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USING A TEABAG INDEX TO INVESTIGATE DECOMPOSITION IN A SHORT-TERM SALT MARSH MESOCOSM EXPERIMENT
Citation:
Tremper, C., C. Wigand, J. Loffredo, AND J. Bishop. USING A TEABAG INDEX TO INVESTIGATE DECOMPOSITION IN A SHORT-TERM SALT MARSH MESOCOSM EXPERIMENT. New England Estuarine Research Society, Virtual, RI, October 15 - 22, 2020.
Impact/Purpose:
Salt marsh restoration is important to maintain and build coastal resiliency to sea level rise and the increase in frequency and severity of flooding in New England. In this salt marsh experiment clean dredge material was used to increase elevation of the marsh platform in greenhouse mesocosms. An increase in the salt marsh elevation by applying dredge material will provide increased resistance to sea level rise and flooding. In this study we report on the use of green and rooibos tea bags as indicators of salt marsh litter decomposition. We compare the decomposition rates of control and dredge-added mesocosms set at low and high marsh flooding regimes. The decomposition rates of the dredge-added mesocosms and at the high marsh flooding regime had significantly greater decomposition rates compared to the salt marsh controls. Increased decomposition rates could affect the service of carbon storage in the marsh. Since this was a short term experiment, in the future, we plan to look at tea bag decomposition trends over longer time periods in a number of existing salt marsh restoration sites in New England.
Description:
A Teabag Index (TBI) was used to determine decomposition rates in dredge soils and marsh peat in a mesocosm salt marsh restoration experiment. Burying bags containing materials (green and rooibos tea) with differing decomposability in close proximity allows calculation of a decomposition rate. Sets of green and rooibos tea bags were placed in three treatments (control, +5 cm added dredge soils, +10 cm added dredge soils) in high and low marsh mesocosms (4 replicates for each treatment) for approximately 3 months. We found that the control mesocosms with natural salt marsh peat had significantly lower decomposition rates than those with added dredge material. There was a trend, albeit not significant, of greater decomposition rates in the high marsh than the low marsh treatments. We hypothesized that dredge material promoted greater decomposition rates because it was less compacted and more aerobic. Further experiments using the TBI in restored marshes that have been underway for a number of years in the field will be beneficial in determining the pattern of changing decomposition rates over time.
