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Long-range atmospheric dust transport affects the climate by impacting radiative transfer, cloud formation and the global carbon cycle. Furthermore, dust plays an important role in pedogenesis, whereas Fe-rich dust in particular influences the primary productivity of the ocean. Transport of Saharan dust via the westerlies to the Caribbean is well recorded, even under present conditions, however, its variability over Quaternary glacial-interglacial cycles is less well understood. Here, we present initial investigations into the speleothem record of long-range Saharan dust transport to the Bahamas. A stalagmite collected from -25.6 m below sea level from Abaco Island, Bahamas, macroscopically displays a tripartite structure beginning and ending with opaque crystalline calcite, but with a middle section containing striking insoluble Fe-rich layers several mm thick that alternate with finer opaque layers. The red layers are interpreted to be formed under vadose conditions and not due to precipitation of an Fe-rich crust in an unsaturated mixing zone. U-Th dating reveals that the opaque calcite sections were deposited during Marine Isotope Stage (MIS) 10 and late MIS 8, with the intervening Fe-rich section being deposited during early MIS 8. Dripstone speleothem deposition during MIS 10 and 8 therefore places an upper constraint on relative sea-level elevation of -25.6 m during those glacial periods, with the interglacial MIS 9 hiatus considered to be sea-level controlled. The Fe-rich section indicates atmospheric dust transport to Abaco Island increased during early MIS 8 synchronous with an episode of cooler sea surface temperatures in the sub-tropical Atlantic. On the other hand, the decline in dust transport during late MIS 8 is associated with higher sea surface temperatures.

Remipedia is a stygobitic group commonly associated with coastal anchialine caves. This class consists of 12 genera, ten of which are found within the Lucayan Archipelago. Herein, we describe a new species within the genus Godzillius from Conch Sound Blue Hole, North Andros Island, Bahamas. Godzillius louriei sp. nov. is the third known remipede observed from a subseafloor marine cave, and the first from the Godzilliidae. Remipedes dwell within notoriously difficult to access cave habitats and thus integrative and comprehensive systematic studies at family or genus level are often absent in the literature. In this study, all species of Godzillius are compared using morphological and molecular approaches. Specifically, the feeding appendages of G. louriei sp. nov., G. fuchsi Gonzalez, Singpiel & Schlagner, 2013 and G. robustus Schram, Yager & Emerson, 1986 were examined using scanning electron microscopy (SEM). Species of Godzillius are identified based on the spines of maxilla 1 segment 4 and by the denticles on the lacinia mobilis of the left mandible. A molecular phylogeny using the mitochondrial 16S rRNA and nuclear histone 3 genes recovered G. louriei sp. nov. within the Godzillius clade and 16S genetic distances revealed a 13–15% difference between species of Godzillius.

Northern Hemisphere tropical paleoclimate records support significant changes associated with Dansgaard Oeschger (D/O) events and Heinrich stadials 1 to 6 during the last 64,000 years. However, few absolutely dated terrestrial records from the western Atlantic span the last six Heinrich stadials. Here we present geochemical results from three new stalagmites collected from a cave in the Bahamas which encompass Heinrich stadials 1 to 6. We build on a previous study of the δ 13 C and δ 18 O values of the calcite and δ 18 O value of fluid inclusions from a single stalagmite from the same cave spanning the last three Heinrich stadials. Absolute geochronometry using U-Th equilibrium series demonstrates that the stalagmites formed between 63.8 and 13.8 kyr BP. The δ 13 C and δ 18 O values of the calcite show higher values associated with Heinrich stadials 1–6, and lower values during the D/O interstadial events. The Sr/Ca ratios of the calcite are shown to be relatively invariant, while in two of the samples the Mg/Ca ratios track the δ 13 C values. Increases in the δ 18 O values across Heinrich stadials 1–6 are interpreted as being driven by lower temperatures. The two deeper occurring stalagmites demonstrate increased Mg/Ca ratios and δ 13 C values during Heinrich stadials 1 and 2 which are interpreted as a signal of reduced flow rates in the epikarst and increased water/rock interactions as a result of increased aridity which potentially occurred across all six Heinrich stadials. The observed reductions in mean annual temperature and amount of precipitation across Heinrich stadials are proposed to be driven by a reduction in sea surface temperatures in the North Atlantic and an expanded Bermuda High. During D/O interstadials, the Bahamas cave records likely indicate warmer and/or wetter climate; however the isotopic shifts are not as significant as the isotopic excursions associated with Heinrich stadials.

