When conservation can keep up with development´s pace: Health status of coral ecosystems in the North Pacific of Costa Rica. Coral reefs are diverse and productive ecosystems, despite this, they are being threatened by human activities that enhance the detrimental impact of the natural phenomenon's like Harmful Algal Blooms (HAB). The north Pacific of Costa Rica has been characterized as one of the best regions for the coral reefs development in the country. However, many of these ecosystems are being lost as a result of eutrophication, overfishing, invasive species and others impacts that affect the region. In the present study, live coral cover in the north Pacific was 5.0 ± 10.4(s.d.) %, with a domination in the ecosystems by turf algae. Twenty-six invertebrate taxa were registered in the region with the predominance of the sea urchin Diadema mexicanum. Ninety-four species of reef fish were identified. Snappers and some planktivores species were the groups with the highest frequency and abundance. The localities previously studied in the 1990 decade, presented a mean live coral cover between 40-50 %, whereby the actual state of the reef reflect a significant deterioration. This decline in coral cover is due to natural events like the El Niño, as well as the decrease in water quality in the region. In recent years, proliferations of the invasive seaweed Caulerpa sertularioides and high densities of bioerosive sea urchins have been reported, mainly associated with HAB events. Likewise, fish communities have low biomass, especially in the vicinity of fishing villages. The state of the reefs in the North Pacific is worrying and requires actions for its recovery and conservation, for which there must be better planning of the development of projects and activities on the coast. Rev. Biol. Trop. 66(Suppl. 1): S280-S308. Epub 2018 April 01.

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Recibido en diciembre de 2004; aceptado en mayo de 2005Resumen Se estudiaron las comunidades y arrecifes coralinos del Parque Nacional Marino Ballena (PNMB), en el Pacífico sur de Costa Rica, mediante tres transectos por sitio, de 10 m de largo cada uno y paralelos a la costa, utilizando una cuadrícula de 1 m 2 . Se encontró un total de 15 especies de corales (11 hermatípicas y 4 ahermatípicas), las que sumadas a informes previos para el parque hacen un total de 18 especies. El coral Porites lobata presentó la mayor cobertura coralina (36.5 ± 3.7%) y fue el único presente en todos los sitios. Las otras especies de coral presentaron bajas coberturas (<10%) y sólo fueron observadas en pocos sitios. El porcentaje de coral muerto fue de 1.8 ± 0.6% y el porcentaje de blanqueamiento (0.7 ± 0.2%) está dado por P. lobata en un solo sitio. El PNMB y la Isla del Caño poseen el mayor número de especies de coral (18 especies) de la región sur de Costa Rica; sin embargo, difieren en su composición. La baja diversidad y la baja cobertura coralina de varios sitios del parque se atribuyen al impacto del fenómeno de El Niño en los últimos años, a la sedimentación y a la dilución de las aguas en época de lluvias. Se sugiere la necesidad de realizar un monitoreo a largo plazo sobre estos ecosistemas y determinar futuras estrategias de manejo y conservación. AbstractThe coral communities and reefs at Ballena Marine National Park, on the southern Pacific coast of Costa Rica, were studied using three 10-m long transects per site, parallel to the coast, with 1-m 2 quadrants. A total of 15 species of corals (11 hermatypic and 4 ahermatypic) were found, which when added to previous reports for the park makes a total of 18 species. Porites lobata showed the highest coral cover (36.5 ± 3.7%) and was the only species present at all sites. The other coral species had low coverage (<10%) and were observed in a few places. Dead coral had a cover of 1.8 ± 0.6% and the percent of bleached coral (0.7 ± 0.2%) was due to P. lobata at only one site. This park and Caño Island have the highest number of coral species (18 species) in the southern region of Costa Rica, but they differ in composition. The low diversity and low coral cover in the park is attributed to the impact of the El Niño phenomenon in recent years, to sedimentation and to the dilution of waters during the rainy season. We suggest that a long-term monitoring program of this ecosystem is needed to determine future management and conservation strategies.