Breeding and heterosexual pairing in the snapping shrimp Alpheus estuariensis (Caridea: Alpheidae) in a tropical bay in northeastern Brazil

Abstract

We investigated aspects of the breeding biology, including the reproductive period, egg production, and heterosexual pairing of the snapping shrimp Alpheus estuariensis Christoffersen, 1984 in Pontal Bay, municipality of Ilheus, state of Bahia, northeastern Brazil. Samples were taken monthly during spring low tides from September 2011 to October 2012, on mud substrate in the intertidal zone. We obtained 305 females, of which 134 were ovigerous. The latter were observed in all months, with peaks in June and October 2012; this corresponded to months of higher rainfall indexes, suggesting continuous seasonal breeding. Seventy-five females had normal-appearing eggs and 59 had abnormal eggs (smaller mean size and whitish color). The abnormal eggs differed significantly in number and volume in relation to normal eggs in stage I. Eggs in three stages of embryonic development were observed, with a non-statistically significant reduction in mean fecundity between stages. Mean fecundity, calculated from females with normal eggs in stage I, was 154 ± 108.06 eggs. The mean volume of the eggs changed significantly during development, increasing 45% from stages I to III. A total of 86 male-female pairs were obtained. The sizes of paired males and females were positively correlated, although paired females were slightly larger than males. Formation of pairs begins early, when the females are smaller than the smallest ovigerous female. The mean size of male-female pairs with females carrying normal eggs was significantly larger than the size of male-female pairs with females carrying abnormal eggs. Based on the results provided here, the possible mating system of A. estuariensis is discussed.