Straits Of Florida Research Articles

Coupling of potential habitat models with particle tracking experiments to examine larval fish dispersal and connectivity in deep water regions.

Computing Lagrangian trajectories with ocean circulation models is a powerful way to infer larval dispersal pathways and connectivity. Defining release areas and timing of particles to represent larval habitat realistically is critical to obtaining representative dispersal pathways. However, it is challenging due to spatial and temporal variability in larval density. Forward-tracking particle experiments were conducted to study larval connectivity of four species (neritic or mesopelagic) in the Gulf of Mexico's (GoM) deep-water region. A seasonal climatology coupled with predicted potential larval habitat models based on generalized additive models was used to delimit the particle dispersal origin. Two contrasting mesoscale circulation patterns were examined: (1) high Loop Current (LC) intrusion, absence of recently detached LC anticyclonic eddies (LC-ACE), and no interaction between LC-ACEs and the semi-permanent cyclonic eddy (CE) in the Bay of Campeche (BoC), and (2) limited LC intrusion, a recently detached LC-ACE, and interaction between LC-ACEs and the BoC's CE. To simulate larval transport, virtual larvae were randomly released in the potential habitats and advected for 30 days with the velocity fields of the HYbrid Coordinate Ocean Model with hourly-resolution assimilation. Potential habitat location and size played a major role in dispersal and connectivity. A greater percentage of particles were retained in potential habitats restricted to the southern BoC, suggesting lower connectivity with other GoM regions than those encompassing most of the BoC or the central Gulf. Mesoscale feature interactions in the western GoM and BoC led to greater dispersion along the western basin. By contrast, the absence of ACE-CE interaction in the BoC led to greater retention and less connectivity between the southern and northern GoM. Under high LC intrusion, particles seeded north of the Yucatan Shelf were advected through the Florida Straits and dispersed within the GoM. Coupling potential habitat models with particle experiments can help characterize the dispersal and connectivity of fish larvae in oceanic systems.

A diminished North Atlantic nutrient stream during Younger Dryas climate reversal

The high rate of biological productivity in the North Atlantic is stimulated by the advective supply of nutrients into the region via the Gulf Stream (nutrient stream). It has been proposed that the projected future decline in the Atlantic Meridional Overturning Circulation (AMOC) will cause a reduction in nutrient supply and resulting productivity. In this work, we examine how the nutrient stream changed over the Younger Dryas climate reversal that marked the transition out of the last ice age. Gulf Stream nutrient content decreased, and oxygen content increased at the Florida Straits during this time of weakened AMOC. The decreased nutrient stream was accompanied by a reduction in biological productivity at higher latitudes in the North Atlantic, which supports the link postulated in theoretical and modeling studies.

20th Century Warming in the Western Florida Keys Was Dominated by Increasing Winter Temperatures

AbstractLong‐lived Atlantic coral species like Orbicella faveolata are important archives of oceanographic change in shallow, marine environments like the Florida Keys. Not only can coral‐based records extend for multiple centuries beyond the limits of the instrumental record, but they can also provide a more accurate representation of in situ conditions than gridded interpolated sea‐surface temperature (SST) products for nearshore reef environments. We use the coral Sr/Ca paleothermometer to produce a 150‐year (1830–1980 C.E.) monthly SST reconstruction from an O. faveolata colony collected in the Marquesas Keys, FL, USA. An important feature of our record is a significant 20th‐century warming trend in winter SSTs. We hypothesize that the winter warming trend was driven partially by a decrease in upwelling associated cyclonic eddies spinning off the Florida Current. A long‐term weakening of winter Florida Current transport over the 20th century could be responsible for decreased cyclonic eddy formation in the Florida Straits. Another feature of the record is pronounced multidecadal fluctuations of mean annual warming and cooling in the record, which correspond to Atlantic Multidecadal Variability (AMV), with the AMV lagging behind western Florida Keys temperatures by 5–11 years. Strong coherence between coral‐based SST reconstructions in the western Florida Keys with broader scale Atlantic oceanographic trends over the past century suggests a common driver of regional SST variability.

Biogeography of Greater Antillean freshwater fishes, with a review of competing hypotheses.