We report extremely low-light-adapted anoxygenic photosynthesis in a thick microbial mat in Magical Blue Hole, Abaco Island, The Bahamas. Sulfur cycling was reduced by iron oxides and organic carbon limitation. The mat grows below the halocline/oxycline at 30 m depth on the walls of the flooded sinkhole. In situ irradiance at the mat surface on a sunny December day was between 0.021 and 0.084 mu mol photons m(-2) s(-1), and UV light (97% sequence identity) of clones affiliated with Prosthecochloris, a genus within the green sulfur bacteria (GSB), which are obligate anoxygenic phototrophs. Typical photopigments of brown-colored GSB, bacteriochlorophyll e and (beta-)isorenieratene, were abundant in mat samples and their absorption properties are well-adapted to harvest light in the available green and possibly even UV-A spectra. Sulfide from the water column (3-6 mu mol L-1) was the main source of sulfide to the mat as sulfate reduction rates in the mats were very low (undetectable-99.2 nmol cm(-3) d(-1)). The anoxic water column was oligotrophic and low in dissolved organic carbon (175-228 mu mol L-1). High concentrations of pyrite (FeS2; 1-47 mu mol cm(-3)) together with low microbial process rates (sulfate reduction, CO2 fixation) indicate that the mats function as net sulfide sinks mainly by abiotic processes. We suggest that abundant Fe(III) (4.3-22.21 mu mol cm(-3)) is the major source of oxidizing power in the mat, and that abiotic Fe-S-reactions play the main role in pyrite formation. Limitation of sulfate reduction by low organic carbon availability along with the presence of abundant sulfide-scavenging iron oxides considerably slowed down sulfur cycling in these mats.

Deciphering how the climate system has controlled North Atlantic tropical cyclone activity through the Holocene will require a larger observational network of prehistoric hurricane activity. Problematically, the tropical North Atlantic is dominated by carbonate landscapes that typically preserve poorer quality coastal sediment records in comparison to their temperate-region counterparts (e.g., sedimentation continuity and rate). Coastal karst basins (CKBs), such as sinkholes, blueholes, and underwater caves, are widely distributed on carbonate platforms and contain overlooked sedimentary records. Here we present a millennium of hurricane deposits on the Little Bahama Bank archived in a 165 cm core that was extracted from 69 m below sea level in a bluehole on Great Abaco Island, The Bahamas. The coarse-grained overwash deposits associated with both hurricanes Jeanne (2004) and Floyd (1999) were identified using radioisotopes (137Cs, 14C, 210Pb), and indicate that the bluehole is sensitive to hurricane-induced sedimentation. Over the last millennium, the Little Bahama Bank experienced heightened hurricane activity from 1350 to 1650 AD. The simplest explanation for this active interval is that favorable climate conditions (El Nino, West African Monsoon, and sea surface temperatures) encouraged North Atlantic hurricane activity at that time. However, asynchronous hurricane activity at similar latitudes in the North Atlantic and Gulf of Mexico suggest that regional oceanography has modulated or amplified regional hurricane activity over the last millennium.

Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval.

We report 95 vertebrate taxa (13 fishes, 11 reptiles, 63 birds, 8 mammals) from late Pleistocene bone deposits in Sawmill Sink, Abaco, The Bahamas. The >5,000 fossils were recovered by scuba divers on ledges at depths of 27-35 m below sea level. Of the 95 species, 39 (41%) no longer occur on Abaco (4 reptiles, 31 birds, 4 mammals). We estimate that 17 of the 39 losses (all of them birds) are linked to changes during the Pleistocene-Holocene Transition (PHT) (∼ 15-9 ka) in climate (becoming more warm and moist), habitat (expansion of broadleaf forest at the expense of pine woodland), sea level (rising from -80 m to nearly modern levels), and island area (receding from ∼ 17,000 km(2) to 1,214 km(2)). The remaining 22 losses likely are related to the presence of humans on Abaco for the past 1,000 y. Thus, the late Holocene arrival of people probably depleted more populations than the dramatic physical and biological changes associated with the PHT.

