Search results for "Ocean"
showing 10 items of 2919 documents
Estimates for Divergence Velocities of Axially Moving Orthotropic Thin Plates
2014
Some models for axially moving orthotropic thin plates are investigated analytically via methods of complex analysis to derive estimates for critical plate velocities. Linearised Kirchhoff plate theory is used, and the energy forms of steady-state models are considered with homogeneous and inhomogeneous tension profiles in the cross direction of the plate. With the help of the energy forms, some limits for the divergence velocity of the plate are found analytically. In numerical examples, the derived lower limits for the divergence velocity are analysed for plates with small flexural rigidity. peerReviewed
Implementing ecosystem approach to fishery management: advances and new tools
2013
Desde la antigüedad, la pesca ha sido una fuente importante de alimentos para la humanidad, así como fuente de empleo y beneficios económicos para quienes se dedican a esta actividad. Sin embargo, con el aumento de los conocimientos científicos y la evolución dinámica de la pesca se hizo evidente de que los recursos acuáticos, aunque renovables, no eran infinitos y era necesario gestionar adecuadamente su contribución al bienestar nutricional, económico y el bienestar social de la población mundial para un crecimiento y desarrollo sostenible. En los últimos años, la pesca mundial se ha convertido en un sector dinámico y de desarrollo de la industria alimentaria. Los estados costeros han pro…
A Methodological Approach to Determine Sound Response Modalities to Coastal Erosion Processes in Mediterranean Andalusia (Spain)
2020
Human occupation along coastal areas has been greatly increasing in recent decades and, in many places, human activities and infrastructures are threatened by erosion processes that can produce relevant economic and human losses. In order to reduce such impacts and design sound management strategies, which can range from the &ldquo
Early Paleocene Paleoceanography and Export Productivity in the Chicxulub Crater
2021
The Chicxulub impact caused a crash in productivity in the world''s oceans which contributed to the extinction of ~75% of marine species. In the immediate aftermath of the extinction, export productivity was locally highly variable, with some sites, including the Chicxulub crater, recording elevated export production. The long-term transition back to more stable export productivity regimes has been poorly documented. Here, we present elemental abundances, foraminifer and calcareous nannoplankton assemblage counts, total organic carbon, and bulk carbonate carbon isotope data from the Chicxulub crater to reconstruct changes in export productivity during the first 3 Myr of the Paleocene. We sh…
Gulf of Maine shells reveal changes in seawater temperature seasonality during the Medieval Climate Anomaly and the Little Ice Age
2011
article i nfo In this study, we use subannually resolved oxygen isotope values of fossil (dead-collected) and modern (live- caught) bivalve shells (Arctica islandica L.) from the northwestern Atlantic (Gulf of Maine, USA) to reconstruct past seasonal changes in seawater temperature. Our results indicate decreased seasonal temperature amplitude of about 1.6 °C (or ∼21%) during Medieval times (ca. AD 1033-1062) compared to shells from the early Little Ice Age (ca. AD 1321-1391) and during the late 19th century (AD 1864-1886). Additionally, seasonal oxygen isotope data suggest that summers were cooler and winters were warmer in the Gulf of Maine during the 11th century compared to summers and …
Pachydema lopadusanorum n.sp. (Coleoptera Melolonthidae) from Lampedusa Island (Sicily Channel, Central Metditerranean Sea, Italy)
2018
In this paper the populations of Pachydema Castelnau, 1832 (Coleoptera Melolonthidae) living in Lampedusa Island (Sicily Channel, Central Mediterranean Sea, Italy), so far attributed to P. hirticollis (Fabricius, 1787) of North Africa, are examined. The comparison of the main morphological characters between these two populations allowed to attribute those of Lampedusa to a new species that is described in the present work. Faunistic and biological observations on these species are provided.
A survey of recent results in passive sampling of water and air by semipermeable membrane devices
1995
Abstract A survey is presented of some recent results for passive sampling of water and air for trace organic contaminants using lipid-filled semipermeable membrane devices (SPMDs). Results of water sampling for trace organochlorine compounds using simultaneously exposed SPMDs and the most universally applied biomonitor (bivalves) are discussed. In general, the total amounts of accumulated analytes available for analysis in bivalves and SPMDs were comparable. However, SPMD controls typically had negligible levels of contamination, which was not always the case for transplanted bivalves, even after prolonged depuration prior to exposure. In surveys of the spatial trends of organochlorines at…
The coralline red alga Lithophyllum kotschyanum f. affine as proxy of climate variability in the Yemen coast, Gulf of Aden (NW Indian Ocean)
2014
Abstract Recent investigations have shown the potential of red coralline algae as paleoclimatic archive. A previously unexplored subfamily of coralline algae, the Lithophylloideae, was investigated from the Gulf of Aden (Balhaf, Yemen). Seasonal changes in Mg/Ca, Li/Ca and Ba/Ca composition of Lithophyllum kotschyanum f. affine were investigated by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). For the first time in coralline algae, the Li/Ca composition was analyzed and showed a highly significant and positive correlation with Mg/Ca and SST. Monthly algal Mg/Ca and Li/Ca variations indicate a positive correlation with sea surface temperature (SST), and sea surface…
The community of Cystoseira brachycarpa J. Agardh emend. Giaccone (Fucales, Phaeophyceae) in a shallow hydrothermal vent area of the Aeolian Islands …
2014
A Cystoseira brachycarpa community from a vent area off Panarea Island (Italy) was investigated in two sites at different pH values. At low pH, species richness and coverage were low and the community displayed a reduced reproductive capacity. Conversely, at normal pH, dense canopies of fertile C. brachycarpa were found.
Can large branchiopods shape microcrustacean communities in Mediterranean temporary wetlands?
2011
It was recently suggested that large branchiopods may play a keystone role in temporary aquatic habitats. Using a microcosm experiment manipulating microcrustacean communities of Mediterranean temporary wetlands (Camargue, Southern France), we tested the following hypotheses: (i) large branchiopods (the notostracan Triops cancriformis and the anostracan Chirocephalus diaphanus) can limit microcrustacean densities through both competition and predation; (ii) notostracans create high suspended-matter concentrations through bioturbation, which can negatively impact microcrustaceans; and (iii) the outcome of these biotic interactions is more detrimental at high salinities. We found a strong pr…