Aspects of the reproductive biology of the freshwater/brackish amphipod Quadrivisio lutzi (Crustacea, Amphipoda) from an unstable coastal lagoon of southeastern Brazil
ABSTRACT The amphipod Quadrivisio lutzi (Shoemaker, 1933) (Maeridae) inhabits the coastal lagoons of southeastern Brazil, which are highly unstable environments. Drastic reduction in the abundance and distribution of this amphipod on these lagoons has been observed. The constant recovery of its populations suggests that this species may show a reproductive strategy that helps it to persist on these environments. Therefore, our aim was to study the reproductive biology of this species in Carapebus lagoon and to answer the question if its reproductive strategy contributes to a rapid population recovery. The size-range at sexual maturity was determined by the relative growth of the gnathopods and by the number of articles in antennal flagella. Brood size, egg diameter, size at first maturity and other relative reproductive parameters were obtained, which were compared to other species using a multivariate Principal Component Analysis (PCA). Females reach maturity at smaller size-range (2.9-3.9 mm body length (BL) than males (4.9 -5.9 mm BL). Mean egg diameter was small (0.35 ± 0.08 mm) and fecundity was high (20.2 ± 9.2 eggs/female; maximum 48 eggs). The relative reproductive parameters observed in Q. lutzi suggest it as iteroparous species. The PCA situated Q. lutzi within the species of high reproductive potential, characterized by small female size at first maturity, small egg diameter, large brood size and iteroparity, which have been largely considered adaptations that allow rapid recovery of population sizes. Therefore, we concluded that the reproductive strategy of this species contributes to its survival in the highly unstable Carapebus lagoon at southeastern Brazil.