Inland blue holes of the Bahamas are anchialine ecosystems with distinct fresh and salt water layers, and anoxic or microoxic conditions at depth. Scientific cave diving and geomicrobiology exploration of blue holes are providing a first glimpse of the geochemistry and microbial life in these vertically stratified karst features. We hypothesized that two geographically adjacent, sunlit blue holes on Abaco Island would have comparable biogeochemistry and microbial life. Water samples were analyzed using in situ multiparameter dataloggers and field and laboratory tests, and diver-retrieved microbial samples were analyzed using nucleic acid analysis. Microbial 16S rRNA genes were dominated by members of the anoxygenic phototroph clade Chlorobi, with smaller numbers of Deltaproteobacteria, in both blue holes. However, spatial distributions of microbial biomass and species present within these major clades were significantly different. We also found that differences in the intensity of solar insolation, terrestrial and marine inputs, water residence time, depth to the halo/chemocline, and cave passage geometry strongly influence geochemical changes with depth. The biogeochemical diversity of inland blue holes in the Bahamas make them valuable as natural laboratories, repositories of microbial diversity, and analogs for stratified and sulfidic oceans present early in Earth’s history.

Temperature reconstructions across Heinrich stadials 1–3 are presented from an absolute-dated speleothem from Abaco Island in the Bahamas to understand the nature of climate change across these intervals in the subtropical Atlantic. The stalagmite carbonate record, dated by the U–Th geochronometry technique, includes higher δ18O and δ13C values within Heinrich stadials 1, 2, and 3 followed by rapid declines at the end of the stadials. To aid in the interpretation of these results, the δ18O of fluid inclusions associated with the Heinrich stadials were also analyzed. These measurements, which allowed for the relative influence of temperature and δ18O of precipitation to be distinguished, demonstrate minimal changes in the δ18O of fluid inclusions, suggesting that changes in the δ18O values of the speleothem carbonate associated with Heinrich stadials 1–3 are principally driven by an average ∼ 4 ° C temperature decrease, rather than a change in the δ18O of the rainfall (hence rainfall amount). These findings support previous work in the North Atlantic and are consistent with the climate response to a weakening of the Atlantic meridional overturning circulation.

The simultaneous effects of grazing and nutrient enrichment on macroalgal communities were experimentally investigated using plastic mesh enclosure/exclosure cages along a natural nutrient (DIN, SRP) gradient from the discharge of a tidal mangrove creek on the west side of Norman’s Pond Cay, Exumas Cays, Bahamas. Nutrient enrichment was the only factor affecting total biomass of macroalgae whereas selective herbivory moderated species composition. Biomass ranged from >2 kg dry weight m 2 at the DIN-enriched Waterfall to

We report Quaternary vertebrate and plant fossils from Sawmill Sink, a “blue hole” (a water-filled sinkhole) on Great Abaco Island, The Bahamas. The fossils are well preserved because of deposition in anoxic salt water. Vertebrate fossils from peat on the talus cone are radiocarbon-dated from ≈4,200 to 1,000 cal BP (Late Holocene). The peat produced skeletons of two extinct species (tortoiseChelonoidisundescribed sp. and CaracaraCaracara creightoni) and two extant species no longer in The Bahamas (Cuban crocodile,Crocodylus rhombifer; and Cooper's or Gundlach's Hawk,Accipiter cooperiiorAccipiter gundlachii). A different, inorganic bone deposit on a limestone ledge in Sawmill Sink is a Late Pleistocene owl roost that features lizards (one species), snakes (three species), birds (25 species), and bats (four species). The owl roost fauna includesRallusundescribed sp. (extinct; the first Bahamian flightless rail) and four other locally extinct species of birds (Cooper's/Gundlach's Hawk,A. cooperii/gundlachii; flickerColaptessp.; Cave Swallow,Petrochelidon fulva; and Eastern Meadowlark,Sturnella magna) and mammals (Bahamian hutia,Geocapromys ingrahami; and a bat,Myotissp.). The exquisitely preserved fossils from Sawmill Sink suggest a grassy pineland as the dominant plant community on Abaco in the Late Pleistocene, with a heavier component of coppice (tropical dry evergreen forest) in the Late Holocene. Important in its own right, this information also will help biologists and government planners to develop conservation programs in The Bahamas that consider long-term ecological and cultural processes.

Blues Holes in the Bahamas are solution collapse features which formed in the Bahamas during the repeated sea-level changes which have occurred over the past 2 million years. Not only were these Blue Holes repositories of well preserved organisms which found their ways into their anoxic waters and therefore have been very well preserved, but the sediments also record a legacy of anthropogenic activities in the area during the Pleistocene. Perhaps the most intriguing aspects of the Blue Holes are the multiple generations of stalagmites which record variations in sea-level, temperature, and precipitation during the numerous sea-level low stands. During these periods the caves were located within the vadose zone and freshwater leached the overlying carbonate. As the waters trickled into the caves