Kannan, K.; Perrota, E.; Thomas, N.J.; Aldous, D.M.
Southern sea otters (Enhydra lutris nereis) from the California coast continue to exhibit a slower population regrowth rate than the population in Alaska. Infectious diseases have been identified as a frequent cause of death. Infectious diseases caused by varied pathogens including bacteria, fungi, and parasites were suggestive of compromised immunological health of mature animals in this population. To test the hypothesis that elevated exposure to immunotoxic contaminants such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) contribute to disease susceptibility via immunosuppression, we determined concentrations of PBDEs and PCBs in livers of 80 adult female sea otters that died of infectious diseases, noninfectious causes, or emaciation. Concentrations of PBDEs and PCBs in sea otter livers varied widely (10a??26,800 ng/g and 81a??210,000 ng/g, lipid weight, respectively). Concentrations of PBDEs in sea otters were some of the highest values reported for marine mammals so far. Although PCB concentrations in sea otters have declined during 1992a??2002, the mean concentration was at the threshold at which adverse health effects are elicited. Concentrations of PBDEs and PCBs were significantly correlated, suggesting co-exposure of these contaminants in sea otters. No significant association was found between the concentrations of PBDEs and the health status of sea otters. Concentrations of PCBs were significantly higher in otters in the infectious disease category than in the noninfectious category, suggesting an association between elevated PCB concentrations and infectious diseases in Southern sea otters.
Bedoya, Claudia A; Dreisigacker, Susanne; Hearne, Sarah; Franco, Jorge; Mir, Celine; Prasanna, Boddupalli M; Taba, Suketoshi; Charcosset, Alain; Warburton, Marilyn L
This study describes the genetic diversity and population structure of 194 native maize populations from 23 countries of Latin America and the Caribbean. The germplasm, representing 131 distinct landraces, was genetically characterized as population bulks using 28 SSR markers. Three main groups of maize germplasm were identified. The first, the Mexico and Southern Andes group, highlights the Pre-Columbian and modern exchange of germplasm between North and South America. The second group, Mesoamerica lowland, supports the hypothesis that two separate human migration events could have contributed to Caribbean maize germplasm. The third, the Andean group, displayed early introduction of maize into the Andes, with little mixing since then, other than a regional interchange zone active in the past. Events and activities in the pre- and post-Columbian Americas including the development and expansion of pre-Columbian cultures and the arrival of Europeans to the Americas are discussed in relation to the history of maize migration from its point of domestication in Mesoamerica to South America and the Caribbean through sea and land routes.
Curtis, Scott; Gamble, Douglas W.
Precipitation totals in the greater Caribbean are known to be affected by interannual variability. In particular, dry conditions in the spring-summer have been physically linked to the positive phase of North Atlantic Oscillation (NAO) in the literature. In this study, it was found through regression analysis that an active Madden-Julian Oscillation (MJO) in winter geographically focused over the Maritime Continent contributes to a positive NAO in March via the generation of Rossby waves in the Northern Hemisphere. Specifically, a negative Pacific-North American pattern develops in the winter and transitions to an Atlantic pattern in spring. The positive NAO is a transient feature of this evolving wave train, but a center of significant positive 200 hPa geopotential heights is entrenched over the southeast U.S. throughout the February to May time period and is manifested as high pressure at the surface. The southern flank of this system increases the speeds of the trade winds and leads to a cooling of the Caribbean sea surface temperatures and, thus, convection suppression and reduced precipitation. Thus, this study advances our understanding of the climate of the greater Caribbean by using climate teleconnections to relate the MJO to rainfall in the region.
Bedoya, Claudia A.; Dreisigacker, Susanne; Hearne, Sarah; Franco, Jorge; Mir, Celine; Prasanna, Boddupalli M.; Taba, Suketoshi; Charcosset, Alain; Warburton, Marilyn L.
