagoonal habitats associated with reef systems are the first areas to be impacted by land-based sources of pollutants and disturbances, defined as “stressors”. Stressors are a link in the chain of events that lead to environmental change or “phase shifts” in natural systems. Stressors as “damaging stimuli” need to be defined in terms of thresholds for both populations of organisms, and ecological communities. Stressors alter the abundance and dynamics of individual populations of organisms, and thus impact the community structure and function. Microbial communities are key to processing nutrients and pollutants from land-based sources, but poorly characterized. The effects of changes in microbial communities usually go unnoticed until visual signs of change occur in macro-organisms (death, disease or a shift in predominate species). Because microbial communities have a major influence on the transformation of nutrients as well as a protective influence, short-term stressors often can result in latent changes in larger back reef communities. The most notable changes in back reef environments from stressors include: 1) Changes in coastal species abundance and diversity (including local extirpation), 2) Changes in natural community structure, 3) Changes in coastal water quality (or the dynamic” habitat), and 4) Changes associated with exotic species invasion. Advances in technologies and research have facilitated the detection of stressors and stress responses. Recent researches in stable isotopes signatures as indicators of nutrient flux across the land-sea interface have helped identify eutrophication sources. Detection of pathogens, advances in microbial ecology (genetic probes), and disease ecology, bleaching and pollutant studies (e.g. pesticides, fungicides, pharmaceuticals) have helped identify chronic stressors to back reef systems. Historical ecology and studies of long-term environmental change remain key to understanding the nature of change and chronic degradation of complex coastal systems. Although we understand the basic ecology of tropical marine systems in a general sense, researchers need to initiate programs to look at integrated processes across the shoreline, particularly in terms of ecosystem function in back reef environments.

Documentation and characterization of the Lower Cretaceous (Valanginian) Calvin and Winn carbonate shelves and shelf margins, onshore northcentral Gulf of Mexico

The Lower Cretaceous stratigraphic section in the northern Gulf of Mexico (GOM) comprises several well-documented carbonate systems that have prominent shelf-margin buildups, including the Berriasian Knowles Limestone ramp and shelf system, Barremian Sligo Formation shelf system, Aptian Pearsall Formation ramp system, and Albian Glen Rose, Edwards, and Stuart City Formations shelf systems. Two lesser known but large-scale Lower Cretaceous Valanginian carbonate shelf to shelf-margin systems are documented in this investigation using core, wireline-log, and regional 2D seismic data. The platform-margin succession of the older Calvin section comprises a shelf-margin buildup (back reef, reef, and fore reef facies) that may be as thick as 2000 ft (610 m). The seaward margin of the shelf, as displayed by seismic data, suggests shelf-to-basin relief of as much as 1000 ft (305 m) and margin-to-lagoon relief of 200 to 500 ft (60 to 140 m) (relief estimates are not decompacted). Major reef-building organisms are Lithocodium, stromatoporoids, and corals. The Winn limestone is younger than the Calvin limestone, and at the shelf margin, it may have been 600 to 800 ft (180 to 245 m) thick. It is composed of organisms similar to those of the Calvin reef complex. Considering the vertical position of the Calvin platform, succeeding the major bypass of Calvin lowstand siliciclastic sands, the platform probably records a transgression, which is consistent with its highly aggradational depositional style. The Winn shelf margin was initiated landward of the Calvin shelf margin and did not prograde as far seaward as the Calvin shelf margin. The recognition of these two Lower Cretaceous carbonate systems is important because they further detail the stratigraphic history and architecture of this deeply buried, lowermost Lower Cretaceous section in the GOM. These formations are also potential deep-gas, tight-carbonate (low-porosity) plays.

Assessment of wild and restored staghorn coral Acropora cervicornis across three reef zones in the Cayman Islands

Interest in restoring staghorn coral Acropora cervicornis has grown following the widespread decline of this species in recent decades. To date, thousands of nursery-reared A. cervicornis have been outplanted to restore degraded reefs, but survivorship and growth among outplanted colonies can be spatially variable. In particular, data on distribution of remnant wild populations and outplant performance in varying reef zones is lacking. To address this gap, we conducted a study to characterize existing wild populations and assess performance of nursery-reared, outplanted A. cervicornis among three reef zones of varying depth at Little Cayman Island: the shallow back reef (0–3 m), the intermediate spur-and-groove reef (8–15 m), and the deep reef terrace (>15 m). Wild populations of A. cervicornis were present in each reef zone, and colony height and prevalence of predation by Stegastes spp. were highest in the intermediate zone. For outplanted A. cervicornis, survivorship differed among sites and was lowest for outplants in the deep zone during the 85-day observation period. Post-outplant growth and branching was lowest among outplants in the shallow zone due to high rates of colony breakage. Following the conclusion of the study, a mortality event occurred in which 90% of outplants at the shallow plots died during a period of elevated sea temperature. The information provided in this study suggests that intermediate spur-and-groove reefs are optimal for outplanting activities in Little Cayman using existing restoration methods. These data could be useful for coral restoration practitioners and government agencies in the Caribbean, particularly the Cayman Islands, which is actively expanding its coral nursery program. New strategies must be developed to improve restoration outcomes in shallow and deep zones.

