Meeting Abstract

P1.18  Jan. 4  The Role of the Chiton Mopalia ciliata in the Creation and Maintenance of Free Space within Marine Fouling Communities MEECE, S.L.*; CRAIG, S.F.; JANIAK, D.; Humboldt State University, Arcata, CA; Humboldt State University, Arcata, CA; Humboldt State University, Arcata, CA ferniberni24@yahoo.com

Grazing and bulldozing by chitons can strongly affect marine community structure by creating free space for new species to settle and grow. Chitons may also act as keystone species, removing superior competitors thereby allowing inferior species to coexist. I therefore predicted that the process of feeding and bulldozing by the chiton Mopalia ciliata would maintain free space, and increase species richness and diversity in marine fouling communities. To test this prediction, I manipulated chiton presence/absence on 42 fouling panels, deployed under floating docks five years previously to allow �natural� fouling communities (with sponges, mussels, hydroids, ascidians and barnacles) to develop. All panels were groomed initially to contain the same set of six species so that changes in species richness due to the presence of chitons could be assessed. To examine the amount of free space that chitons could maintain, I created three free space treatments by scraping all organisms off patches of the surface on these panels to establish fourteen replicates each of: (1) 25% free space, (2) 50% free space, and (3) 75% free space. Half the panels in each treatment contained a single grazing chiton, whereas chitons on the other half were removed. Analysis of this ongoing experiment shows that, regardless of size, chitons are able to maintain significantly high levels of free space in these communities, and frequently limit the growth of superior competitors. Thus far, the chiton Mopalia ciliata appears to be a keystone species with strong effects on marine fouling community structure.