In biogeography, vicariance and long-distance dispersal are often characterised as competing scenarios. However, they are related concepts, both relying on collective geological, ecological, and phylogenetic evidence. This is illustrated by freshwater fishes, which may immigrate to islands either when freshwater connections are temporarily present and later severed (vicariance), or by unusual means when ocean gaps are crossed (long-distance dispersal). Marine barriers have a strong filtering effect on freshwater fishes, limiting immigrants to those most capable of oceanic dispersal. The roles of vicariance and dispersal are debated for freshwater fishes of the Greater Antilles. We review three active hypotheses [Cretaceous vicariance, Greater Antilles-Aves Ridge (GAARlandia), long-distance dispersal] and propose long-distance dispersal to be an appropriate model due to limited support for freshwater fish use of landspans. Greater Antillean freshwater fishes have six potential source bioregions (defined from faunal similarity): Northern Gulf of México, Western Gulf of México, Maya Terrane, Chortís Block, Eastern Panamá, and Northern South America. Faunas of the Greater Antilles are composed of taxa immigrating from many of these bioregions, but there is strong compositional disharmony between island and mainland fish faunas (>90% of Antillean species are cyprinodontiforms, compared to <10% in Northern Gulf of México and Northern South America, and ≤50% elsewhere), consistent with a hypothesis of long-distance dispersal. Ancestral-area reconstruction analysis indicates there were 16 or 17 immigration events over the last 51 million years, 14 or 15 of these by cyprinodontiforms. Published divergence estimates and evidence available for each immigration event suggests they occurred at different times and by different pathways, possibly with rafts of vegetation discharged from rivers or washed to sea during storms. If so, ocean currents likely provide critical pathways for immigration when flowing from one landmass to another. On the other hand, currents create dispersal barriers when flowing perpendicularly between landmasses. In addition to high salinity tolerance, cyprinodontiforms collectively display a variety of adaptations that could enhance their ability to live with rafts (small body size, viviparity, low metabolism, amphibiousness, diapause, self-fertilisation). These adaptations likely also helped immigrants establish island populations after arrival and to persist long term thereafter. Cichlids may have used a pseudo bridge (Nicaragua Rise) to reach the Greater Antilles. Gars (Lepisosteidae) may have crossed the Straits of Florida to Cuba, a relatively short crossing that is not a barrier to gene flow for several cyprinodontiform immigrants. Indeed, widespread distributions of Quaternary migrants (Cyprinodon, Gambusia, Kryptolebias), within the Greater Antilles and among neighbouring bioregions, imply that long-distance dispersal is not necessarily inhibitory for well-adapted species, even though it appears to be virtually impossible for all other freshwater fishes.

The Communist Closet: Secrecy, Sexuality, and Ideology in the Cuban Cold War

Why were homosexuality and Communism so closely knit together in the discursive logic of the Cold War? This article explores the convergence of sexuality and ideology in scholarly and popular conversations about the Cuban Revolution. These included a transnational panic over the purported links between homosexuality and Communism, psychiatric efforts in Cuba and the Cuban exile community to link homosexuality to suspicious ideological affiliations (Communist or anti-Communist), and a shared concern with rooting out covert political threats on both sides of the Florida Straits. Situating Cuba in hemispheric perspective, I propose that secrecy itself was at issue in the widespread and conjoined preoccupation with ideology and sexuality. This turned the closet, on the one hand, and coming out, on the other, into all-purpose, politically charged signifiers in Cuban culture writ large.

Robust Weakening of the Gulf Stream During the Past Four Decades Observed in the Florida Straits

AbstractThe Gulf Stream is a vital limb of the North Atlantic circulation that influences regional climate, sea level, and hurricane activity. Given the Gulf Stream's relevance to weather and climate, many studies have attempted to estimate trends in its volumetric transport from various data sets, but results have been inconclusive, and no consensus has emerged whether it is weakening with climate change. Here we use Bayesian analysis to jointly assimilate multiple observational data sets from the Florida Straits to quantify uncertainty and change in Gulf Stream volume transport since 1982. We find with virtual certainty (probability P &gt; 99%) that Gulf Stream volume transport through the Florida Straits declined by 1.2 ± 1.0 Sv in the past 40 years (95% credible interval). This significant trend has emerged from the data set only over the past ten years, the first unequivocal evidence for a recent multidecadal decline in this climate‐relevant component of ocean circulation.

