A 6500-Yr Paleoenvironmental Reconstruction of No Man’s Land Sink, Abaco Island, A Large Inland Lake in the Northern Bahamas

No Man’s Land Sink is one of the largest inland lakes on the Little Bahama Bank in the northern Bahamas, so its paleoenvironmental history may provide insight into how the regional hydroclimate and groundwater systems developed over the Holocene. In its modern state, the site is shallow, brackish (20.6 psu), 170 m in diameter, and located ~700 m from the coastline. Prior to 6400 Cal yrs BP, the accumulation of peat deposits and no aquatic invertebrates (e.g., ostracodes, foraminifera, aquatic mollusks) indicate that the site was a terrestrial ecosystem. However, the site transitioned into a subaqueous freshwater environment at 6400 Cal yrs BP, when the site became palustrine-lacustrine environment until 4200 Cal yrs BP. During this time, widespread palustrine-lacustrine carbonate deposition and the appearance of freshwater to low mesohaline microfossils indicates a likely oligohaline environment in the sinkhole (charophytes, ostracodes: Candona annae, Cypridopsis vidua, foraminifera: Helenina davescottensis, mollusks: Planorbis, Hydrobia). A salinity increase at 4200 Cal yrs BP is inferred from the appearance of the ostracode Cyprideis americana that typically prefers salinities exceeding 10 psu, and deposition of laminated microbial mats. Thereafter, an organic-rich, algal sapropel unit (56.9% bulk organic matter) accumulated that was devoid of any microfossils or mollusks. This unit suggests that the lake hosted a stratified water column, where surface waters supported phytoplankton primary productivity and corrosive or anoxic bottom water conditions hampered microfossil growth or precluded their preservation. The transition to the modern environment (~20 psu) at 2600 cal yrs BP is characterized by diversification of brackish ostracodes (Aurila floridana, Dolerocypria inopinata, and Hemicyprideis setipunctata), foraminifera (Elphidium spp., Ammonia beccarii, Triloculina oblonga) and mollusks (Anomalocardia, Cerithidea). Over the middle to late Holocene, No Man’s Land has experienced abrupt salinity increases that are most likely driven by southern migration of the Intertropical Convergence Zone, hurricane-induced mixing and salinization of the topmost section of the coastal aquifer, and shoreline migration and groundwater-level rise in response to Holocene sea-level rise

Drought in the Northern Bahamas from 3300 to 2500 Years Ago

Intensification and western displacement of the North Atlantic Subtropical High (NASH) is projected for this century, which can decrease Caribbean and southeastern American rainfall on seasonal and annual timescales. However, additional hydroclimate records are needed from the northern Caribbean to understand the long-term behavior of the NASH, and better forecast its future behavior. Here we present a multi-proxy sinkhole lake reconstruction from a carbonate island that is proximal to the NASH (Abaco Island, The Bahamas). The reconstruction indicates the northern Bahamas experienced a drought from ∼3300 to ∼2500 Cal yrs BP, which coincides with evidence from other hydroclimate and oceanographic records (e.g., Africa, Caribbean, and South America) for a synchronous southern displacement of the Intertropical Convergence Zoneand North Atlantic Hadley Cell. The specific cause of the hydroclimate change in the northeastern Caribbean region from ∼3300 to 2500 Cal yrs BP was probably coeval southern or western displacement of the NASH, which would have increased northeastern Caribbean exposure to subsiding air from higher altitudes

Culture-negative infections in orthopedic surgery

During the recent transition between acute diseases caused by swarms of single planktonic bacteria, and chronic infections caused by bacteria growing in slime-enclosed biofilms, a general clinical consensus has emerged that pathologies with bacterial etiologies are frequently culture negative. Because biofilm infections now affect 17 million Americans per year (killing approximately 450,000), the suggestion that these common and lethal infections regularly go unnoticed by the only FDA-approved method for their detection and characterization is a matter of urgent concern. Biologically, we would expect that planktonic bacterial cells would colonize any new surface, including the surface of an agar plate, while the specialized sessile cells of a biofilm community would have no such proclivity. In the study of biofilm diseases ranging from otitis media to prostatitis, it was found that direct microscopy and DNA- and RNA-based molecular methods regularly document the presence of living bacteria in tissues and samples that are culture negative. The editors selected orthopedic biofilm infections as the subject of this book because these infections occur against a background of microbiological sterility in which modern molecular methods would be expected to find bacterial DNA, RNA-based microscopic methods would be expected to locate bacterial cells, and cultures would be negative. Moreover, in Orthopedics we find an already biofilm-adapted surgical group in which current strategies are based on the meticulous removal of compromised tissues, antibiotic options as based on high biofilm-killing local doses, and there are practical bedside strategies for dealing with biofilm infections. So here is where the new paradigm of biofilm infection meets the equally new paradigm of the culture negativity of biofilms, and this volume presents a conceptual synthesis that may soon combine the most effective molecular methods for the detection and identification of bacteria with a surgical discipline that is ready to help patient