PARENT SESSION
Poster Session # 19: Insect and Invertebrate Ecology.

Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Relationships between coarse woody debris, particulate organic matter, and crayfish in southeastern coastal plain streams.

Mitchell, Richard^*,1, Maloney, Kelly¹, Miller, Stephanie¹, Feminella, Jack¹, Mulholland, Patrick², ¹ Department of Biological Sciences, Auburn, AL, United States² Environmental Sciences Division, Oak Ridge, TN, 37831

ABSTRACT- The purpose of our study was to assess the role of instream coarse woody debris (>2 cm, CWD) and coarse/fine particulate organic matter (<2 cm, POM) on density, biomass, and size frequency of crayfish (Cambaridae) within small sandy-bottom streams of the Southeastern Coastal Plain. CWD and sand are the predominant substrates in these low-gradient streams, but only limited work has been done to assess the degree to which CWD and/or POM influence crayfish population dynamics, despite the high bioenergetic importance of crayfish. Three streams containing varying amounts of CWD (4 -10% of stream bottom surface) were sampled for crayfish, POM, and other physicochemical parameters at the Fort Benning Military Reservation, Georgia. Crayfish (kick seine) and POM (substrate cores) were sampled monthly and seasonally, respectively, at 5 sites per stream. Surprisingly, abundance of submerged CWD alone did not predict crayfish density, but rather density was a combined function of CWD and POM levels, with highest densities (up to 11 crayfish/m²) occurring in sites with highest CWD and POM. Our preliminary findings suggest that CWD may only indirectly increase crayfish density and biomass by influencing retention of POM, a potential food resource, within the streambed. In addition to quantifying the direct and/or indirect importance of CWD on crayfish populations, we also are studying the influence of CWD structure (debris dams vs snags) and the nature of instream wood (debris vs live rootwads) on POM retention and crayfish size, diet, growth, and production in these streams.

Key words: coarse woody debris, streams, crayfish, particulate organic matter