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Population structure of the clam, Asaphis deflorata, in Caurantica, gulf of Paria, Sucre state, Venezuela

Abstract:

Populations structure and bioecological aspects of the bivalve Asaphis deflorata were evaluated in locality of Caurantica, northeasthern of Guiria, Gulf of Paria, Sucre state, Venezuela. Samples were collected monthly from March 2005 until February 2006, using a stratified random sampling with a quadrate of 0.25 m2. During sampling water temperature and salinity were measured. In order to test the spatial dispersion, the area was divided into 3 zones parallel to the coast and 4 fringes perpendicular to it, according to the topographical characteristics of the substrate. The population presented a length interval from 10 until 74 mm, with a predominance of the lengths between 48-54 mm, although since September 2005 there were organisms with lengths smaller than 26 mm incorporated into the population. A aggregated microespatial dispersion was observed in each zone, with an increase of the length of bivalves from of the zone of low to one high tide. Relationships between morphometric parameters were highly significative and length (Lt)-total mass (TM) relationship was represented by the equation TM = 0.0003*Lt 2.806 (r2= 0.93). Average biomass and density were 400.33 g/m2 and 69.33 ind/m2. The biomass presented maximum values in the zone of low tide, whereas the maximum density was observed in zone of high tide. There were not detected significant differences in average biomass and density among zones, but among fringes. Condition factor presented its maximum value in May 2005 (36.6%) and minimum in August 2005 (28.8%) 2005. We suggest that salinity variation in the region has influence on the physiological condition of the species.