Capture of anemones and polychaetes in artificial collectors for ornamental purposes, effects of: Depth, deployment period, and time of immersion

Abstract

This research aimed to test the catching of ornamental invertebrates in artificial collectors, comparing different types of collectors (vertical and horizontal), deployment period (seasons) and time of immersion (1 to 8 months). The experiments were carried out in an area of mussel farming in Caraguatatuba, southeastern Brazil. Collectors were made of braided nets, both measuring 1 m. Batches of 32 collectors were deployed into the sea at Winter and Spring 2011 and Summer and Autumn 2012. Half of collectors were positioned horizontally at the surface of the sea and the others were positioned vertically, both tied to a floating structure 50 m long. Monthly, two vertical and two horizontal collectors were removed from each batch and examined for detecting ornamentals. Two species were caught: the anemone Bunodosoma caissarumm and the polychaete Branchiomma luctuosum. Occurrence of anemones was significantly higher in horizontal collectors and lower in collectors deployed during summer. Occurrence was also higher after two to five months of immersion. Polychaete occurrence was significantly higher in vertical collectors deployed during Autumn, being higher after seven months of immersion. We concluded that the system was technically feasible, but an economical evaluation must be done in further studies.