Research interests - background
Biogeochemical fluxes of carbon in the ocean control its transfer from the atmosphere to the deep sea, where it may remain stored for thousands of years and form the largest carbon reservoir on Earth. Therefore oceanic controls on carbon cycling have serious repercussions for climate. Furthermore, carbon fluxes into the ocean interior provide the main energy source for many benthic and pelagic ecosystems.
The vast majority of marine organic matter is produced in the surface of the ocean (ca. first 100 m) by phytoplankton through photosynthesis. Phytoplankton is then grazed mainly by zooplankton or dies and sinks.
Over time the "rain" of sinking particles rich in carbon remove large amounts
of CO2 from the atmosphere (a process known as the biological pump), thus playing a important role in regulating of Earth's
climate. Many questions however remain. For example how much organic carbon escapes the first 100 metres into the ocean interior? Does the ratio of produced carbon vs. escaped (or exported) carbon change spatially and temporally (with season or from year to year)? Does phytoplankton composition affects the sinking process? How do different zooplankton communities respond? Do ocean currents, tides and ocean topography affect the sinking processes? What is the impact of the changing climate to primary production and the biological pump?
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Furthermore the organic detritus that falls into the oceanic
interior is the major energy source of most deep sea (benthic) ecosystems which
occupy 50% of the planet. However we know surprisingly little about the fate of organic matter as soon as it escapes
the first 100 m and
how it affects deep sea ecosystems (e.g. their distribution, biomass,
diversity). For example the origin and transformations of organic matter
often determine its bioavailability (e.g. terrestrial organic matter
is more recalcitrant than marine organic matter); this is important
in understanding the functioning of marine ecosystems and the ultimate
fate of carbon in the ocean.
My approach: biomarkers and isotopes
The chemical composition of
water particles and sediments holds invaluable information
about the recent and past carbon and nitrogen cycles. For example certain
chemical compounds such as lipids (e.g. fatty acids and sterols),
pigments (e.g. chlorophyll products and carotenoids) or some amino
acids can retain information on their biological origin. These compounds
are thus labelled biomarkers and their distributions
used together with their carbon and nitrogen stable isotopic
composition (also diagnostic for origin, burial or trophic modification) can shed light to the transformation pathways
of marine organic matter and thus the cycling of carbon in the ocean.
Biogeochemistry of Seamounts - Funded by Census of Seamounts
Twilight zone to deep-ocean floor. Developing an understanding of particle dynamics and trophic interactions using a molecular experimental approach. NERC funded (OCEANS 2025 Programme, Theme 5)
Hotspot Ecosystem Research and Man's Impact On European Seas (HERMIONE) - EU funded
Hotspot Ecosystem Research on the Margins of European Seas (HERMES) - EU funded
Oceanic seamounts: An integrated study (OASIS) - EU funded
Atlantic Coral Ecosystem Study (ACES) - EU funded
Environmental Controls on Mound Formation Along the European Margin (ECOMOUND) - EU funded
High-Resolution Temporal and Spatial Study of the Benthic Biology and Geochemistry of a north-eastern Atlantic Abyssal Locality (BENGAL) - EU funded