Southeastern Seaboard Research Articles

Causes and multiyear predictability of the rapid acceleration of U.S. Southeast Sea level rise after 2010

The rate of sea level rise (SLR) along the Southeast Coast of the U.S. increased significantly after 2010. While anthropogenic radiative forcing causes an acceleration of global mean SLR, regional changes in the rate of SLR are strongly influenced by internal variability. Here we use observations and climate models to show that the rapid increase in the rate of SLR along the U.S. Southeast Coast after 2010 is due in part to multidecadal buoyancy-driven Atlantic meridional overturning circulation (AMOC) variations, along with heat transport convergence from wind-driven ocean circulation changes. We show that an initialized decadal prediction system can provide skillful regional SLR predictions induced by AMOC variations 5 years in advance, while wind-driven sea level variations are predictable 2 years in advance. Our results suggest that the rate of coastal SLR and its associated flooding risk along the U.S. southeastern seaboard are potentially predictable on multiyear timescales.

Atlantic meridional overturning circulation increases flood risk along the United States southeast coast

The system of oceanic flows constituting the Atlantic Meridional Overturning Circulation (AMOC) moves heat and other properties to the subpolar North Atlantic, controlling regional climate, weather, sea levels, and ecosystems. Climate models suggest a potential AMOC slowdown towards the end of this century due to anthropogenic forcing, accelerating coastal sea level rise along the western boundary and dramatically increasing flood risk. While direct observations of the AMOC are still too short to infer long-term trends, we show here that the AMOC-induced changes in gyre-scale heat content, superimposed on the global mean sea level rise, are already influencing the frequency of floods along the United States southeastern seaboard. We find that ocean heat convergence, being the primary driver for interannual sea level changes in the subtropical North Atlantic, has led to an exceptional gyre-scale warming and associated dynamic sea level rise since 2010, accounting for 30-50% of flood days in 2015-2020.

Physics-based sizing functions for ocean-to-estuary shallow-water models

Modeling ocean processes requires a discrete representation of the system geometry, which itself contains multiple degrees of freedom, especially for systems of large geographical scale. This paper assesses the unstructured meshing requirements for a large-scale, astronomic-tide model domain of the western North Atlantic Ocean, Gulf of Mexico and Caribbean Sea with telescopic focus of the South Atlantic Bight (United States southeastern seaboard) and its estuaries. The methodologies of localized truncation error analysis (LTEA), which account only for the model interior and LTEA plus complex derivatives (+CD), which account for the model interior and boundary, are exploited due to their foundations stemming directly from tidal physics. LTEA and LTEA+CD are applied for the M2 tidal harmonics resulting from linear and nonlinear solutions of the ADCIRC (advanced circulation) model based on a highly resolved uniform mesh. The resultant target element size distributions are interrogated distinctively for the inshore (estuarine) region of the South Atlantic Bight, the inlet-punctuated coastline, the shelf-slope-rise triad and deep ocean, and the open-ocean boundary. The relatively large size of the LTEA computational molecule makes it the suitable choice for the deep ocean, offshore and shelf regions where the tidal dynamics are predominantly linear and smoothly changing in space. LTEA+CD is the logical choice for the shallows and estuaries because of the spatial coverage afforded by the combined utility of interior and boundary estimators (computational molecules), as well as its accounting for the nonlinearities in the evaluation of local truncation error. The combination of the two methods enables an almost complete coverage of the domain for generating spacing requirements, with LTEA+CD extending beyond the interior-only definition of LTEA to capture the inshore regions and model boundaries. Implementing the approach with LTEA and LTEA+CD to target finer resolution in areas with sharper gradients in the hydrodynamics, while relaxing resolution in areas with smoother hydrodynamics, resulted in a mesh with a far-reduced number of elements (∼1.3M) relative to an overly resolved uniform mesh (>10M elements) that is comparable in accuracy with ±5% tidal amplitude error for 99% of the domain.

