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Mass Bleachings on Atlantic Coral Reefs
... Vicente and Goenaga (1984) reported on the mass mortality of the black sea-urchin, Diadema antillarum, around the coastline of Puerto Rico and provided a general description of dying specimens from direct observations in the field. A series of reports of massive coral bleaching in the waters of Puerto Rico were produced in the late 1980s (Bunkley- Williams and Williams, 1987;Williams and Bunkley-Williams, 1989;Goenaga et al., 1989;Williams and Bunkley-Williams, 1990a,b). These studies highlighted the permanent damage of the bleaching phenomena on reef corals and associated the periodic bleaching events to elevated SSTs. ...
The Coral Reef Monitoring Program for Puerto Rico, which is sponsored by the National Oceanic and Atmospheric Administration (NOAA) and administered by the Puerto Rico Department of Natural and Environmental Resources (DNER), is now fully implemented and has achieved its initial goals in collaboration with Federal and local governmental agencies and marine scientists from research institutions. This chapter provides an assessment of the status of coral reef systems in Puerto Rico. A synopsis of scientific research undertaken in characterization of coral reefs is included, along with an evaluation of temporal and spatial trends of reef community structure and health, as suggested by the data emerging from ongoing monitoring programs. Quantitative baseline characterizations of sessile-benthic and fish communities at natural reserve sites and other sensitive coastal areas represent the basis for this assessment of Puertorrican coral reefs. Inferences derived from basic research on coral diseases, coral bleaching, mass mortalities and potentially relevant environmental and anthropogenic stressors, such as global warming, storms, eutrophication, fishing, sediment runoff, dredging activities and others are also presented. Adescription of the major ongoing programs on coral reef community characterizations and monitoring is included, along with a database on percent cover and taxonomic composition of live corals and fishes from reefs surveyed around Puerto Rico. Conservation management strategies that include active marine protected area (MPA) programs and revisions to fishing laws are presented and evaluated. Preliminary conclusions about the status of coral reefs and recommendations for management are also included in this chapter.
Garcia-Sais, J., R. Appledoorn, A. W. Bruckner, C. Caldow, J. D. Christensen, C. Lilyestrom, M. E. Monaco, J. Sabater, E. H. Williams, Jr., and E. Diaz. 2005. The State of Coral Reef Ecosystems of the Commonwealth of Puerto Rico. Pages 91-134 In: J. Waddell (Ed.) The State of the Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2005. NOAA Technical Memorandum National Ocean Service, National Centers for Coastal Ocean Science 11, Center for Coastal Monitoring and Assessment's Biogeography Team, Silver Spring, Maryland, 522 pp. [also ccma.nos.noaa.gov/ecosystems/coralreef/coral_report_2005/CoralReport2005_C.pdf] [305]
... Coral reefs near Guánica and La Parguera have declined, with dramatic reductions in living colonies of reef-building stony corals like the Boulder Star Coral, Orbicella annularis ( Fig. 3-4). Bleaching events in 1981, 1987, 1990, 1998 and 2005 caused by elevated sea surface temperature have also adversely affected stony corals Bunkley-Williams 1989, 1990;Williams et al. 1987;Goenega et al. 1989;Velazco-Domínguez et al. 2003;García-Sais et al. 2006Miller and Lugo 2009). Disease outbreaks have increased in number, prevalence and spatial distribution (Gladfelter 1982;Weil et al. 2003Weil et al. , 2009Weil and Rogers 2011;Bruckner 1997, 2006;Cróquer and Weil 2009;Harvell et al. 2009), causing further decline in stony coral communities. ...
This report demonstrates the application of a structured decision-making (SDM) process
in the Guánica Bay watershed (GBW) in southwestern Puerto Rico. SDM is an organized
approach for helping people, especially groups, identify creative options and make
informed, defensible and transparent choices. It is particularly useful in complex
decision situations. SDM has six steps: 1) clarify the decision context; 2) define
objectives and evaluation criteria; 3) develop alternatives; 4) estimate consequences;
5) evaluate trade-offs and select alternatives and 6) implement, monitor and review.
Key to the SDM process is the engagement of stakeholders, experts and decision-makers
in a deliberative environment that deals rigorously with facts and values in
decision-making.
... In 1987 a massive bleaching event occurred on many western Atlantic coral reefs (Williams et al. 1987). Variability in the detailed respnses of zooxanthellate organisnls (within-and betweenspecimens , species, habitats, localities and geographic regions) was so high as to preclude a simple explanation for this phenonlenon (Lang 1988, Williams & Bunkley-Williams 1988). ...
