Análisis espacio temporal de la biología reproductiva y el reclutamiento del molusco bivalvo Anadara tuberculosa en la costa del Pacífico colombiano Abstract.-The reproductive cycle, recruitment and maturity size of the mangrove cockle Anadara tuberculosa was studied between August 2009 and August 2010 at the 4 departments of the Colombian Pacific coast. Biological samples were collected on three 50 m 2 plots of each region following the traditional method of capture. To determine the state of sexual development, monthly macro and microscopy (using standard histological techniques) observations were performed. The reproductive cycle was divided in 4 stages, resting, development, maturity and spawning. Spawning events were evident throughout the study period, with higher reproductive activity between December and March, and a second short event between June and August. The average maturity size (46.68 ± 9.29 mm) and mean first maturity size (43.50 mm) are below the minimum legal size of capture (50.00 mm) in Colombia. Temporal variation of reproductive activity and recruitment shows no evidence of sexual maturity synchrony in the Colombian Pacific, important for the establishment of management strategies of the resource. Three percent of hermaphroditism was found which is considered protandric due to the imbalance of sex ratio between females and males (2.46:1) and size difference between sexes.Key words: Mangrove cockle, size of sexual maturity, living mass weight, hermaphroditism, sexual synchronyResumen.-Se estudió el ciclo reproductivo, reclutamiento y tallas de madurez de la piangua Anadara tuberculosa entre agosto de 2009 y agosto de 2010 en cuatro departamentos de la costa Pacífica colombiana. Se realizaron muestreos biológicos en 3 parcelas de 50 m 2 para cada región, siguiendo la metodología tradicional de captura. Para determinar el estado de desarrollo sexual, mensualmente se realizaron observaciones macroscópicas e histología rutinaria. Para el análisis reproductivo se definieron los estados de reposo, desarrollo, madurez y desove. Eventos de desove fueron evidentes durante todo el tiempo de estudio, con mayor actividad reproductiva entre diciembre y marzo, y otro evento corto entre junio y agosto. En términos generales, las tallas medias de madurez sexual (46,68 ± 9,29 mm) y de primera madurez (43,50 mm), están por debajo de la talla mínima legal de captura (50,00 mm) en Colombia. La variación temporal de la actividad reproductiva y del reclutamiento, muestra que no se presenta una sincronía de madurez sexual evidente en el Pacífico colombiano, lo cual es información importante para establecer estrategias de manejo del recurso. Se presentó el 3% de hermafroditismo, considerado protándrico, debido a las diferencias en proporción sexual entre hembras y machos (2,46:1) y a la diferencia de tallas entre sexos.Palabras clave: Piangua, talla de madurez sexual, rendimiento de carne, hermafroditismo, sincronía sexual

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Regular sea-urchins are one of the main bioeroding organisms affecting coral reefs around the world. The abundance, distribution and bioerosion rate of the sea-urchin Centrostephanus coronatus, were determined in different reef zones of Playa Blanca fringing reef (Gorgona Island, Colombian pacific coast) during 1997 and 1998. The erosion rates were determined calcinating the gut content of the sea-urchins to eliminate all organic components and preserve the inorganic portion of calcium carbonate. C. coronatus showed the highest densities towards the central zones of the reef (plain-crest and front) (12.4 ind/m 2 ; range 0-48 ind/m 2 ). The highest mean bioerosion rate was 0.103 kgCaCO 3 /m 2 /yr in the reef plain-crest (0-0.69 kgCaCO 3 /m 2 /yr). In the other zones, (back reef and reef front) the mean bioerosion rates were 0.071 (range 0-0.39) and 0.052 (range 0-0.31) kgCaCO 3 /m 2 /yr respectively. According to the present data, it can be seen that the destruction of coralline skeletons, produced in this reef by sea-urchins is rather low, compared with the abrasion caused by these organisms in other places of the world. However, the combined action of C. coronatus and other bioeroding organisms (borers and grazers), along with some adverse environmental factors to corals, can be causing a negative balance between normal processes of reef accretion-destruction in Gorgona Island reefs. Aunque la bioerosión no es un fenómeno reciente en la naturaleza, actualmente se considera como uno de los procesos más destructivos para los arrecifes coralinos, ya que debilita los andamios arrecifales volviéndolos más susceptibles a cambios ambientales (cambio climático global, El Niño, etc), presiones biológicas y a la influencia antropogénica directa (e.g. turismo, contaminación, sobre-pesca) e indirecta (e.g. hipersedimentación) (Hardy et al. 1992, Grigg 1995, Jennings et al. 1995, Laroche y Ramananarivo 1995, Allison 1996, Hubbard y Parsons 1996, Acosta et al. 1996, Jiménez 2001a, 2001b, Jiménez y Cortés 2001, Vázquez-Domínguez 2003.La bioerosión en los arrecifes coralinos puede ser realizada por dos mecanismos: la abrasión y la perforación. En el primer mecanismo, utilizado principalmente por erizos y algunas especies de peces, el sustrato es raspado para extraer principalmente algas (filamentosas y/o calcáreas) y en algunas ocasiones, el tejido coralino; esta categoría de organismos (abrasivos) han sido considerados como los mayores agentes bioerosionadores en todo el mundo (solamente los erizos regulares son responsables de aproximadamente el 75% de la bioerosión total en el Caribe) (Bak 1994). El segundo proceso erosivo es utilizado por ciertos moluscos, sipuncúlidos, poliquetos, esponjas, etc., quienes ya sea para refugio o alimentación, perforan el esqueleto coralino debilitando su estructura. En ambos casos, la acción del hidrodinamismo marino generalmente acaba por desprender las colonias,

Leaf consumption by herbivores in mangroves of the Dagua river estuary, Pacific coast of Colombia. Herbivore leaf consumption of various mangrove species in relation to environmental factors and leaf hardness were studied in the Dagua river estuary, Colombia. Leaf consumption and damage were assessed by measuring the percentage of area attacked by herbivores, distinguishing between consumption and damage. The species that suffered the highest consumption, such as Avicennia germinans (Avicenniaceae) and Laguncularia racemosa (Combretaceae), had softer leaves and less herbivore species when compared with Rhizophora spp. (Rhizophoraceae) and Pelliciera rhizophorae (Theaceae). The abundance and diversity of leaf grazing and its variability among mangrove species in the Dagua River estuary, show the importance of the trophic dynamics of live vegetable matter, in spite of their relatively low contribution to removing organic matter.