Contribution of shredder macroinvertebrates and aquatic hyphomycetes to litter decomposition in remote insular streams

Dissertação de Mestrado, Biodiversidade e Biotecnologia, 31 de janeiro de 2019, Universidade dos Açores.É bem conhecido que os trituradores desempenham um papel crucial no processamento de matéria orgânica. Nos sistemas oceânicos dulçaquícolas, onde os ribeiros são caracterizados por uma baixa densidade e riqueza de trituradores, os microrganismos (hifomicetes aquáticos) parecem ser os principais decompositores da folhada. No entanto, o que aconteceria se a densidade de trituradores fosse maior? Contribuiriam ativamente para a decomposição da folhada? Aqui tentamos responder a estas questões avaliando os efeitos dos trituradores e hifomicetes aquáticos na decomposição da folhada em ribeiros insulares. Três espécies de folhas com características físicas e químicas distintas, Alnus glutinosa, Clethra arborea e Cryptomeria japonica, foram colocadas em sacos de rede com malha grossa e fina para permitir e evitar a entrada de macroinvertebrados, respectivamente, e incubadas em seis ribeiros ao longo de um gradiente de Limnephilus atlanticus (Trichoptera) na ilha de São Miguel. Na presença de trituradores, a perda de massa foliar foi maior nos sacos de malha grossa. No entanto, nenhuma diferença significativa foi encontrada na perca de massa entre os tipos de sacos em ribeiros sem L. atlanticus. A decomposição da folhada na presença de trituradores foi significativamente mais rápida para A. glutinosa do que C. arborea e C. japonica. Os resultados mostram que, quando L. atlanticus está presente em densidades altas, pode ter um papel significativo no processamento de matéria orgânica, enquanto que a decomposição da folhada é principalmente mediada por microorganismos quando a densidade de L. atlanticus é baixa, ou estão ausentes, mesmo na presença de outros trituradores. Além disso, a decomposição depende da qualidade da folhada, sendo as folhas com alta concentração de nutrientes e baixa concentração de compostos secundários preferidas pelos trituradores e hifomicetes aquáticos.ABSTRACT: It is well known that shredders play a crucial role in organic matter processing. In oceanic freshwater systems were streams are characterized by low shredder density and richness, microbes seem to be the main litter decomposers. However, what would happen if the densities of shredders were greater? Would they contribute actively to litter decomposition? Here we try to answer these questions by evaluating the effects of shredders and aquatic hyphomycetes on litter decomposition in insular streams. Three leaf species differing in physical and chemical characteristics, Alnus glutinosa, Clethra arborea and Cryptomeria japonica, were enclosed in bags of coarse and fine mesh to allow and avoid macroinvertebrate access to the litter, respectively, and incubated in six streams along a gradient of Limnephilus atlanticus (Trichoptera) density in São Miguel island. In the presence of shredders, leaf mass loss was higher in coarse mesh bags. However, no difference in litter mass loss was found between bag types in streams with no L. atlanticus, despite the presence of other shredder taxa. Litter decomposition in the presence of shredder was significantly faster for A. glutinosa than C. arborea and C. japonica. These results suggest that when L. atlanticus are present at relatively high densities they may have a significant role on organic matter processing, while microbes mainly drive litter decomposition when L. atlanticus density is low, or they are absent. Moreover, litter decomposition depend on litter quality, with leaves with high nutrient concentration and low concentration of secondary compounds being more preferred by shredder and aquatic hyphomycetes

Hacia una historiografía del exilio republicano cultural: retos y propuestas

This article discusses two recent books where a reconceptualization of Republican exile in the context Spanish history is proposed. The purpose is to trace the genealogies of their respective conceptualisations and how they enter into a dialogue, and the challenge that these books pose as symptoms of a process of ideological struggle within the field of culture to establish a view of modernity and the democratic tradition is Spain. Following from these considerations, the article concludes by proposing the need for –and the challenge of– an alternative historiography to account for the cultural production of Republican exile

La capilla sixtina y los estudios culturales en la obra de Manuel Vázquez Montalbán

This paper focuses La Capilla Sixtina, Manuel Vázquez Montalbán's novel written under Franco’s censorship. It seeks to stand the outstanding cultural critic that author carried out working as writer and journalist. Vázquez Montalbán's work proposes a cultural deconstruction that claims to resist, against lies and falsehoods of Spanish tyrant government

Lagrangian Descriptors for Stochastic Differential Equations: A Tool for Revealing the Phase Portrait of Stochastic Dynamical Systems

In this paper we introduce a new technique for depicting the phase portrait of stochastic differential equations. Following previous work for deterministic systems, we represent the phase space by means of a generalization of the method of Lagrangian descriptors to stochastic differential equations. Analogously to the deterministic differential equations setting, the Lagrangian descriptors graphically provide the distinguished trajectories and hyperbolic structures arising within the stochastic dynamics, such as random fixed points and their stable and unstable manifolds. We analyze the sense in which structures form barriers to transport in stochastic systems. We apply the method to several benchmark examples where the deterministic phase space structures are well-understood. In particular, we apply our method to the noisy saddle, the stochastically forced Duffing equation, and the stochastic double gyre model that is a benchmark for analyzing fluid transport

The case for obsolescence: thinking time and space in Joaquim Jorda's Numax presenta

Book synopsis: This richly illustrated volume brings together fresh insights into the changing urban space of Barcelona from the beginning of the twentieth century to the present day. The collection focuses primarily on the complicated relationship between environment, identity, and performance as they were seen, explored, and portrayed by countercultural and avant-garde artists and communities from the 1960s to today. Drawing crucial links between theory and practice, and aesthetics and environment—and paying particular attention to the role of the avant-garde in challenging and disrupting dominant art forms and uses of urban space—Barcelona presents a variety of perspectives and approaches, drawing on art history, cultural geography, performance studies, and institutional critique