MEPS 414:167-177 (2010)  -  DOI: https://doi.org/10.3354/meps08708

ABSTRACT: The potential influence of fiddler crab burrow density on the processes controlling organic matter (OM) accumulation was examined in Virginia salt marshes. As burrows may affect important chemical and biological processes that influence belowground plant production and decomposition, experimental manipulations were designed to modify fiddler crab burrow density by either increasing them (artificially constructed holes) or decreasing them (exclosures) and comparing them to areas naturally with and without fiddler crab burrows. The only significant difference among treatments was associated with the presence of holes without regard for whether they were artificial or natural. Higher burrow density resulted in an increase in soil redox potential, which most likely caused higher decomposition, even though sulfate-reduction rates were not different among treatments. Belowground production decreased with increased burrow density resulting in less OM addition to the soil. Higher decomposition and lower belowground production resulted in a net loss of 3 g C m^–2 yr^–1 in marshes with higher burrow densities, while areas with few to no burrows accumulated up to 245 g C m^–2 yr^–1, equaling a surface accretion rate of 4 mm yr^–1. Examination of 6 other salt marshes in the region revealed a negative correlation between fiddler crab density and soil OM content, lending strength to the argument that bioturbation is a potentially important explanatory factor of OM accumulation in salt marshes and may influence how sea level rise impacts coastal marshes.

KEY WORDS: Carbon sequestration · Decomposition · Plant production · Sea-level rise · Long-term ecological research · LTER