This study describes the genetic diversity and population structure of 194 native maize populations from 23 countries of Latin America and the Caribbean. The germplasm, representing 131 distinct landraces, was genetically characterized as population bulks using 28 SSR markers. Three main groups of maize germplasm were identified. The first, the Mexico and Southern Andes group, highlights the Pre-Columbian and modern exchange of germplasm between North and South America. The second group, Mesoamerica lowland, supports the hypothesis that two separate human migration events could have contributed to Caribbean maize germplasm. The third, the Andean group, displayed early introduction of maize into the Andes, with little mixing since then, other than a regional interchange zone active in the past. Events and activities in the pre- and post-Columbian Americas including the development and expansion of pre-Columbian cultures and the arrival of Europeans to the Americas are discussed in relation to the history of maize migration from its point of domestication in Mesoamerica to South America and the Caribbean through sea and land routes. PMID:28403177
Daryabor, Farshid; Abu Samah, Azizan; Hai Ooi, See
The ecosystem off the east coast of Peninsular Malaysia is controlled by multiple physical processes during the monsoons (winter and summer) , including the air-sea interaction (such as net heat and surface freshwater fluxes), the small-scale eddies off the southern South China Sea (SSCS), and the monsoon wind induced coastal upwelling. Using high-resolution Regional Ocean Modeling System (ROMS), in-situ observations and remote sensing data, this paper attempts to study the hydrodynamics of the shelf and coastal processes as well as thermohaline circulation in response to changes in the hydrological seasonal cycle especially in the summer monsoon. In addition, we investigate its impacts on the spatial patterns of chlorophyll biomass which acts as a proxy for primary productivity in the SSCS. This study looks into not only the detailed small-scale-circulation such as localized eddies but also the link between the southern South China Sea and the Indian Ocean through the Straits of Malacca and the Java Sea. The flow through the Strait of Malacca and the Java Sea is not only important for navigational purpose but also has an influence on the seasonal spatial and temporal variations of primary productivity in the region. Keywords: southern South China Sea; summer monsoon; coastal upwelling; primary productivity
Fettweis, Michael; Nechad, Bouchra; Van den Eynde, Dries
A study is presented where satellite images (SeaWiFS), in situ measurements (tidal cycle and snapshot) and a 2D hydrodynamic numerical model have been combined to calculate the long term SPM (Suspended Particulate Matter) transport through the Dover Strait and in the southern North Sea. The total amount of SPM supplied to the North Sea through the Dover Strait is estimated to be 31.74×10 6 t. The satellite images provide synoptic views of SPM concentration distribution but do not take away the uncertainty of SPM transport calculation. This is due to the fact that SPM concentration varies as a function of tide, wind, spring-neap tidal cycles and seasons. The short term variations (tidal, spring-neap tidal cycle) have not been found in the satellite images, however seasonal variations are clearly visible. Furthermore the SPM concentration in the satellite images is generally lower than in the in situ measurements. The representativness of SPM concentration maps derived from satellites for calculating long term transports has therefore been investigated by comparing the SPM concentration variability from the in situ measurements with those of the remote sensing data. The most important constraints of satellite images are related to the fact that satellite data is evidence of clear sky conditions, whereas in situ measurements from a vessel can be carried out also during rougher meteorological conditions and that due to the too low time resolution of the satellite images the SPM concentration peaks are often missed. It is underlined that SPM concentration measurements should be carried out during at least one tidal cycle in high turbidity areas to obtain representative values of SPM concentration.
Al-Mikhlafi, Ahmed Saif; Edwards, Lawrence R.; Cheng, Hai
Results of U-series dating of late Pleistocene raised coral reef terraces from the Bab al-Mandab area, define two distinct groups: (1) well-preserved aragonitic fossil corals recorded from the Al-Hajaja terrace (Tr3) yield ages for last-interglacial period (LIG); and (2) calcitic fossil corals recovered from Perim Island terrace (Tr1) show varying degrees of U-series open system behavior and yield coral assemblage ages of LIG and older ages. Fossil corals from Tr1 are recrystallized corals, have anomalously high initial δ234U ranged from (152 ± 2‰ to 287 ± 7‰), corresponding to ages of ∼120 ka and ∼406 ka, respectively. Applying age reliability criteria on the current data suggest majority of the ages cannot be considered reliable and all are suspected for open system behavior associated with U loss/addition that significantly affects the 230Th/U ages. The diagenesis shown by these corals occurred probably due to extensive interaction of fossil corals with freshwater during the wet periods prevailed in southern Arabia coeval with the African monsoon, which led to U loss. Post-depositional U loss suggest (230Th/238U) increase, which shift the U-Th ages to unexpectedly higher levels as it is shown here. Measured elevation at the Al-Hajaja terrace (Tr3) is ∼4 ± 2 m above present sea level (apsl) consistent with eustatic sea level changes and indicates that the Bab al-Mandab area is stable at least since the LIG period. The Perim Island terrace (Tr1) is at elevation of 7 ± 2 m apsl; its reef yields diageneticaly-altered corals of multiple ages and cannot be used for sea level reconstructions.
