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Although shell middens and mounds often occupy the same intertidal spaces as coastal wetlands, biophysical interactions between these cultural features and wetlands are under-investigated. To this end, our geoarchaeological and zooarchaeological research at three coastal archaeological sites within the Tampa Bay Estuary, USA, sought to understand the interactions between shell-bearing sites, sea-level rise, storms, and migrating wetland habitats. Percussion core transects document the accretion of mangrove peat atop intact shell midden, illustrating the ability of mangrove forests to encroach shell midden and preserve cultural material below. Landward wetland deposits are thicker and muddier than those along the seaward margin of the sites, suggesting that shell-bearing sites attenuate wave energy much like other shoreline stabilization structures. Differences in sedimentology, stratigraphy, and invertebrate species compositions highlight the variability in storm impacts between sites. Storm-driven depositional events are identified by medium-to-fine sand beds with high densities of fragmented shell and small intertidal zone snails. Geospatial analyses indicate that wetland encroachment is already occurring at 247 archaeological sites within the Tampa Bay Estuary. Approximately 100 additional archaeological sites currently located in upland habitats may provide topographic relief for migrating coastal wetlands in the future. We contend that shell middens and mounds constructed by Indigenous peoples are important components within estuarine mosaics, as they have been for millennia. We advocate for further collaboration between archaeologists and estuary managers and the inclusion of descendant communities to co-manage the future of their past.
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Reorganizing the Waterscape: Asymmetric Loss of Wetlands and Gain of Artificial Water Features in a Mixed-use Watershed
Abstract Between the 1780 and 1980s, more than half of the wetlands in the conterminous US were lost. As wetlands have been lost, numerous artificial water features (AWFs), such as stormwater retention ponds, golf course water features, and reservoirs, have been constructed. We contrasted the loss of wetland area and perimeter to the gain of AWF area and perimeter and further explored how this transformation has altered the spatial characteristics of the waterscape. We conducted this analysis in the Tampa Bay Watershed, a large coastal watershed that lost 33% of its wetland area between the 1950s-2007. Trends have been towards fewer, smaller wetlands and more, smaller AWFs. The loss of wetland area far exceeds the gain in AWF area, leading to an overall loss of 23% of the combined wetland and AWF area. However, the loss of wetland perimeter almost equals the gain in AWF perimeter, leading to an overall loss of just 2% of the combined wetland and AWF perimeter. The loss of wetlands and gain of AWFs have predominantly occurred in different geographic locations, with the loss of wetlands predominantly in the headwaters and the gain in AWFs predominantly adjacent to Tampa Bay. Wetlands became further apart, though generally retained their natural distribution, while AWFs became closer to one another and now mirror the more natural wetland distribution. Overall, the physical structure of the waterscape of today is different than in the past, which likely reflects a change in functions performed and related ecological services provided at local and landscape scales.
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- PAR ID:
- 10468265
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- Wetlands
- Volume:
- 43
- Issue:
- 7
- ISSN:
- 0277-5212
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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