Anomalously high water temperatures, associated with climate change, are increasing the global prevalence of coral bleaching, coral diseases, and coral-mortality events. Coral bleaching and disease ...outbreaks are often inter-related phenomena, since many coral diseases are a consequence of opportunistic pathogens that further compromise thermally stressed colonies. Yet, most coral diseases have low prevalence (<5%), and are not considered contagious. By contrast, we document the impact of an extremely high-prevalence outbreak (61%) of white-plague disease at 14 sites off southeastern Florida. White-plague disease was observed near Virginia Key, Florida, in September 2014, and after 12 months had spread 100 km north and 30 km south. The disease outbreak directly followed a high temperature coral-bleaching event and affected at least 13 coral species. Eusmilia fastigiata, Meandrina meandrites, and Dichocoenia stokesi were the most heavily impacted coral species, and were reduced to <3% of their initial population densities. A number of other coral species, including Colpophyllia natans, Pseudodiploria strigosa, Diploria labyrinthiformis, and Orbicella annularis were reduced to <25% of their initial densities. The high prevalence of disease, the number of susceptible species, and the high mortality of corals affected suggests this disease outbreak is arguably one of the most lethal ever recorded on a contemporary coral reef.
Annual coral bleaching events, which are predicted to occur as early as the next decade in the Florida Keys, are expected to cause catastrophic coral mortality. Despite this, there is little field ...data on how Caribbean coral communities respond to annual thermal stress events. At Cheeca Rocks, an inshore patch reef near Islamorada, FL, the condition of 4234 coral colonies was followed over 2 yr of subsequent bleaching in 2014 and 2015, the two hottest summers on record for the Florida Keys. In 2014, this site experienced 7.7 degree heating weeks (DHW) and as a result 38.0% of corals bleached and an additional 36.6% were pale or partially bleached. In situ temperatures in summer of 2015 were even warmer, with the site experiencing 9.5 DHW. Despite the increased thermal stress in 2015, only 12.1% of corals were bleached in 2015, which was 3.1 times less than 2014. Partial mortality dropped from 17.6% of surveyed corals to 4.3% between 2014 and 2015, and total colony mortality declined from 3.4 to 1.9% between years. Total colony mortality was low over both years of coral bleaching with 94.7% of colonies surviving from 2014 to 2016. The reduction in bleaching severity and coral mortality associated with a second stronger thermal anomaly provides evidence that the response of Caribbean coral communities to annual bleaching is not strictly temperature dose dependent and that acclimatization responses may be possible even with short recovery periods. Whether the results from Cheeca Rocks represent an aberration or a true resilience potential is the subject of ongoing research.
A repeated-measures coral monitoring program established as part of the PortMiami expansion program provided an unparalleled opportunity to quantify the levels of coral mortality that resulted from ...both local dredging stress and as a result of climate-related bleaching stress and the subsequent outbreak of a white-plague-like disease (WPD) epizootic. By comparing measured rates of coral mortality at 30 sites throughout Miami-Dade County to predicted mortality levels from three different coral mortality scenarios, we were able to evaluate the most likely source of coral mortality at both the local and regional levels during the 2014–2016 coral bleaching and WPD event. These include scenarios that assume (1) local dredging increases coral disease mortality, (2) regional climate-related stress is the proximal driver of coral disease mortality, and (3) local and regional stressors are both responsible for coral disease mortality. Our results show that species-specific susceptibility to disease is the determining factor in 93.3% of coral mortality evaluated throughout Miami-Dade County, whereas local dredging stress only accurately predicted coral mortality levels 6.7% of the time. None of the monitoring locations adjacent to the PortMiami expansion had levels of coral mortality that exceeded predictions when coral community composition was taken into account. The novel result of this analysis is that climate-mediated coral disease mortality was more than an order of magnitude (14x) more deadly than even the largest marine construction project performed in the USA, and that until climate change is addressed, it is likely that local attempts to manage coral resilience will continue to fail.
