Monsters in the dark: Systematics and biogeography of the stygobitic genus godzillius (crustacea: Remipedia) from the lucayan archipelago

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

Dripwater and Calcite Geochemistry Variations in a Monitored Bahamas Cave

A cave‐monitoring study in Hatchet Bay Cave on the island of Eleuthera, Bahamas, has examined the origins of variations in oxygen and carbon isotopic and minor element composition in cave calcites. Every 3 to 8 months, between 2012 and 2016, temperature, humidity, cave air (δ13CCO2), dripwaters (δ18O and δ2H values, and Ca, Sr, and Mg concentrations), and the chemical composition of precipitating calcite (δ18O and δ13C values, and Ca, Sr, and Mg concentrations) were analyzed in two rooms in the cave. Results from the elemental analyses show that throughout the cave prior calcite precipitation was a driver of the elemental chemistry of the precipitated calcites. In addition, cave calcites show that δ13C and δ18O values were positively correlated with Mg/Ca ratios. The Mg/Ca ratios were also positively correlated with lower calcite precipitation rates. Therefore, water/rock interactions may also influence δ13C and δ18O values and Mg/Ca ratios of the calcite. Differences were observed between the two rooms, with the Main Room of the cave exhibiting increased prior calcite precipitation, more ventilation, lower calcite precipitation rates, and δ18O values, which were farther from equilibrium when compared to the more isolated portion of the cave. These results also validated previous interpretations from Pleistocene stalagmites collected from a nearby Bahamian cave suggesting that a positive covariation between Mg/Ca and δ13C values reflects water/rock interactions. Key Points A cave monitoring study was carried out for ~4 years in Hatchet Bay Cave Eleuthera, Bahamas The cave is well ventilated, and prior calcite precipitation and water/rock interactions are drivers of the elemental chemistry Differences in ventilation of the cave demonstrate that certain locations precipitate closer to δ18O equilibrium than other

Multi-proxy evidence of millennial climate variability from multiple Bahamian speleothems

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 δ13C and δ18O values of the calcite and δ18O 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 δ13C and δ18O 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 δ13C values. Increases in the δ18O 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 δ13C 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. •Three new stalagmites from the Bahamas were analyzed.•Geochemistry shows variations on millennial scale.•Heinrich stadials reflect decreased temperature and increased aridity.•Good agreement is observed with records from the western Atlantic

Multi-proxy evidence of millennial climate variability from four Bahamian stalagmites

Northern Hemisphere tropical paleoclimate records support significant hydrologic and climatic changes associated with Dansgaard Oeschger (D/O) events and Heinrich stadials 1 to 6. However, few absolutely dated terrestrial records from the western Atlantic span the last six Heinrich stadials. Here we present geochemical results from four stalagmites collected from a cave in the Bahamas which encompass Heinrich stadials 1 to 6. Absolute geochronometry using U-Th equilibrium series demonstrated that the stalagmites formed between 63.8 to 13.8 kyr before present. The delta (super 13) C and delta (super 18) O values of the calcite showed higher values associated with Heinrich stadials 1-6 and lower values during the D/O interstadial events. The delta (super 18) O value of fluid inclusions from one stalagmite demonstrated minimal variation in the formation water delta (super 18) O value during Heinrich stadials 1 to 3. The Sr/Ca ratios of the calcite are shown to be relatively invariant, while in two of the samples the Mg/Ca ratios tracked the delta (super 13) C values. Increased calcite delta (super 18) O values across Heinrich stadials 1-6 are interpreted as being driven by lower temperatures, as supported by the fluid inclusion results. The two deeper occurring stalagmites demonstrate increased Mg/Ca ratios and delta (super 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

Temporal Variability of Precipitation and Temperature across Heinrich Events from Bahamian Stalagmites

During the last glacial period there is substantial evidence for global variability in climate dominated by Heinrich and Dansgaard-Oeschger events. Heinrich events have been shown to correlate with rapid climate change such as cooling in the North Atlantic, precipitation decrease in Africa and Asia and warming in Antarctica. While a comprehensive picture of climate patterns is emerging, the climate in the topical Atlantic is still not as well understood. In this study, a stalagmite from the Bahamas has been analyzed for carbon and oxygen isotopes and fluid inclusion isotopic analysis across Heinrich events 1-3. The combination of both methodologies allows for the determination of the temporal drip water isotopic variability and in addition the temperature at the time of formation. The stalagmites were dated using U/Th and analyzed for stable carbon and oxygen isotopes at a resolution of 20 μm (approximately one sample every 2 years). Fluid inclusion analyses were conducted at a resolution of about 1.5 cm. Fluid inclusion analysis is the analysis of microscopic, water filled cavities within the stalagmite. These cavities preserve drip water at the time of formation and allow for the measurement of the δ18O composition of the formation water. In the subtropics, it has been demonstrated that higher volume rainfall events generally leads to a depleted δ18O and δ13C signal, whereas heavier δ18O and δ13C values are attributed to lower amounts of rainfall. The fluid inclusion data help constrain the origin of the large changes in the oxygen isotopic composition of the speleothem itself across the Heinrich events, which averages about 4 ‰ for C and 2 ‰ for O for Heinrich events 1-3. These results may support a rapid shift from an arid and colder to a much wetter and warmer climate in the Bahamas associated with Heinrich events

Vertebrate Community on an Ice-Age Caribbean Island

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 \u3e5,000 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 pinewoodland), sea level (rising from -80 m to nearly modern levels), and island area (receding from ∼17,000 km2 to 1,214 km2). 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

Low-Light Anoxygenic Photosynthesis and Fe-S-Biogeochemistry in a Microbial Mat

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

Monsters in the dark: Systematics and biogeography of the stygobitic genus godzillius (crustacea: Remipedia) from the lucayan archipelago

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

Monsters in the dark: systematics and biogeography of the stygobitic genus Godzillius (Crustacea: Remipedia) from the Lucayan Archipelago

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

Data_Sheet_1_Low-Light Anoxygenic Photosynthesis and Fe-S-Biogeochemistry in a Microbial Mat.DOCX

<p>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 μmol photons m^-2 s^-1, and UV light (<400 nm) was the most abundant part of the spectrum followed by green wavelengths (475–530 nm). We measured a light-dependent carbon uptake rate of 14.5 nmol C cm^-2 d^-1. A 16S rRNA clone library of the green surface mat layer was dominated (74%) by a cluster (>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 (β-)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 μmol 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 μmol L^-1). High concentrations of pyrite (FeS₂; 1–47 μmol 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) (4.3–22.2 μmol 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.</p