The potential for self-seeding by the coral Pocillopora spp. in Moorea, French Polynesia.

Coral reefs in Moorea, French Polynesia, suffered catastrophic coral mortality through predation by Acanthaster planci from 2006 to 2010, and Cyclone Oli in 2010, yet by 2015 some coral populations were approaching pre-disturbance sizes. Using long-term study plots, we quantified population dynamics of spawning Pocillopora spp. along the north shore of Moorea between 2010 and 2014, and considered evidence that population recovery could be supported by self-seeding. Results scaled up from study plots and settlement tiles suggest that the number of Pocillopora spp. colonies on the outer reef increased 1,890-fold between 2010 and 2014/2015, and in the back reef, 8-fold between 2010 and 2014/2015. Assuming that spawning Pocillopora spp. in Moorea release similar numbers of eggs as con-generics in Hawaii, and fertilization success is similar to other spawning corals, the capacity of Pocillopora spp. to produce larvae was estimated. These estimates suggest that Pocillopora spp. in Moorea produced a large excess of larvae in 2010 and 2014 relative to the number required to produce the recruits found in the back reef and outer reef in 2010 and 2014, even assuming that ∼99.9% of the larvae do not recruit in Moorea. Less than a third of the recruits in one year would have to survive to produce the juvenile Pocillopora spp. found in the back and outer reefs in 2010 and 2014/2015. Our first order approximations reveal the potential for Pocillopora spp. on the north shore of Moorea to produce enough larvae to support local recruitment and population recovery following a catastrophic disturbance.

Diversidad y cobertura de la comunidad bentónica del arrecife Enmedio, Sistema Arrecifal Lobos-Tuxpan, México

La cobertura bentónica es un atributo importante para gestionar eficientemente los arrecifes coralinos, sin embargo, muchos ecosistemas marinos de Veracruz aún carecen de esta información y el arrecife Enmedio es un claro ejemplo; por esta razón, se estimó la diversidad y cobertura bentónica en el arrecife frontal, arrecife posterior y laguna arrecifal, utilizando cuadrantes de 1 m2, los cuales fueron colocados a cada 5 m sobre tres transectos de 50 m de largo. Con los datos recabados se estimaron la riqueza específica, equitatividad, dominancia de Simpson, diversidad de Shannon y diversidad verdadera, asimismo, se determinaron diferencias significativas mediante análisis de similitud y ordenación. La cobertura biótica promedio estimada para el arrecife fue de 37.3%, principalmente se destacan los corales dado que aportaron la mayor cobertura con 19.8% (±18.8). Las especies más importantes en cobertura fueron: Orbicella annularis, Erytropodium caribaeorum, Colpophyllia natans y Pseudodiploria clivosa. Los ambientes arrecifales son significativamente diferentes en composición y cobertura biótica con base en las pruebas de similitud y ordenamiento, ya que el arrecife posterior registró un mayor número de especies y de cobertura, básicamente por corales masivos; en cambio en la planicie arrecifal se determinaron varias zonaciones bentónicas que tienden a ser equitativas y con mayor número de especies efectivas, mientras en el arrecife frontal decrecen la diversidad, la cobertura y la equitatividad debido a que predomina el pavimento. Estos contrastes registrados en el arrecife Enmedio en la cobertura por especie y por ambiente arrecifal parecen ser normales dado que también han sido reportados para varios arrecifes del SAV.

The effects of ocean acidification on wound repair in the coral Porites spp.

Scleractinian corals on tropical reefs are exposed to many natural and anthropogenic disturbances, and while much is known about their responses to such conditions, it is unclear whether the responses will remain the same in a future affected by climate change and ocean acidification. To evaluate how one aspect of these effects — wound repair — might be influenced by ocean acidification, small colonies of massive Porites spp. from the back reef of Moorea, French Polynesia, were damaged to simulate the effects of single bites by corallivorous fishes, and healing was measured under contrasting PCO2 regimes. Using experiments lasting 19–20d and employing superficial (2013) or deep (2014) lesions, the effects of damage were evaluated at ~400μatm (ambient) and ~1000μatm PCO2 (both at ~28.5°C) using calcification and healing as dependent variables. Damage reduced calcification of massive Porites spp. in 2013, but not in 2014, and PCO2 had no effect on area-normalized calcification or healing in both years, although biomass-normalized calcification was reduced by high PCO2 in 2014. Overall these results reveal the physiological resilience of this functional group of corals to the extent of ocean acidification expected by the end of this century, and suggest that over this period small colonies will remain capable of recovery from minor damage arising from fish corallivory.