Distributional and biometrical study of appendicularians from the west south Atlantic ocean

Abstract

This study deals with appendicularians from 21 superficial plankton samples collected in the coast of Argentina, Uruguay and Brazil in October–November, 1972. Seventeen species were identified and their distribution established and compared with the results of previous authors. Megalocercus abyssorum received particular attention because it is a very infrequent species in the Atlantic Ocean. Specimens of the family Oikopleuridae were measured, taking data from trunk and tail. From the state of development of the gonads three different stages were established. The data from each station, grouped by species and state of maturity, were subjected to a conventional statistical treatment, obtaining the mean and standard error for each parameter. In addition, the use of statistical testing techniques validated the three developmental stages established, because from the analysis of variance for all the measurements highly significant results were obtained. An exception must be made for Oikopleura dioica since the only difference is in the height of the trunk. The same pertains to the difference between males and females. Oikopleura longicauda showed significant differences between specimens from coastal and pelagic samples in all measurements of the tail.