Caribbean Sites Research Articles

Tropical cyclone activity over the past 1200 years at the Pelican Cays, Belize

Tropical cyclone (TC) models indicate that continued planet warming will likely increase the global proportion of powerful TCs (specifically Categories 4 and 5 hurricanes), increasingly jeopardizing low-lying coastal communities and resources such as the Pelican Cays, Belize. The combination of increased coastal development and continued relative sea-level rise puts these communities at even higher risk of damage from TCs. The short TC observational record for the western Caribbean hampers the extensive study of TC activity on centennial timescales, which hinders our ability to fully understand past TC climatology and improve the accuracy of TC models. To better assess TC risk, paleotempestological studies are necessary to put future scenarios in perspective. Here, we present a high-resolution reconstruction of coarser-grained sediment deposits associated with TC (predominately ≥ Category 2 hurricanes) passages over the past 1200 years from Elbow and Lagoon Cays, two coral reef-bounded lagoons at the northern and southern end of the Pelican Cays; the most southern Belizean paleotempestological site to date. Coincident timing of historic storms with statistically significant coarser-grained deposits within cay lagoon sediment cores allows us to determine which historic TCs likely generated event layers (tempestites) archived in the sediment record. Our compilation frequency analysis indicates one active interval (above-normal TC activity) from 1740-1950 CE and one quiet interval (below-normal TC activity) from 850-1018 CE. The active and quiet intervals in the Pelican Cays composite record are anticorrelated with those from nearby and re-analyzed TC records to the north, including the Great Blue Hole (∼100 km north) and the Northeast Yucatan (∼380 km northwest). This site-specific anticorrelation in TC activity along the western Caribbean indicates that we cannot rely on any one single TC record to represent regional TC activity. However, we cannot discount that these anticorrelated periods between the western Caribbean sites are due to randomness. To confirm that the anticorrelation in TC activity among sites from the western Caribbean is indeed a function of climate change and not randomness, an integration of more records and TC model simulations over the past millennium is necessary to assess the significance of centennial-scale variability in TC activity recorded in reconstructions from the western Caribbean.

Invertebrate Grazing on Live Turtlegrass (Thalassia testudinum): A Common Interaction That May Facilitate Fungal Growth

In coastal wetlands and tropical reefs, snails can regulate foundation species by feeding on marsh grasses and hard corals. In many cases, their impacts are amplified because they facilitate microbial infection in grazer-induced wounds. Whether snails commonly graze live plants and facilitate microbial growth on plants in tropical seagrass systems is less explored. On a Belizean Caye, we examined patterns in snail-generated grazer scars on the abundant turtlegrass (Thalassia testudinum). Our initial survey showed the occurrence of snail-induced scarring on live turtlegrass blades was common, with 57% of live leaves scarred. Feeding trials demonstrated that two of five common snails (Tegula fasciata–smooth tegula and Smaragdia viridis–emerald nerite) grazed unepiphytized turtlegrass blades and that smooth tegula abundance had a positive relationship with scarring intensity. Subsequent surveys at three Caribbean sites (separated by >150 km) also showed a high occurrence of snail-induced scars on turtlegrass blades. Finally, simulated herbivory experiments and field observations of a turtlegrass bed in Florida, United States suggests that herbivore damage could facilitate fungal growth in live seagrass tissue through mechanical opening of tissue. Combined, these findings reveal that snail grazing on live turtlegrass blades in the Caribbean can be common. Based on these results, we hypothesize that small grazers could be exerting top-down control over turtlegrass growth directly via grazing and/or indirectly by facilitating microbial infection in live seagrass tissue. Further studies are needed to determine the generality and relative importance of direct and indirect effects of gastropod grazing on turtlegrass health.