... While bleaching events have affected the wider Caribbean since the early 1980s (Lasker et al. 1984, Williams et al. 1987, there were no records of mass bleaching of corals on the Belize (Mesoamerican) barrier reef system before the El Niño-Southern Oscillation (ENSO) episode of 1995 (Burke et al. 1996, McField 1999. Associated with this event, McField (1999) measured over 50% coral bleaching on the forereef region off Belize. ...
Over recent decades, coral reefs worldwide have experienced severe sea-surface temperature (SST) anomalies. Associated with an El Ni (n) over tildeo-Southern Oscillation (ENSO) event of 1997-1998, nearly 100% mortality of the space-dominant coral Agaricia tenuifolia was reported at several shelf lagoonal sites of the Belize barrier reef system; a less abundant congener, A. agaricites, had lower mortality rates. We assessed A. agaricites and A. tenuifolia populations at coral reef ridges in the south-central sector of the Belize shelf lagoon and forereef sites to document recovery following the 1998 ENSO event and subsequent passage of Hurricane Mitch. To investigate the difference in heat stress tolerance between the 2 species, heat shock protein (HSP) expression was examined in the laboratory under ambient (28degreesC) and elevated (+6degreesC) temperatures. Populations of A, agaricites and A. tenuifolia surveyed at forereef sites in 1999 showed after effects from the 2 disturbances (partial colony mortality was similar to23 and 30% for A. agaricites and A. tenuifolia, respectively), but partial mortality declined by 2001. At reef ridge sites, A. tenuifolia exhibited 75 to 95% partial colony mortality in 1999 compared to 18% in the less abundant A. agaricites. We measured a significant increase in percentage live cover at ridge sites for both Agaricia species from 1999 to 2001, except at Tunicate Ridge; at this site, which has restricted water flow, live A. tenuifolia cover remained low (similar to10%) 3.5 yr after the 1998 warming event, due in part to high sponge cover (> 75%). Immunoblotting results indicated that A. agaricites had twice as much HSC 70 (16.9 mug cm(-2)) as A. tenuifolia (8.7 mug cm(-2)) at ambient temperatures and 6x as much under the +6degreesC treatment. In addition to the inducible response by A. agaricites, this species expressed HSP 90, whereas A, tenuifolia did not. The distinctive patterns of population recovery and HSP expression suggest that A. tenuifolia has a lesser ability to produce HSPs for protection against environmental stress than A. agaricites. Such differences in resilience to large-scale environmental disturbances such as intermittent ENSO episodes may drive a dramatic change in coral species abundance patterns.
Large-scale marine disturbances, called marine major ecological disturbances (MMEDs), have drastically increased in the last 2025 years. Coral-reef bleaching has repeatedly killed or weakened coral-reef organisms throughout the Caribbean since 1979. Longspine sea urchins were almost extirpated from the Caribbean in 1983-84, and recurrences have followed, along with smaller die-offs of other sea urchins. A large array of new, epizootic diseases has emerged or become more common or widespread in the last few years to devastate Caribbean coral reefs, and some of the older diseases have also become epizootic. Sea fan mass mortalities removed most of these animals from the Southwestern Caribbean in the early 1980s and possibly related sea fan disturbances now threaten those remaining Caribbean sea fans. A Caribbean-wide fish mass mortality was possibly caused by slime-blotch disease (SBD) in 1980. Since then similar SBD mass mortalities have occurred in South Florida, Bermuda, and the Eastern Caribbean. Recent outbreaks of external lesions on fishes throughout the Caribbean seem to be due to SBD. Green Turtles began suffering a Caribbean-wide epizootic of fibropapillomas in the mid-1980s. These gross, external tumors continue to endanger this sea turtle. Although few non-coral reef mass mortalities (marine mammals, molluscs, seagrasses, sea stars, sponges etc; losses from harmful algal blooms) occur in the Caribbean Region, more coral-reef related disturbances occur here than in any other region. Research efforts require more coordination and cohesiveness. We believe MMEDs are driven by the most important phenomena of our times: global changes due to direct and indirect human impacts.
+Williams, E. H., Jr. and L. Bunkley-Williams. 2000. Marine major ecological disturbances of the Caribbean. Infectious Disease Review 2: 110-127. Google Scholar [265]
In the last seven years, four marine major environmental disturbances have occurred in the Greater Caribbean region (Atwood, 1984; Glynn, 1984; Lessios et al., 1984; Williams et al., 1983, 1986, 1987; and Williams and Williams, 1987). These disasters may be becoming more frequent and more extensive. The most recent event was the 1987-1988 bleaching of coral reef animals. We update cause and significance, geographic extent and timing, species bleached and depth, and research in progress.