Extrapolation of electromagnetic pointing error corrections for Sentinel-1 Doppler currents from land areas to the open ocean

By utilizing single-look complex data from synthetic aperture radar (SAR), the Doppler centroid anomaly method (DCA) can be employed to determine the velocity of the sea surface current field along the radar line-of-sight direction. However, due to the influence of platform or antenna perturbations, SAR Doppler shift measurements are subject to electromagnetic pointing error (EPE). These errors can typically be reduced by using echo information from land areas (including islands) within the SAR images to correct the Doppler shift. This allows the successful estimation of Doppler shifts due to sea surface factors and, in turn, the retrieval of ocean currents in the radar line-of-sight. However, in cases where SAR images lack data over land, uncorrectable EPE can result in significant inaccuracies in the retrieval of ocean currents. This study utilizes data captured by Sentinel-1A on four orbits in the Florida Strait region of the Gulf Stream from July 2020 to October 2022 to investigate the variation characteristics of EPE. To address the issues of calculating these in SAR images lacking land data, an EPE fitting method is proposed. The correction significantly reduces the error of S1A retrieved current velocity compared with line-of-sight current velocity from the HYCOM model and in situ HF radar, indicating that the proposed method provides an effective way to reduce the impact of EPE in SAR images, even when land is not directly observed.

Acoustic characterization of the seabed with a single-element time-reversal mirror

Motivated by the 2012 Florida Straits Noise Interferometry Experiment, this paper investigates a time-reversal-based approach to acoustic remote sensing of the ocean. The signal processing mimics operation of a physical time-reversal mirror. The input data for the simulated time-reversal mirror can be obtained using either a compact, broadband sound source or cross-correlation of the diffuse noise recorded by spatially separated receivers. Low-frequency sound propagation is considered over ranges that are large compared to the water depth. The approach exploits the notion that the “best” focusing of the backpropagated time-reversed signal occurs at the “right point,” when the backpropagation takes place in the same propagation medium as the one, where the data have been acquired. Various metrics of the focusing quality are considered. A combination of spatial and temporal characteristics of the focus is proposed that leads to a robust and unique solution of the geoacoustic inverse problems considered for a single-element passive time-reversal mirror. Inputs with rather low signal-to-noise ratio prove acceptable, which is particularly important in the passive remote sensing context.

Causal relations between the loop current penetration and the inflow/outflow conditions inferred with a rigorous quantitative causality analysis

The causal relationship between the Loop Current (LC) penetration into the Gulf of Mexico and the inflow/outflow conditions in the Yucatan Channel and the Straits of Florida is analyzed using a recently developed causality analysis, which is quantitative in nature, and rigorously derived from first principles. Long-term time series from a 23-year high-resolution reanalysis product reveals that the LC penetration is associated with a dipole (tripole) mode of transport (vorticity flux) in both channels. These relationships, though significant from a perspective of correlation, do not necessarily imply causality. By applying the causality analysis, we identify a clear asymmetry of causality, that is, the flow conditions in the Yucatan Channel and the Straits of Florida can both cause the LC penetration. Conversely, the LC path state is less causal to the current variability in the two channels. The spatial causal structures further reveal that the upstream influence from the Yucatan Channel is strong in the main body of the LC as well as its extension area, while the downstream influence from the Straits of Florida is confined within the eastern branch of the LC. The asymmetric causal relations obtained from the data-assimilative reanalysis product are further confirmed in a free-running model simulation forced by three repeated cycles of atmospheric forcing, although the strength of the causality could vary from one simulation cycle to another, due to the intrinsic variability of the LC system.

Reconsidering the Relationship Between Gulf Stream Transport and Dynamic Sea Level at U.S. East Coast

AbstractThe relationship between Gulf Stream (GS) transport and coastal sea level is investigated using monthly GS transport between 1993 and 2019 at Florida Straits and 10 altimeter tracks. The results show that GS transport decorrelates quickly along its path, indicating it is misleading to assume that transport at a particular location represents strength of the GS as a whole. GS transport south of Cape Hatteras is significantly correlated with coastal sea level in South Atlantic Bight from both altimetry and tide gauges. North of Cape Hatteras, sea level changes associated with GS transport decay rapidly away from GS on the onshore side and become negligible approximately 300 km northwest of GS axis. In this region, the correlations between GS transport and sea level are primarily in the deep ocean and rarely on the shelf, indicating that coastal sea level is unlikely to be driven by geostrophic adjustment to changes in GS transport.

