The effects of single and repeat bleaching on photosynthesis, respiration, and feeding rates in three species of Caribbean coral

Bleaching events are predicted to increase in frequency and intensity as a result of rising sea surface temperatures. Paired fragments of the Caribbean corals Montastraea faveolata, Porites astreoides, and Porites divaricata were experimentally bleached (treatment) or nonbleached (control) in outdoor flow-through seawater tanks. Half of the fragments were immediately collected, and half were returned to the reef to recover for one year at ambient temperature, followed by repeat bleaching the following summer. Our findings show that the mounding coral P. astreoides is the most tolerant, and the branching coral P. divaricata is the least tolerant, of single bleaching. Unexpectedly, it is the branching P. divaricata that appears to be the most tolerant of repeat bleaching and indicates that the underlying mechanisms for bleaching resilience are fundamentally different in repeat bleached corals compared to singly bleached corals. This study provides insight into how coral species’ diversity and abundance could shift on Caribbean coral reefs in the coming decades.NSFOSU Edward Mayers travel fellowshipShell Exploration and Production CompanyNo embarg

THE IMPACTS OF ANTHROPOGENIC GLOBAL CHANGE AND LOCAL HUMAN ACTIVITIES ON REEF-BUILDING CORALS ON THE BELIZE MESOAMERICAN BARRIER REEF SYSTEM

Coral reefs are some of the most diverse and important ecosystems on earth, yet they are experiencing global scale declines in coral cover, diversity, and ecosystem health due to the impacts of climate change, ocean acidification, and local human impacts such as land-use change, overfishing, and pollution. This dissertation explores the impacts of thermal history on coral community composition (Chp 1), coral-associated Symbiodinium community structure (Chp 2), coral growth rates (Chp 3), and the acclimatization and/or local adaptation capacity of Sidereastrea siderea and Pseudodiploria strigosa corals (Chp 4) on the Belize Mesoamerican Barrier Reef System (MBRS). The Belize MBRS can be subdivided into three distinct thermal regimes following a nearshore-offshore gradient of warmer and more thermally variable to cooler and less thermally variable seawaters. Nearshore reefs (warmer and more thermally variable) experienced lower coral cover and diversity and that weedy and stress-tolerant coral species persisted on these reefs (Chp 1). Coral-associated Symbiodinium communities varied by thermal regime in one of the three study species, and that thermally tolerant Symbiodinium did not dominate in warmer nearshore reefs (Chp 2). This finding suggested that Symbiodinium likely did not play a large role in providing some corals with the capacity to sustain themselves in the warmest and most thermally variable thermal regimes. Nearshore corals grew faster than offshore conspecifics, yet suffered declining growth rates, while growth rates of offshore corals remained stable (Chp 3) suggesting that historically there has been a growth advantage to living nearshore. However, recent declines suggest that compounding negative impacts outweigh this growth advantage, leading to declining growth. In a follow-up reciprocal transplant experiment, native and transplant S. siderea and P. strigosa corals preferred the nearshore, indicating that nearshore species may not exhibit greater acclimatization ability when transplanted (Chp 4). Overall, low diversity nearshore reefs appear especially threatened by continued ocean warming, as corals on these reefs exhibit declining growth rates and are not better equipped to acclimatize to new conditions than do offshore corals. A swift and significant reduction in emissions combined with continued local scale mitigation would provide hope for the future survival of these corals.Doctor of Philosoph

The Role of Expectations: An Application to Internal Migration

This paper examines the impact of unemployment on migration. In a theoretical model, we show that unemployment, per se, does not affect migration. Rather, migration only occurs when unemployment shocks force residents to update their expectations of the area\u27s unemployment rate. Once these expectations change, migration reallocates labor to bring the economy back to equilibrium. To test this theory, we devise an empirical strategy using state level data in the U.S. from 2000 to 2010, we find strong empirical evidence that unemployment shocks outside of expectations have a far greater impact on migration than unemployment shocks that are within expectations

Avalanche Mixing of Granular Solids

Mixing of two fractions of a granular material in a slowly rotating two-dimensional drum is considered. The rotation is around the axis of the upright drum. The drum is filled partially, and mixing occurs only at a free surface of the material. We propose a simple theory of the mixing process which describes a real experiment surprisingly well. A geometrical approach without appealing to ideas of self-organized criticality is used. The dependence of the mixing time on the drum filling is calculated. The mixing time is infinite in the case of the half-filled drum. We describe singular behaviour of the mixing near this critical point.Comment: 9 pages (LaTeX) and 2 Postscript figures, to be published in Europhys. Let

Kinetics of the long-range spherical model

The kinetic spherical model with long-range interactions is studied after a quench to $T < T_c$ or to $T = T_c$. For the two-time response and correlation functions of the order-parameter as well as for composite fields such as the energy density, the ageing exponents and the corresponding scaling functions are derived. The results are compared to the predictions which follow from local scale-invariance.Comment: added "fluctuation-dissipation ratios"; fixed typo

Religion as practices of attachment and materiality: the making of Buddhism in contemporary London

This article aims to explore Buddhism’s often-overlooked presence on London’s urban landscape, showing how its quietness and subtlety of approach has allowed the faith to grow largely beneath the radar. It argues that Buddhism makes claims to urban space in much the same way as it produces its faith, being as much about the practices performed and the spaces where they are enacted as it is about faith or beliefs. The research across a number of Buddhist sites in London reveals that number of people declaring themselves as Buddhists has indeed risen in recent years, following the rise of other non-traditional religions in the UK; however, this research suggests that Buddhism differs from these in several ways. Drawing on Baumann’s (2002) distinction between traditionalist and modernist approaches to Buddhism, our research reveals a growth in each of these. Nevertheless, Buddhism remains largely invisible in the urban and suburban landscape of London, adapting buildings that are already in place, with little material impact on the built environment, and has thus been less subject to contestation than other religious movements and traditions. This research contributes to a growing literature which foregrounds the importance of religion in making contemporary urban and social worlds

On logarithmic extensions of local scale-invariance

Ageing phenomena far from equilibrium naturally present dynamical scaling and in many situations this may generalised to local scale-invariance. Generically, the absence of time-translation-invariance implies that each scaling operator is characterised by two independent scaling dimensions. Building on analogies with logarithmic conformal invariance and logarithmic Schr\"odinger-invariance, this work proposes a logarithmic extension of local scale-invariance, without time-translation-invariance. Carrying this out requires in general to replace both scaling dimensions of each scaling operator by Jordan cells. Co-variant two-point functions are derived for the most simple case of a two-dimensional logarithmic extension. Their form is compared to simulational data for autoresponse functions in several universality classes of non-equilibrium ageing phenomena.Comment: 23 pages, Latex2e, 2 eps figures included, final form (now also includes discussion of KPZ equation

Quarks, gluons, colour: Facts or fiction?

A general method is presented which allows one to determine from the local gauge invariant observables of a quantum field theory the underlying particle and symmetry structures appearing at the lower (ultraviolet) end of the spatio--temporal scale. Particles which are confined to small scales, i.e., do not appear in the physical spectrum, can be uncovered in this way without taking recourse to gauge fields or indefinite metric spaces. In this way notions such as quark, gluon, colour symmetry and confinement acquire a new and intrinsic meaning which is stable under gauge or duality transformations. The method is illustrated by the example of the Schwinger model.Comment: 22 pages, ams-latex; the article had to be replaced because of tex problems, there are no changes in the tex

Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral—Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11–36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling