PARENT SESSION
Oral Session #46: Disturbance Ecology.
Presiding: M. Slocum
Tuesday, August 6. 1:00 PM to 4:45 PM. Grand Ballroom East, Radisson.

Biotic disturbance, recolonization and early succession of bacterial assemblages in intertidal sediments.

Plante, Craig^*,1, ¹ College of Charleston, Charleston, SC;, plantec@cofc.edu

ABSTRACT- The role of disturbance in structuring microbial communities has been largely unexplored. Disturbance associated with invertebrate ingestion can reduce bacterial numbers and biomass, and alter metabolic activities and compositions of bacterial assemblages in marine sediments. The primary objective of the research presented here is to determine the mechanisms by which bacterial assemblages recover following deposit-feeder ingestion. In intertidal sediments, microbial recovery could be due to regrowth of bacterial populations surviving gut passage or to migration from adjacent sediments. We used field manipulative experiments to exclude migration by isolating freshly extruded fecal coils of three deposit-feeding species from surrounding sediments, or we excluded regrowth with the use of bacteria-free "mock" fecal coils. We then followed the quantitative and qualitative recovery in egesta and sediments through time using epifluorescence microscopy and PCR-DGGE analysis of 16S rDNA. Our findings indicate that 1) the nature of the disturbance to bacterial assemblages varies among deposit-feeding taxa, and 2) recovery in biotically disturbed sediments is dominated by immigration.

KEY WORDS: bacteria, deposit feeder, disturbance, recolonization