In 2012 we lost Jean Jacques Peters, former engineer of Flanders Hydraulics Research (1964 till 1979) and international expert in sediment transport, river hydraulics and morphology. As a tribute to him we have created potamology, a virtual memorial archive whose aim is to preserve and disseminate his way of thinking and his morphological approach to river problems all over the world.This archive provides four modules, each with its specific information set relevant to Peters’ work. Where available and if not confidential, there will also be access to the full text. In dialogue with Peters’ family we continue to make his life’s work accessible.
Effects of enhanced temperature and ultraviolet B radiation on a natural plankton community of the Beagle Channel (southern Argentina): a mesocosm study
Moreau, S.; Mostajir, B.; Almandoz, G.O.; Demers, S.; Hernando, M.; Lemarchand, K.; Lionard, M.; Mercier, B.; Roy, S.; Schloss, I.R.; Thyssen, M.; Ferreyra, G.A. (2014). Effects of enhanced temperature and ultraviolet B radiation on a natural plankton community of the Beagle Channel (southern Argentina): a mesocosm study. Aquat. Microb. Ecol. 72(2): 156-174. dx.doi.org/10.3354/ame01694
Marine planktonic communities can be affected by increased temperatures associated with global climate change, as well as by increased ultraviolet B radiation (UVBR, 280-320 nm) through stratospheric ozone layer thinning. We studied individual and combined effects of increased temperature and UVBR on the plankton community of the Beagle Channel, southern Patagonia, Argentina. Eight 2 m(3) mesocosms were exposed to 4 treatments (with 2 replicates) during 10 d: (1) control (natural temperature and UVBR), (2) increased UVBR (simulating a 60% decrease in stratospheric ozone layer thickness), (3) increased temperature (+ 3 degrees C), and (4) simultaneous increased temperature and UVBR (60% decrease in stratospheric ozone; + 3 degrees C). Two distinct situations were observed with regard to phytoplankton biomass: bloom (Days 1-4) and postbloom (Days 5-9). Significant decreases in micro-sized diatoms (> 20 mu m), bacteria, chlorophyll a, and particulate organic carbon concentrations were observed during the post-bloom in the enhanced temperature treatments relative to natural temperature, accompanied by significant increases in nanophytoplankton (10-20 mu m, mainly prymnesiophytes). The decrease in micro-sized diatoms in the high temperature treatment may have been caused by a physiological effect of warming, although we do not have activity measurements to support this hypothesis. Prymne-siophytes benefited from micro-sized diatom reduction in their competition for resources. The bacterial decrease under warming may have been due to a change in the dissolved organic matter release caused by the observed change in phytoplankton composition. Overall, the rise in temperature affected the structure and total biomass of the communities, while no major effect of UVBR was observed on the plankton community.