Tropical North Atlantic sea surface temperatures and low-latitude rainfall covary, but prehistoric subtropical rainfall records are often misaligned. Here, a submarine groundwater discharge record from the northern Bahamas archives regional water balance in the northeastern Atlantic Warm Pool. We compare the reconstruction to the tropical North Atlantic seasonal temperature gradient, which can help inform how northeastern Caribbean rainy seasons are influenced by the Atlantic Warm Pool. A positive water balance in the northern Bahamas aligned with a ~0.9 °C seasonal temperature gradient from 0 to 950 CE, with both covarying on multi-decadal timescales. Aridity began at ~950 CE when a ~2.2 °C seasonal temperature gradient increase likely shortened the wet season. From 1450 to 1850 CE, frequent hurricanes offset aridity in the northeastern Caribbean by elevating rainfall. This record archives time-transgressive changes in hydroclimate forcing, and suggests that projected changes to rainfall seasonality must be considered when assessing tropical water security risk. The balance between precipitation and evaporation in the Caribbean region during the Common Era can be estimated through analyses of sedimentary foraminiferal assemblages that record submarine groundwater discharge.

In Southwest Florida (SWFL) red tide (Karenia brevis) is a natural hazard and produces potent toxins, to both human and marine life, known as brevetoxins. Red tide, a microscopic alga species, is responsible for environmental, economic, and human health problems in this region. However, our understanding of natural and anthropogenic drivers of red tide are still poorly understood. This study endeavors to reconstruct brevtoxins records in marine sediments with the purpose to better understand present day blooms compared to historic red tide blooms in SWFL. This may be best achieved by looking at sediment cores from blue holes along the West Florida shelf. Blue Holes are natural geologic formations originating on land, as sink holes, which filled over time as global sea level rose. Generally, anoxic conditions found in blue holes provide excellent preservation of long geologic records and provide a unique opportunity to study brevetoxin as biomarkers in sediment cores. In 2023, sediment cores were collected from the Amber Jack Blue Hole off the coast of SWFL. The sediment cores were sliced at 1 cm intervals, and solvent extracted for the analysis of brevetoxins using a LC-MS/MS. The sediments were also analyzed for grain size analysis and scanned using x-ray. This study examines the vertical preservation depth of Karenia brevis and analyzes historic red tide events preserved within the Amber Jack blue hole sediments. This research provides the first opportunity to study red tide chemical biomarkers in high resolution blue hole sediment cores.

Islands in active carbonate depositional systems can profoundly impact local wave, wind and tidal energy distributions, affecting sediment factories and facies distributions. Island development and facies were investigated for South Joulter Cay, located within the modern Joulters ooid sandbody of Great Bahama Bank, using high-resolution imagery, a digital elevation model, field observations and radiocarbon dating of weakly cemented rock samples. Island ridge morphology exhibits three distinct developmental stages spanning the last 1400 years, with differences in ooid sand distribution, tidal channels, wind, waves and longshore currents driving island development. Radiocarbon dating suggests that the nucleation and development of South Joulter Cay occurred in stages over the last 1400 years. Island development started with linear ridges oriented SE-NW and extending approximately 2 km, and this was followed by a second stage of arcuate ridges influenced by local tidal channels. The third stage consisted of triangular cuspate ridges driven by longshore currents and bidirectional winds and waves. Storm activity and associated shifts in local hydrodynamics appear to have played an important role in forming the initial ridges and those created during transitions between growth stages. Although a single storm event is unlikely to cause lasting changes, prolonged periods of intense storm activity over decades are more probably to drive the island's changes and development. Periods with elevated hurricane activity in the northern Bahamas during the Medieval Climate Anomaly or Little Ice Age may be a possible control on the punctuated development of South Joulter Cay.

