A 34-month sediment trap experiment at the Cape Verde Ocean Observatory (CVOO, December 2009 - October 2012)

Anticyclonic mesoscale eddies (ACME) have been proposed as a mechanism by which new nutrients are episodically delivered into the euphotic zone, thereby enhancing new production as well as shifting phytoplankton community structure. In this paper, we report on a 34-month sediment trap experiment at the Cape Verde Ocean Observatory (CVOO; ca. 18°N, 24°E; December 2009-October 2012), occasionally influenced by ACME passages. The typically oligotrophic, weakly seasonal particle flux pattern at the CVOO is strongly modified by the appearance of a highly productive and low oxygen ACME. Out of four recorded diatom flux maxima at CVOO, three were associated with the passage of ACMEs. The recorded diatom maxima events support the view that local ACME dynamics promotes upward nutrient supply into the euphotic zone leading to a rapid response of diatoms. This response is clearly reflected by the flux seasonality: between 40% and 60% of the total annual diatom flux at the CVOO site was intercepted in a relatively short time interval (<60 days). A highly diverse diatom community characterized the diatom fluxes throughout. Along with the ACME passages, small species of the genus Nitzschia, and Thalassionema nitzschioides var. parva dominated and delivered a major portion of the opal and organic carbon into deeper waters at site CVOO. Several pelagic, warm-water background species became dominant during intervals with low nutrient availability in the euphotic zone. Results of our interannual time-series suggest that ACMEs impact on total diatom production and the species-specific composition of the assemblage north of the Cave Verde Islands, and can strengthen the biological pump in open-ocean, oligotrophic subtropical regions of the world ocean. Our observations are useful for testing biogeochemical ocean models and will also help in improving the knowledge of processes and mechanisms behind interannual time-series of bulk components and microorganisms in pelagic and hemipelagic ocean areas.

Organic carbon sources and their transfer in a gulf of Mexico coral reef ecosystem

Coral reefs face unprecedented threats throughout most of their range. Poorly planned coastal development has contributed increased nutrients and sewage contamination to coastal waters, smothering some corals and contributing to overgrowth by macroalgae. My approach to assessing the degree to which coral reef ecosystems have been influenced by terrestrial and anthropogenic organic carbon inputs is through the use of carbon (C) and nitrogen (N) stable isotopes and lipid biomarkers in a marine protected area, the Coral Reef System of Veracruz: Parque Nacional Sistema Arrecifal Veracruzano (PNSAV) in the southwest Gulf of Mexico. Firstly, I used a C and N stable isotope mixing model and a calculated fatty acid (FA) retention factor to reveal the primary producer sources that fuel the coral reef food web. Secondly, I used lipid classes, FA and sterol biomarkers to determine production of terrestrial and marine biogenic material of nutritional quality to pelagic and benthic organisms. Finally, I used coprostanol to determine pollutant loading from sewage in the suspended particulate matter. Results indicate that phytoplankton is the major source of essential metabolite FA for marine fish and that dietary energy from terrestrial sources such as mangroves are transferred to juvenile fish, while seagrass non-essential FA are transferred to the entire food web mainly in the rainy season. Sea urchins may be the main consumers of brown macroalgae, especially in the dry season, while surgeon fish prefer red algae in both dry and rainy seasons. C and N isotopic values and the ratio C:N suggest that fertilizer is the principal source of nitrogen to macroalgae. Thus nitrogen supply also favored phytoplankton and seagrass growth leading to a better nutritional condition and high retention of organic carbon in the food web members during the rainy season when river influence increases. However, the great star coral Montastrea cavernosa nutritional condition decreased significantly in the rainy season. The nearest river to the PNSAV was polluted in the dry season; however, a dilution effect was detected in the rainy season, when some coral reefs were contaminated. In 2013, a new treatment plant started working in the area. I would suggest monitoring δ¹⁵N and the C: N ratio in macroalgae as indicators of the nitrogen input and coprostanol as an indicator of human feces pollution in order to verify the efficiency of the new treatment plant as part of the management program of the PNSAV.

