Date of Award



© 2013 Matt Simon

Document Type


Degree Name

Master of Science in Biological Sciences


Biological Science

First Advisor

Steven Travis

Second Advisor

Gregory Zogg

Third Advisor

Pamela Morgan


Coastal salt marshes are under stress from anthropogenic climate change-induced sea level rise (SLR). Sediment microbial decomposition is a major driver of marsh subsidence and any impact of SLR on this biotic process would have a direct effect on marsh surface elevation relative to sea level. Furthermore, sensitivity to SLR of microbial community composition may play a role in the functional response. I collected sediment from six coastal marshes on the United States Atlantic East coast, exposed it to simulated sea level rise and measured total respired carbon over a three week period. My results indicated that SLR caused a decrease in microbial decomposition but that this functional response varied among sites and between elevations within sites (Chapter 1 of this thesis). Although differences in decomposition rates among sites were related to organic matter content, differential functional responses to sea-level rise among sites and elevations could not be explained by organic matter, nor a suite of environmental variables that have the potential to effect microbial activity (i.e., porewater pH, salinity and redox potential). In order to determine if changes in community composition might explain the functional response that I observed, I conducted a terminal-restriction fragment length polymorphism analysis of 16S rDNA extracted from sediment from the Massachusetts and New Hampshire sites (Chapter 2 of this thesis). I found that microbial community composition varied between the two sites. Furthermore, increased inundation caused a decrease in microbial community compositional shift that corresponded to a decline in decomposition rate. My results suggest that microbial functional response to SLR may be linked to changes in community composition.


Master's thesis