Coral reefs in the Bay of Cartagena, Colombia, have been heavily disturbed by anthropogenic perturbations since the founding of Cartagena in 1533. A prominent perturbation was the construction of Canal del Dique, a channel built by the Spaniards to shorten the access to the Magdalena River, a major waterway used by Colombian authorities for colonization and later for commercial purposes. Canal del Dique turned the clear waters of Cartagena Bay into a seasonally fluctuating, highly turbid, and eutrophied body of water with high sedimentation, and most coral reefs within the Bay disappeared (Restrepo et al. 2006). Even reefs outside the Bay, like those of Rosario Islands, were negatively affected. Only a few reefs remained, though they were also severely affected by human activities, such as the dredging of one of the natural mouths of the bay for seaport access.Recently, while looking for excavating sponges at Varadero (10°18¢10 †N, 75°34¢55 †W), an area adjacent to the dredged channel, we found what might be one of the best coral reefs on the continental shelf of Colombia in terms of coral cover (up to 80 %) and dominated by Orbicella spp. (Fig. 1). The total extension of this formation is close to 1 km 2 . A well-developed coral reef in such a highly degraded environment is contrary to expectations. With massive coral colonies >3 m in diameter and a total scleractinian richness of at least 30 species, this reef challenges traditional paradigms regarding ideal conditions for the growth and development of coral reefs (i.e., oligotrophic and clean waters with good sunlight penetration). The largest colonies found must have survived repeated human disturbances. Corals in shallow areas of this reef exhibit the flattened and encrusting growth forms typical of greater depths (>15-20 m). This coral formation is a unique resource that should be conserved and further studied considering its high species diversity, the large size of some of its coral colonies, and the atypical conditions under which it developed.
ReferenceRestrepo JD, Zapata P, Díaz JM, Garzón-Ferreira J, García CB (2006)
Populations of anemonefish species often show signs of local isolation due limited dispersal potential and oceanographic conditions. Additionally, anthropogenic pressure, such as overharvesting and coral reef exploitation causes reduced population size, eventually leading to local extinction. The understanding of the genetic population structure, as well as the influence of both historical and current connectivity, is required to design effective marine protected area (MPA) networks. In this study, the genetic structure of Clark's Anemonefish (Amphiprion clarkii) populations of the Indo-Malay Archipelago (IMA) is assessed through mitochondrial control region (mtCR) sequences and nuclear microsatellites. Results provided evidence of a significant genetic structure (mtCR: Φst = 0.42039, Φct = 0.63852; microsatellites: Fst = 0.01449, Fct = 0.05199). Genetic breaks were identified among Western (Padang Karimunjawa), Central (Sulawesi, Borneo, Bali, Komodo, Timor), and Eastern (Biak) IMA populations, which matches with patterns obtained for congeneric and other coral reef taxa. Due to the restricted connectivity among these three regions, it is suggested to consider them as separate management areas in the design of MPA networks.
El género Pavona comprende 18 especies de las cuales Pavona chiriquiensis ha sido recientemente descrita y registrada en varias localidades del Pacífico oriental tropical. A partir de observaciones y colecciones realizadas en arrecifes de las islas Gorgona y Malpelo entre 1999 y 2005 se confirma su presencia en Colombia. El tardío registro de P. chiriquiensis en estas islas pudo ser debido a su similitud y confusión con P. varians, o a su reciente colonización del Pacífico colombiano.
We report the occurrence of a major corallivore, the Crown-of-thorns Starfish Acanthaster planci, on the coral reefs of Gorgona Island, Tropical Eastern Pacific. Three individuals were sighted on opposite sides of the island, where they fed on small coral colonies of Pavona varians and Pocillopora damicornis. These sightings are noteworthy in light of reports that have demonstrated that the geographic distribution of A. planci is gradually increasing in the equatorial eastern Pacific, particularly south of the Gulf of Chiriquí (Panama) where it was previously absent.
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