DISTRIBUTION AND CHARACTERIZATION OF THE MATURITY STAGES

CAPITANIO, F; MARSCHOFF, E.; ESNAL, G.

IHERINGIA. SéRIE ZOOLOGIA

FUNDACAO ZOOBOTANICA RIO GRANDE SUL

Año: 1995 vol. 79 p. 59 - 66

0073-4721

The distribution of Oikopleura dioica was studied in the frontal area of Península Valdés, Argentina. The plankton sampling was conducted along four transects with five stations each, at five levels from O to 50m in depth. Oikopleura dioica densities depend on latitude (the southernmost transects showed the greatest densities) and distance to shore (at coastal stations O. dioica was more abundant).The vertical dishibution of the species in the water column was affected by the thermocline and differed among hansects. At well stratified stations, densities were greater below the thermocline. In mixed areas, the upper levels were more abundant. Morphometric analysis of developmental stages demonstrated that trunk length cannot be directly used to distinguish among developmental stages, since the species attains sexual maturity at different lengths. Although a high size variability was found within the mature stage (0.60-1.20mm). males and females differed in gonad height, being higher in males. Oikopleura dioica was studied in the frontal area of Península Valdés, Argentina. The vertical dishibution of the species in the water column was affected by the thermocline and differed among hansects. At well stratified stations, densities were greater below the thermocline. Morphometric analysis of developmental stages demonstrated that trunk length cannot be directly used to distinguish among developmental stages, since the species attains sexual maturity at different lengths. Although a high size variability was found within the mature stage (0.60-1.20mm). males and females differed in gonad height, being higher in males.