Browsing by Author "Runcie, J. W."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Acoustic monitoring of O2 production of a seagrass meadowPublication . Felisberto, P.; Jesus, S. M.; Zabel, F.; Santos, Rui; Silva, João; Gobert, S.; Beer, S.; Bjork, M.; Mazzuca, S.; Procaccini, G.; Runcie, J. W.; Champenois, W.; Borges, A. V.Acoustic data were acquired in October 2011 over a Posidonia oceanica meadow in the Bay of la Revellata, Calvi, Corsica. The purpose was to develop an acoustic system for monitoring the oxygen (O2) production of an entire seagrass meadow. In a shallow water area (<38m), densely covered by P. oceanica, a sound source transmitted signals in 3 different bands (400-800Hz, 1.5-3.5kHz and 6.5-8.5kHz) toward three self-recording hydrophones at a distance of 100m, over the period of one week. The data show a high correlation between the diel cycle of the acoustic signals' energy received by the hydrophones and the temporal changes in water column O2 concentration as measured by optodes. The results thus show that a simple acoustic acquisition system can be used to monitor the O2-based productivity of a seagrass meadow at the ecosystem level with high temporal resolution. The finding of a significant production of O2 as bubbles in seagrass ecosystems suggests that net primary production is underestimated by methods that rely on the mass balance of dissolved O2 measurements. © 2015 Elsevier B.V.
- Compared photophysiology of native seagrasses with an invasive macroalga in Sydney Harbour, AustraliaPublication . Silva, João; Runcie, J. W.; Barrote, Isabel; Costa, Monya; Santos, RuiThe comparative photophysiology of the seagrasses Zostera capricorni and Halophila ovalis and the invasive macroalgae Caulerpa taxifolia was investigated in a shallow mixed meadow at Chowder Bay (Sydney, Australia), where the three species coexist. This study was developed under the auspices of the COST Action “Seagrasses: from genes to ecosystems”, targeting one of its objectives, the development of innovative devices for the continuous measurement of seagrass photosynthesis. Automated multi-channel chlorophyll fluorometers were deployed for 24-hour periods to examine and compare the changes in the photosynthetic efficiency and energy quenching mechanisms of the 3 species. Tissue samples were collected at predawn and noon, frozen and analysed by HPLC for detailed pigment analysis. The invasive C. taxifolia showed generally higher photosynthetic efficiency than both Z. capricorni and H. ovalis. Both seagrass species showed down-regulation of photosynthesis at noon, evidenced by the low quantum yield and the significant reduction of the antennae pigments between pre-dawn and noon. In contrast, C. taxifolia showed no reduction in antennae pigments or total photosynthetic pigments along the day. While both seagrasses showed 3- to 7-fold increases in the epoxidation state of xanthophyll cycle pigments between pre-dawn and noon, in C. taxifolia there was no significant change. Our results show that C. taxifolia is better adapted to high light conditions than Z. capricorni and H. ovalis, which means that, from the photophysiological point of view, this invasive macroalgae constitutes a serious competitor for seagrasses in shallow areas with high irradiance.
- Establishing research strategies, methodologies and technologies to link genomics and proteomics to seagrass productivity, community metabolism and ecosystem carbon fluxesPublication . Mazzuca, S.; Bjork, M.; Beer, S.; Felisberto, P.; Gobert, S.; Procaccini, G.; Runcie, J. W.; Silva, João; Borges, A. V.; Brunet, C.; Buapet, P.; Champenois, W.; Costa, M. M.; D'Esposito, D.; Gullström, M.; Lejeune, P.; Lepoint, G.; Olivé, Irene; Rasmusson, L. M.; Richir, J.; Ruocco, M.; Serra, I. A.; Spadafora, A.; Santos, RuiA complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research.This enables the predictionof change and possibly the mitigation of the consequences ofanthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 “Seagrasses productivity. From genes to ecosystem management,” is the calibration and synthesis of various methods and the development of innovative techniques and protocolsfor studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwater acoustics) gathered at The Station de Recherches Sous-marines et Océanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as “pristine site” where environmental disturbances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general.