Wednesday, June 6, 2007 - 2:00 PM
262

Intra-patch dynamics of a sponge-associated invertebrate community: assembly, production and life-cycles

John R. Wallace, Ph.D.1, M. Eric Benbow2, Jill M. Rudy1, and Cindy Willman-Kinsey1. (1) Department of Biology, Millersville University, Lancaster, PA 17551, (2) Entomology, Michigan State University, East Lansing, MI 48824

Habitat patches vary in both space and time, and are influenced by interactions of an external matrix with internal processes.  Living patches defined as host organisms to a community of parasites are no exception.  Spongillaflies (Neuroptera: Sisyridae) are specialized parasites of freshwater sponges, restricted to life on these living patches, and little is known about intra-patch dynamics of these insects and other transient invertebrates.  Our objectives were to measure intra-patch dynamics of invertebrates on freshwater sponges (Porifera: Spongilla lacustris) that were collected monthly from February – December 2006 using SCUBA along a depth gradient in a Pennsylvania quarry: 6.7 m, 10.4 m, 11.3 m.  Highest densities of Climacia areolaris occurred from February – April, and included a density depth shift from shallow to deeper depths over the year.  At mid-depth, patch size (i.e., sponge volume) significantly decreased with increasing temperature, and this was associated with a negative seasonal relationship between C. areolaris and other invertebrate taxa.  These inter-specific interactions may have been related to patch size changes or life-cycle features of the Sisyridae.  Larval body size of C. areolaris showed peaks in March and July; however, densities lowered population biomass by 5-fold after May, when other invertebrate taxa increased.