Rudnick et al. Observations

• During our time series of benthic flux measurements at several sites in the bay and ponds, we have encountered mass mortality of SAV at two sites - Little Madeira Bay (LMAD) and Taylor Pond 1 (TP). 
• LMAD was dominated by Thalassia, while TP was dominated by Ruppia and Chara.
•  Aboveground biomass peaked at about 70 g dry wt. /m2 at our LMAD site in May 99 (we have quarterly measurements, at best), while it peaked at about 90 g DW/m2 in TP. 
• LMAD mortality occurred prior to Oct. 99, when it was 0 g/m2 (mortality occurred around Aug-Sept, based on communication with Lee Hefty), while SAV dropped in Pond 1 to about 20 g/m2 in 5/98 and was <1 g/m2 by 9/98.

The hypothesis of die-off being a nutrient source to the water column, either long-term or short-term, can be assessed from these data.  At both sites,  a relatively high pulse of NH4 out of the sediment was observed (LMAD in Oct. 99 and Pond 1 in May 98).  At LMAD,  a pulse of total phosphorus in Oct. 99 was also observed.  However, there is no evidence of a long-term increase in nutrient release after this pulse.  For Pond 1, there are results from 5 measurements after 5/98, so this conclusion is fairly sound.  For LMAD, it's too soon to tell, because there are only results from one incubation after Oct. 99.  This incubation showed fluxes with typical rates for N and P.  Based on this limited evidence,  Rudnick et al.  infers that the hypothesis that algal blooms were stimulated by a sedimentary release of nutrients that was directly derived from seagrass die-off is not likely to be true.