Old World Methods, New World Pots. The Introduction of the Potter’s Wheel to the Spanish Colonies of Concepción de la Vega and Cotuí (Dominican Republic 1495–1562)

Wheel-made ceramics from early colonial Caribbean sites (1492–1562) have traditionally been labelled as European imports. This paper challenges that assumption, as the intercultural interactions within colonies in the New World have led to the creation of new social identities and changing material culture repertoires. Macro-trace ceramic analysis from the sites of Concepción de la Vega and Cotuí (Hispaniola, present-day Dominican Republic) show that the potter’s wheel was in fact introduced to the Spanish colonies at an early stage. The evidence of RKE (rotative kinetic energy) on sherds and the discovery of parts of a potter’s wheel are the earliest traces of the potter’s wheel found in the Americas. Here we aim to present how the potter’s wheel was introduced within the context of transcultural pottery forming. This paper will show that traditional coiling techniques were supplemented with finishing techniques on the wheel. The transformation processes within ceramic repertoires are assessed through theories of colonialism and learning processes, combined with archaeological and ethnoarchaeological assessment of the ceramic chaîne opératoire. Evidence from ceramic analysis is combined with historical sources to understand social processes surrounding the technological changes behind the introduction of the potter’s wheel to the New World colonies.

Introduction: “The Unexpected Caribbean” Part II

Introduction: “The Unexpected Caribbean” Part II

Entangled Caribbean rewriting, C.L.R. James, Aimé Césaire, and their books as postcolonial lieux de mémoire

This article argues that books such as C.L.R. James’s The Black Jacobins (1938) and Aimé Césaire’s Cahier d’un retour au pays natal (1939) can be important postcolonial lieux de mémoire (sites or realms of memory). Examining where memory is crystallized in book form, the article explores the entangled genealogies and rewriting of both key Caribbean works. Both James’s history and Césaire’s poem were rewritten repeatedly over the decades. My argument is that these two Caribbean foundation stones are themselves key Caribbean sites of memory in their own right. Césaire’s Cahier becomes a crucial new element in James’s rewritten history. The article tracks the ongoing and layered process of memory as palimpsest through which James’s 1963 revised edition of The Black Jacobins is itself constituted. James’s creative translation and ‘misreading’ of Césaire’s poem is analysed as the means through which the Trinidadian Marxist makes the poem his own. This article explores a range of postcolonial memory sites including the 1968 Cultural Congress in Havana, Cuba, where both writers met, and the 1969 London performance of Cahier readings. Finally, the article considers the writers’ gravestones to see how the writers’ words have been used to memorialize James, Césaire, and their writing.

Strong differences in migratory connectivity patterns among species of Neotropical‐Nearctic migratory birds revealed by combining stable isotopes and abundance in a Bayesian assignment analysis

AbstractAimConservation planning for migratory species requires knowing how populations are connected throughout the annual cycle. We measured migratory connectivity for five migratory songbird species by combining stable‐hydrogen isotopes in feathers (δ2HF) with citizen science data on breeding range abundance.LocationCaribbean Basin and North America.TaxaNeotropical migratory birds: Mniotilta varia, Setophaga ruticilla, Seiurus aurocapilla, Setophaga americana, and Setophaga discolor.MethodsWe analyzed δ2HF in feathers grown on North American breeding grounds and sampled at 20 Caribbean Basin sites across most of the non‐breeding range of each species. We made Bayesian assignments to breeding origin by combining δ2HF values and North American Breeding Bird Survey abundance data. For each species, we used cluster analysis to group Caribbean sites into non‐breeding regions that shared birds with similar breeding ground assignment probabilities. We then mapped assignment probabilities for the non‐breeding regions of each species onto breeding ground δ2HF surfaces and estimated the strength of migratory connectivity.ResultsApart from some general similarities, the five species demonstrated different patterns of migratory connectivity. Species with larger non‐breeding ranges exhibited stronger migratory connectivity compared to those with smaller non‐breeding ranges. Despite geographical overlap, birds from each non‐breeding region had mostly unique breeding ground origins.Main conclusionsThe contrasting patterns of migratory connectivity shown by the five species suggest that geographic distribution during the non‐breeding period is a poor indicator of breeding ground origin. Our results indicate that full annual cycle conservation planning, which requires migratory connectivity information, should proceed on a species‐specific basis.

