Andrew W. Bruckner

One-third of reef-building corals face elevated extinction risk from climate change and local impacts

The conservation status of 845 zooxanthellate reef-building coral species was assessed by using International Union for Conservation of Nature Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds that of most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories, whereas the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures.

Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005

Background The rising temperature of the worlds oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watchs Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.

Revealing the Appetite of the Marine Aquarium Fish Trade: The Volume and Biodiversity of Fish Imported into the United States

The aquarium trade and other wildlife consumers are at a crossroads forced by threats from global climate change and other anthropogenic stressors that have weakened coastal ecosystems. While the wildlife trade may put additional stress on coral reefs, it brings income into impoverished parts of the world and may stimulate interest in marine conservation. To better understand the influence of the trade, we must first be able to quantify coral reef fauna moving through it. Herein, we discuss the lack of a data system for monitoring the wildlife aquarium trade and analyze problems that arise when trying to monitor the trade using a system not specifically designed for this purpose. To do this, we examined an entire year of import records of marine tropical fish entering the United States in detail, and discuss the relationship between trade volume, biodiversity and introduction of non-native marine fishes. Our analyses showed that biodiversity levels are higher than previous estimates. Additionally, more than half of government importation forms have numerical or other reporting discrepancies resulting in the overestimation of trade volumes by 27%. While some commonly imported species have been introduced into the coastal waters of the USA (as expected), we also found that some uncommon species in the trade have also been introduced. This is the first study of aquarium trade imports to compare commercial invoices to government forms and provides a means to, routinely and in real time, examine the biodiversity of the trade in coral reef wildlife species.

Ten years of change to coral communities off Mona and Desecheo Islands, Puerto Rico, from disease and bleaching.

Remote reefs off southwest Puerto Rico have experienced recent losses in live coral cover of 30 to 80%, primarily due to the decline of Montastraea annularis and M. faveolata from disease and bleaching. These species were formerly the largest, oldest, and most abundant corals on these reefs, constituting over 65% of the living coral cover and 40 to 80% of the total number of colonies. From 1998 to 2001, outbreaks of yellow band disease (YBD) and white plague (WP) affected 30 to 60% of the M. annularis (complex) colonies. Disease prevalence declined beginning in 2002, and then increased immediately following the 2005 mass bleaching event. Colonies of M. annularis (complex) have been reduced in abundance by 24 to 32%, and remaining colonies are missing more than half their tissue. Both M. annularis and M. faveolata have failed to recruit, resheeting has been minimal, and exposed skeletal surfaces are being colonized by macroalgae, bioeroding sponges, and hydrozoans. Other scleractinian corals were smaller in size (mean = 28 cm diameter) and exhibited lower levels of partial mortality; these taxa were affected to a lesser extent by coral diseases and bleaching-associated tissue loss over the last decade. The numbers of small colonies (1 to 9 cm) of these species identified since 2005 also exceeded numbers of larger colonies that died. These reefs appear to be exhibiting shifts in species assemblages, with replacement of M. annularis (complex) by shorter-lived brooding species and other massive and plating corals (Agaricia, Porites, Meandrina, Eusmilia, Diploria, and Siderastrea spp.). To avoid a catastrophic and permanent loss of the dominant, slow-growing reef-building corals, the causes and effects of diseases need to be better understood, and possible control mechanisms must be developed. In particular, steps must be taken to mitigate environmental and anthropogenic stressors that increase the spread and severity of disease.

Red Sea Coral Reef Trajectories Over 2 Decades Suggest Increasing Community Homogenization and Decline in Coral Size

Three independent line intercept transect surveys on northern Red Sea reef slopes conducted in 1988/9 and 1997/8 in Egypt and from 2006–9 in Saudi Arabia were used to compare community patterns and coral size. Coral communities showed scale-dependent variability, highest at fine spatial and taxonomic scale (species-specific within and among reef patterns). At coarser scale (generic pattern across regions), patterns were more uniform (regionally consistent generic dominance on differently exposed reef slopes and at different depths). Neither fine- nor coarse-scale patterns aligned along the sampled 1700 km latitudinal gradient. Thus, a latitudinal gradient that had been described earlier from comparable datasets, separating the Red Sea into three faunistic zones, was no longer apparent. This may indicate subtle changes in species distributions. Coral size, measured as corrected average intercept of corals in transects, had decreased from 1997 to 2009, after having remained constant from 1988 to 1997. Recruitment had remained stable (∼12 juvenile corals per m2). Size distributions had not changed significantly but large corals had declined over 20 years. Thus, data from a wide range of sites taken over two decades support claims by others that climate change is indeed beginning to show clear effects on Red Sea reefs.

