Environmental context explains Lévy and Brownian movement patterns of marine predators

An optimal search theory, the so-called Levy-flight foraging hypothesis(1), predicts that predators should adopt search strategies known as Levy flights where prey is sparse and distributed unpredictably, but that Brownian movement is sufficiently efficient for locating abundant prey(2-4). Empirical studies have generated controversy because the accuracy of statistical methods that have been used to identify Levy behaviour has recently been questioned(5,6). Consequently, whether foragers exhibit Levy flights in the wild remains unclear. Crucially, moreover, it has not been tested whether observed movement patterns across natural landscapes having different expected resource distributions conform to the theory's central predictions. Here we use maximum-likelihood methods to test for Levy patterns in relation to environmental gradients in the largest animal movement data set assembled for this purpose. Strong support was found for Levy search patterns across 14 species of open-ocean predatory fish (sharks, tuna, billfish and ocean sunfish), with some individuals switching between Levy and Brownian movement as they traversed different habitat types. We tested the spatial occurrence of these two principal patterns and found Levy behaviour to be associated with less productive waters (sparser prey) and Brownian movements to be associated with productive shelf or convergence-front habitats (abundant prey). These results are consistent with the Levy-flight foraging hypothesis(1,7), supporting the contention(8,9) that organism search strategies naturally evolved in such a way that they exploit optimal Levy patterns.

The effect of ocean acidification on carbon storage and sequestration in seagrass beds; a global and UK context

Ocean acidification will have many negative consequences for marine organisms and ecosystems, leading to a decline in many ecosystem services provided by the marine environment. This study reviews the effect of ocean acidification (OA) on seagrasses, assessing how this may affect their capacity to sequester carbon in the future and providing an economic valuation of these changes. If ocean acidification leads to a significant increase in above- and below-ground biomass, the capacity of seagrass to sequester carbon will be significantly increased. The associated value of this increase in sequestration capacity is approximately 500 and 600 billion globally between 2010 and 2100. A proportionally similar increase in carbon sequestration value was found for the UK. This study highlights one of the few positive stories for ocean acidification and underlines that sustainable management of seagrasses is critical to avoid their continued degradation and loss of carbon sequestration capacity.

There are no whole truths in meta-analyses: all their truths are half truths

In a recent letter, Thomsen & Wernberg (2015) rean-alyzed data compiled for our recent paper (Lyonset al., 2014). In that paper, we examined the effectsof macroalgal blooms and macroalgal mats on sevenimportant measures of community structure and eco-system functioning and explored several ecologicaland methodological factors that might explain someof the variation in the observed effects. Thomsen &Wernberg (2015) re-analyzed two small subsets of the data, focusing on experimental studies examining effects of blooms/mats on invertebrate abundance.Their analyses revealed two interesting patterns.First, they showed that macroalgal blooms reducedthe abundance of communities that Thomsen andWernberg categorized as ‘mainly infauna’, whileincreasing the abundance of communities categorized as ‘mainly epifauna’. Second, they showed that theimpacts of macroalgal blooms on ‘mainly infauna’communities increased with algal density in experiments that included multiple levels of algal density.These findings, as well as the conclusions that Thomsen & Wernberg (2015) draw from them, are largely consistent with our own expectations and interpretations. However, we also feel that some caution is required when interpreting the results of their analyses.

Relationships between biodiversity and the stability of marine ecosystems: comparisons at a European scale using meta-analysis.

The relationship between biodiversity and stability of marine benthic assemblages was investigated using existing data sets (n = 28) covering various spatial (m-km) and temporal (1973-2006) scales in different benthic habitats (emergent rock, rock pools and sedimentary habitats) through meta-analyses. Assemblage stability was estimated by measuring temporal variances of species richness, total abundance (density or % cover) and community species composition and abundance structure (using multivariate analyses). Positive relationships between temporal variability in species number and richness were generally observed at both quadrat (<1 m2) and site (100 m2) scales, while no relationships were observed by multivariate analyses. Positive relationships were also observed at the scale of site between temporal variability in species number and variability in community structure with evenness estimates. This implies that the relationship between species richness or evenness and species richness variability is slightly positive and depends on the scale of observation, suggesting that biodiversity per se is important for the stability of ecosystems. Changes within community assemblages in terms of structure are, however, generally independent of biodiversity, suggesting no effect of diversity, but the potential impact of individual species, and/or environmental factors. Except for sedimentary and rock pool habitats, no relationship was observed between temporal variation of the aggregated variable of total abundances and diversity at either scale. Overall our results emphasise that relationships depend on scale of measurements, type of habitats and the marine systems (North Atlantic and Mediterranean) considered.

