Crab Burrows, Soil Nutrients, and Spartina alterniflora : organic content in Brownsville, VA 1992

The effect of Crab Burrows on Soil Nutrients and Spartina alterniflora by Winli Lin This study investigated the effects of fiddler crab (Uca pugnax) burrows on soil nutrients and the marsh grass Spartina alterniflora. Tall-form Spartina alterniflora (1-2m tall) typically dominates the marsh area that is flooded daily by tides. The short-form S. alterniflora(<0.5m tall) generally occupies the higher tidal heights (Bertness 1985). These short-form S. alterniflora are charterized by reduced soil drainage (Mendelssohn and Senecs 1980; Howes et al. 1981; Mendelssohn et al. 1981) and increased soil sulfide levels (King et al. 1982). From comparing control areas devoid of burrrows to those with burrows added, an increase in above-ground Spartina alterniflora production has been observed along with an increase of soil drainage rates and redox potential levels (Bertness 1985). Others have looked at how nutrient availability (Mendelssohn 1979) and sulfide accumulation (King et al. 1982; Howarth and Giblin 1983) may be the primary limiting factors controlling the production and success of S. alterniflora. While soil water movement has been shown to influence the soil parameters, (i.e., sulfide concentration and redox potential) that directly affect cordgrass production (King et al. 1982; Koch et al. 1990), little has been studied on how biotic modifications, such as crab burrows, mediate these physical factors. The Uca pugnax, are burrowing deposit-feeders that excavate and maintain semi-permanent burrows in the marsh surface. They have been found to not only oxygenate marsh soils (Howes et al 1981) and modify sediment meiofaunal abundance, they could also provide a suitable environment for continued burrowing and, as a byproduct, increase the marsh grass production and maintain the tall-form S. alterniflora. Uca pugnax, the mud fiddler crab, is the dominant form of crab seen in Brownsville, VA. Their burrows are primarily restricted to areas of tall-form S. alterniflora, due