Tropical cyclone (TC) impacts along the western Atlantic and Caribbean margin are not spatially uniform. Proxy based reconstructions of Common Era TC activity highlight this non-uniform distribution at centennial-millennial timescales. However, the sparse geographic scope of these reconstructions impedes our assessment of TC landfalls across broader spatial domains. This work presents a compilation of new and existing TC reconstructions from the Yucatan Peninsula for comparison with a contemporaneous compilation from New England, showing that these regions occupy distal nodes of a low-frequency TC dipole. Increased Yucatan (New England) storminess is closely linked to intervals of Northern Hemisphere warming (cooling) and the expansion (contraction) of the Intertropical Convergence Zone, suggesting that secular shifts in the mean climate state mediate dipole orientation.

Despite increased Atlantic hurricane risk, projected trends in hurricane frequency in the warming climate are still highly uncertain, mainly due to short instrumental record that limits our understanding of hurricane activity and its relationship to climate. Here we extend the record to the last millennium using two independent estimates: a reconstruction from sedimentary paleohurricane records and a statistical model of hurricane activity using sea surface temperatures (SSTs). We find statistically significant agreement between the two estimates and the late 20th century hurricane frequency is within the range seen over the past millennium. Numerical simulations using a hurricane-permitting climate model suggest that hurricane activity was likely driven by endogenous climate variability and linked to anomalous SSTs of warm Atlantic and cold Pacific. Volcanic eruptions can induce peaks in hurricane activity, but such peaks would likely be too weak to be detected in the proxy record due to large endogenous variability.

Sinkholes develop on carbonate landscapes when caves collapse and can subsequently become lake-like environments if they are flooded by local groundwater. Sediment cores retrieved from sinkholes have yielded high-resolution reconstructions of past environmental change, hydroclimate, and hurricane activity. However, our understanding of the internal sedimentary processes of these systems remains incomplete. Here, we use a multiproxy approach including sedimentology (stratigraphy, coarse-grained particle density, bulk organic matter content), micropaleontology (ostracods), and geochemistry (δ13C and δ2H on n-alkanoic acids) to reconstruct evidence for paleolimnology and regional hydroclimate from a continuous stratigraphic record (Emerald Pond sinkhole) in the northern Bahamas that spans the middle to late Holocene. Basal peat at 8.9 m below modern sea level documents the maximum sea-level position at 8200 cal. yr BP. Subsequent upward vertical migration of the local aquifer caused by regional sea-level rise promoted carbonate-marl deposition from 8300 to 1700 cal. yr BP. A shift in coarse particle deposition and ostracods at 5500 cal. yr BP suggests some environmental change, which may be related to one or multiple internal or external drivers. Sapropel deposition from 1700 to 1300 cal. yr BP indicates a fundamental change in limnology to promote increased organic matter preservation, perhaps related to the regional cooling during the Dark Ages Cold Period. We find δ2H28 values are largely invariant from 7700 to 6150 cal. yr BP suggesting a generally stable hydroclimate (mean − 133‰, 1σ = 5‰). The shift to more depleted values (− 156‰, 1σ = 19‰) at 6000–4800 cal. yr BP may be linked to a weakened (eastern displaced) North Atlantic Subtropical High. Nevertheless, additional local hydroclimate records are needed to better disentangle uncertainties from either internal or external influences on the resultant measurements.

Abandoned river channels on alluvial floodplains represent areas where sediments, organic matter, and pollutants preferentially accumulate during overbank flooding. Theoretical models describing sedimentation in floodplain lakes recognize the different stages in their evolution, where the threshold for hydrological connectivity increases in older lakes as a plug-bar develops. Sedimentary archives collected from floodplain lakes are widely used to reconstruct ecological and hydrological dynamics in riverine settings, but how floodplain lake evolution influences flow velocities and sedimentation patterns on an event scale remains poorly understood. Here we combine sediment samples collected in and around a floodplain lake with hydraulic modelling simulations to examine inundation, flow velocity, and sedimentation patterns in a floodplain lake along the Trinity River at Liberty, Texas. We focus our analyses on an extreme flood event associated with the landfall of Hurricane Harvey in August 2017 and develop a series of alternative lake bathymetries to examine the influence of floodplain lake evolution on flow velocity patterns during the flood. We find that sediments deposited in the lake after the Hurricane Harvey flood become thinner and finer with distance from the tie-channel in accordance with simulated flow velocities that drop with distance from the tie-channel. Flow velocity simulations from model runs with alternative plug-bar geometries and lake depths imply that sedimentation patterns will shift as the lake evolves and infills. The integration of sediment sampling and hydraulic model simulations provides a method to understand the processes that govern sedimentation in floodplain lakes during flood events that will improve interpretations of individual events in sedimentary archives from these contexts.

