Population structure and feeding ecology of the bat star Asterina stellifera (Mobius, 1859): Omnivory on subtidal rocky bottoms of temperate seas

During four years we surveyed the southernmost population of the sea star Asterina stellifera, which has been declared endangered in the central and northern parts of its distribution, and studied their feeding ecology by in situ observations and a short-term manipulative experiment. Contrary to our expectation we found abundant populations with densities up to 72 ind.m(-2). The individuals grew slowly over four years with no replacement in the smaller size classes. In the short term, presence of A. stellifera negatively impacted the abundance of all macrobenthic species analyzed, including sessile and moving animals and algae. We demonstrate that this sea star feeds in a non-selective way on several items belonging to different trophic levels. In addition, it displays a microphagous feeding behavior, so its direct impact might extend to settlers, modifying the recruitment of benthic populations. Indirect effects were not detected, likely due to the experiments lasting for a very short period. As an abundant omnivore, A. stellifera is likely affecting the stability of trophic webs of which they are part. (C) 2012 Elsevier B.V. All rights reserved.