Plant Consumption by Early-Middle Neolithic Peoples in Guangxi, South China: Archaeobotanical Evidence From the Dingsishan Site

The Dingsishan Site, located in Nanning City, Guangxi Zhuang Autonomous Region, is one of the most important Neolithic archaeological sites in the Lingnan region of China’s southeastern seaboard. Plant microfossil remains recovered from excavated artifacts and human teeth suggest that the site’s ancient inhabitants practiced a subsistence system based on foraging. Wild plant food resources dominated their vegetal diet. Starch granules extracted from residue samples represent various taxa, including plant roots and tubers, aquatic plant fruits, beans, and wild cereals, defining the primary vegetal diet of Dingsishan’s Neolithic occupants. In addition, residue samples from shell artifacts yielded starch granules and phytolith remains, providing significant clues as to the function of these tools. We also identified millet starch granules from Dingsishan Cultural Phases 3-4 (ca. 7,000–6000 BP), albeit in extremely low quantities. Holocene paleoecological conditions in the Lingnan area provided diverse and plentiful wild food resources, allowing the relatively late emergence of agriculture. Our study suggests that Middle Neolithic human groups in the Yong River drainage consumed various plants, and their subsistence pattern was relatively stable through the four Cultural Phases identified at Dingsishan. Our conclusions enhance understanding the diversity of plant food resources exploited by foraging societies and interpretations of differences in patterns of agricultural origins in different ecological regions of China.

Vessels Pulsing with Energies and Stories to Tell

In this article, attention is drawn to stories arising from some southern African contemporary everyday ceramics utilityware created by selected local South African eastern seaboard potters, with an eye to identifying certain characteristics that result in works by these potters being most regularly used in the writer's household and studio. This conversation then takes a prehistoric turn, via a fingerprint on a fired lump of clay, to a brief discussion around potters of our southern African eastern seaboard Precolonial Farmer era, and some main characteristics of Kalundu Tradition utilityware ceramics. One particularly interesting characteristic is that excavations have revealed that some perfectly serviceable utilityware items were repurposed by means of post-firing partial or full piercing on the shoulder, belly, or base. Attention then moves towards the flame-firing techniques of Nesiwe Nongebeza and Lindsay Scott, as well as of woodburners Nina Shand and Paul de Jongh. Finally, it is lightly speculated that one of the reasons many potters enjoy working with clay and have certain favourite ceramic items in daily use is because they bestow some of their own energies into the works and recognise that others have also done so, thereby adding something special that users and collectors appreciate.

Interannual Sea Level Variability Along the Southeastern Seaboard of the United States in Relation to the Gyre‐Scale Heat Divergence in the North Atlantic

AbstractThe low‐amplitude, large‐scale, interannual, and longer‐term sea level changes are linked to the variations of ocean heat and freshwater content and strongly controlled by ocean dynamics. Near the coast, especially in low‐lying and flood‐vulnerable regions, these changes can provide background conditions favorable for the occurrence of extreme sea levels that represent a threat for coastal communities and ecosystems. In this study, we identify a tripole mode of the ocean gyre‐scale sea surface height variability in the North Atlantic and show that this mode is responsible for most of the interannual‐to‐decadal sea surface height changes along the southeast coast of the United States, including the Gulf of Mexico. We also show that these changes are largely driven by the large‐scale heat divergence related to the Atlantic Meridional Overturning Circulation and linked to the low‐frequency North Atlantic Oscillation.

Using Empirical Data to Quantify Port Resilience: Hurricane Matthew and the Southeastern Seaboard

AbstractThe economic significance of the U.S. Marine Transportation System (MTS) generates a need to understand the resilience of the MTS. Resilience is defined herein as a system’s ability maintai...

Differences in the population structure of Neisseria meningitidis in two Australian states: Victoria and Western Australia.