Microhabitats of sharknose goby (Elacatinus evelynae) cleaning stations and their links with cleaning behaviour

Coral reefs are renowned for the complexity of their habitat structures and their resulting ability to host more species per unit area than any another marine ecosystem. Dedicated cleaner fish, which acquire all their food resources through client interactions, rely on both the habitat structures (by using topological cleaning stations) and the wide diversity of fish species available on coral reefs, to function. As a result of natural and anthropogenic threats, coral reef habitat structures and their complexity are being lost—despite this threat it is unclear how important reef geometry is to key ecological interactions, like cleaning. Using an established Caribbean reef study site, three-dimensional constructions of discrete coral heads were used to investigate how fine-scale structural complexity traits (structural complexity—measured by rugosity and vector dispersion—height, volume, surface area, percentage live coral cover and refuge availability) relate to cleaner occupancy, abundance and their cleaning interactions with clients. Coral height was a particularly important trait for cleaning, correlating with both the occurrence of cleaning stations on a reef, and with increased cleaning durations and reduced cleaning frequencies/rates. Cleaning stations were also more structurally complex than non-cleaning coral heads, and the increased availability of uneven surfaces (creating cracks and crevices) and refuge availability linked with increased cleaning durations/rates. By understanding habitat features important to cleaner fish on a typical Caribbean fringing reef, we can gain a better understanding of how important reef geometry might be for governing the occurrence and dynamics of such mutualisms.

A Simple Method for Quantifying Compositional Correspondence Between Zooarchaeological Assemblages Using Paired Similarity Indices

Archaeologists employ an array of comparative approaches to assess zooarchaeological assemblages and the human behavior that produced them. Similarity indices are a simple and effective method for evaluating correspondence between the taxa present and their abundances in two zooarchaeological assemblages. Yet, these indices are not as widely used as other approaches. Here, I review several similarity metrics and present a method for measuring assemblage similarity using paired incidence- and abundance-based indices. The combined results of these measures can be used to classify a set of assemblages according to their dissimilarity, qualitative similarity, quantitative similarity, or substantive similarity. The paired-index approach is demonstrated employing the corrected Forbes and Morista-Horn indices in two zooarchaeological case studies from the Caribbean sites of Sabazan (Carriacou), Sandy Ground (Anguilla), and Creve Coeur (Martinique) in the Lesser Antilles. I show that the method (1) provides a means to quantify the similarity between assemblages along a defined, meaningful scale; (2) offers a straightforward approach for understanding how the dimensions of assemblage similarity interact based on a proposed classification scheme; and (3) constitutes a simple-to-apply technique requiring minimal technical skills. I conclude by discussing the strengths and limitations of this method and its potential wider application in archaeology.

An Archaeobotanical Approach to Well-Being: Enslaved Plant Use at Estate Cane Garden, 19th Century St. Croix

ABSTRACT Recent paleoethnobotanical approaches in historical archaeology have successfully explored the intersection of plantation foodways, social relations, and the environment in contexts of enslavement, including in the colonial period Caribbean. This article presents an analysis of macrobotanical remains from Estate Cane Garden, a 19th century a.d. plantation hospital in St. Croix, U.S. Virgin Islands. In this study, we demonstrate how enslaved people actively negotiated the adverse conditions of slavery by using plant resources to secure their own well-being, by examining the types of plants found at the hospital, interpreting potential plant use, and by situating the hospital assemblage within a broader Caribbean comparative analysis. Ultimately, we argue for the need for a greater number of paleoethnobotanical studies of historic (16th–19th century) Caribbean sites to develop more robust intersite comparisons in order to reach a more nuanced understanding of the roles of plants in plantation lifeways.

Do the Fish Scales Shape of Mugil curema Reflect the Genetic Structure Using Microsatellites Markers and the Mexican Marine Ecoregions Classification?

