## 5 Conclusions  
This study investigated the recent sedimentation and carbon sequestration of four distinct mangrove hydrogeomorphic settings in two Southwest Florida tidal creeks. We found the following: sedimentation rates, calculated with the \({}^{210}\)Pb constant rate of supply (CRS) method were lowest in the dwarf mangroves (1.41 mm\(\cdot\) year\({}^{-1}\)) and basin mangroves (1.68-1.58 mm\(\cdot\) year\({}^{-1}\)), and substantially higher in fringe mangroves (2.28-2.23 mm\(\cdot\) year\({}^{-1}\)) and in riverine mangroves (3.04-5.43 mm\(\cdot\) year\({}^{-1}\)). The \({}^{210}\)Pb CRS method proved to be more effective than the \({}^{137}\)Cs method for estimating sedimentation rates as a result of mobility of \({}^{137}\)Cs in marine environments. Our study supports the conclusions of others that mangrove wetlands sequester a disproportionately high amount of carbon per unit area compared to other marine ecosystems and more frequently studied northern boreal peatlands. The mean carbon sequestration rate of our study sites (98 g-C m\({}^{-2}\cdot\) year\({}^{-1}\)) is lower than published global averages (174 g-C m\({}^{-2}\cdot\) year\({}^{-1}\)) for mangroves, but is consistent with carbon sequestration rates from other South Florida mangrove wetlands. Rates of carbon sequestration were highest in the riverine mangroves, followed by fringe mangroves, and lowest in the basin mangroves, validating the research of others that differences in hydrology and autochthonous production _versus_ allochthonous input can have profound effects on carbon sequestration in tidal mangrove wetlands. Rates of recent carbon sequestration in mangroves were significantly higher in the reference tidal creek (113 g-C m\({}^{-2}\cdot\) year\({}^{-1}\)) than in the hydrologically disturbed tidal creek (83 g-C m\({}^{-2}\cdot\) year\({}^{-1}\)), suggesting that hydrologic and landscape changes in the upstream watershed can negatively affect carbon sequestration. Only one to two of the seven sampling sites that we investigated may be sustainable with current rates of sea-level rise for this region of Southwest Florida, let alone with any accelerated sea level rise that could occur in the future. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Location** & **Hydrogeomorphic** & **Sequestation Rate** & **References** \\  & **Environment** & **(g-C m\({}^{-2}\cdot\) year\({}^{-1}\))** & **References** \\ \hline  & Riverine & 162 & \\ Susan’s Creek (reference tidal creek) & Fringe & 127 & \\  & Basin & 50 & \\  & Dwarf & 21 & \\ \hline  & Riverine & 125 & \\ Hamilton Avenue Creek (disturbed tidal creek) & Fringe & 73 & This study \\  & Basin & \(\Delta\)F & \\ \hline Global Average & & 174 \(\pm\) 23 & [9] \\ \hline Global Average & & 163 & [11] \\ \hline Global Average & & 226 \(\pm\) 39 & [15] \\ \hline Everglades, Southeast Florida & & 123 \(\pm\) 19 & [58] \\ \hline Rookery Bay, Southwest Florida & Fringe & 69 & [24] \\ \hline Rookery Bay, Southwest Florida & Fringe & 99 & [24] \\ \hline Henderson Creek, Southwest Florida & & 20 & Cahoon and Lynch unpublished \\ \hline Henderson Creek, Southwest Florida & & 39 & Cahoon and Lynch unpublished \\ \hline Florida Keys & & 209 & [57] \\ \hline Florida Keys & & 67 & [57] \\ \hline Shark River, Southeast Florida & & 151 & [58] \\ \hline Terminos Lagoon, Mexico & Riverine & 137 & [24] \\ \hline Tamandare,Brazil & & 949 & [62] \\ \hline Tat, Thailand & Riverine & 600 & [63] \\ \hline Hinchbrook Channel, Australia & & 26 & [63] \\ \hline Hinchbrook Channel, Australia & & 336 & [63] \\ \hline Irian Jaya, Indonesia & & 412 & [63] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of mangrove carbon sequestration rates in this study with other published local, regional, and global rates of carbon sequestration in mangrove wetlands.