Lu, Yin; Waldmann, Nicolas; Nadel, Dani; Marco, Shmuel
In addition to tectonics and climatic changes, humans have exerted a significant impact on surface erosion over timescales ranging from years to centuries. However, such kind of impact over millennial timescales remains unsubstantiated. The Dead Sea drainage basin offers a rare combination of well-documented substantial climate change, intense tectonics and abundant archaeological evidence for past human activity in the Southern Levant. It serves as a natural laboratory for understanding how sedimentation rates in a deep basin are related to climate change, tectonics, and anthropogenic impacts on the landscape. Here we show how basin-wide erosion rates are recorded by thicknesses of rhythmic detritus laminae and clastic sediment accumulation rates in a long core retrieved by the Dead Sea Deep Drilling Project in the Dead Sea depocenter. During the last 11.5 kyr the average detrital accumulation rate is 3-4 times that during the last two glacial cycles (MIS 7c-2), and the average thickness of detritus laminae in the last 11.6 kyr is 4.5 times that between 21.7 and 11.6 ka, implying an increased erosion rate on the surrounding slopes during the Holocene. We estimate that this intensified erosion is incompatible with tectonic and climatic regimes during the corresponding time interval and further propose a close association with the Neolithic Revolution in the Levant (beginning at 11.5 ka). We thus suggest that human impact on the landscape was the primary driver causing the intensified erosion and that the Dead Sea sedimentary record serves as a reliable recorder of this impact since the Neolithic Revolution.
Wolff, George A.; Billett, David S. M.; Bett, Brian J.; Holtvoeth, Jens; FitzGeorge-Balfour, Tania; Fisher, Elizabeth H.; Cross, Ian; Shannon, Roger; Salter, Ian; Boorman, Ben; King, Nicola J.; Jamieson, Alan; Chaillan, Frédéric
The addition of iron to high-nutrient low-chlorophyll (HNLC) oceanic waters stimulates phytoplankton, leading to greater primary production. Large-scale artificial ocean iron fertilization (OIF) has been proposed as a means of mitigating anthropogenic atmospheric CO2, but its impacts on ocean ecosystems below the photic zone are unknown. Natural OIF, through the addition of iron leached from volcanic islands, has been shown to enhance primary productivity and carbon export and so can be used to study the effects of OIF on life in the ocean. We compared two closely-located deep-sea sites (∼400 km apart and both at ∼4200 m water depth) to the East (naturally iron fertilized; +Fe) and South (HNLC) of the Crozet Islands in the southern Indian Ocean. Our results suggest that long-term geo-engineering of surface oceanic waters via artificial OIF would lead to significant changes in deep-sea ecosystems. We found that the +Fe area had greater supplies of organic matter inputs to the seafloor, including polyunsaturated fatty acid and carotenoid nutrients. The +Fe site also had greater densities and biomasses of large deep-sea animals with lower levels of evenness in community structuring. The species composition was also very different, with the +Fe site showing similarities to eutrophic sites in other ocean basins. Moreover, major differences occurred in the taxa at the +Fe and HNLC sites revealing the crucial role that surface oceanic conditions play in changing and structuring deep-sea benthic communities. PMID:21695118
Ciesielski, Tomasz; Góral, Marta; Szefer, Piotr; Jenssen, Bjørn Munro; Bojanowski, Ryszard
This study provides information on baseline concentrations of the radionuclides Cesium-137, Potassium-40 and Polonium-210 in sea mammals from the Baltic Sea. The radionuclides were analyzed in the liver, kidney and muscle of harbor porpoises, striped dolphins, and gray and ringed seals from the Polish coast by γ- and α-spectrometry. Median (137)Cs activities were 14.8, 13.2 and 23.2 Bq kg(-1) w.w. in the liver, kidney and muscles, respectively. Activities of (40)K and (210)Po in the respective tissues were found to be 79.1, 79.8 and 111 Bq kg(-1) for (40)K and 58.1, 59.2 and 32.9 Bq kg(-1) for (210)Po. The measured (137)Cs concentrations were extraordinarily high in comparison to those reported in sea mammals from other locations. However, dose assessments did not imply health effects from (137)Cs exposure in Baltic Sea mammals. Correlations between (137)Cs tissue activities and reported sea water concentrations highlight the potential use of marine mammals for biomonitoring purposes. Copyright © 2015 Elsevier Ltd. All rights reserved.