Neisseria meningitidis is the causative agent of invasive meningococcal disease (IMD). A recombinant vaccine called Bexsero® incorporates four subcapsular antigens (fHbp, NHBA, NadA and PorA) which are used to assign a Bexsero® antigen sequence type (BAST) to each meningococcal strain. The vaccine elicits an immune response against combinations of variants of these antigens which have been grouped into specific BAST profiles that have been shown to have different distributions within geographical locations thus potentially affecting the efficacy of the vaccine. In this study, invasive meningococcal disease isolates from the western seaboard of Australia (Western Australia; WA) were compared to those from the south-eastern seaboard (Victoria; VIC) from 2008 to 2012. Whole-genome sequencing (WGS) of 131 meningococci from VIC and 70 meningococci from WA were analysed for MLST, FetA and BAST profiling. Serogroup B predominated in both jurisdictions and a total of 10 MLST clonal complexes (cc) were shared by both states. Isolates belonging to cc22, cc103 and cc1157 were unique to VIC whilst isolates from cc60 and cc212 were unique to WA. Clonal complex 41/44 represented one-third of the meningococcal population in each state but the predominant ST was locally different: ST-6058 in VIC and ST-146 in WA. Of the 108 BAST profiles identified in this collection, only 9 BASTs were simultaneously observed in both states. A significantly larger proportion of isolates in VIC harboured alleles for the NHBA-2 peptide and fHbp-1, antigenic variants predicted to be covered by the Bexsero® vaccine. The estimate for vaccine coverage in WA (47.1% [95% CI: 41.1–53.1%]) was significantly lower than that in VIC (66.4% [95% CI: 62.3–70.5%]). In conclusion, the antigenic structure of meningococci causing invasive disease in two geographically distinct states of Australia differed significantly during the study period which may affect vaccine effectiveness and highlights the need for representative surveillance when predicting potential impact of meningococcal B vaccines.

Optimum spectral and geometric parameters for early detection of laurel wilt disease in avocado

Abstract Avocado ( Persea americana ) is a crop that is second in importance in Florida behind citrus with a wholesale value of $35 million and represents approximately 60% of the tropical fruit crop acreage. Laurel wilt (LW) is a lethal disease that has spread rapidly along the southeastern seaboard of the United States affecting commercial avocado production. This article evaluates the spatial and spectral requirements for quick and accurate detection of LW. Spectral data from healthy (H), Phytophthora root rot (PPR) and LW leaves were analyzed using ANOVA and two neural networks, multilayer perceptron (MLP) and radial basis function (RBF). The most effective wavelengths were identified and the filters were updated to a MCA-6 Tetracam camera (580–10 nm, 650–10 nm, 740–10 nm, 750–10 nm, 760–10 nm and 850–40 nm). Then, the MCA camera was used to take multispectral aerial images from a helicopter at three altitudes (180, 250 and 300 m) in an avocado field with trees at different stages of LW development, early, intermediate and late. The analyses were conducted based upon 2-class and 4-class systems. The 2-class system was designed to differentiate H and LW trees sufficient to identify trees for removal and the 4-class system was used to differentiate H plants and the three stages of LW development. Aerial image analysis proved the utility of the selected filters for successful identification of LW, even for trees in early stage of disease development with minimal symptoms. The ideal flight altitude of 250 m (15.3 cm pixel size) was selected according to the M-values and biological parameters such as canopy size and orchard size. The optimum VIs determined by higher M-values were TCARI 760–650 as well as GNDVI, NIR/G, Redge/G and VIGreen using any of the bands related to Redge (740 and 750 nm) or NIR regions (760 and 850 nm). Results reported on the utility of the 2-class and 4-class systems using the above VIs to discriminate LW; however it would be more convenient to develop the algorithm based on the 4-class system (H, early, intermediate and late). The early detection of LW through the methodology proposed in this research could allow farmers to control the movement of this disease through proper management strategies.

The impact of invasive cane toads on native wildlife in southern Australia.

Commonly, invaders have different impacts in different places. The spread of cane toads (Rhinella marina: Bufonidae) has been devastating for native fauna in tropical Australia, but the toads' impact remains unstudied in temperate-zone Australia. We surveyed habitat characteristics and fauna in campgrounds along the central eastern coast of Australia, in eight sites that have been colonized by cane toads and another eight that have not. The presence of cane toads was associated with lower faunal abundance and species richness, and a difference in species composition. Populations of three species of large lizards (land mullets Bellatorias major, eastern water dragons Intellagama lesueurii, and lace monitors Varanus varius) and a snake (red-bellied blacksnake Pseudechis porphyriacus) were lower (by 84 to 100%) in areas with toads. The scarcity of scavenging lace monitors in toad-invaded areas translated into a 52% decrease in rates of carrion removal (based on camera traps at bait stations) and an increase (by 61%) in numbers of brush turkeys (Alectura lathami). The invasion of cane toads through temperate-zone Australia appears to have reduced populations of at least four anurophagous predators, facilitated other taxa, and decreased rates of scavenging. Our data identify a paradox: The impacts of cane toads are at least as devastating in southern Australia as in the tropics, yet we know far more about toad invasion in the sparsely populated wilderness areas of tropical Australia than in the densely populated southeastern seaboard.

