Spatio-temporal changes in sea star populations of the genus Astropecten inhabiting soft bottoms in the northwestern Mediterranean Sea

•Sympatric Astropecten species occur in Maresme coast.•Spatio-temporal differences were observed in asteroidean populations.•Each sea star species showed specific habitat requirements.•Monthly fluctuations in the density were noted at local scale.

Astropecten species inhabit soft-bottom habitats worldwide, from intertidal areas to the deep sea. Sympatric Astropecten species (Astropecten aranciacus, Astropecten irregularis pentacanthus, Astropecten platyacanthus Astropecten jonstoni and Astropecten spinulosus) occur in the shallow coastal area of the Maresme coast (northwestern Mediterranean Sea). This study analyzes spatio-temporal differences in asteroidean population between the periods 2004–2006 and 2010–2011. Our results showed variations in density and spatial distribution in A. aranciacus, and a change in its diet between the two study periods. A. irregularis pentacanthus reduced its spatial distribution, concentrating in smaller areas. A. platyacanthus was absent in the first period but abundant in the second. A. jonstoni and A. spinulosus were scarce in the first period and absent in the second. The results also showed the specific habitat requirements for each sea star species with regard to sediment characteristics, prey availability and depth.