Mugil curema is a teleost fish of economic importance that shows wide phenotypic variability in the coasts of Mexico. Intraspecific morphological variability might replicate either genetic dissimilarity between groups or environmental conditions according to phenotypic plasticity. Fish scales shape were used to discriminate location variants, genetic structure obtained by microsatellite markers and ichthyological provinces of Mexico. The present study uses landmarks and geometric morphometric statistical approaches to address the specific question: if and how fish scale shape varies with genetic structure or with ichthyological provinces. This is assessed using seven landmarks by scale, the coordinates of which were subjected to a generalized Procrustes analysis, followed by a principal components analysis and quadratic discriminant analysis with cross-validation analysis on shape. Also, the significance of classifications was assessed by Mancova. The proportion of total shape variance explained by total length and by centroid size was 3.8% and 3.0%, respectively. Therefore, only shape (without size), was used for the analysis. Mancova was significant in all cases, with locations, genetic structure and ichthyological provinces. The cross-validated discriminant analysis by location correctly classified 42.2% while with the genetic structure prearrangement and ichthyological provinces the identification rates were 58.3 and 57.0%, respectively. It was surprising that, as the same as in the genetic structure (microsatellite analysis), San Antonio Bay, Texas formed a group with Sabancuy, Campeche, Celestun and Sisal, Yucatan (the Caribbean locations). Likewise, Huave Lagoon System, Oaxaca located in the Pacific coast is more similar to the Caribbean sites unlike the other locations from the Pacific area, which are similar results depicted with microsatellite analysis. On the other hand, using the ichthyological provinces arrangement, the findings indicate that the Mexican and the Panamanian provinces were very different as opposed to the two provinces from the Gulf of Mexico more similar in fish scale shape. The Mexican province shows more identification rate (80.4%) while the rest of provinces discriminate less than 53.3%. Possibly, hydrographic features as currents or upwellings circumscribe boundaries between provinces and this could produce inherent genetic structure.

Sources of organic matter in two contrasting tropical coastal environments: The Caribbean Sea and the eastern Pacific

In this study, we evaluate sources of organic matter (OM) in two contrasting tropical coastal environments in Colombia, using a combination of glycerol dialkyl glycerol tetraethers (GDGTs) and n-alkane lipid biomarkers. A clear difference between the less productive Caribbean Sea and the more productive eastern Pacific is observed, with higher terrestrial contributions into the eastern Pacific strongly associated with riverine inputs. Although higher land plant-derived n-alkanes can be transported as eolian dust, our results suggest mainly riverine sources for our samples. When looking at the branched GDGT compositions, in situ production could be identified in most Caribbean stations and some of the more coastal sites in the Pacific with #ringstetra index values of above 0.7. The remaining stations in the eastern Pacific display soil-eroded GDGTs inputs associated with river discharges and deposited in the proximity of the coast. Marine production as measured by short chain n-alkanes and crenarchaeol are also higher in the eastern Pacific. It appears that the terrestrial inputs would bring nutrients as well as OM fueling both auto- and heterotrophs making the eastern Pacific overall more productive. We also observe OM of petrogenic origin, albeit in a low amount, especially in coastal Caribbean sites located near main harbors. This study helps improve the understanding of the complex mixture of OM inputs, origins and transport mechanisms into Colombian coastal areas. The present work emphasizes the need to integrate climate, geological setting and hydrology to fully understand the carbon cycle at a regional scale.

Assessing the association between subsistence strategies and the timing of weaning among indigenous archaeological populations of the Caribbean

AbstractHuman breastfeeding is a biocultural process shaped by the interaction of numerous biological, cultural, economic, and social factors. Although previous studies have found that a society's subsistence economy alone does not determine weaning timing, subsistence may still have a profound effect on weaning food choices. This paper analyses nitrogen and carbon stable isotopes in bone collagen and apatite of individuals from six precolonial Caribbean sites grouped into four subsistence categories: Hunter‐Fisher‐Gatherers (Cueva del Perico I and Cueva Calero, Cuba), Horticulturalists (Canímar Abajo, Cuba), Agriculturalists from the Antilles (Paso del Indio, Puerto Rico), and Agriculturalists of Mesoamerica (Marco Gonzalez and San Pedro, Belize) in order to explore how subsistence economy affected the different groups' breastfeeding and weaning practices. Ages for the start and the end of weaning, and the isotopic characteristics of possible food sources used as supplements during the weaning process, were assessed using the Bayesian probability model “Weaning Age Reconstruction with Nitrogen isotopes.” Model results indicate (a) a major dietary change around 2 years of age for most of the study populations, (b) that supplements seem to have been introduced into nonadults diet at earlier ages than has been observed in ethnographic populations of the area, (c) no direct correlation between the start of weaning and the availability of cultigens, but (d) that groups that had access to cultigens would appear to have weaned their children using foods with lower nitrogen isotope values, suggesting that plants (likely domesticates) may have had an important role as weaning foods.

