Zooplankton capture rates by the octocoral species Dentomuricea aff. meteor and Viminella flagellum in the Azores Archipelago

The majority of octocoral species are found in waters deeper than 50m where they create three-dimensional and highly heterogenous habitats known as coral gardens. The Azores Archipelago is an octocoral biodiversity hotspot and coral gardens are one of the most prominent deep-sea communities encountered regionally. Although food availability and flow have been recognized as key factors in determining the dynamics of suspension feeder communities, very little information exists on how flow affects the feeding capacity of deep octocoral species. The study focused on two common habitat-forming octocoral species in the Azores, Dentomuricea meteor and Viminella flagellum, aiming at determining their ability to capture zooplankton prey under variable flow velocities. The rotifer Branchionus plicatilis was used as prey, while three flow velocities were established in recirculating 13L flumes: 3 cm/s, 6 cm/s and 9 cm/s. Both species efficiently captured zooplankton prey. Capture rates were lower under 3 cm/s, however no difference was detected between 6 and 9 cm/s. Dentomuricea meteor reached higher capture rates per polyp than V.flagellum, possibly due to their differences in polyp size and density.