This study is a multi-pronged description of a temperature-induced outbreak of white-band disease (WBD) that occurred in Acropora cervicornis off northern Miami Beach, Florida (USA), from July to ...October 2014. We describe the ecology of the disease and examine diseased corals using both histopathology and next-generation bacterial 16S gene sequencing, making it possible to better understand the effect this disease has on the coral holobiont, and to address some of the seeming contradictions among previous studies of WBD that employed either a purely histological or molecular approach. The outbreak began in July 2014, as sea surface temperatures reached 29°C, and peaked in mid-September, a month after the sea surface temperature maximum. The microscopic anatomy of apparently healthy portions of colonies displaying active disease signs appeared normal except for some tissue atrophy and dissociation of mesenterial filaments deep within the branch. Structural changes were more pronounced in visibly diseased fragments, with atrophy, necrosis, and lysing of surface and basal body wall and polyp structures at the tissue-loss margin. The only bacteria evident microscopically in both diseased and apparently healthy tissues with Giemsa staining was a Rickettsiales-like organism (RLO) occupying mucocytes. Sequencing also identified bacteria belonging to the order Rickettsiales in all fragments. When compared to apparently healthy fragments, diseased fragments had more diverse bacterial communities made up of many previously suggested potential primary pathogens and secondary (opportunistic) colonizers. Interactions between elevated seawater temperatures, the coral host, and pathogenic members of the diseased microbiome all contribute to the coral displaying signs of WBD.
Aim To examine the uniqueness and relationship of islands in the San Diegan Province using reef fishes. Location Pacific coast of Baja and Southern California. Methods Quantitative scuba surveys and ...statistics were used. Between June 2000 and August 2002, the nearshore rocky-reef fishes of eight southern California and Baja California islands were quantitatively surveyed. The islands surveyed were: Santa Cruz, San Nicolas, Santa Barbara, Santa Catalina, San Clemente, North Coronado, San Martin and San Benito. These islands span the latitudinal range of offshore islands within the San Diegan marine province. This regional scale approach provided not only the first quantitative description of rocky-reef fishes at five of these islands, but also allowed comparisons with known biogeographical patterns. Results Here we discuss the distribution and abundance of 84 conspicuous rocky-reef fishes from 35 families. In general, the richness, diversity and composition of fish assemblages at these islands were found to reflect previously described biogeographical processes. The rocky reef fish assemblages of all islands in the survey were found to be significantly distinctive form each other. Phenetic analyses revealed two clusters. San Clemente, Santa Catalina and North Coronado clustered as a warm-water assemblage in the middle of the San Diegan Province. The remaining islands grouped together as a cold-water assemblage, despite the geographically disjunct position of the islands within this cluster. The relatedness of islands was independent of distance. Examination of the most common fish species at all islands revealed that while some conformed to the north-south trending density distributions predicted by previous investigators, the distribution of others could not be explained by latitude or temperature regimes. No single pattern explained the density of fishes at all islands. Both the rock croaker, Pareques sp., and flag cabrilla, Epinephelus labriformis, were observed at San Benito during these surveys, representing northern range extensions and may be indicators of the warming trend observed in this marine province. Main conclusion For nearshore rocky-reef fishes, the islands of the San Diegan marine province are distinct and their interrelatedness is independent of the distance between them.
Four hurricanes impacted the reefs of Florida in 2005. In this study, we evaluate the combined impacts of hurricanes Dennis, Katrina, Rita, and Wilma on a population of Acropora palmata using a newly ...developed video‐mosaic methodology that provides a high‐resolution, spatially accurate landscape view of the reef benthos. Storm damage to A. palmata was surprisingly limited; only 2 out of 19 colonies were removed from the study plot at Molasses Reef. The net tissue losses for those colonies that remained were only 10% and mean diameter of colonies decreased slightly from 88.4 to 79.6 cm. In contrast, the damage to the reef framework was more severe, and a large section (6 m in diameter) was dislodged, overturned, and transported to the bottom of the reef spur. The data presented here show that two‐dimensional video‐mosaic technology is well‐suited to assess the impacts of physical disturbance on coral reefs and can be used to complement existing survey methodologies.