Sprenk, D.; Weber, M. E.; Kuhn, G.; Rosén, P.; Röhling, H.-G.
The Southern Ocean plays an important role in transferring CO2 via wind-induced upwelling from the deep sea to the atmosphere. It is therefore one of the key areas to study climate change. Bioproductivity in the Southern Ocean is mostly influenced by the extent of sea ice, upwelling of cold nutrient- and silica-rich water, and the availability of light. Biogenic opal (BSi) is a significant nutrient in the Southern Ocean, and according to recent investigations only marginally affected by preservation changes. It can therefore be used as bioproductivity proxy. Here we present several methods to determine BSi, discuss them and put the results into context with respect to regional bioproductivity changes in Southern Ocean during the last glacial cycle. We studied deep-sea sediment core sites MD07-3133 and MD07-3134 from the central Scotia Sea with extraordinary high sedimentation rates of up to 2.1 to 1.2 m/kyr, respectively covering the last 92.5 kyr. BSi leaching according to Müller & Schneider (1993) is very time-consuming and expensive, so we measured only 253 samples from large-amplitude variation core sections. In addition, we determined BSi using non-destructive measurements of sediment colour b*, wet-bulk density, and Ti/Si count ratios. Furthermore, we provide the first attempts to estimate BSi in marine sediment using Fourier transform infrared spectroscopy (FTIRS), a cost-efficient method, which requires only 11 mg of sediment. All estimation methods capture the main BSi trends, however FTIRS seems to be the most promising one. In the central Scotia Sea, south of the modern Antarctic Polar Front, the BSi flux reflects a relatively complicated glacial-to-interglacial pattern with large-amplitude, millennial-scale fluctuations in bioproductivity. During Antarctic Isotopic Maxima, BSi fluxes were generally increased. Lowest bioproductivity occur at the Last Glacial Maximum, while upwelling of mid-depth water was reduced, atmospheric CO2 low, and sea-ice cover
Tinker, M. Tim; Tomoleoni, Joseph; LaRoche, Nicole; Bowen, Lizabeth; Miles, A. Keith; Murray, Mike; Staedler, Michelle; Randell, Zachary
The re-colonization of the Santa Barbara channel by sea otters brings these ESA-listed marine mammals closer to active oil and gas production facilities, shipping lanes and naturally occurring oil and gas seeps. However, the degree to which sea otters may actually be affected by human-caused oil spills or exposure to natural oil seeps is currently unknown. Between 2012 and 2014, the U.S. Geological Survey and collaborating agencies conducted a telemetry-based study of sea otters in Santa Barbara channel, in order to provide critical information for resource managers (specifically the Bureau of Ocean Energy Management, henceforth BOEM, and the U.S. Fish and Wildlife Service, henceforth USFWS) about the spatial ecology, population status, and potential population threats to sea otters in Santa Barbara Channel, with particular reference to exposure to manmade structures and sources of oil and natural gas. Analysis of spatial monitoring data using a Bayesian-based synoptic model allowed for description of sea otter home ranges, identification of hot-spots of use, and insights into habitat selection behavior by male and female sea otters. Important findings included the deeper modal depth preferred by males versus females, strong preferences by both sexes for areas with persistent kelp canopy, and greater use of soft-sediment areas by males. The synoptic model also provided the ability to predict population-level density distribution for each sex in new habitats: by calculating the value of these probability density distributions at the known locations of natural seeps, we were able to identify those seeps with higher potential for sea otter encounters. The relative probability of occurrence at locations near to some seeps was sufficiently high (about 1% likelihood of occurrence for some of our study animals) that one would anticipate occasional encounters. Data on male and female survival, reproductive success, activity budgets, and body condition all indicated that
Drinkwater, M.; Early, D.; Long, D.