Sediment core-top GDGT data from the Arctic, the North Pacific and the Southern Ocean

TEX86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) is a sea surface temperature (SST) proxy based on the distribution of archaeal isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs). In this study, we appraise the applicability of TEX86 and TEX86L in subpolar and polar regions using surface sediments. We present TEX86 and TEX86L data from 160 surface sediment samples collected in the Arctic, the Southern Ocean and the North Pacific. Most of the SST estimates derived from both TEX86 and TEX86L are anomalously high in the Arctic, especially in the vicinity of Siberian river mouths and the sea ice margin, plausibly due to additional archaeal contributions linked to terrigenous input. We found unusual GDGT distributions at five sites in the North Pacific. High GDGT-0/crenarchaeol and GDGT-2/crenarchaeol ratios at these sites suggest a substantial contribution of methanogenic and/or methanotrophic archaea to the sedimentary GDGT pool here. Apart from these anomalous findings, TEX86 and TEX86L values in the surface sediments from the Southern Ocean and the North Pacific do usually vary with overlaying SSTs. In these regions, the sedimentary TEX86-SST relationship is similar to the global calibration, and the derived temperature estimates agree well with overlaying annual mean SSTs at the sites. However, there is a systematic offset between the regional TEX86L-SST relationships and the global calibration. At these sites, temperature estimates based on the global TEX86L calibration are closer to summer SSTs than annual mean SSTs. This finding suggests that in these subpolar settings a regional TEX86L calibration may be a more suitable equation for temperature reconstruction than the global calibration.

Development and Optimization of Four-dimensional Magnetic Resonance Imaging (4D-MRI) for Radiation Therapy

A tenet of modern radiotherapy (RT) is to identify the treatment target accurately, following which the high-dose treatment volume may be expanded into the surrounding tissues in order to create the clinical and planning target volumes. Respiratory motion can induce errors in target volume delineation and dose delivery in radiation therapy for thoracic and abdominal cancers. Historically, radiotherapy treatment planning in the thoracic and abdominal regions has used 2D or 3D images acquired under uncoached free-breathing conditions, irrespective of whether the target tumor is moving or not. Once the gross target volume has been delineated, standard margins are commonly added in order to account for motion. However, the generic margins do not usually take the target motion trajectory into consideration. That may lead to under- or over-estimate motion with subsequent risk of missing the target during treatment or irradiating excessive normal tissue. That introduces systematic errors into treatment planning and delivery. In clinical practice, four-dimensional (4D) imaging has been popular in For RT motion management. It provides temporal information about tumor and organ at risk motion, and it permits patient-specific treatment planning. The most common contemporary imaging technique for identifying tumor motion is 4D computed tomography (4D-CT). However, CT has poor soft tissue contrast and it induce ionizing radiation hazard. In the last decade, 4D magnetic resonance imaging (4D-MRI) has become an emerging tool to image respiratory motion, especially in the abdomen, because of the superior soft-tissue contrast. Recently, several 4D-MRI techniques have been proposed, including prospective and retrospective approaches. Nevertheless, 4D-MRI techniques are faced with several challenges: 1) suboptimal and inconsistent tumor contrast with large inter-patient variation; 2) relatively low temporal-spatial resolution; 3) it lacks a reliable respiratory surrogate. In this research work, novel 4D-MRI techniques applying MRI weightings that was not used in existing 4D-MRI techniques, including T2/T1-weighted, T2-weighted and Diffusion-weighted MRI were investigated. A result-driven phase retrospective sorting method was proposed, and it was applied to image space as well as k-space of MR imaging. Novel image-based respiratory surrogates were developed, improved and evaluated.

Stimulation of GABAergic neurons of the lateral septum and its effect on movement speed

The lateral septum is associated with the regulation of innate behavior, motivation, and locomotion. Its complex interconnections with cognitive and affective regions such as the hippocampus, hypothalamus, and medial septum have made it an attractive region for studying how motivation regulates behavior in context-specific settings. This GABAergic brain region’s main output is the lateral hypothalamus, which provides downstream signaling of motor commands. Even though stimulation of lateral septum projections to the hypothalamus have shown to decrease running speed in free behaving mice, characterizing movement kinematics due to LS activation has not been studied. GABAergic medium spiny neurons of the lateral septum were selectively activated through the use of optogenetic techniques in transgenic mice. Photostimulation of the lateral septum at theta frequencies caused a non-significant decrease in head and back speed. 3D motion analysis of body movement under photostimulation was quantified, revealing a slow, linear decrease of body speed as photostimulation progressed. These results support the role of lateral septum activation in movement regulation and shed light on the specific manner in which stimulation of the LS gradually decreases movement speed.