Williams, E. H., Jr. and L. B. Williams. 1988. Bleaching of coral reef animals in 1987-1988: An updated summary. In: J. Ogden and R. Wicklund (eds.) Mass bleaching of coral reefs in the Caribbean: A research strategy. National Undersea Research Program, NOAA, Research Report 88-2, Appendix III: 19-21.
Coral cover is declining worldwide due to multiple interacting threats. We compared the effects of elevated nutrients and temperature on three Caribbean corals: Acropora cervicornis, Orbicella faveolata, and Siderastrea siderea. Colonies hosting different algal symbionts were exposed to either ambient nutrients (A), elevated NH4 (N), or elevated NH4 + PO4 (N + P) at control temperatures (26 °C) for > 2 months, followed by a 3-week thermal challenge (31.5 °C). A. cervicornis hosted Symbiodinium (S. fitti) and was highly susceptible to the combination of elevated nutrients and temperature. During heat stress, A. cervicornis pre-exposed to elevated nutrients experienced 84%–100% mortality and photochemical efficiency (Fv/Fm) declines of 41–50%. In comparison, no mortality and lower Fv/Fm declines (11–20%) occurred in A. cervicornis that were heat-stressed but not pre-exposed to nutrients. O. faveolata and S. siderea response to heat stress was determined by their algal symbiont community and was not affected by nutrients. O. faveolata predominantly hosted Durusdinium trenchii or Breviolum, but only corals hosting Breviolum were susceptible to heat, experiencing 100% mortality, regardless of nutrient treatment. S. siderea colonies predominantly hosted Cladocopium C1 (C. goreaui), Cladocopium C3, D. trenchii, or variable proportions of Cladocopium C1 and D. trenchii. This species was resilient to elevated nutrients and temperature, with no significant mortality in any of the treatments. However, during heat stress, S. siderea hosting Cladocopium C3 suffered higher reductions in Fv/Fm (41–56%) compared to S. siderea hosting Cladocopium C1 and D. trenchii (17–26% and 10–16%, respectively). These differences in holobiont susceptibility to elevated nutrients and heat may help explain historical declines in A. cervicornis starting decades earlier than other Caribbean corals. Our results suggest that tackling only warming temperatures may be insufficient to ensure the continued persistence of Caribbean corals, especially A. cervicornis. Reducing nutrient inputs to reefs may also be necessary for these iconic coral species to survive.
Effects of elevated seawater temperatures on deep-water benthos has been poorly studied, despite reports of increased seawater temperature (up to 4 °C over 24 hrs) coinciding with mass mortality events of the sponge Geodia barretti at Tisler Reef, Norway. While the mechanisms driving these mortality events are unclear, manipulative laboratory experiments were conducted to quantify the effects of elevated temperature (up to 5 °C, above ambient levels) on the ecophysiology (respiration rate, nutrient uptake, cellular integrity and sponge microbiome) of G. barretti. No visible signs of stress (tissue necrosis or discolouration) were evident across experimental treatments; however, significant interactive effects of time and treatment on respiration, nutrient production and cellular stress were detected. Respiration rates and nitrogen effluxes doubled in responses to elevated temperatures (11 °C & 12 °C) compared to control temperatures (7 °C). Cellular stress, as measured through lysosomal destabilisation, was 2–5 times higher at elevated temperatures than for control temperatures. However, the microbiome of G. barretti remained stable throughout the experiment, irrespective of temperature treatment. Mortality was not evident and respiration rates returned to pre-experimental levels during recovery. These results suggest other environmental processes, either alone or in combination with elevated temperature, contributed to the mortality of G. barretti at Tisler reef.
In this paper, we report on the quasi-isentropic compression of an iron sample using ramp shaped laser irradiation. This technique allows us to quasi-isentropically compress iron up to 700 GPa and 8500 K. To our knowledge, these data are the highest pressures reached on iron in off-Hugoniot conditions and the closest to the thermodynamic states thought to exist in Earth-like planetary cores. The experiment was performed on the Ligne d'Integration laser facility at CESTA, Bordeaux, France. (C) 2015 AIP Publishing LLC.
High energy lasers are a unique tool to create high pressure states above 10 Mbar at ns time scales, which allow to study material properties under these extreme conditions. These conditions are, for example, comparable with planetary cores, where material properties play an important role for the properties and evolution of a planet. The rapid compression allows also to study dynamic effects of phase transitions as compression times are comparable to relaxation times. We will present recent results of laser compression of iron reaching conditions of so called “super-Earth” cores. A description of the compression schemes as well as present and future diagnostics is presented. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
In the letter by Peter S. Ashton et al. (28 Oct., p. 366), reference 2 was incorrect. It should have read, "E. Marshall, Science 221, 242 (1983)."