Coregistered ERS-1 SAR and Scatterometer data are presented for the Weddell Sea, Antarctica. Calibrated image backscatter statistics are extracted from data acquired in regions where surface measurements were made during two extensive international Weddell Sea experiments in 1992. Changes in summer ice-surface conditions, due to temperature and wind, are shown to have a large impact on observed microwave backscatter values. Winter calibrated backscatter distributions are also investigated as a way of describing ice thickness conditions in different location during winter. Coregistered SAR and EScat data over a manned drifting ice station are used to illustrate the seasonal signature changes occurring during the fall freeze-up transition.
Shinn, E.A.; Smith, G.W.; Prospero, J.M.; Betzer, P.; Hayes, M.L.; Garrison, V.; Barber, R.T.
The vitality of Caribbean coral reefs has undergone a continual state of decline since the late 1970s, a period of time coincidental with large increases in transatlantic dust transport. It is proposed that the hundreds of millions of tons/year of soil dust that have been crossing the Atlantic during the last 25 years could be a significant contributor to coral reef decline and may be affecting other ecosystems. Benchmark events, such as near synchronous Caribbean-wide mortalities of acroporid corals and the urchin Diadema in 1983, and coral bleaching beginning in 1987, correlate with the years of maximum dust flux into the Caribbean. Besides crustal elements, in particular Fe, Si, and aluminosilicate clays, the dust can serve as a substrate for numerous species of viable spores, especially the soil fungus Aspergillus. Aspergillus sydowii, the cause of an ongoing Caribbean-wide seafan disease, has been cultured from Caribbean air samples and used to inoculate sea fans.
Devriese, Lisa I; van der Meulen, Myra D; Maes, Thomas; Bekaert, Karen; Paul-Pont, Ika; Frère, Laura; Robbens, Johan; Vethaak, A Dick
This study assessed the capability of Crangon crangon (L.), an ecologically and commercially important crustacean, of consuming plastics as an opportunistic feeder. We therefore determined the microplastic content of shrimp in shallow water habitats of the Channel area and Southern part of the North Sea. Synthetic fibers ranging from 200μm up to 1000μm size were detected in 63% of the assessed shrimp and an average value of 0.68±0.55microplastics/g w. w. (1.23±0.99microplastics/shrimp) was obtained for shrimp in the sampled area. The assessment revealed no spatial patterns in plastic ingestion, but temporal differences were reported. The microplastic uptake was significantly higher in October compared to March. The results suggest that microplastics >20μm are not able to translocate into the tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.
Sorlien, C. C.; Seeber, L.; Diebold, J.; Shillington, D.; Steckler, M. S.; Gurcay, S.; Kucuk, H. M.; Akhun, S. D.; Timur, D.; Dondurur, D.; Kurt, H.; Perincek, E.; Ozer, P.; Imren, C.; Coskun, S.; Buyukasik, E.; Cevatoglu, M.; Cifci, G.; Demirbag, E.