Impact of long-range transport over the Atlantic Ocean on Saharan dust optical and microphysical properties based on AERONET data

Abstract. Arid regions are a major source of mineral dust aerosol. Transport from these sources can have a great impact on aerosol climatology in distant regions. In order to assess the impact of dust on climate we must understand how dust properties change after long distance transport from sources. This study addresses the changes in columnar aerosol properties when mineral dust outbreaks from western Africa arrive over the eastern Caribbean after transport across the Atlantic Ocean, a transit of 5–7 days. We use data from the NASA Aerosol Robotic Network (AERONET) located at five Caribbean and two western Africa sites to characterize changes in columnar aerosol properties: aerosol optical depth (AOD), size distribution, single scattering albedo, and refractive indexes. We first characterized the local aerosol climatology at each site and then using air mass back trajectories we identified those days when trajectories over Caribbean sites back-tracked to western Africa. Over the period 1996–2014 we identify 3174 days, an average of 167 days per year, when the air mass over the Caribbean sites could be linked to at least one of the two western Africa sites. For 1162 of these days, AOD data are available for the Caribbean sites as well as for the corresponding western Africa sites about 5–7 days earlier, when the air mass passed over these sites. We identified dust outbreaks as those air masses yielding AOD ≥ 0.2 and an Ångström exponent below 0.6. On this basis of the total 1162 days, 484 meet the criteria for mineral dust outbreaks. We observe that the AOD at 440 nm decreases by about 0.16 or 30 % during transport. The volume particle size distribution shows a similar decrease in the volume concentration, mainly in the coarse mode. The single scattering albedo, refractive indexes, and asymmetry factor remain unchanged. The difference in the effective radius over western Africa sites with respect to Caribbean sites ranges between 0 and −0.3 µm. Finally we conclude that in about half of the cases only non-spherical dust particles are present in the atmosphere over the western Africa and Caribbean sites, while in the other cases dust particles were mixed with other types of aerosol particles.

Tracking Interannual‐ to Multidecadal‐Scale Climate Variability in the Atlantic Warm Pool Using Central Caribbean Coral Data

AbstractAtlantic Warm Pool (AWP) climate variability is subject to multiple influences of remote and local forcing. However, shortage of observational data before the midtwentieth century and of long‐term sea surface temperature (SST) and climate records has hampered the detection and investigation of decadal‐ and longer‐scale variability. We present new seasonally resolved 125‐year records of coral δ18O and Sr/Ca variations in the Central Caribbean Sea (Little Cayman, Cayman Islands; Diploria strigosa). Both geochemical proxies show decreasing long‐term trends, indicating long‐term warming. Sr/Ca indicates much stronger regional warming than large‐scale grid‐SST data, while δ18O tracks large‐scale SST changes in the Atlantic Warm Pool. Seawater δ18O variations are reconstructed, indicating a drying trend over the past century. High spatial correlation between coral δ18O and SST in the region of the Loop Current and Gulf Stream system suggests that Little Cayman is a sensitive location for detecting past large‐scale temperature variability beyond the Central Caribbean region. More specifically, our δ18O data track changes in North Atlantic Oscillation variability on decadal and multidecadal time scales providing insights into the temporal and spatial nonstationarity of the North Atlantic Oscillation. A combination of our δ18O record with two coral records from different Caribbean sites reveals high spatial correspondence between coral δ18O and SST variability in the North Atlantic subtropical gyre, where few instrumental measurements and proxies are available prior to the twentieth century. Our results clearly demonstrate the potential of combining proxy data to provide information from sparsely sampled areas, helping to reduce uncertainty in model‐based projections.

Black Atlas: Geography and Flow in Nineteenth-Century African American Literature by Judith Madera