Diseases, Harmful Algae Blooms (HABs) and Their Effects on Gulf Coral Populations and Communities

Corals in the Gulf exist in a harsh environment, which only allows a small subset of the typical Indo-Pacific fauna and flora to persist and/or form viable populations (Sheppard and Sheppard 1991; Sheppard et al. 1992; Samimi-Namin and van Ofwegen 2009; Chaps. 11 and 12). Environmental factors have been identified as the major killers of corals and these factors regulate population dynamics and coral reef community structure (Chaps. 2, 5, 10 and 16). Among these, extreme temperature variability, salinity variability and turbidity (as a result of coastal construction, Chap. 16) have been isolated as prime killers.

Tight coupling between coral reef morphology and mapped resilience in the Red Sea.

Lack of knowledge on the conservation value of different reef types can stymie decision making, and result in less optimal management solutions. Addressing the information gap of coral reef resilience, we produce a map-based Remote Sensed Resilience Index (RSRI) from data describing the spatial distribution of stressors, and properties of reef habitats on the Farasan Banks, Saudi Arabia. We contrast the distribution of this index among fourteen reef types, categorized on a scale of maturity that includes juvenile (poorly aggraded), mature (partially aggraded), and senile (fully aggraded) reefs. Sites with high reef resilience can be found in most detached reef types; however they are most common in mature reefs. We aim to stimulate debate on the coupling that exists between geomorphology and conservation biology, and consider how such information can be used to inform management decisions.

The Status, Threats, and Resilience of Reef-Building Corals of the Saudi Arabian Red Sea

The Saudi Arabian Red Sea (SARS) contains diverse shallow water coral reef systems that include attached (fringing and dendritic reefs) and detached (platform, patch, tower, ribbon, and barrier reefs) reef systems extending up to 90 km offshore. To better understand the current status of coral reefs in SARS, the Living Oceans Foundation conducted assessments of representative reef environments in the Farasan Islands (2006), Ras Al-Qasabah (2007), Al Wajh and Yanbu (2008), and the Farasan Banks (2009). A combination of belt transects and quadrats was used to assess the diversity, size structure, partial mortality, condition, and recruitment of the dominant reef-building corals. Most sites had high structural complexity, with up to 52 genera of scleractinian corals recorded from a single region. Living corals varied in abundance and cover by region, habitat, and depth, with the highest species richness documented in the south (Farasan Banks), followed by Al Wajh and Yanbu and lowest at Ras Al-Qasabah. On most reefs, a single species was dominant. The reef architecture was constructed by massive and columnar Porites, with unusually large (1–4 m diameter) colonies in shallow water (up to 80 % live cover in 2–10 m depth) and a deeper reef Porites framework that was mostly dead. Porites lutea was the single most abundant coral throughout SARS, and the dominant species on leeward reef crests and slopes, while reef slopes and deeper coral carpets were predominantly Porites columnaris and P. rus. Faviids (Goniastrea and Echinopora) were the next most abundant corals, especially in areas that had experienced a disturbance, although these were small (most 50 %) in shallow water and rapid decline with increasing depth. In each region, many reefs (15–36 %) showed signs of damage and had less than 5 % live coral cover. These degraded sites were characterized by extensive dead skeletons in growth position, substrates colonized by thick mats of turf algae and soft corals (Xenia), and surviving massive and plating corals that were subdivided by partial mortality into numerous small (<10 cm) ramets. Mortality was attributed to bleaching events, disease, and outbreaks of corallivores occurring over the last 10–15 years. Several sites also exhibited signs of recent mortality from crown of thorns sea stars (Acanthaster), coral-eating snails, and coral disease. In many cases, the Porites framework had been recolonized by faviids, acroporids, and other corals and these had subsequently died. Most degraded areas appeared to be rebounding, as substrates had high cover of crustose coralline algae (CCA), little macroalgae, and high numbers of coral recruits and juvenile corals.

Significance of new records of Tridacna squamosa Lamarck, 1819, in the Tuamotu and Gambier Archipelagos (French Polynesia)

The giant clam subfamily Tridacninae (family Cardiidae) is an important group of bivalve molluscs found throughout the Red Sea and Indo-Pacific, from East Africa to the Eastern Pacific biogeographic region. The Tridacna genus is currently revised with numerous cryptic species identified with molecular markers. New Tridacna records from the fringe of the known distribution areas are extremely useful to identify genetically unique species, geographic ranges, and to examine processes associated with species differentiation. While Tridacna maxima is abundant in French Polynesia (Central South Pacific Ocean) the larger fluted giant clam Tridacna squamosa was formerly reported only in the Austral Islands in the south. Following a recent survey that spanned 23 islands and atolls of the Society, Tuamotu and Gambier Archipelagos, the presence of T. squamosa between the Cook Islands and Pitcairn Islands is confirmed using both morphological and molecular information, suggesting a relic distribution across the Central Pacific Ocean. Tridacna squamosa is rare, but present throughout Tuamotu and Gambier. However, it remained undetected from the Society Islands, probably due to historical over-fishing. This species is valued by local inhabitants, and is sought after mainly as gifts and also for a limited local shell trade. The rarity of T. squamosa may call for conservation measures in the near future.