Bruckner, A.

The Caribbean region is highly vulnerable to coastal hazards since a relatively high percentage of the population lives right at the coast. Tourism, a major economic factor on many islands, is concentrated in coastal areas as well. The “traditional” hazards along the coasts of the Caribbean, as perceived some decades ago, are earthquakes, volcanism and storm surges during hurricanes. This focus is justified in the light of the devastating earthquake of Haiti in 2010, which represents a regional maximum in magnitude with a death toll of more than 230,000. The eruption of Mount Pelée on Martinique, which destroyed St. Pierre, the former principal town of the island, and killed around 28,000 inhabitants, and the Great Hurri-cane of 1780 with a similar number of fatalities along the Antilles island arc were outstanding disasters in terms of magnitude. Moreover, the frequency during the 500 years of historical documentation is high as well.
However, history tells that the Caribbean is also prone to the risk of tsunamis. One hundred twenty-seven possible tsunamis were documented during the last 500 years, of which 53 were finally considered to be real tsunamis.

Tsunami hazard on Bonaire
Since we found geological traces of potential tsunamis at almost all sites investigated along the coast of Bonaire, we consider the entire coastline to be prone to tsunami hazard. Along the windward coast, the largest boulders point to the occurrence of tsunami wave heights in the order of 8-10 m. This height estimate is similar to tsunami wave heights observed at the Venezuelan coast in historical times, e.g. at Paria in 1530 or at Puerto Tuy in 1900 [5]. The minimum inundation of such a tsunami on the carbonate platform along the windward side would be 300 m, possibly even more than 500 m. However, findings of candidate tsunami deposits in the sediment cores of the bays, bokas and saliñas, such as Boka Bartol, Saliña Tam or Lagun far inland indicate that especially these low-lying areas provide pathways for inundation and destruction by a tsunami. Thus, a low topography, as found on the entire southern part of Bonaire, is more prone to tsunami inundation.

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.