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Revista de Biología Tropical

On-line version ISSN 0034-7744Print version ISSN 0034-7744

Abstract

GUZMAN, Héctor M.  and  GUEVARA, Carlos A.. Arrecifes coralinos de Bocas del Toro, Panamá: distribución, estructura y estado de conservación de los arrecifes continentales de la Laguna de Chiriquí y la Bahía Almirante. Rev. biol. trop [online]. 1998, vol.46, n.3, pp.601-623. ISSN 0034-7744.

The distribution of continental reefs is presented along 83 km of shore within Babia Almirante and 125 km within the ChIriquí Lagoon, Bocas del Toro, Panamá. Reef community structure (diversity, cover, zonation) is described on 15 coral reefs for both regions, representing tlie diversity of hydrologicat and orographical condiiions affecting the coastal zone. The coral reefs found in Bahía Almirante are well developed down to a maximum depth of 23 m, and a diversity of hard corais of 33 species, which represents approximately a 53% of the total diversity known for Panamá. Coral cover observed for the studied region ranged between 20% and 50% depending on the depth, and a total average of 35% is estimated, nearly twice the cover informed for other regions of Panamá (San Blas), where it is presumed that the reefs are better  protected from human disturbances. Vertical distribution and composition of species are similar across the area; Porites furcata dominates shallow reefs down to 2 m depth, with a cover estimated at 90%, followed by a zone dominated by Agaricía tenuifolia   (40%) down to 6 m depth, followed by a zone composed mainly of A. tenuifolia (15%), Madracis mirabilis (7%), and  Siderastrea siderea (5%) down to 15 rn deep, .and finishing in a deeper zone dorninated by coralline algae and the coral S. siderea. The existence of a semi-continuous Porites furcata fringing reef of ca. 22 km in length, borders the entire coastal zone of Ensenada Grande de Almirante, is informed for the first tirne for the region. Sponges, second sessile organisms in importance, are widely distributed in all reefs with a diversity of 31 species and average cover of 6%. Curiously, the highest algae coverage was found in one reef (10%) while the remaining reefs presented an average cover of 4%. Only one coral reef was found in the Chiriquí Lagoon with development limited to 3 m, a diversity of corals no higher than 7 species, and coral cover of 24% (Porites furcata). The coast of the Chiriquí Lagoon is affected by continuous sediment discharges coming from various rivers, mailnly the Cricamola, Manantí, Uyama, Guarumo, and Cauchero, whose plumes of freshwater and silt extend for many kilometers, limiting the distribution and development of coral reef communities. The vertical distribution, composition, and dominance of certain coral species in the reefs described here (e.g., Siderastrea siderea, Porites furcata, Agaricia tenuifolia, Madracis decactis, and M. mirabilis) indicate that these communities were formed adapting gradually to unfavorable conditions in water quality (lower salinity, low light penetration) which has limited a more vigorous reef development, and perhaps more diverse community. These species, in spite of heing quite resistant lo environmental changes and building healthy reefs in waters of low clarity, presently live near tbeir limits of ecophysiological tolerance, which makes them particularly vulnerable to puncluated changes in the environment. It is expected that any unplanned development project in the region rnight increase sedimentation toward the coastal zone, which could weaken all reef organisms, affecting ecosystem function.

Keywords : Coral reef; biodiversity; Caribbean; reef assessment; ecology.

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