Increasing evidence suggests that the earth and oceans have warmed over the past decades, providing evidence that the earth is undergoing long-term climate change. Cyanobacteria, a microorganism present in sea water and lakes, assimilates carbon dioxide and plays a significant role in the carbon cycle that impacts global warming induced greenhouse effects.

Investigation of the effects of cyanobacterial blooms on climate change and its responses to changing environmental patterns are important subjects for research. There are several research works that been completed to monitor phytoplankton blooms in coastal waters, however, most of these works are based on passive remote sensing techniques using either MODIS or MERIS data etc. These techniques are not accurate enough to map cyanobacterial blooms in the Baltic sea due to the complex composition of the water (e.g. due to CDOM) and the lack of in situ data in the Baltic sea for validation purposes, which sometimes cause erroneous detection.

Here, we plan to measure coastal cynaobacterial colonies and if possible, sample a bloom as and when it is observed from satellite. We plan to carry out in-situ measurement of cyanobacterial bloom in the Baltic sea in the summer of 2012, when the blooms are likely to take place, involves the measurements of cyanobacterial specific pigments such as phycocyanin and chlorophyll-a in order to derive the biomass of cyanobacteria and its fluorescent properties. Such measurements can be used for validation of satellite derived information in order to assess the capability of different satellites to detect cyanobacterial blooms in the Baltic sea. Of central importance, we plan to measure the vertical profile of cyanobacterial properties such as fluorescence during the times when the blooms occur, which will help us to understand what vertical distribution is like during the blooming period and how these different distributions affect the accuracy of satellite data.

Background

Cyanobacteria, a micro-organism present in marine ecosystems and other extreme environments such as deserts and dry valleys of Antarctica, have a long evolutionary history, starting about 3-3.5 billion years ago. Cyanobacteria are known to have dominated the oceans after past mass extinction events. Cyanobacteria can evolve under anoxic (low oxygen) conditions and are well adapted to environmental stress including exposure to UV, high solar radiation and temperatures.

Cyanobacteria assimilate carbon dioxide, playing a significant role in the carbon cycle that impacts global warming and climate change. More recently deep water cyanobacteria were also held responsible for breaking down residual oil-spills after the BP Deepwater Horizon disaster according to reports from the US NOAA.

The project proposed is concerned with monitoring the state of health of cyanobacteria in oceanic continental shelves through measurement of the fluorescent properties of their pigmentation resulting from their photosynthetic activity. In these coastal regions, not only will human health be affected by food contamination from land-based effluent resulting in the formation of toxic blooms of red algae but also changes in sea-surface temperatures will suppress the take-up of CO2 implicit in photosynthetic processing by cyanobacteria.

Currently, most monitoring is forced to take place from space due to the vast sizes of the areas, which need to be monitored, particularly in remote areas with low population densities such as the Arctic circle. Solar-induced fluorescence, and in future spaceborne lidar-induced is an extremely promising technique for mapping photosynthetic activity on a continental to global scale. A programme of laboratory measurements of field samples from the Baltic sea coupled with remotely-sensed observations of fluorescent properties. Therefore, we plan to improve our assessment of the potential of fluorescent measurements to improve our understanding of photosynthesis. In particular, the relationship between fluorescence and the number of organisms and hence the biomass in coastal regions.

University College London, Space and Climate Physics, Mullard Space Science Laboratory

Jan-Peter Muller, professor, jpm@mssl.ucl.ac.uk
Daoxi Zhang, PhD-student
Dale Potts, drp2@mssl.ucl.ac.uk

University of Stockholm, Department of Systems Ecology

Therese Arredal Harvey, therese(at)ecology.su.se