Growth pattern and changes in abundance of the endangered bat star Asterina stellifera

PABLO E. MERETTA; NAHUEL EMILIANO FARIAS; MAXIMILIANO CLEDÓN; C. R. R. VENTURA

Marine Ecology

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 37 p. 1423 - 1433

The sea star Asterina stellifera has declined during the last decades and currently is only abundant in the southern limit of its former range. We surveyed this population over five years to model individual growth and explore the relationship between changes in local abundance with environmental factors and the reproductive status of individuals. Nine growth models were assessed and compared using Information Theory approach, being the best the von Bertalanffy growth model. Our results show that A. stellifera is a species with slow growth and relatively long lifespan.. Contrary to the expected for temperate species, growth rates were fairly constant through the year and therefore models including seasonal oscillations were inappropriate. The abundance of this species increased significantly during the reproductive season (from early spring to early summer). This is suggested to be due to increased activity and small scale aggregation of reproductive individuals. In spite of the high local abundance of mature individuals, we did not detect major recruitment events. Therefore, A. stellifera seems to be particularly vulnerable to local extinction. This study was performed prior to the arrival of the kelp Undaria pinnatifida and the nudibranch Pleurobranchaea maculata, species that threatens the community structure where A. stellifera lives. Therefore, the data reported here are essential information to assess the future effects of these exotic species on these sea star´s populations.