We collected high-resolution multichannel seismic reflection (MCS) and chirp seismic data across the North Anatolian Fault (NAF) system in the Marmara Sea aboard the R/V K. Piri Reis during July 2008. Three 1200+ m-deep bathymetric basins are arrayed along the North strand of the NAF. This strand passes closest to Istanbul and is considered to carry most of the current and late Holocene plate motion, but other strands to the south are active and may have been more important in the past. The transverse Central Marmara Ridge, formed by a contractional anticline, separates two of the basins. Filled sedimentary basins underlie the southern shelf, and, adjacent to that shelf, the partly-filled North Imrali basin underlies a 400 m-deep platform. Our chirp data image several strands of the southern fault system, 50 km south of the northern NAF on the inner (southern) shelf, that offset strata which postdate the ~12 ka marine transgression. Another W-striking fault that deforms post-12 ka strata cuts the mid-southern shelf. A WNW-striking segment of the Imrali fault system is associated with normal-separation, 300 m-high sea floor scarps that separate the shelf from the North Imrali basin. This basin is cut by numerous NW-striking normal-separation faults, some deforming the sea floor. At least 4 complexes of shelf edge deltas, whose tops were formed near sea level or lake level, are stacked between 500 and 900 m depth in this downthrown block of the Imrali fault. The originally sub- horizontal tops of each delta are now locally progressively tilted and folded near an ENE-striking branch of the Imrali fault (known as the Yalova fault). Lacking stratigraphic control, we infer that the deltas represent glacial intervals spaced at 100 ka during the late Pleistocene. Assuming a locally constant subsidence rate, with lowstands near -90 m, and the observed 130 m vertical spacing between the deltas, subsidence rates would be ~1.3 mm/yr, and the youngest well-preserved delta would
Crise, A; Kaberi, H; Ruiz, J; Zatsepin, A; Arashkevich, E; Giani, M; Karageorgis, A P; Prieto, L; Pantazi, M; Gonzalez-Fernandez, D; Ribera d’Alcalà, M; Tornero, V; Vassilopoulou, V; Durrieu de Madron, X; Guieu, C; Puig, P; Zenetos, A; Andral, B; Angel, D; Altukhov, D; Ayata, S D; Aktan, Y; Balcıoğlu, E; Benedetti, F; Bouchoucha, M; Buia, M-C; Cadiou, J-F; Canals, M; Chakroun, M; Christou, E; Christidis, M G; Civitarese, G; Coatu, V; Corsini-Foka, M; Cozzi, S; Deidun, A; Dell’Aquila, A; Dogrammatzi, A; Dumitrache, C; Edelist, D; Ettahiri, O; Fonda-Umani, S; Gana, S; Galgani, F; Gasparini, S; Giannakourou, A; Gomoiu, M-T; Gubanova, A; Gücü, A-C; Gürses, Ö; Hanke, G; Hatzianestis, I; Herut, B; Hone, R; Huertas, E; Irisson, J-O; İşinibilir, M; Jimenez, J A; Kalogirou, S; Kapiris, K; Karamfilov, V; Kavadas, S; Keskin, Ç; Kideyş, A E; Kocak, M; Kondylatos, G; Kontogiannis, C; Kosyan, R; Koubbi, P; Kušpilić, G; La Ferla, R; Langone, L; Laroche, S; Lazar, L; Lefkaditou, E; Lemeshko, I E; Machias, A; Malej, A; Mazzocchi, M-G; Medinets, V; Mihalopoulos, N; Miserocchi, S; Moncheva, S; Mukhanov, V; Oaie, G; Oros, A; Öztürk, A A; Öztürk, B; Panayotova, M; Prospathopoulos, A; Radu, G; Raykov, V; Reglero, P; Reygondeau, G; Rougeron, N; Salihoglu, B; Sanchez-Vidal, A; Sannino, G; Santinelli, C; Secrieru, D; Shapiro, G; Simboura, N; Shiganova, T; Sprovieri, M; Stefanova, K; Streftaris, N; Tirelli, V; Tom, M; Topaloğlu, B; Topçu, N E; Tsagarakis, K; Tsangaris, C; Tserpes, G; Tuğrul, S; Uysal, Z; Vasile, D; Violaki, K; Xu, J; Yüksek, A; Papathanassiou, E
PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
Brothers, Daniel Stephen
Five studies along the Pacific-North America (PA-NA) plate boundary offer new insights into continental margin processes, the development of the PA-NA tectonic margin and regional earthquake hazards. This research is based on the collection and analysis of several new marine geophysical and geological datasets. Two studies used seismic CHIRP surveys and sediment coring in Fallen Leaf Lake (FLL) and Lake Tahoe to constrain tectonic and geomorphic processes in the lakes, but also the slip-rate and earthquake history along the West Tahoe-Dollar Point Fault. CHIRP profiles image vertically offset and folded strata that record deformation associated with the most recent event (MRE). Radiocarbon dating of organic material extracted from piston cores constrain the age of the MRE to be between 4.1–4.5 k.y. B.P. Offset of Tioga aged glacial deposits yield a slip rate of 0.4–0.8 mm/yr. An ancillary study in FLL determined that submerged, in situ pine trees that date to between 900-1250 