1,721,050 research outputs found
The invasive gastropod Crepidula fornicata: reproduction and recruitment in the intertidal at its northernmost range in Wales, UK, and implications for its secondary spread
No full textThe establishment and spread of a non-native species in an introduced range depends to a large extent on the performance of the species under the prevailing environmental conditions. The spawning, larval and spatfall periods of the invasive gastropod Crepidula fornicata were monitored in the intertidal zone at its northernmost range in Wales, UK, between February 2010 and January 2011. The duration of the reproductive season was similar to that recorded from more southerly European populations. Spawning and larval release occurred throughout most of the year even at low seawater temperatures of <7 °C, but benthic recruitment was observed over a much shorter period at seawater temperatures >16 °C. Recruitment was low and likely controlled by post-settlement mortality. These observations suggest that C. fornicata’s northwards spread in Welsh waters will not be limited by seawater temperature negatively affecting reproduction, but by processes acting after larval release. These data show the importance of incorporating settlement and post-settlement processes into studies on recruitment success when aiming to predict the potential spread of a potentially harmful invader such as C. fornicata
Ecosystems: The Rocky Road to Regime-Shift Indicators
No full textEcosystems can undergo dramatic shifts from one stable state to another. While indicators of such shifts are well known, experimental tests are few and far between. A new study on rocky shore ecosystems now offers a test of warning indicators
ecological education and practice-based design
Full text linkDieser Titel ist parallel zur Online-Version in gedruckter Form im Universitätsverlag der TU Berlin unter der ISBN 978-3-7983-2726-9 erschienen.Urbane Landwirtschaft ist ein Thema, dass viele anspricht und dabei ständig neue AnhängerInnen gewinnt. Es scheint ein zutiefst menschliches Bedürfnis zu sein, sich trotz fortschreitender Urbanisierung mit der Herkunft und Erzeugung von Nahrungsmitteln auseinanderzusetzen und sich damit sowohl der Natur als auch einer nachhaltigen Zukunft (wieder) ein Stück anzunähern.
Spiel/Feld Urbane Landwirtschaft eröffnet den Lesenden das kreative Potenzial produktiver Stadtlandschaften durch die Vorstellung eines Projektbeispieles – Spiel/Feld Marzahn -, welches das Fachgebiet Stadt & Ernährung der Technischen Universität Berlin zwischen 2011 und 2014 betreute.
Von am Projekt beteiligten sowie zusätzlich eingeladenen AutorInnen werden besonders solche Fragen genauer beleuchtet, die sich mit den vielfältigen Wechselwirkungen von Urbaner Landwirtschaft und ökologischer Bildung beschäftigen. Ziel ist es zum einen, die Notwendigkeit solcher Verknüpfungen aufzuzeigen und zum anderen darzustellen, wie sie praktisch umsetzbar und erfahrbar sein können.
Das Buch richtet sich an alle, die mehr über Themen der Urbanen Landwirtschaft und produktiven Stadtlandschaft und über mögliche Lehr- und Lernmethoden zu ihrer Verbreitung erfahren bzw. erleben möchten. Von GraswurzelaktivistInnen bis zu StadtplanerInnen, von KleingärtnerInnen bis zu urbanen AgrarunternehmerInnen, vom Schulkind zu Studierenden zu Niemalsauslernenden sind Menschen aller Herkunft und Schichten angesprochen.Urban agriculture is a topic that is currently finding an increasing number of supporters. For good reason: Despite the progression of urbanisation, it seems to be a human desire to understand our food’s origin and its methods of production as a means of getting closer again to nature and a sustainable future.
Playing/Field Urban Agriculture introduces the reader to the creative potential of productive urban landscapes by looking at a case study project – Playing/Field Marzahn – that was supervised by the Department City & Nutrition at the Technical University between 2011 and 2014.
In this book, questions concerning the manifold interdependencies of urban agriculture and ecological education will be discussed by those involved in the project and other invited authors. Our goal is to not only show the necessity of such connections, but also to illustrate how they may be practically implemented and become experienceable.
