Appendix A. Photographs of feeding fronts of Oreaster reticulatus and Strongylocentrotus droebachiensis.
FIG. A1. (A) A feeding front of the sea star Oreaster reticulatus off St. Croix, U.S. Virgin Islands. The front is moving from left to right. Feeding mounds (fm) of darker sediment surrounded by lighter halos can be seen behind the front on the highly turbated sand bottom. In advance of the front, the sediment appears darker because of a microalgal film which has developed in the absence of sea star grazing in the previous weeks. Average sea star diameter is 0.26 m. (B) A feeding front of the urchin Strongylocentrotus droebachiensis grazing on the kelp Laminaria digitata and L. longicruris near Halifax, Nova Scotia, Canada. The recently created barren ground behind the front (on the right) is denuded of erect macro-algae. Average urchin diameter is 0.04 m.