Populations of the ecologically important sea urchin Diadema antillarum suffered severe mass mortalities throughout the Caribbean. This mortality was first observed at Panama in January 1983; by January 1984 it had spread to the rest of the Caribbean and to Bermuda. The sequence of mortality events in most areas is consistent with the hypothesis that the causative agent was dispersed by major surface currents over large distances. However, some of the late die-offs in the southeastern Caribbean do not fit this pattern. Several lines of indirect evidence suggest that the phenomenon is due to a water-borne pathogen. If so, this is the most extensive epidemic documented for a marine invertebrate.
The regular echinoid genera Eucidaris, Diadema and Echinometra are represented on the two sides of Central America by geminate species, believed to have resulted from the emergence of the Isthmus of Panama in the late Pliocene. Divergence between the members of each geminate pair (and of an additional Caribbean species of Echinometra from its congeners) was studied electrophoretically and morphometrically in an effort to gain an understanding of the changes in structural genes and external anatomy in populations isolated by a geographic barrier for a known period of time. Analysis of 18 presumptive loci (15 in Eucidaris), encoding a total of 13 enzymatic proteins, revealed pronounced differences in degree of differentiation in the three species pairs. Pacific populations of Diadema have diverged from their Atlantic counterparts no more than they have from populations on the same coast. Eucidaris and Echinometra, on the other hand, exhibit interoceanic genetic distances 16 and 37 times greater than intraspecific ones. Transisthmian distance in Echinometra is 20 times larger than it is in Diadema. The third species of Echinometra, E. viridis, has diverged from its sympatric Caribbean congener, E. lucunter, only one-fifth as much as the latter has diverged from its Pacific congener, E. vanbrunti. Morphometric differentiation between the members of each pair, assessed on approximately 20 characters and quantified with the Mahalanobis generalized distance, is not substantially different from local variation within each species. The contention of previous authors that morphological evidence argues for a geminate relationship of these species is, therefore, confirmed. Discriminant analysis indicates that populations of geminate species can be distinguished from each other, but that the variation which aids in this discrimination is not substantially different from local variation within each species. The ratio (but not the absolute values) of inter- to intraspecific mean Mahalanobis distances is lowest in Diadema, intermediate in Eucidaris, and highest in Echinometra, a pattern that agrees with the one displayed by the average Nei's indices calculated from electrophoretic data. This is the only instance of congruence between molecular and morphological data, and it is limited to interoceanic comparisons. The Caribbean species of Echinometra show no concordance between the two sets of characters. While on the molecular level, E. viridis has diverged little from E. lucunter, the mean morphological distance between them is twice as large as their mean intraspecific distances, a magnitude of differentiation that surpasses that of E. lucunter from the eastern Pacific E. vanbrunti. This pattern may result from different sensitivities of each level of integration to different components of the environment: allozyme frequencies may be primarily influenced by physical variables, while morphology is more likely to reflect the type of substratum that each species occupies. Rates of divergence on the two levels are, therefore, judged to be independent of each other; they only vary in unison when the components of the environment to which each is related also vary in parallel. Divergence in allopatry seems to have proceeded in rates dependent on the environmental differences as each genus (and each level of integration) has perceived them. Divergence in sympatry has been more rapid on the morphological level, possibly because of habitat separation between the closely related congeners. In a recent article Vawter et al. (1980) have claimed that data from geminate species of fish support the molecular clock hypothesis; they also criticized my suggestion (Lessios, 1979a) that the sea urchin data are inconsistent with its predictions. I present arguments as to why, in my opinion, the fish data are not adequate to test this hypothesis, while the conclusions drawn from the sea urchin data should stand.
Very extensive bleaching of coral reef communities occurred after severe flood rains over eastern Jamaica. The loss of color
was due to the mass expulsion of zooxanthellae from the tissues of Millepora, Scleractinia, Zoanthidea, and Actiniaria living
in the shallow reef zones. The polyps of the bleached individuals continued to expand and feed in their normal fashion. It
is believed that expulsion of the zooxanthellae was induced by contact with water of lowered osmotic pressure on the surface
of the sea, rather than by sedimentation or fouling. Regeneration of the depleted zooxanthellar populations was very slow;
many of the bleached colonies survived well despite the near total absence of zooxanthellae from their tissues for over 2
months.