Detection of laurel wilt disease in avocado using low altitude aerial imaging.

Laurel wilt is a lethal disease of plants in the Lauraceae plant family, including avocado (Persea americana). This devastating disease has spread rapidly along the southeastern seaboard of the United States and has begun to affect commercial avocado production in Florida. The main objective of this study was to evaluate the potential to discriminate laurel wilt-affected avocado trees using aerial images taken with a modified camera during helicopter surveys at low-altitude in the commercial avocado production area. The ability to distinguish laurel wilt-affected trees from other factors that produce similar external symptoms was also studied. RmodGB digital values of healthy trees and laurel wilt-affected trees, as well as fruit stress and vines covering trees were used to calculate several vegetation indices (VIs), band ratios, and VI combinations. These indices were subjected to analysis of variance (ANOVA) and an M-statistic was performed in order to quantify the separability of those classes. Significant differences in spectral values among laurel wilt affected and healthy trees were observed in all vegetation indices calculated, although the best results were achieved with Excess Red (ExR), (Red–Green) and Combination 1 (COMB1) in all locations. B/G showed a very good potential for separate the other factors with symptoms similar to laurel wilt-affected trees, such as fruit stress and vines covering trees, from laurel wilt-affected trees. These consistent results prove the usefulness of using a modified camera (RmodGB) to discriminate laurel wilt-affected avocado trees from healthy trees, as well as from other factors that cause the same symptoms and suggest performing the classification in further research. According to our results, ExR and B/G should be utilized to develop an algorithm or decision rules to classify aerial images, since they showed the highest capacity to discriminate laurel wilt-affected trees. This methodology may allow the rapid detection of laurel wilt-affected trees using low altitude aerial images and be a valuable tool in mitigating this important threat to Florida avocado production.

Uptake and elimination of brevetoxin in the invasive green mussel, Perna viridis, during natural Karenia brevis blooms in southwest Florida.

Perna viridis is a recently introduced species to US coastal waters and have vigorously spread throughout the southeastern seaboard since their invasion. Little information regarding their response to local environmental factors has been reported including responses to the local HAB species, Karenia brevis. This study monitored the tissue toxin concentration of brevetoxins in P.viridis from existing populations throughout two consecutive natural K.brevis blooms. The results showed P.viridis to rapidly accumulate PbTx upon exposure to the bloom, far exceeding the peak tissue concentrations of oysters, Crassostrea virginica, sampled during the same period, 57,653±15,937 and 33,462±10,391ngg(-1) PbTx-3 equivalent, respectively. Further, P.viridis retained high PbTx concentrations in their tissues post bloom remaining above the regulatory limit for human consumption for 4-5 months, significantly longer than the depuration time of 2-8 weeks for native oyster and clam species. In the second year, the bloom persisted at high cell concentrations resulting in prolonged exposure and higher PbTx tissue concentrations indicating increased bioaccumulation in green mussels. While this species is not currently harvested for human consumption, the threat for post bloom trophic transfer could pose negative impacts on other important fisheries and higher food web implications.

Managing the Anthropocene marine transgression to the year 2100 and beyond in the State of Florida U.S.A.

We simulate the vulnerability of all 35 Florida coastal counties to the ongoing Anthropocene marine transgression using a bathtub model unconstrained by the artificial end date of year 2100. Our projections are based upon the association between rising sea level and atmospheric temperature; a 2.3 m rise per each 1 °C increase (Levermann et al., Proc Natl Acad Sci 10.1073/pnas.1219414110, 2013). Results are organized into seven regions based upon an assessment of hypsographic and geologic attributes. Each represents an area of common vulnerability characterized in this study as high (10 to 29 % average land loss), higher (15 to 77 % average land loss), and highest (43 to 95 % average land loss). This regional approach is designed to facilitate the implementation of effective adaptation activities by providing a logical basis for establishing or re-enforcing collaboration based upon a common threat and the utility of shared technical and financial resources. The benefits of a regional perspective in formulating an actionable response to climate change have already been demonstrated in south Florida. It is our intent to facilitate regional adaptation activities in other parts of the state and adjacent southern and southeastern seaboard.