(Table 1) Diatom events for AND1-1B, CIROS-2, DVDP-10, and DVDP-11 cores including observed and placed depths

Late Neogene stratigraphy of southern Victoria Land Basin is revealed in coastal and offshore drill cores and a network of seismic data in McMurdo Sound, Antarctica. These data preserve a record of ice sheet response to global climate variability and progressive cooling through the past 5 million years. Application of a composite standard age model for diatom event stratigraphy to the McMurdo Sound drill cores provides an internally precise mechanism to correlate stratigraphic data and derive an event history for the basin. These marine records are indirectly compared to data obtained from geological outcrop in the Transantarctic Mountains to produce an integrated history of Antarctic Ice Sheet response to climate variability from the early Pliocene to Recent. Four distinct chronostratigraphic intervals reflect stages and steps in a transition from a relatively warm early Pliocene Antarctic coastal climate to modern cold polar conditions. Several of these stages and steps correlate with global events identified via geochemical proxy data recovered from deep ocean cores in mid to low latitudes. These correlations allow us to consider linkages between the high southern latitudes and tropical regions and establish a temporal framework to examine leads and lags in the climate system through the late Neogene and Quaternary. The relative influence of climate-tectonic feedbacks is discussed in light of glacial erosion and isostatic rebound that also influence the history along the Southern Victoria Land coastal margin.

(Table 2) Copepod carbon production in the upper 50 m in Godthabsfjord and Fyllas Banke, West Greenland

This study describes differences in plankton community structure and in chemical and physical gradients between the offshore West Greenland Current system and inland regions close to the Greenland Ice Sheet during the post-bloom in Godthabsfjorden (64° N, 51° W). The offshore region had pronounced vertical mixing, with centric diatoms and Phaeocystis spp. dominating the phytoplankton, chlorophyll (chl) a (0.3 to 3.9 µg/l) was evenly distributed and nutrients were depleted in the upper 50 m. Ciliates and heterotrophic dinoflagellates constituted equal parts of the protozooplankton biomass. Copepod biomass was dominated by Calanus spp. Primary production, copepod production and the vertical flux were high offshore. The water column was stratified in the fjord, causing chl a to be concentrated in a thin sub-surface layer. Nutrients were depleted above the pycnocline, and Thalassiosira spp. dominated the phytoplankton assemblage close to the ice sheet. Dinoflagellates dominated the protozooplankton biomass, whereas copepod biomass was low and was dominated by Pseudocalanus spp. and Metridia longa. Primary production was low in the outer part of the fjord but considerably higher in the inner parts of the fjord. Copepod production was exceeded by protozooplankton production in the fjord. The results of both physical/chemical factors and biological parameters suggest separation of offshore and fjord systems.

Under-ice fauna, sea-ice concentration, sea-ice thickness and under-ice water parameters from the Eurasian central Arctic Ocean during POLARSTERN cruise ARK-XXVII/3 (PS80) in August-September 2012