Genesis of the Gulf Stream Subseasonal Variability in the Florida Straits

AbstractThe properties and generation mechanisms of the Florida Current on the subseasonal timescale (20–100 days) are evaluated from in‐situ and satellite observations. The Florida Current volume transport estimates from submarine cable measurements reveal that subseasonal variability accounts for 37% of the total transport variance and is most variable from September to November. Here we show that coastal‐trapped waves are the primary driver of the subseasonal variability in the Florida Current transport. The role of local winds and open ocean signals is of secondary importance. The alongshore wind component of the anomalous North Atlantic subtropical anticyclone generates the subseasonal coastal‐trapped waves off the northern South Atlantic Bight coast. The subseasonal coastal‐trapped waves propagate from Cape May to Apalachicola, behaving as Kelvin waves in the Florida Straits and as continental shelf waves along the rest of the waveguide. They affect the Florida Current transport by up to 2.6 Sv, on average. As the subseasonal waves propagate into the Gulf of Mexico, their energy substantially dissipates. The wave amplitude at Port Canaveral of up to 15 cm is three times higher than at Apalachicola. Concurrent subseasonal changes of the meridional overturning circulation in the subtropical North Atlantic are discussed.

Sedimentary Accumulation of Black Carbon on the East Coast of The United States

AbstractThe occurrence, trends and sources of soot black carbon (BC) in coastal sediments are poorly understood, particularly during the Anthropocene. Two sediment cores, covering the last ∼100 years from the US East Coast, off North Carolina and in the Florida Straits, were analyzed for organic carbon (OC), BC fluxes and BC sources. BC fluxes were 0.1 g cm−2 year−1 at both sites and accounted for 8%–22% of total OC. Carbon stable isotope values indicated OC to be of marine origin, while the BC was mostly terrestrially derived, C3‐plant material. Radiocarbon values revealed BC originating mostly from fossil fuels or pre‐aged carbon (fraction modern of 14%–31%) at North Carolina, while in the Florida Strait the BC was mostly derived from biomass burning (fraction modern of 70%–74%), in‐line with continental (NC) or marine (FS) air mass origins. Ratios of polycyclic aromatic hydrocarbons broadly supported different BC sources at the two sites.

First Record of the Genus Tiburnella Thomas &amp; Barnard, 1983 (Amphipoda, Platyischnopidae) from the Deep-Sea Gulf of Mexico, with the Description of a New Species

Platyischopidae Barnard &amp; Drummond, 1979 represents an amphipod family with 10 genera and 18 species documented as benthic organisms inhabiting from shallow to deep–sea ecosystems worldwide. During 1965, the oceanographic expedition Kovaliewsky— Academic—RV was carried out in the southern Gulf of Mexico (GOM), Straits of Florida, and SW—NE Cuba. Several shallow and deep—sea benthic samples were collected from soft bottoms. From1966 through 2000, a few manuscripts were published regarding benthic invertebrates collected from this expedition, however, other data remain unreported. The present work describes and illustrates in detail a new deep water platyischnopid amphipod species of the genus Tiburonella Thomas &amp; Barnard, 1983, collected from bathyal soft bottoms of the Bay of Campeche, GOM at 2,321 m. Additionally, a dichotomous key for identification of the only 3 known Tiburonella species worldwide is provided.

In situ imaging across ecosystems to resolve the fine‐scale oceanographic drivers of a globally significant planktonic grazer