MADERA, JUDITH. Black Atlas: Geography and Flow in Nineteenth-Century African American Literature. Durham: Duke University Press, 2015. 312 pp. $94.95 cloth, $25.95 paperback. Simply put: Black Atlas flows. It is not narratively or conceptually simplistic--far from it. Rather, the flow of Black Atlas surfaces by way of a consistent unmooring of static meanings of geography. Adroitly, Madera conducts readers through fluid valences of locale, terrain at once domestic, international, human, and economic. Indeed, by volume's end, one grasps that territory is discursive and ideological, yet material and felt. In Black Atlas, milieu defies scale, while at the same time directly mediating architecture and aesthetics. Setting is productive and participatory. Further, land articulates a set of relationships in the nineteenth century: between the United States, Mexico, and Central America; in and between Caribbean sites such as Cuba and Haiti; and between West Africa, the Niger Valley, and Canada. Problematizing dominant space versus place binaries as well as exclusionary, temporal attributes of space, Madera traces the ways black authors have troubled normative topographic distinctions embedded in North/South and industry/agriculture, as well as in legal domains such as that created by the Fugitive Slave Law of 1850. Even the boundaries of relatively invariable entities such as antique maps exist in flux. Black Atlas flows. Foregrounding novels, travelogues, black serials, and national maps published in the period from 1849 to 1900, Madera engages process geography and close reading methodologies to interrogate of dissension (following Michel Foucault) and nonrepresentational geographies (following Bruno Latour) as traverse broad cultural debates on diaspora and hemispheric expansionism. Pinpointing how African American intellectual production maps ways of knowing slavery and Native American removal, for instance, Madera exposes cartographic imagining as a mode of complicity and resistance. Ultimately, Black Atlas situates an agile worldview not on the outskirts but as a hallmark of early black literature and performance. Chapter one, National Geographic: The Writings of William Wells emphasizes Brown's attentiveness to the relationship between travel and subjectivity in Clotel; or, the President s Daughter: A Narrative of Slave Life in the United States (1853). To do so, Madera showcases moments of literary counter-transit in Brown's representation of Quaker homesteads and the Ohio River, as well as in panic such as Vicksburg. Virginia. Panic cartographies are spaces of dissimilitude, straining against their containing form. Madera writes: they are alternately sites of eruption and sites of quietude. But in their form house the potential to undo not only what is close or proximate, but the broader collective (26). Nineteenth-century black authors such as Brown mobilize spatial representation--often regional in scope and riddled with conflict--to contest the jurisdiction of North American law and nation. By juxtaposing midcentury Mississippi and Connecticut, the slave pens of Washington, DC, and labor discord in Richmond, VA, and Brown's striking emblems of place including iron collars, Madera captures the stakes of black self-making-as-world-making in the context of slavery and its aftermath. Indigenes of Territory: Martin Delany and James Beckwourth, the second chapter, pairs a text by an African American writer as eminent as Brown, Martin Delany's Blake: or, the Huts of America (1859-62), with one comparatively less well known, James Beckwourth's The Life and Adventures of James P. …

First Documented Evidence of a Rookery of the Critically Endangered Hawksbill Sea Turtle (Eretmochelys imbricata) in North East Tobago

Abstract In the context of declining global hawksbill sea turtle (Eretmochelys imbricata) populations, the wider Caribbean region is of global conservation importance. This study compiles and presents previously unpublished sea turtle nesting-activity data for North East Tobago (11°19′13.53″N, −060°33′1.57″E) and reports the results of the first comprehensive survey of sea turtle nesting beaches at this southern Caribbean site. The results of this study quantify a previously undocumented, regionally important rookery for the globally critically endangered hawksbill sea turtle, consisting of untagged reproductive females.

Species richness and relative species abundance of Lepidoptera: Nymphalidae between primary forest and border sites in the north-central Caribbean of Costa Rica

Measurements of species richness and species abundance can have important implications for regulations and conservation. This study investigated species richness and abundance of butterflies in the family Nymphalidae at undisturbed, and disturbed habitats in Tirimbina Biological Reserve and Nogal Private Reserve, Sarapiquí, Costa Rica. Traps baited with rotten banana were placed in the canopy and the understory of three habitats: within mature forest, at a river/forest border, and at a banana plantation/forest border. In total, 71 species and 487 individuals were caught and identified during May and June 2011 and May 2013. Species richness and species abundance were found to increase significantly at perturbed habitats (p < 0.0001, p < 0.0001, respectively). The edge effect, in which species richness and abundance increase due to greater complementary resources from different habitats, could be one possible explanation for increased species richness and abundance.

