GAMETOGENIC CYCLE OF Lytechinus variegatus (LAMARCK, 1816) (ECHINOIDEA: TOXOPNEUSTIDAE) IN NORTHEASTERN BRAZIL

Ciclo gametogênico de Lytechinus variegatus (Lamarck, 1816) (Echinoidea: Toxopneustidae) no Nordeste do Brasil

Abstract

Some reproductive aspects of Lytechinus variegatus were described including sex ratio, gonad index (GI) and histological examination of the gonads. Ninety individuals (63.44 mm ± 6.17) were sampled from March 2017 to January 2018 randomly collected by hand at Enseada da Ribeira (municipality of Salvador, northeastern Brazil: 12º54'488''S, 38º29'872''W). The sex ratio did not differ from 1:1 and the GI showed no significant differences (p>0.05) for both sexes. Males and females continuously release its gametes, presenting a greater reproductive effort during the dry and warmer periods of the year. A wide range of food supply for the individuals guarantees the maintenance of the long reproductive period. Immediate metabolic expenditure may explain the lack of variation in GI, as gonads are not storage organs in this species. L. variegatus populations present variability in strategies for using and allocating energy resources in response to environmental interactions in situ, regardless of latitude. Along the Brazilian coast, an inverse relationship is observed between oocyte size and the effort devoted to reproduction in different populations of this species. Quantitative oogenesis evaluations over time are assertive analytical techniques for assessing the reproductive cycle of echinoids.

Keywords: Lytechinus variegatus, sea urchin, histology, reproductive cycle, gonadal index, cytometric analysis