The year 2020 Common Era (CE) experienced the highest number of named tropical cyclones in the Atlantic Ocean since 1850 CE, but the short instrumental record makes it challenging to assess if this level of activity is statistically meaningful. Here, we present two near‐annually resolved hurricane reconstructions from sediment archived in two blue holes located only 300 m apart on the northern margin of Grand Bahama. These two blue holes provide a replicated signal of hurricanes passing within a 50–100 km radius over the last 1,800 years, and the long‐term reconstructions document multiple 50‐to‐150‐year intervals when hurricane frequency was significantly higher than it has been over the last 100 years. These two records were first merged into a single stack, and then compiled with five other high‐resolution reconstructions from across the Bahamian Archipelago to form a single 1500‐year record of Bahamian hurricane frequency. This new Bahamian Compilation documents more hurricanes passing ∼75°W from 21°N to 26°N during the Little Ice Age (LIA; 1300–1850 CE) relative to the prior millennium and the last 170 years. The US Eastern Seaboard also experienced heightened hurricane activity during the LIA, whereas the Gulf of Mexico and Southern Caribbean were inactive. This suggests that despite a globally cooler climate, regional climate conditions during the LIA remained favorable for cyclogenesis and intensification along certain Atlantic hurricane pathways. Perhaps heightened Sahel rainfall during the LIA indicates an increase in African Easterly waves, which in turn possibly seeded more tropical cyclones in the Atlantic Main Development Region.

Submerged caves are potentially rich but relatively untapped sources of paleoenvironmental, paleontological, and archaeological data. The purpose of this study is to undertake a paleohydrological and paleoecological reconstruction of an underwater cave, Cueva Chicharrones, in Matanzas, Cuba. Technical cave divers collected sediment cores from within the cave, which were studied for grain size, seeds, ostracods, and pollen, and were dated by radiocarbon and luminescence methods. The chronology of the sediments and the resulting paleohy-drological reconstruction, based on the interpretation of the sedimentary facies, help to constrain the timing of water level changes in the cave, which appear to be driven by a combination of relative sea level and regional climatic variability. Specifically, the results indicate that the cave was likely dry prior to 7000 cal yr BP, and was flooded by 6500 cal yr BP (a time consistent with humid conditions in much of the northern Caribbean). Then, water levels decreased between 6500 and 2000 cal yr BP, when regional climate was drier, and increased around 1000 cal yr BP, due to a shift to a more humid climate. The seeds found in some of the cores consist of the genera Ficus, Cecropia, and Solanum and may have been deposited by frugivorous bats, although the possibility of transport by storm water cannot be ruled out. The pollen data are consistent with the information derived from the seeds, and indicate that pollen spectra variability was probably driven by changes in water level, environ -mental and climatic conditions, and possibly bat activity. This study is the first of its kind from a submerged cave in Cuba and highlights the potential of underwater caves as archives of regional paleoclimatic and relative sea level data. In addition, given the presence of abundant vertebrate fossils present in the cave, our work will provide important context for the study of these remains and help inform on Caribbean paleoecology and paleontology.