AD are related to a medieval megadrought in the Lake Tahoe Basin. The timing and severity of this event match medieval megadroughts observed in the western United States and in Europe. CHIRP profiles acquired in the Salton Sea, California provide new insights into the processes that control pull-apart basin development and earthquake hazards along the southernmost San Andreas Fault. Differential subsidence (>10 mm/yr) in the southern sea suggests the existence of northwest-dipping basin-bounding faults near the southern shoreline. In contrast to previous models, the rapid subsidence and fault architecture observed in the southern part of the sea are consistent with experimental models for pull-apart basins. Geophysical surveys imaged more than 15 ˜N15°E oriented faults, some of which have produced up to 10 events in the last 2-3 kyr. Potentially 2 of the last 5 events on the southern San Andreas Fault (SAF) were synchronous with rupture on offshore faults, but it appears that ruptures on
Schneider, Simon; Jager, Manfred; Kroh, Andreas; Mitterer, Agnes; Niebuhr, Birgit; Vodrazka, Radek; Wilmsen, Markus; Wood, Christopher J.; Zagorsk, Kamil
Schneider, S., Jager, M., Kroh, A., Mitterer, A., Niebuhr, B., Vodražka, R., Wilmsen, M., Wood, C.J. and Zagoršek, K. 2013. Silicified sea life – Macrofauna and palaeoecology of the Neuburg Kieselerde Member (Cenomanian to Lower Turonian Wellheim Formation, Bavaria, southern Germany). Acta Geologica Polonica, 63(4), 555-610. Warszawa. With approximately 100 species, the invertebrate macrofauna of the Neuburg Kieselerde Member of the Wellheim Formation (Bavaria, southern Germany) is probably the most diverse fossil assemblage of the Danubian Cretaceous Group. Occurring as erosional relicts in post-depositional karst depressions, both the Cretaceous sediments and fossils have been silicified during diagenesis. The Neuburg Kieselerde Member, safely dated as Early Cenomanian to Early Turonian based on inoceramid bivalve biostratigraphy and sequence stratigraphy, preserves a predominantly soft-bottom community, which, however, is biased due to near-complete early diagenetic loss of aragonitic shells. The community is dominated by epifaunal and semi-infaunal bivalves as well as sponges that settled on various (bio-) clasts, and may widely be split into an early bivalve-echinoid assemblage and a succeeding sponge-brachiopod assemblage. In addition to these groups we document ichnofauna, polychaete tubes, nautilids and bryozoans. The fauna provides evidence of a shallow to moderately deep, calm, fully marine environment, which is interpreted as a largescale embayment herein. The fauna of the Neuburg Kieselerde Member is regarded as an important archive of lower Upper Cretaceous sea-life in the surroundings of the Mid-European Island.
Neukermans, Griet; Ruddick, Kevin; Bernard, Emilien; Ramon, Didier; Nechad, Bouchra; Deschamps, Pierre-Yves
Geostationary ocean colour sensors have not yet been launched into space, but are under consideration by a number of space agencies. This study provides a proof of concept for mapping of Total Suspended Matter (TSM) in turbid coastal waters from geostationary platforms with the existing SEVIRI (Spinning Enhanced Visible and InfraRed Imager) meteorological sensor on the METEOSAT Second Generation platform. Data are available in near real time every 15 minutes. SEVIRI lacks sufficient bands for chlorophyll remote sensing but its spectral resolution is sufficient for quantification of Total Suspended Matter (TSM) in turbid waters, using a single broad red band, combined with a suitable near infrared band. A test data set for mapping of TSM in the Southern North Sea was obtained covering 35 consecutive days from June 28 until July 31 2006. Atmospheric correction of SEVIRI images includes corrections for Rayleigh and aerosol scattering, absorption by atmospheric gases and atmospheric transmittances. The aerosol correction uses assumptions on the ratio of marine reflectances and aerosol reflectances in the red and near-infrared bands. A single band TSM retrieval algorithm, calibrated by non-linear regression of seaborne measurements of TSM and marine reflectance was applied. The effect of the above assumptions on the uncertainty of the marine reflectance and TSM products was analysed. Results show that (1) mapping of TSM in the Southern North Sea is feasible with SEVIRI for turbid waters, though with considerable uncertainties in clearer waters, (2) TSM maps are well correlated with TSM maps obtained from MODIS AQUA and (3) during cloud-free days, high frequency dynamics of TSM are detected.