Arctic sea-ice decline is expected to have a significant impact on Arctic marine ecosystems. Ice-associated fauna play a key role in this context because they constitute a unique part of Arctic biodiversity and transmit carbon from sea-ice algae into pelagic and benthic food webs. Our study presents the first regional-scale record of under-ice faunal distribution and the environmental characteristics of under-ice habitats throughout the Eurasian Basin. Sampling was conducted with a Surface and Under-Ice Trawl, equipped with a sensor array recording ice thickness and other physical parameters during trawling. We identified 2 environmental regimes, broadly coherent with the Nansen and Amundsen Basins. The Nansen Basin regime was distinguished from the Amundsen Basin regime by heavier sea-ice conditions, higher surface salinities and higher nitrate + nitrite concentrations. We found a diverse (28 species) under-ice community throughout the Eurasian Basin. Change in community structure reflected differences in the relative contribution of abundant species. Copepods (Calanus hyperboreus and C. glacialis) dominated in the Nansen Basin regime. In the Amundsen Basin regime, amphipods (Apherusa glacialis, Themisto libellula) dominated. Polar cod Boreogadus saida was present throughout the sampling area. Abrupt changes from a dominance of ice-associated amphipods at ice-covered stations to a dominance of pelagic amphipods (T. libellula) at nearby ice-free stations emphasised the decisive influence of sea ice on small-scale patterns in the surface-layer community. The observed response in community composition to different environmental regimes indicates potential long-term alterations in Arctic marine ecosystems as the Arctic Ocean continues to change.

Bulk and amino acid parameters of core SO188-342KL from the Northern Bay of Bengal for the last 18 ka

The Northern Bay of Bengal (NBoB) is a globally important region for deep-sea organic matter (OM) deposition due to massive fluvial discharge from the Ganges-Brahmaputra-Meghna (G-B-M) rivers and moderate to high surface productivity. Previous studies have focused on carbon burial in turbiditic sediments of the Bengal Fan. However, little is known about the storage of carbon in pelagic and hemipelagic sediments of the Bay of Bengal over millennial time scales. This study presents a comprehensive history of OM origin and fate as well as a quantification of carbon sediment storage in the Eastern Bengal Slope (EBS) during the last 18 ka. Bulk organic proxies (TOC, TIC, TN, d13CTOC, d15NTN) and content and composition of total hydrolysable amino acids (THAA) in a sediment core (SO188-342KL) from the EBS were analyzed. Three periods of high OM accumulation were identified: the Late Glacial (LG), the Bölling/Alleröd (B/A), and the Early Holocene Climatic Optimum (EHCO). Lower eustatic sea level before 15 ka BP allowed a closer connection between the EBS and the fluvial debouch, favoring high terrestrial OM input to the core site. This connection was progressively lost between 15 and 7 ka BP as sea level rose to its present height and terrestrial OM input decreased considerably. Export and preservation of marine OM was stimulated during periods of summer monsoon intensification (B/A and EHCO) as a consequence of higher surface productivity enhanced by cyclonic-eddy nutrient pumping and fluvial nutrient delivery into the photic zone. Changes in the THAA composition indicate that the marine plankton community structure shifted from calcareous-dominated before 13 ka BP to siliceous-dominated afterwards. They also indicate that the relative proportion of marine versus terrestrial OM deposited at site 342KL was primarily driven by relative sea level and enlarged during the Holocene. The ballasting effect of lithogenic particles during periods of high coastal proximity and/or enhanced fluvial discharge promoted the export and preservation of OM. The high organic carbon accumulation rates in the EBS during the LG (18-17 ka BP) were 5-fold higher than at present and comparable to those of glacial upwelling areas. Despite the differences in sediment and OM transport and storage among the Western and Eastern sectors of the NBoB, this region remains important for global carbon sequestration during sea level low-stands. In addition, the summer monsoon was a key promotor of terrestrial and marine OM export to the deep-ocean, highlighting its relevance as regulator of the global carbon budget.

Juniperus navicularis - a study of Portuguese population structure and fitness

Juniperus navicularis Gand. is a dioecious endemic conifer that constitutes the understory of seaside pine forests in Portugal, areas currently threatened by increasing urban expansion. The aim of this study is to assess the conservation status of previously known populations of this species located on its core area of distribution. The study was performed in south-west coast of Portugal. Three populations varying in size and pine density were analyzed. Number of individuals, population density, spatial distribution and individual characteristics of junipers were estimated. Female cone, seed characteristics and seed viability were also evaluated. Results suggest that J. navicularis populations are vulnerable because seminal recruitment is scarce, what may lead to a reduction of genetic variability due solely to vegetative propagation. This vulnerability seems to be strongly determined by climatic constraints toward increasing aridity. Ratio between male and female shrubs did not differ from 1:1 in any population. Deviations from 1:1 between mature and non-mature plants were found in all populations, denoting population ageing. Very low seed viability was observed. A major part of described Juniperus navicularis populations have disappeared through direct habitat loss to urban development, loss of fitness in drier and warmer locations and low seed viability. This study is the first to address J. navicularis conservation, and represents a valuable first step toward this species preservation. 

