160-14 Ponds, Pines, and People: 6500-Year Record of a Wetland Floral Community from Poisonwood Blue Hole, New Providence, The Bahamas

Abstract:

The Bahamas is projected to experience significant effects of contemporary climate change, such as sea level rise and increased hurricane intensity. There is no precedent to how local terrestrial environments will respond to these predicted climatic shifts, as many Bahamian islands have few, if any, pre-human terrestrial fossil records. Data preceding human influence is important for determining an ecological baseline which can be used to understand how communities shift in response to both natural and anthropogenic factors. Pollen records are direct proxies of plant community shifts throughout time and indirect proxies of local environmental conditions. To determine how Bahamian floral communities have shifted due to environmental flux and anthropogenic stress, we analyzed the pollen record of Poisonwood Blue Hole (PWBH) located on New Providence Island, The Bahamas; creating the first palynological record from this island.

Within the PWBH pollen record, there are four distinct zones defined by differing floral diversity and abundance. The bottom-most zone, beginning ~6500 yBP, is defined by an abundance of the wetland fern Acrostichum aureum and accompanied by hardwood tree species like Swietenia mahagoni and Picrodendron baccatum, suggesting the presence of a wet hardwood coppice. The next zone is defined by the appearance of the freshwater species Sagittaria lancifolia, indicating a permanent flooding of the area by freshwater. The following interval is defined by a shift to overwhelming dominance of Pinus sp., a well-known signal of initial Lucayan colonization and agricultural burnings. The last zone, defined by the loss of all hardwood species and increase in disturbance species, is representative of European colonization and land clearing. Utilizing this pollen data in conjunction with other proxy records (XRF, LOI, etc.) we are able to define an ecological baseline for New Providence Island, determine the tolerance of the plant community to environmental and anthropogenic stress, and make informed suggestions on potential local conservation efforts.

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