UVPHYTOMAA · UV photochemical bleaching of phytoplankton and Coloured Dissolved Organic Matter and the interactive effects on the inhibition of photosynthesis and the production of phytoplankton sunscreeens.
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2006-01-15 → 2008-01-14
- EU contribution
- €172,770
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - UVPHYTOMAA (UV photochemical bleaching of phytoplankton and coloured dissolved organic matter and the interactive effects on the inhibition of photosynthesis ...)
The objective of the present project was to determine the impact of Ultra-Violet (UV) radiation on phytoplankton photosynthesis and photo-protection mechanisms (e.g. production of mycosporine-like amino-acids or MAAs) and coloured dissolved organic matter (CDOM) photo-degradation, in situ over contrasting biomes and seasons and in the laboratory on phytoplankton cultures. The interactive effect of UV on phytoplankton and CDOM have been poorly addressed in previous studies, but is critical for estimating the impact of stratospheric ozone depletion on ocean carbon cycling and the associated increase in surface UV-B radiation over mid- and high latitudes. These effects were examined; i) in situ, both at a coastal UK time-series site off Plymouth (L4 site) and in the Southern Ocean as part of an international study (SAZ-Sense), and ii) in the laboratory, on cultures of phytoplankton species representative of UK and Sub-Antarctic waters. The SAZ-Sense study was conducted in austral mid-summer (17 Jan to 20 Feb) 2007 to examine microbial ecosystem structure and biogeochemical processes in Sub-Antarctic Zone waters, west and east of Tasmania, and in the Polar Frontal Zone (55 degrees south). The project brought together research teams from Australasia, Europe, and North America. As part of the EIF, we examined the biochemical, photo-physiological, and bio-optical responses of phytoplankton and CDOM to variable UV irradiance. Kinetics experiments were conducted by incubating surface water samples over 1 to 2 days. In parallel, the spectral optical properties of the water column were characterised and water samples were taken for the determination of phytoplankton photosynthetic parameters, pigments composition and the concentration of UV photo-protective compounds (MAAs). These field studies showed contrasting responses of phytoplankton and CDOM to different UV scenarios as a result of changes in phytoplankton assemblage composition, water column optical properties (UV and visible) and environmental conditions (e.g., vertical mixing conditions, temperature and nutrient availability).
Data: CORDIS, © European Union
Project objective
Phytoplankton is the most important biomass producer in aquatic ecosystems. Recent research has shown a pronounced sensitivity of phytoplankton to ultra-violet (UV) radiation as a consequence of the substantial decrease in stratospheric ozone over high and mid latitude waters, which can result in a significant inhibition of photosynthesis. Solar UV radiation (in particular UV-B) affects the marine ecosystem through various processes, from photo-damage of phytoplankton cells and photo-inhibition of photosynt hesis, to photochemical bleaching of the colored fraction of dissolved organic matter (CDOM). Phytoplankton has developed various strategies to prevent from photo-damage and photo-inhibition under high irradiance i) in the visible through the production of photo-protective pigments (e.g., xanthophylls cycle), and ii) in the UV spectral range through the production of UV-absorbing compounds such as mycosporine-like amino acids (MAAs) which act as sunscreens. Colored dissolved organic matter is one of the mai n components controlling light penetration in the water column at shorter wavelengths. CDOM photochemical bleaching will thus result in a deeper penetration of light in the visible and UV range, and consequently can affect phytoplankton photosynthesis. The interactive effects of UV radiation on CDOM photochemical bleaching, and phytoplankton photosynthesis and photoprotective mechanisms requires further study. This proposal aims at examining these interactive effects using laboratory experiments on phytopla nkton cultures and field studies in open ocean and coastal waters in the English Channel over a seasonal cycle. State-of-the-art of optical techniques will be used to characterize the underwater optical properties and phytoplankton photosynthesis and natur al samples will be incubated under different light intensities. The link between UV dosage and Chla and CDOM will be investigated using radiative transfer optical models and MODIS and MERIS satellite data.
Original text from CORDIS.
Participants
- PLYMOUTH MARINE LABORATORY · PLYMOUTHCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union