The influence of balanced and imbalanced resource supply on biodiversity – functioning relationship across ecosystems

Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.

The influence of balanced and imbalanced resource supply on biodiversity – functioning relationship across ecosystems

Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.

GIS technologies and spatial organization patterns among hunter-gatherers: an archaeological case study from Southern Patagonia (southern South America)

This paper discusses some aspects of hunter-gatherer spatial organization in southern South Patagonia, in later times to 10,000 cal yr BP. Various methods of spatial analysis, elaborated with a Geographic Information System (GIS) were applied to the distributional pattern of archaeological sites with radiocarbon dates. The shift in the distributional pattern of chronological information was assessed in conjunction with other lines of evidence within a biogeographic framework. Accordingly, the varying degrees of occupation and integration of coastal and interior spaces in human spatial organization are explained in association with the adaptive strategies hunter-gatherers have used over time. Both are part of the same human response to changes in risk and uncertainty variability in the region in terms of resource availability and environmental dynamics.

Incised Pleistocene valleys in the Western Belgium coastal plain: Age, origins and implications for the evolution of the Southern North Sea Basin

The Belgian coastal plain occupies a key position as it is located at the transition between the Southern North Sea Basin and the Strait of Dover. It is characterized by thick sequences (> 20 m) of Pleistocene terrestrial and littoral sediments. Yet the wider stratigraphical and palaeo-environmental significance of these sediments received little attention. In this paper we draw on the results of a recent sedimentological study based on > 100 drillings that spans the Pleistocene sequence, and present new biostratigraphical (pollen, foraminifera, ostracods) data, all revealing a complex history of deposition. The record includes evidence of the development of incised-valley systems that were initiated in the late Middle and Late Pleistocene. Five phases of fluvial incision can be identified. The majority of the infills are deposited in an estuarine environment that passes into a fluvial environment land inward, except the Weichselian infill which has a predominant fluvial origin. The greatest part of the most seaward located zone of the western coastal plain was free of valley incisions, there, shallow marine sediments built up the record. Local biostratigraphical investigations provide a timeframe. The result is placed in a regional context.

Inverse Association Between Gluteofemoral Obesity and Risk of Barrett's Esophagus in a Pooled Analysis

BACKGROUND & AIMS: Gluteofemoral obesity (determined by measurement of subcutaneous fat in hip and thigh regions) could reduce risks of cardiovascular and diabetic disorders associated with abdominal obesity. We evaluated whether gluteofemoral obesity also reduces risk of Barrett's esophagus (BE), a premalignant lesion associated with abdominal obesity.

METHODS: We collected data from non-Hispanic white participants in 8 studies in the Barrett's and Esophageal Adenocarcinoma Consortium. We compared measures of hip circumference (as a proxy for gluteofemoral obesity) from cases of BE (n=1559) separately with 2 control groups: 2557 population-based controls and 2064 individuals with gastroesophageal reflux disease (GERD controls). Study-specific odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using individual participant data and multivariable logistic regression and combined using random effects meta-analysis.

RESULTS: We found an inverse relationship between hip circumference and BE (OR per 5 cm increase, 0.88; 95% CI, 0.81-0.96), compared with population-based controls in a multivariable model that included waist circumference. This association was not observed in models that did not include waist circumference. Similar results were observed in analyses stratified by frequency of GERD symptoms. The inverse association with hip circumference was only statistically significant among men (vs population-based controls: OR, 0.85; 95% CI, 0.76-0.96 for men; OR, 0.93; 95% CI, 0.74-1.16 for women). For men, within each category of waist circumference, a larger hip circumference was associated with decreased risk of BE. Increasing waist circumference was associated with increased risk of BE in the mutually adjusted population-based and GERD control models.

CONCLUSIONS: Although abdominal obesity is associated with increased risk of BE, there is an inverse association between gluteofemoral obesity and BE, particularly among men.