John W. Runcie

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Electron transport rate (ETR) calculations require values of irradiance, effective quantum yield of chlorophyll fluorescence (DF=F0 m), the distribution of energy between PSII and PSI and leaf-specific photosynthetic absorptance. We conducted virtually simultaneous replicated measurements of diel changes in DF=F0 m of Posidonia australis in situ, and(More)
Direct comparisons between photosynthetic O2 evolution rate and electron transport rate (ETR) were made in situ over 24 h using the benthic macroalga Ulva lactuca (Chlorophyta), growing and measured at a depth of 1.8 m, where the midday irradiance rose to 400–600 μmol photons m−2 s−1. O2 exchange was measured with a 5-chamber data-logging apparatus and ETR(More)
Some ecosystems can undergo abrupt transformation in response to relatively small environmental change. Identifying imminent 'tipping points' is crucial for biodiversity conservation, particularly in the face of climate change. Here, we describe a tipping point mechanism likely to induce widespread regime shifts in polar ecosystems. Seasonal snow and(More)
Blue diode-based pulse amplitude modulation (PAM) technology can be used to measure the photosynthetic electron transport rate (ETR) in a purple nonsulfur anoxygenic photobacterium, Afifella (Rhodopseudomonas) marina. Rhodopseudomonads have a reaction center light harvesting antenna complex containing an RC-2 type bacteriochlorophyll a protein (BChl a(More)
A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research. This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609(More)
Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression(More)
a LARSyS, University of Algarve, Faro, Portugal b MarSensing Lda, Faro, Portugal c Marine Plant Ecology Research Group, Center of Marine Sciences (CCMar), University of Algarve, Faro, Portugal d Laboratory of Oceanology MARE Centre, University of Liège, Belgium e Department of Plant Sciences, Tel Aviv University, Tel Aviv, Israel f Department of Ecology,(More)
Uptake, assimilation and compartmentation of phosphate were studied in the opportunist green macroalgaUlva lactucaand the estuarine red algal epiphyteCatenella nipae. The Michaelis–Menten model was used to describe uptake rates of inorganic phosphate (Pi) at different concentrations. Maximum uptake rates (V max) of P-starved material exceededV maxof(More)
Ecosystems are entities comprising both communities of interacting organisms and physical aspects of the environment in which they live. Healthy coastal ecosystems can be characterised as having high species diversity and high rates of productivity (although there are of course exceptions to this). The growth of primary producers requires adequate light and(More)