Search results for "assemblage"
showing 10 items of 143 documents
Mediterranean bioconstructions along the Italian coast
2018
Marine bioconstructions are biodiversity-rich, three-dimensional biogenic structures, regulating key ecological functions of benthic ecosystems worldwide. Tropical coral reefs are outstanding for their beauty, diversity and complexity, but analogous types of bioconstructions are also present in temperate seas. The main bioconstructions in the Mediterranean Sea are represented by coralligenous formations, vermetid reefs, deep-sea cold-water corals, Lithophyllum byssoides trottoirs, coral banks formed by the shallow-water corals Cladocora caespitosa or Astroides calycularis, and sabellariid or serpulid worm reefs. Bioconstructions change the morphological and chemicophysical features of prima…
Mediterranean rocky reefs in the Anthropocene: Present status and future concerns
2021
Global change is striking harder and faster in the Mediterranean Sea than elsewhere, where high levels of human pressure and proneness to climate change interact in modifying the structure and disrupting regulative mechanisms of marine ecosystems. Rocky reefs are particularly exposed to such environmental changes with ongoing trends of degradation being impressive. Due to the variety of habitat types and associated marine biodiversity, rocky reefs are critical for the functioning of marine ecosystems, and their decline could profoundly affect the provision of essential goods and services which human populations in coastal areas rely upon. Here, we provide an up-to-date overview of the statu…
Italian marine reserve effectiveness: does enforcement matter?
2008
Marine protected areas (MPAs) have become popular tools worldwide for ecosystem conservation and fishery management. Fish assemblages can benefit from protection provided by MPAs, especially those that include fully no-take reserves. Fish response to protection can thus be used to evaluate the effectiveness of marine reserves. Most target fish are high-level predators and their overfishing may affect entire communities through trophic cascades. In the Mediterranean rocky sublittoral, marine reserves may allow fish predators of sea urchins to recover and thus whole communities to be restored from coralline barrens to macroalgae. Such direct and indirect reserve effects, however, are likely t…
Etude d'un emmanchement fretté compte tenu de l'effet combiné des défauts de forme et d'état de surface
2012
The main purpose of this thesis is to present two contributions in the field of shrink fitassembly taking into account the defects of form and roughness surfaces. The first contributionconcerns the study of the influence of the defect forme on the characteristics of shrinked assemblyusing an approach based on finite element modeling. We found that this defect has a significantinfluence on the resistance of the assembly. The work already done in the laboratory of mechanicsat the University of Bourgogne have been confirmed. In the second contribution, we proposed tointegrate the surface defects (roughness) by creating a homogenized finite element interface. Thistechnique has facilitated the m…
Santa Rosalia, the icon of biodiversity
2010
This article summarizes the results presented in a series of invited contributions which were submitted to celebrate the fiftieth anniversary of publication of the seminal article ‘‘Homage to Santa Rosalia or why are there so many kinds of animals’’ by G.E. Hutchinson. The authors were asked to explore old and new paradigms of biodiversity in aquatic ecosystems. The contributions by Hutchinson in this field are truly landmarks in the history of modern ecological sciences. The authors of the contributed articles, stimulated by one of the most fruitful concept articles in ecology that has appeared over the last half century, have shown that scientific investigation, although still seeking the…
Performative Regional (dis)Integration: Transnational Markets, Mobile Commodities, and Bordered North–South Differences
2011
Being implicated in an ambivalent play of both border crossing and drawing, global commodity chains are an ideal organizational field to analyze the fundamental paradox of global connectivity. Approaching the contingency of borders from a perspective informed by the performativity approach to markets, this paper starts from the assumption that this paradox is particularly salient in the context of commodity chains which connect the Global South with the Global North. Taking the example of one single agrocommodity, the tomato, and two border regions (Morocco–EU and Mexico–USA), we follow the links and heterogeneous associations which stretch from the border to the fields, supermarket shelves…
Dissimilar joining of copper to stainless steel and TA6V to stainless steel by high power beams : understanding and modeling of physicochemical pheno…
2010
The present study is dedicated to the comprehension of the mechanism of materials mixing during dissimilar welding by high power beam sources. We have been interested in joining of two couples of metallic materials which present different metallurgical problems: •copper- stainless steel (miscibility gap, important difference in physical properties);•TA6V- stainless steel (oxidation on air, formation of intermetallic phases which made the joint brittle).For the first couple of materials, continuous laser Nd:YAG welding and electron beam welding have been applied. The experimental study of morphology evolution, composition, microstructure and mechanical properties has allowed establishing the…
Into the world of e-waste: mobility among e-scrappers in Nigeria
2017
AbstractIn the management of e-waste, mobility of e-scrappers plays a pivotal role, especially in e-waste acquisition and sales of extracted materials. This research examines the relationship between e-scrappers and the locations of their work by analysing the influence of environmental and social factors on their mobility behaviour in Nigeria. A qualitative analysis of video material collected from 29 male e-scrappers in Nigeria between 2014 and 2015 reveals that e-waste has inherent properties that intermittently mobilise e-scrappers to search for recyclable and valuable electronic trash. Applying the new mobilities paradigm and the new materialism theory, we present that e-scrappers’ mob…
Gastropod evidence against the Early Triassic Lilliput effect
2010
4 pages; International audience; Size reduction in the aftermath of the Permian-Triassic mass extinction event has repeatedly been described for various marine organisms, including gastropods (the Lilliput effect). A Smithian gastropod assemblage from Utah, USA, reveals numerous large-sized specimens of different genera as high as 70 mm, the largest ever reported from the Early Triassic. Other gastropods reported from Serbia and Italy are also as large as 35 mm. Size frequency distributions of the studied assemblages indicate that they were not unusually small when compared with later Mesozoic and modern faunas. The occurrence of large-sized gastropods less than 2 Ma after the Permian-Trias…
A late Permian ichthyofauna from the Zechstein Basin, Lithuania-Latvia Region
2019
AbstractThe late Permian is a transformative time, which ended in one of the most significant extinction events in Earth’s history. Fish assemblages are a major component of marine foods webs. The macroevolution and biogeographic patterns of late Permian fish are currently insufficiently known. In this contribution, the late Permian fish fauna from Kūmas quarry (southern Latvia) is described for the first time. As a result, the studied late Permian Latvian assemblage consisted of isolated chondrichthyan teeth ofHelodussp., ?Acrodussp., ?Omanoselachesp. and euselachian type dermal denticles as well as many osteichthyan scales of the Haplolepidae and Elonichthydae; numerous teeth ofPalaeonisc…