La Web Semántica y los archivos de televisión: estado de la cuestión

Se analizan y describen las principales líneas de trabajo de la Web Semántica en el ámbito de los archivos de televisión. Para ello, se analiza y contextualiza la web semántica desde una perspectiva general para posteriormente analizar las principales iniciativas que trabajan con lo audiovisual: Proyecto MuNCH, Proyecto S5T, Semantic Television y VideoActive.

Andrew Marvell's Latin Poetry: From Text to Context (356pp.)

David Norbrook, Review of English Studies 56 (Sept. 2005), 675-6.
‘We have waited a long time for a study of Marvell’s Latin poetry; fortunately, Estelle Haan’s monograph generously makes good the loss ... One of her most intriguing suggestions … is that Marvell may have presented paired poems like ‘Ros’ and ‘On a Drop of Dew’, and the poems to the obligingly named Dr Witty, to his student Maria Fairfax as his own patterns for the pedagogical practice of double translation. Perhaps the most original parts of the book, however, move beyond the familiar canon to cover the generic range of the Latin verse. Haan offers a very full contextualization of the early Horatian Ode to Charles I in seventeenth-century exercises in parodia. In a rewarding reading of the poem to Dr Ingelo she shows how Marvell deploys the language of Ovid’s Tristia to present Sweden as a place of shivering exile, only to subvert this model with a neo-Virgilian celebration of Christina as a virtuous, city-building Dido. She draws extensively on historical as well as literary sources to offer very detailed contextualizations of the poem to Maniban and ‘Scaevola Scotto-Britannus’... This monograph opens up many new ways into the Latin verse, not least because it is rounded off with new texts and prose translations of the Latin poems. These make a substantial contribution in their own right. They are the best and most accurate translations to date (those in Smith’s edition having some lapses); they avoid poeticisms but bring out the structure of the poems' wordplay very clearly. This book brings us a lot closer to seeing Marvell whole.'

The New Face of Global Hollywood: Black Hawk Down and the Politics of Meta-Sovereignty

This paper uses Ridley Scott’s 2001 film blockbuster Black Hawk Down to examine the claim that popular film is the ‘newest component of sovereignty’. While the topic of the film – the 1993 UN/US intervention in Somalia – lends itself to straightforward politicisation, this paper is equally interested in the film’s production history and its reception by global audiences. While initial reactions to the film focused on its ideological commitments (e.g. racism, collusion between Hollywood and the Pentagon, post-11 September patriotism), these readings continually posed an imagined ‘America’ against ‘the world’. This paper argues that Black Hawk Down is not about sovereignty as traditionally conceived, that is, about national interest shaping global affairs. Rather, Black Hawk Down articulates, and is articulated by, a new and emerging global order that operates through inclusion, management and flexibility. Drawing on recent theoretical debates over this new logic of rule, this paper illustrates how Black Hawk Down invoked much more diffuse, complex and deterritorialized categories than national sovereignty. In effect, Scott’s film goes beyond traditional notions of sovereignty altogether: its production, signification and reception deconstruct simple notions of ‘America’ and ‘the world’ in favour of what Hardt and Negri call ‘Empire’, what Zizek calls ‘post-politics’, and what we refer to as ‘meta-sovereignty’.

A 'ruin of all space, shattered glass and toppling masonry': Joyce's Orientalism in the Context of 11 September 2001 and 1922

Chapters 3 and 15 of Joyce's Ulysses exhibit glimpses of three dreams, fantasies and eventual nightmares linked to the figure of 'Haroun al Raschid.' Historically speaking, the latter was a powerful Caliph of Baghdad, a medieval potentate about whom many of the most memorable of The Thousand and One Nights or The Arabian Nights' Entertainments were once and then again spun as tales of pleasure. Joyce seizes upon the figure of 'Haroun al Raschid' as a fictive measure to articulate the 'orientalist' fantasies of Stephen Dedalus and Leopold Bloom. However, this evocative figure of Near Eastern history, of fabulous narrative and the progressively converging fantasies of two modern European literary characters is riddled with paradox. Such material provides Joyce a perceptive and proleptic sense of the paradoxes and brutal historical contradictions through which Western and Eastern dreams of theocratic nationalism, ethnic zealotry, colonial rebellion and Zionism are to be played out. W. B. Yeats' poem 'The Gift of Harun al-Raschid', written in 1923, the year after the book publication of Ulysses, provides both a fitting foil and a significant socio-historical point of reference for Joyce's own figurative use of the Caliph of Baghdad.