A supervised classification routine was used to classify munitions targets and basic seabed types from underwater images. Additional features that were based on the local relief, or height, of the ...seabed were then added to the classifier and new results computed using the expanded feature set. The height data were generated from the input images themselves using structure-from-motion computer vision techniques. The initial image classifier was shown to distinguish munitions from non-munitions (background) with generally > 80% accuracy except that many false positive matches for munitions were observed. Extending the algorithm to also use height data derived from stereo reconstruction showed that incorporating such "2.5-D" data greatly improved the classification results. Using the 2.5-D information reduced the number of false positives. Furthermore, improved accuracy was observed not only on the basic, binary munitions / non-munitions classes. Adding 2.5-D information also improved the capability to discriminate different types of munitions from one another.
Understanding recent decades of coral community change has been hindered by a shortage of long-term monitoring and a lack of tools that provide a lasting record of benthic reef communities. To ...increase our understanding of Caribbean coral reef dynamics, this dissertation research developed and used innovative technologies involving landscape mosaic images and 3D reef models, to analyze a novel 40 year dataset of coral community health from Andros Island, Bahamas. Historical data from Andros Island (1968–2000) were provided as part of a Cooperative Research and Development Agreement (CRADA) between the University of Miami and the Naval Undersea Warfare Center Division Newport. Long-term monitoring at Andros Island revealed that reef decline was a-typical over recent decades. Coral mortality and disease increased significantly between 1970 and 2000, whereas macroalgal cover did not. To complement studies of coral mortality and disease, the resilience and resistance of individual coral species at Andros were measured from 1972 to 2008. Of the 24 species studied, only three (Siderastrea siderea, Montastraea cavernosa, and Porites astreoides) were resistant to recent disturbance histories, whereas Porites porites was resilient. Further studies using 3D models explored relationships between coral population dynamics and spatial patterns of coral species. Results indicated that the arrangement of dominant coral species and the processes of recruitment, growth, and mortality were non-random over time. In summary, the application of mosaic images and 3D reef models to a previously un-published long-term coral health dataset led to improved understanding of factors controlling past reef communities.
Understanding recent decades of coral community change has been hindered by a shortage of long-term monitoring and a lack of tools that provide a lasting record of benthic reef communities. To ...increase our understanding of Caribbean coral reef dynamics, this dissertation research developed and used innovative technologies involving landscape mosaic images and 3D reef models, to analyze a novel 40 year dataset of coral community health from Andros Island, Bahamas. Historical data from Andros Island (1968-2000) were provided as part of a Cooperative Research and Development Agreement (CRADA) between the University of Miami and the Naval Undersea Warfare Center Division Newport. Long-term monitoring at Andros Island revealed that reef decline was a-typical over recent decades. Coral mortality and disease increased significantly between 1970 and 2000, whereas macroalgal cover did not. To complement studies of coral mortality and disease, the resilience and resistance of individual coral species at Andros were measured from 1972 to 2008. Of the 24 species studied, only three (Siderastrea siderea, Montastraea cavernosa, and Porites astreoides) were resistant to recent disturbance histories, whereas Porites porites was resilient. Further studies using 3D models explored relationships between coral population dynamics and spatial patterns of coral species. Results indicated that the arrangement of dominant coral species and the processes of recruitment, growth, and mortality were non-random over time. In summary, the application of mosaic images and 3D reef models to a previously un-published long-term coral health dataset led to improved understanding of factors controlling past reef communities.
Four hurricanes impacted the reefs of Florida in 2005. In this study, we evaluate the combined impacts of hurricanes Dennis, Katrina, Rita, and Wilma on a population of Acropora palmata using a newly ...developed video-mosaic methodology that provides a high-resolution, spatially accurate landscape view of the reef benthos. Storm damage to A. palmata was surprisingly limited; only 2 out of 19 colonies were removed from the study plot at Molasses Reef. The net tissue losses for those colonies that remained were only 10% and mean diameter of colonies decreased slightly from 88.4 to 79.6 cm. In contrast, the damage to the reef framework was more severe, and a large section (6 m in diameter) was dislodged, overturned, and transported to the bottom of the reef spur. The data presented here show that two-dimensional video-mosaic technology is well-suited to assess the impacts of physical disturbance on coral reefs and can be used to complement existing survey methodologies.
The original document contains color images. Published in the Jnl. of Marine Ecology ISSN 0173-9565 p254-258 2006.
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