AbstractDoliolids are common gelatinous grazers in marine ecosystems around the world and likely influence carbon cycling due to their large population sizes with high growth and excretion rates. Aggregations or blooms of these organisms occur frequently, but they are difficult to measure or predict because doliolids are fragile, under sampled with conventional plankton nets, and can aggregate on fine spatial scales (1–10 m). Moreover, ecological studies typically target a single region or site that does not encompass the range of possible habitats favoring doliolid proliferation. To address these limitations, we combined in situ imaging data from six coastal ecosystems, including the Oregon shelf, northern California, southern California Bight, northern Gulf of Mexico, Straits of Florida, and Mediterranean Sea, to resolve and compare doliolid habitat associations during warm months when environmental gradients are strong and doliolid blooms are frequently documented. Higher ocean temperature was the strongest predictor of elevated doliolid abundances across ecosystems, with additional variance explained by chlorophyll a fluorescence and dissolved oxygen. For marginal seas with a wide range of productivity regimes, the nurse stage tended to comprise a higher proportion of the doliolids when total abundance was low. However, this pattern did not hold in ecosystems with persistent coastal upwelling. The doliolids tended to be most aggregated in oligotrophic systems (Mediterranea and southern California), suggesting that microhabitats within the water column favor proliferation on fine spatial scales. Similar comparative approaches can resolve the realized niche of fast‐reproducing marine animals, thus improving predictions for population‐level responses to changing oceanographic conditions.

Marine Heat Waves over Natural and Urban Coastal Environments of South Florida

Marine Heat Wave (MHW) events are increasingly recognized as an important factor in the sustainability of coastal environments (both natural and urban), in the context of climate change. They are related to increasing trends of Sea Surface Temperature (SST) at the adjacent ocean waters. SST is an important parameter of the earth’s climate and increasing SST trends have been associated with adverse effects on coastal ecosystems, with important environmental and socioeconomic implications. This study focuses on the SST interannual variability over the coastal marine environment of South Florida, which contains several fragile ecosystems, and draws associate effects with adjacent large urban coastal settlements. The methodology is based on high-resolution satellite-derived SST data during a 40-year period (1982–2021), augmented by recent high-resolution model simulations (2012–2020). A generally increasing trend has been detected in the observations over the entire region (0.19 °C/decade). The unusual temperature levels have been associated with the formation of extensive MHW events, which showed interannual positive trends (0.75 events/decade) during the 40-year study period. Specifically, the six most recent years (2015–2021) were characterized by the strongest formation of MHWs with a peak in 2015, 2019 and 2020, with more than 8 events/year and approximately 70 to 110 days/year duration in total. The Florida Keys, especially along the Straits of Florida (southern island coasts), revealed very strong increasing trends. Miami Beach is also characterized by strong interannual trends (1.1 events/decade and 10 days/decade) compared to the enclosed basin of Biscayne Bay. In addition to the influence of atmospheric conditions over all regions around South Florida, the formation of MHWs near the eastern Florida coasts was also controlled by ocean dynamics, related to the warm Florida Current (FC). The evolution of the FC close to the eastern coasts (e.g., Miami Beach) was found to be a pre-condition of MHW formation. Several disastrous events on the biotic environment of South Florida near large urban settlements have been related to the formation of MHWs. The detected positive trends, and especially the recent high peaks of MHW events, may enhance the loss of specific heat-sensitive species, damaging the biodiversity of this tropical coastal environment and weakening the natural coastal protection against tropical storms. Urban planning for sustainable development in South Florida’s coastal cities must take into account MHW trends.

Nepheloid layers in the deep Gulf of Mexico

The first measurements of bottom nepheloid layers in the central and southern deep waters of the Gulf of Mexico west of the Yucatan peninsula were made during the three summers of 2015–2017. Particulate matter concentrations (PM) were estimated from optical profiles of beam attenuation due to particles (cp). Near-bottom maps and vertical sections of cp and PM converted from cp show evidence of sediment resuspension, possibly linked with topographic Rossby waves, loop current eddies, or eddy-topography interactions. Additional cp profiles were made along cross-slope transects around the entire Gulf of Mexico, including across the Yucatan Channel and Straits of Florida in 2017. Near-bottom PM concentrations were barely elevated in the deep Yucatan Channel and Straits of Florida at that time, except in about the surface 200 m along the northern and western boundaries. Comparison was made between areas with benthic nepheloid layers and Eddy Kinetic Energy (EKE) patterns in the deep Gulf of Mexico. Regions of high EKE or strong bottom currents in the central and eastern Gulf were found over a large region of deeply eroded furrows in the seafloor previously imaged using 3-D seismic profiling and submersible observations. Few PM measurements were obtained in the high EKE areas during these expeditions, however, historical and recent sampling show very strong nepheloid layers at stations within and westward of the region of the actively eroding furrows.