The collapse of the Maya civilization in the late 1st/early 2nd millennium CE has been attributed to multiple internal and external causes including overpopulation, increased warfare, and environmental deterioration. Yet the role hurricanes may have played in the fracturing of Maya socio-political networks, site abandonment, and cultural reconfiguration remains unexplored. Here we present a 2200 yearlong hurricane record developed from sediment recovered from a flooded cenote on the northeastern Yucatan peninsula. The sediment archive contains fine grain autogenic carbonate interspersed with anomalous deposits of coarse carbonate material that we interpret as evidence of local hurricane activity. This interpretation is supported by the correlation between the multi-decadal distribution of recent coarse beds and the temporal distribution of modern regional landfalling storms. In total, this record allows us to reconstruct the variable hurricane conditions impacting the northern lowland Maya during the Late Preclassic, Classic, and Postclassic Periods. Strikingly, persistent above-average hurricane frequency between ~ 700 and 1450 CE encompasses the Maya Terminal Classic Phase, the declines of Chichén Itza, Cobá, and subsequent rise and fall of the Mayapán Confederacy. This suggests that hurricanes may have posed an additional environmental stressor necessary of consideration when examining the Postclassic transformation of northern Maya polities.

Islands across the Bahamian Archipelago have been devastated by five major hurricanes from 2010 to 2020 CE, including Category 5 Hurricane Dorian in 2019 that inundated parts of Abaco and Grand Bahama with up to 4 m of surge, killing 84 people and leaving >245 others missing. Up to 1 m relative sea-level rise is estimated for The Bahamas by 2100 CE, which could enhance flooding from weaker storms (= Category 1 hurricanes passing within 115 km during the 170-year instrumental record (1850 CE-present) and may also document intense tropical or winter storms. Hine's Hole archives similar to 16 intense storms per century from 1850 to 2016 CE, but documents three periods from 1505 to 1530 CE, 1570 to 1620 CE, and similar to 1710 to 1875 CE with over twice as many intense storms per century. These active periods correspond to other high-resolution reconstructions from the Bahamian Archipelago and Florida Keys, but the magnitude of the increase is much higher given that Hine's Hole archives evidence of weaker and more distal storms. As such, this reconstruction provides unprecedented insight into changes in hurricane activity within the pre-industrial climate system and demonstrates that recurrence intervals based on the 170-year instrumental record can severely underestimate the threat hurricanes pose certain localities.

Prokaryotes constitute the majority of sedimentary biomass, where they cycle organic carbon and regulate organic matter transformation. The microbes inhabiting sediment are diverse and the factors controlling microbial community composition are not fully understood. Here, we characterized the prokaryotic community using 16S rRNA gene sequencing in 24 stratigraphic layers within a 89 cm (dated to ~1900 years old) sediment core from an anchialine sinkhole in the Bahamas with a stratified water column and anoxic bottom water. The microbial community was dominated by members of the Alphaproteobacteria, Dehalococcoidia, Gammaproteobacteria, Bathyarchaeota, and Campylobacter classes. Most interestingly, subsurface microbial community structure could be correlated to previous evidence for timewise changes in the main source of organic matter that was supplied to the sediment accumulating during the last 2000 years, which itself was caused by regional terrestrial vegetation changes. The C:N ratio was correlated to the relative abundance of the microbial classes, and the microbial communities followed three previously determined time periods based on the source of organic matter, which suggests that the carbon source at time of deposition influences the resultant subsurface microbial community composition. These results show that carbon source is a driver of the microbial community composition inhabiting anoxic sediment, which could have implications for improving understanding of carbon cycling in coastal sedimentary basins.