This book addresses those who would like to explore the topics of urban agriculture and productive urban landscapes, as well as possible teaching and learning methods for their further expansion
Larval microhabitat associations of the non-native gastropod Crepidula fornicata and effects on recruitment success in the intertidal zone
No full textHabitat-specific distributions of marine benthic invertebrates can be caused by several processes acting prior to, during or after settlement, including differential settlement and varying levels ofmortality between habitat types following adaptation of the benthicmode. The non-native gastropod Crepidula fornicata is known for its gregarious settlement patterns, yet associations with other shellfish species are also common. In the present study, a series of no-choice and choice laboratory assays were undertaken in which larvae were offered different settlement substrata, separately and simultaneously, to investigate whether differential settlement of C. fornicata larvae occurs in favour of specific microhabitat types. A field experiment was also conducted to test if recruitment success in the intertidal differed between microhabitat types, by comparing densitiesof young (b2 weeks) andolder (b8 weeks) settlers. The laboratory studies indicated that settlement occurs in larger numbers in association with certain habitats. However, settlement in association with specific microhabitat types was not observed in the intertidal. Instead, the distribution of C. fornicata recruits is established after settlement, as the distribution of older recruits, but not younger ones, differed between microhabitat types. Our findings show that the availability of certain complex structures in the intertidal zone is highly important in determining survival success of C. fornicata, due to varying levels of post-settlement mortality
The importance of larval supply, larval habitat selection and post-settlement mortality in determining intertidal adult abundance of the invasive gastropod Crepidula fornicata
No full textUnderstanding the processes that drive the recruitment of invasive non-native species is of critical importance in evaluating their potential to colonise previously unoccupied habitats. The slipper limpet Crepidula fornicata has spread rapidly into most European waters since its first introduction from the North West Atlantic in the late 19th century. Its invasion success is thought to have been aided by its long larval phase and its tolerance towards a wide range of environmental conditions. The Milford Haven Waterway in Wales, U.K. supports a population with highly variable densities in the intertidal as well as the subtidal zone. In the present study, we tested a series of existing models to investigate the roles of larval supply, larval habitat selection and post-settlement mortality in determining the final distribution of C. fornicata in the intertidal zone of the Milford Haven Waterway. During the main reproductive season of 2011, data on total settlement rates and recruitment were collected by deploying slate panels for varying durations in the low intertidal zone, and data on larval abundances were obtained by taking frequent plankton samples at two sites with contrasting adult densities: Beggars Reach (~ 15 ± 13 ind m? 2) and Pennar (~ 343 ± 360 ind m? 2). Total larval densities were much higher at Pennar, but densities of late-stage larvae (i.e. larval supply) were similar at both sites, indicating that local hydrodynamics may have resulted in the spatial homogenisation of supply of late-stage, metamorphically competent larvae, despite the higher larval production at the high adult abundance site. Settlement rates also did not differ between sites. Seasonal recruitment was overall low, indicating that post-settlement mortality, likely as a consequence of exposure to intertidal conditions, is very high. The lack of a relationship between adult abundance and settlement rates indicates that the final distribution of C. fornicata in the intertidal may be a result of differential post-settlement mortality. Understanding recruitment patterns in non-native species is essential for developing management strategies for potentially harmful invaders such as C. fornicata
Mapping urban agriculture potentials in Nerima City, Tokyo
No full textViljoen presents abstracted and applied mappings forming part of the ongoing investigation, ‘Laboratories for Urban Agriculture’. Here, field work from Nerima City in Tokyo provided the raw material for a set of mappings using collage, montage, photography and drawing to communicate new readings of functional agricultural land use and to develop replicable strategies for reintegrating fragmented farmland into the city’s urban fabric. An inductive approach is applied to original primary place-based mappings made by the author to explore and describe mapping as a design research method and technique. Thematically this chapter focuses on urban food growing sites and their potential to catalyse sustainable spatial and place making innovations. Refencing collage, montage and work of early modernist artists such as Schwitters, it is argued that mapping methods drawing on these legacies can be propositional and generative, for near future scenario building that value green infrastructure, nature-based solutions, walkable neighbourhoods and wellbeing
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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