Variability and Trends of the Florida Current and Implications for the Future of the Gulf Stream

Pietrafesa, L.J.; Bao, S.; Gayes, P.T.; Carpenter, D.D., and Kowal, J.C., 2022. Variability and trends of the Florida current and implications for the future of the Gulf Stream. Journal of Coastal Research, 38(6), 1096–1103. Coconut Creek (Florida), ISSN 0749-0208. The Gulf Stream, the North Atlantic Ocean Basin Western Boundary Current, plays a key role in moderating the climate of the North Atlantic Ocean Basin and surrounding landmasses. However, the Gulf Stream has been widely reported in the public media to be slowing down in its volumetric transport to the north, related to the reported weakening of the Atlantic Meridional Overturning Circulation. The recent exposé claims that the Gulf Stream may be in the throes of an irreversible collapse. This would have serious implications for the future climate of not only the United States, Canada, Greenland, Iceland, Scandinavia, the British Isles, and Europe, but for the entire planet, per se. In this study, investigations of the volumetric flux of the Florida Current took place that constitutes the formative beginning of the Gulf Stream at the Florida Straits to determine if there is evidence of a slowing of this major Western Boundary Current at the latitude of its beginning source. Findings include multiple, well-defined frequency and amplitude modulated internal modes of current variability in the 38-year record of Florida Current volumetric transport, ranging from weekly to monthly to seasonally to annually to interannually and decadal. The time series reveals an overall slowing of approximately 0.98×106 meters3/second (equivalent to approximately one Sverdrup), or a 2.795% drop over the nearly four past decades of daily observations.

Sea level variability in the Gulf of Mexico since 1900 and its link to the Yucatan Channel and the Florida Strait flows

Sea level variability in the Gulf of Mexico since 1900 and its link to the Yucatan Channel and the Florida Strait flows

Inorganic Carbon Transport and Dynamics in the Florida Straits

AbstractOcean heat and carbon are transported through the Florida Straits, contributing to the Atlantic Meridional Overturning Circulation, and playing an important role in climate. Insufficient observations of carbonate chemistry within the Florida Straits have limited our understanding of ocean acidification within this region. To examine carbonate chemistry and carbon transport dynamics within this region, we developed an algorithm to estimate dissolved inorganic carbon (DIC) using more routinely measured input parameters (temperature, salinity, and dissolved oxygen [DO]) and the corresponding sampling date, depth, and longitude. The developed DIC algorithm output demonstrates good agreement with limited existing in situ observations. By applying this algorithm, we developed a seasonally resolved time series of DIC spanning from 2002 to 2018 for the Florida Straits at 27°N. This time series suggests that short‐term variations in surface water DO and DIC were strongly influenced by the Florida Current transport. The long‐term increase in DIC was mainly caused by anthropogenic carbon accumulation and DO decrease. The highest increasing rate in DIC was found in North Atlantic Central Water where DO decrease was fastest while the decreasing rate in pH was highest in Antarctic Intermediate Water (AAIW) because of the lower buffer capacity of this water mass. The long‐term pH decrease, especially in AAIW, can impact the health of deep corals in the Florida Straits. Quantifying carbon transport between the coast of Florida and the Bahamas is important to understanding the carbonate chemistry dynamics and the long‐term acidification of this important region.

Evidence of Spatial Stability in Core Fauna Community Structure of Holopelagic Sargassum

As Sargassum biomass continues to increase globally, it is critical to develop a better understanding of how it functions as habitat, therefore, community structure of Sargassum-associated organisms was examined from 11 sampling locations spanning the tropical Florida Straits to the more temperate Gulf Stream off the coast of Savannah, Georgia from May to September 2018 using a combination of modified shrimp trawls and dip nets. A total of 5413 organisms were collected from Sargassum habitat representing 14 species from 10 families. A core group of organisms (Platynereis dumerilii, Litiopa melanostoma, Portunus sayi, Portunus spinimanus, Leander tenuicornis, and Latreutes fucorum) were found throughout the entirety of the geographic range surveyed. This core community did not vary significantly with increasing distance to shore or latitude, nor did it correlate with environmental variables such as salinity and temperature. However, community structure did vary with clump size, with larger clumps harboring more speciose communities. The Sargassum community in the Florida Straits and Gulf Stream appear to provide habitat for a consistent group of epifaunal organisms. In turn, this stable group offers a consistent prey source for a variety of important, higher trophic level organisms.