Obituary| July 20, 2022 Obituary for David B. Scott, B.S., M.S., Ph.D., 1947‐2021 Peter J. van Hengstum Peter J. van Hengstum Department of Marine and Coastal, Environmental Science, Texas A&M University at Galveston, 200 Seawolf Parkway, Bldg. 3029, OCSB 383, Galveston, TX 77553, E-mail: vanhenp@tamug.edu Search for other works by this author on: GSW Google Scholar Author and Article Information Peter J. van Hengstum Department of Marine and Coastal, Environmental Science, Texas A&M University at Galveston, 200 Seawolf Parkway, Bldg. 3029, OCSB 383, Galveston, TX 77553, E-mail: vanhenp@tamug.edu Publisher: Cushman Foundation for Foraminiferal Research First Online: 20 Jul 2022 Online ISSN: 1943-264X Print ISSN: 0096-1191 Journal of Foraminiferal Research (2022) 52 (3): 189–192. https://doi.org/10.2113/gsjfr.52.3.189 Article history First Online: 20 Jul 2022 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Peter J. van Hengstum; Obituary for David B. Scott, B.S., M.S., Ph.D., 1947‐2021. Journal of Foraminiferal Research 2022;; 52 (3): 189–192. doi: https://doi.org/10.2113/gsjfr.52.3.189 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search View largeDownload slideDAVID B. SCOTT, B.S., M.S., PH.D. 1947-2021View largeDownload slideDAVID B. SCOTT, B.S., M.S., PH.D. 1947-2021 On 21 December 2021, Professor David B. Scott passed away in the province of Nova Scotia in Canada at the age of 74 with his cherished wife, Kumiko, by his side. He is first remembered as a fantastic father and husband who enjoyed fishing, canoeing, and international travel with his family. Outside of the formalities of academia, Dave also enjoyed visiting local elementary schools to talk about dinosaurs or take young students on trips to Nova Scotia's fossiliferous... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The environmental conditions and habitats in Bermudian underwater caves have responded to vertical aquifer migration and groundwater salinity changes associated with sea-level rise since the last glacial maximum. Recently, a large database of modern benthic foraminifera in Bermudian caves were found to be highly sensitive to both the amount and source of particle organic carbon (POC) transported to the sediment-water interface, consistent with similar timewise analysis of foraminifera in a Mexican flooded cave. Here we provide evidence that while benthic meiofaunal communities in Bermuda’s underwater caves are primarily controlled by groundwater salinity changes on millennial timescales from sea-level change, they are secondarily controlled by the POC source and supply deposited in the cave through time. Benthic foraminiferal assemblages were evaluated in the best-preserved stratigraphic succession currently known from an underwater cave. In the case of Palm Cave, POC flux changes were driven by changes in seawater-groundwater circulation dynamics caused by flooding on the carbonate banktop, and the inherited geometry of the cave system itself. These results demonstrate that benthic meiofaunal communities in anchialine environments are highly sensitive to changes in the source and quantity of POC through time. This work also enables a better understanding of the environmental conditions associated with preserved meiofaunal remains in global cave sediment. These results indicate that if the POC flux to the subsurface increases from coastal urbanization on karst landscapes, subsurface anchialine communities are likely to respond.

Sedimentary records of past hurricane activity indicate centennial‐scale periods over the past millennium with elevated hurricane activity. The search for the underlying mechanism behind these active hurricane periods is confounded by regional variations in their timing. Here, we present a new high resolution paleohurricane record from The Bahamas with a synthesis of published North Atlantic records over the past millennium. We reconstruct hurricane strikes over the past 1,050 years in sediment cores from a blue hole on Long Island in The Bahamas. Coarse‐grained deposits in these cores date to the close passage of seven hurricanes over the historical interval. We find that the intensity and angle of approach of these historical storms plays an important role in inducing storm surge near the site. Our new record indicates four active hurricane periods on Long Island that conflict with published records on neighboring islands (Andros and Abaco Island). We demonstrate these three islands do not sample the same storms despite their proximity, and we compile these reconstructions together to create the first regional compilation of annually resolved paleohurricane records in The Bahamas. Integrating our Bahamian compilation with compiled records from the U.S. coastline indicates basin‐wide increased storminess during the Medieval Warm Period. Afterward, the hurricane patterns in our Bahamian compilation match those reconstructed along the U.S. East Coast but not in the northeastern Gulf of Mexico. This disconnect may result from shifts in local environmental conditions in the North Atlantic or shifts in hurricane populations from straight‐moving to recurving storms over the past millennium.

