Biologia populacional de Divaricella quadrisulcata (d’Orbigny, 1842) (Mollusca, Bivalvia, Lucinidae) na praia de Bom Jesus dos Pobres, Saubara, Bahia

Abstract

Divaricella quadrisulcata (d'Orbigny, 1842) is a bivalve mollusc that represents one of the main components of the meso-fauna on the beaches of the Recôncavo, not showing interest from an economic point of view nor food. The present study aimed to analyze the quantitative structure of the population of Divaricella quadrisulcata from the relative frequency of length and total weight, length-weight relationship, condition factor, and reproductive aspects. For both collections were carried out monthly between November/09 to October/10 on the beach of Bom Jesus dos Pobres, Saubara, Bahia, through an effort of capturing 40 min/man. The material was transported to the laboratory of Zoology of invertebrates of UFRB where took place the measurement of biometric variables: total length (Lt mm), weight of soft parts (Wb g) and weight of the shell (Wsh), total weight (Wt), the length-weight relationship and the condition factor, in addition to the income derived from meat and shell. It was held also the sexing and observation of macroscopic gonad maturation stages and determination of the minimum size of first maturation. The abiotic parameters of the water such as pH, temperature and salinity were obtained from a multi-parameter probe (HANNA HI 9828). We used the statistical program BioEstat 5.0 to check the arithmetical mean (x), variance, standard deviation, coefficient of variation (c.v.), standard error of the mean or average deviation (Sx). The average pH was alkaline 8.27 area, the average salinity was 33.79 ‰ and the average annual temperature was 31.23°C, considered normal for the location. Was sampled a total of 539 individuals. The average annual length of the shells (Lt, in mm) D. quadrisculcata, on the beach of Bom Jesus dos Pobres was 16.91 mm (+ 3.2). The average weight of meat (Wb) 0.45 g (+ 0.28) the average weight of the shell (Wsh) the average was 1.21 g (+ 0.80). The total average weight (Wt) was 1.67 g (+ 1.03). For the variable of length-weight relationship was positive allometric growth can be observed for the variables Wb x Lt and Wt x Lt. The condition factor of total weight (Wt) was greater than the weight of meat (Wb), however, both showed great "conditions". The average yield of the flesh (Re b %) was 29 and the average value of the shell (Re sh %) was 71, the good income reflects in good condition of the individual. The sex ratio, considering males and females (M:F), was 1.4: 1. It was possible to note the continuing disposal of gametes and the length of the first sexual maturity of individuals was 10.74 mm.