Domestic cattle mobility in early farming villages in southern Africa: harvest profiles and strontium (87Sr/86Sr) isotope analyses from Early Iron Age sites in the lower Thukela River Valley of South Africa

Several researchers have suggested that Early Iron Age (i.e., first millennium ad) farmers in the mountainous valleys along the southeastern seaboard of southern Africa moved their livestock in a transhumant or seasonal fashion between grazing areas in order to take advantage of differentiation in availability of pasture. Until now, there have been no data to systematically test this hypothesis. This study presents new zooarchaeological and preliminary strontium isotope data from the Early Iron Age sites of Ndondondwane, Mamba I and Wosi in the lower Thukela River Valley of South Africa. Harvest profiles of domestic stock suggest that herds were present year-round in the valley bottom, despite the advantages of a transhumant pastoral system. In order to resolve the discrepancy between the harvest profiles and the expected mobility patterns, a pilot isotopic study collected modern baseline strontium data in an effort to establish the local valley signature. The isotopic signatures from the zooarchaeological cattle specimens from the three sites show variation between sites, which is indicative of both limited and variable patterns of mobility throughout the valley. In addition, the strontium data suggest that some cattle may have been moved through social and/or economic exchanges from outside the valley.

Can the cultivation of microalgae meet U.S. energy demands?

As biofuels such as ethanol and esters become increasingly attractive alternatives to nonrenewable resources such as oil and coal, scientists have become interested in determining the feasibility of biofuels to help meet U.S. energy demands in light of governmental efforts to develop cleaner‐burning, renewable fuels. Of particular interest are microalgae—single‐celled, photosynthetic organisms—which have been shown to have high biomass yields per acre cultivated. But does the United States have the resources to cultivate microalgae as a viable alternative to fossil fuel consumption? To answer this question, Wigmosta et al. sought to quantify how much water and land would be needed for commercial‐scale algal biofuel production, based on where production could feasibly occur. They find that with current technology, the United States has the potential to produce 220 billion liters per year of microalgal oil, equivalent to about 48% of current domestic imports. However, they caution that meeting this potential would require that roughly 5.5% of land in the continental United States and 3 times the amount of water currently used for irrigation be devoted to algal production, though optimizing the locations of microalgae production to maximize efficiency of water usage could significantly reduce water demands. These optimal locations include areas around the Great Lakes, the Gulf Coast, and the southeastern seaboard; these coastal locations would allow a 75% reduction in freshwater use and a 67% reduction in land use to cultivate biofuel resources. Moreover, biofuel production through these optimized locations could substitute for up to 17% of oil currently imported for transportation, indicating that with proper planning, U.S. goals for renewable fuels could be met. (Water Resources Research, doi:10.1029/2010WR009966, 2011)

National microalgae biofuel production potential and resource demand

Microalgae are receiving increased global attention as a potential sustainable “energy crop” for biofuel production. An important step to realizing the potential of algae is quantifying the demands commercial‐scale algal biofuel production will place on water and land resources. We present a high‐resolution spatiotemporal assessment that brings to bear fundamental questions of where production can occur, how many land and water resources are required, and how much energy is produced. Our study suggests that under current technology, microalgae have the potential to generate 220 × 109 L yr−1 of oil, equivalent to 48% of current U.S. petroleum imports for transportation. However, this level of production requires 5.5% of the land area in the conterminous United States and nearly three times the water currently used for irrigated agriculture, averaging 1421 L water per liter of oil. Optimizing the locations for microalgae production on the basis of water use efficiency can greatly reduce total water demand. For example, focusing on locations along the Gulf Coast, southeastern seaboard, and Great Lakes shows a 75% reduction in consumptive freshwater use to 350 L per liter of oil produced with a 67% reduction in land use. These optimized locations have the potential to generate an oil volume equivalent to 17% of imports for transportation fuels, equal to the Energy Independence and Security Act year 2022 “advanced biofuels” production target and utilizing some 25% of the current irrigation demand. With proper planning, adequate land and water are available to meet a significant portion of the U.S. renewable fuel goals.

Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography

Tomographic images of the mantle beneath East Asia were obtained from the inversion of traveltime data from global and regional seismograph networks and from temporary arrays on and around the Tibetan plateau. Our results are consistent with previous studies but the unprecedented resolution of mantle heterogeneity provides new insight into the large‐scale tectonic framework of the continental India‐Asia collision in the western part of the study region and subduction of the oceanic lithosphere in the east. In the realm of continental collision, west of ∼100°E, a relatively slow P‐wave speed characterizes the upper mantle beneath much of the Tibetan plateau but the wave speed is high beneath cratonic India, the southern and western part of the Tibetan plateau, Hindu‐Kush, and the Tian Shan. In the subduction realm, east of ∼110°E, the main structures are (i) pronounced low‐wave‐speed anomalies at a depth of between 100 and 400 km beneath Asia's southeastern seaboard and the back‐arc regions of ongoing subduction; (ii) narrow, fast anomalies in the upper mantle beneath major subduction zones; and (iii) widespread fast anomalies at a depth of 500–700 km beneath the Sea of Japan, the northern part of the Philippine Sea plate, and southeastern China. If the latter anomalies represent stagnant slabs, their fragmented nature and large lateral extent suggest that they are produced by different episodes of subduction beneath western Pacific island arcs, along the old SE margin of Asia, or during the Mesozoic collision of cratonic units in Southeast Asia. Attribution to ancient subduction systems implies that slab fragments can reside in the transition zone for (at least) several tens of millions of years. Shallow, slow anomalies beneath the Red River fault region connect to deep anomalies beneath the South China fold belt and South China Sea, suggesting a causal relationship between the evolution of the continental lithosphere of SW China and deeper mantle processes. Between the collision and the subduction realms, tomography reveals high‐wave‐speed continental roots beneath the western part of the North China craton (Ordos block) and the South China, or Yangtze, craton (Sichuan Basin) to a depth of ∼300 km.

Extending traditional explanations of illiteracy: historical and cross‐cultural perspectives

Providing a richer understanding of why the populations of economically underdeveloped countries are less literate than those who live in wealthier nations is the goal of this paper. Our analysis relies primarily on insights from our own research: ethnographic studies concerning literacy learning and use among unschooled and under‐schooled women conducted during the late 1990s in Mexico City and historical studies of literacy in Virginia, North Carolina and Georgia along the southeastern seaboard of the USA. We examine three social mechanisms that potentially obstruct access to literacy: (1) cultural ideas and practices about schooling and written language; (2) family and personal attitudes towards literacy: (3) the impact of poverty on family life and access to literacy. Any one of these mechanisms may impede the dispersion of literacy. If all three are present, as they frequently are, then the spread and use of literacy is likely to be severely hindered.

Monetary policy in a heterogeneous monetary union: the Australian experience

Australia is a monetary union with strong regional specialization. Manufacturing and service industries are located in the population centres on the south-eastern seaboard, and mining and pastoral activities take place in the interior and north of the continent. Monetary policy affects the interior and north more strongly than the south-eastern seaboard because Australian primary goods are mostly exported and the exchange rate provides the main transmission channel for monetary policy. The Reserve Bank of Australia must consider the economic interests of the interior and north and the south-eastern seaboard. Since monetary policy cannot differentiate between regions, there is a need for interregional macroeconomic risk-sharing.

Restoration of the Tropical Dry Evergreen Forest of Peninsular India

The Tropical Dry Evergreen Forest (TDEF) of India is only found on the south eastern seaboard of the peninsular. It has a very limited range, and extends only 60 km inland. The TDEF occurs in an area of high population density and consequently it is the rarest type of forest ecosystem found in the subcontinent. The establishment of the Auroville International Township in 1968 initiated a major work of eco-restoration which has turned a highly eroded lateritic plateau into a re-emerging ecosystem of the TDEF. The work now spreads out beyond the boundaries of the international township and involves working with local people, especially women and children. Many lessons have been learnt and the work continues to reintegrate the forest in the social fabric of a rapidly changing rural environment.