Long-Term Fire Trends in Hispaniola and Puerto Rico from Sedimentary Charcoal: A Comparison of Three Records

Charcoal preserved in lake sediments is commonly used to reconstruct past trends in fire occurrence. However, interpretation of the charcoal record is often complicated, as changes in charcoal influx could represent natural shifts in fire regimes associated with changes in climate, changes in vegetation, or changes in patterns of anthropogenic burning. Here we examine sedimentary charcoal records from three lakes on the Caribbean islands of Hispaniola and Puerto Rico: Laguna Saladilla in the Dominican Republic, Lake Miragoane in Haiti, and Laguna Tortuguero in Puerto Rico. All records are based on microscopic charcoal fragments quantified from pollen slides and cover the last 7,000 or more years of the Holocene. We compare charcoal influx values to archeological and palynological evidence of human activity and explore the role of increasing winter insolation over the Holocene in driving increased charcoal deposition beginning ca. 6,000–5,000 cal yr BP. An increase in charcoal influx at Laguna Tortuguero at ca. 5,200 cal yr BP, previously interpreted as a signal of human settlement predating archeological evidence, may instead reflect insolation-driven shifts in winter drying that led to more frequent and possibly more intense natural fires. Decreased charcoal influx around 3,200 cal yr BP may signal human modification of the environment that altered fire frequency and/or intensity. Comparing the records from these three lowland Caribbean sites highlights possible intervals of synchronous, climate-driven burning as distinct from more localized anthropogenic burning.

The seawater neodymium and lead isotope record of the final stages of Central American Seaway closure

AbstractThe shoaling and final closure of the Central American Seaway (CAS) resulted in a major change of the global ocean circulation and has been suggested as an essential driver for strengthening of Atlantic Meridional Overturning Circulation (AMOC). The exact timing of CAS closure is key to interpreting its importance. Here we present a reconstruction of deep and intermediate water Nd and Pb isotope compositions obtained from fossil fish teeth and the authigenic coatings of planktonic foraminifera in the eastern equatorial Pacific (Ocean Drilling Program (ODP) Site 1241) and the Caribbean (ODP Sites 998, 999, and 1000) covering the final stages of CAS closure between 5.6 and 2.2 Ma. The data for the Pacific site indicate no significant Atlantic/Caribbean influence over this entire period. The Caribbean sites show a continuous trend to less radiogenic Nd isotope compositions during the Pliocene, consistent with an enhancement of Upper North Atlantic Deep Water (UNADW) inflow and a strengthening of the AMOC. Superimposed onto this long‐term trend, shorter‐term changes of intermediate Caribbean Nd isotope signatures approached more UNADW‐like values during intervals when published reconstructions of seawater salinity suggested complete closure of the CAS. The data imply that significant deep water exchange with the Pacific essentially stopped by 7 Ma and that shallow exchange, which still occurred at least periodically until approximately 2.5 Ma, may have been linked to the strength of the AMOC but did not have any direct effect on the intermediate and deep Caribbean Nd isotope signatures through mixing with Pacific waters.

Coral Settlement on Oil/Gas Platforms in the Northern Gulf of Mexico: Preliminary Evidence of Rarity

In recent decades, there have been two areas of shallow hard substrate available for zooxanthellate coral colonization in the North Gulf of Mexico: the Flower Garden Banks (FGB) and oil and gas platforms. We assessed coral recruitment on platforms possessing adult corals around the FGB. In this preliminary experiment, we used terra cotta plates mounted on racks, deployed on six platforms at depths of 15–27 m for a duration of ≤1 yr in two consecutive years. Data on coral spat taxonomic identification, distribution, and densities were collected. Platform spat densities on plates averaged <1/450 cm2, a low value when compared with the East-FGB (E-FGB; data from earlier similar experiment), other Caribbean sites, or the Great Barrier Reef. Spat density was not significantly different between platforms, suggesting that distance between the platforms and the E-FGB, a potential larval source, was large enough (>0.6–1.2 km) to permit extensive larval diffusion. Total spat density also did not vary significantly between settlement racks, indicating that settlement at the spatial scale of meters was relatively homogeneous. Only three species of spat were found—Tubastraea coccinea, Madracis decactis, and Montastraea sp.; the taxonomic composition of coral spat varied from those observed earlier on the E-FGB—Agaricia and Porites. The dominant recruits matched the dominant adults on the platforms— an unusual situation. Tubastraea and Madracis spat densities, respectively, did not vary significantly between platforms or between racks. Because of low recruitment levels, these artificial reef communities may be considered fragile in comparison to many natural ones because of the time required for recovery in the event of a mass coral mortality. These low recruitment levels, however, when integrated over ~30 yr, can result in the successful establishment of adult coral communities on the platforms.