Meridional shifts of the North Atlantic Subtropical High (NASH) western edge create a dipole that drives hydroclimate variability in the southeastern United States and Caribbean region. Southwest displacements suppress rainfall in the southern Caribbean. Northwest displacements drive southeast United States and northern Caribbean drying. Projections for the 21st century suggest a more meridionally displaced NASH, which jeopardizes Caribbean island communities dependent on rain‐fed aquifers. While recent work indicates that Atlantic and Pacific Ocean‐atmosphere variability influenced the NASH during the instrumental period, little is known about NASH behavior and subsequent hydroclimate responses over longer timescales. To address this limitation, we developed a ∼6000‐years long rainfall record through the analysis of calcite raft deposits archived within sediments from a coastal sinkhole in the northeast Bahamas (Abaco Island). Increased (decreased) calcite raft deposition provides evidence for increased (decreased) rainfall driven by NASH variability. We use simulations from the Community Earth System Model to support this interpretation. These simulations improve our understanding of NASH behavior on timescales congruous with the reconstruction and suggest an important role for the state of the Pacific Ocean. Furthermore, model simulations and a compilation of regional hydroclimate reconstructions reveal that the NASH‐driven dipole dominates northern and southern Caribbean rainfall on centennial timescales. These results bring Holocene Caribbean hydroclimate variability into sharper focus while providing important context for present and future changes to regional climate. Additionally, this study highlights the need for improved future predictions of the state of the Pacific Ocean to best inform water scarcity mitigation strategies for at‐risk Caribbean communities.

Coastal communities are vulnerable to sea-level rise and hurricane-induced flooding. Our ability to assess flooding risk at coastal locations is restricted by the short observational record and limited knowledge on storm surge generation during hurricanes of different strength, size and orientation. Here, we present a transect of sediment cores collected from a blue hole near Middle Caicos in the Turks & Caicos Islands. Storm deposits found across cores in the transect record the passage of hurricanes passing to the south of Middle Caicos over the past 1500 years including Hurricane Irma in 2017. The record indicates historically unprecedented multi-decadal periods of elevated storm strikes on the island. We add this new reconstruction to a compilation of near-annually resolved paleohurricane records of the past millennium in The Bahamas. This compilation indicates increased storm activity in The Bahamas from 650 to 800 CE, 930 to 1040 CE, and 1400 to 1800 CE. Taken together with compilations of published paleohurricane records from New England and the Gulf Coast of Florida, we observe periods of elevated hurricane activity in all three spatially disparate regions over the past millennium and periods when New England and the Bahama Archipelago are active while the Gulf Coast of Florida is not. We argue that both regional-scale changes in vertical wind shear patterns and shifting storm tracks may explain the discrepancies we observe between different regions of the North Atlantic. This research informs how hurricane frequency has changed over the past 1500 years specifically in the Turks & Caicos Islands and regionally along the Bahama Archipelago.

Storminess and sea-level can both have a significant impact on landforms in cyclone-prone coastal regions, although much of our understanding comes from shorttimescale modern observations. This study aims to understand the variability of sediment transport and deposition in the Choctawhatchee Bay/Santa Rosa Island in the northern Gulf of Mexico, establishing the dominant sediment transport processes and morphological response of the barrier system to long-term variations in storminess and rising sea-levels. Here, we study the spatial and temporal changes in physicochemical properties of the sedimentary record of Choctawhatchee Bay to examine the character and fidelity of records of storm impacts spanning the Holocene. Proxies for marine and terrestrial conditions in the cores situated closer to the present barrier (proximal) show that sedimentation in coastal areas and marine influence of the bay during the last similar to 8000 yrs. were mainly determined by barrier response to the Holocene transgression and changes in storminess. In contrast, sedimentation close to the landward shore was governed by terrigenous input. The correlation of grain size and terrigenous proxies with regional hurricane records indicates that hinterland erosion by the rainfall during hurricane events is likely the dominant terrigenous sediment transport mechanism in areas close to the landward shore of the bay. These results suggest that sediment archives in large coastal deposition environments are equally suitable for sea level and cyclone modulated coastal morphological studies and paleo tropical cyclone studies, depending on the location, selected with an understanding of sedimentation processes in the vicinity.