The biology of Phallusia nigra Savigny, 1816 (Tunicata: Ascidiacea) in southern Brazil: Spatial distribution and reproductive cycle

Some aspects of the life cycle of the ascidian Phallusia nigra at São Sebastião (southern Brazil) were studied and compared with its life history traits studied at Jamaica. Population dynamics was monitored on natural substrates sampled on a monthly basis. Longevity, recruitment and mortality rates were obtained by monitoring permanent quadrats. The breeding period was assessed by dissection of animals and searching for full gonoducts. P. nigra adults are 5–8 cm long and are distributed mostly on vertical and inclined surfaces. Recruits are found throughout the year, but a marked peak of abundance was observed during the fall (April to June). Adults had full gonoducts during summer (November to February). High mortality was observed during the first 3 mo after juveniles were observed the first time. Most animals died before the first year of life, but a few would persist for at least 2 yrs. Some life history traits of the Brazilian population, such as timing of reproduction and the number of recruitment peaks per year, are similar to those shown by the Caribbean population. On the other hand, size of adults, mean longevity and abundance of recruits were all lower in the Brazilian animals.