Details of Award
NERC Reference : NE/L00013X/1
Size fractionated estimates of phytoplankton primary production from satellite in the UK shelf seas.
Training Grant Award
- Lead Supervisor:
- Dr GH Tilstone, Plymouth Marine Laboratory, Remote Sensing Group
- Grant held at:
- Plymouth Marine Laboratory, Remote Sensing Group
- Science Area:
- Marine
- Overall Classification:
- Marine
- ENRIs:
- Biodiversity
- Global Change
- Science Topics:
- None
- Abstract:
- The fixation of atmospheric carbon by phytoplankton contributes significantly to carbon flux through different trophic pathways in the marine environment, though this differs depending on the phytoplankton group or class. Size matters: Phytoplankton taxa can be classified into three different size classes (micro, nano and pico), which is broadly related to ecosystem function and photo-physiology. State of the art: Over the past decade, a range of remote-sensing algorithms have been developed to detect the phytoplankton size biomass from ocean colour data, which has enabled high resolution global estimates of size-fractionated phytoplankton chlorophyll-a (Chla). Variability in size specific Chla is related to environmental factors, such as light, nutrients and temperature, which in turn influence phytoplankton photo-physiology. Recently, models of size fractionated primary production (PP) have been developed based on depth dependent relationships in size fractions between photosynthetic rates and euphotic depth. At temperate latitudes, this model predicts that the spring bloom is dominated by micro (50% of total) and that nano remain substantial all year round (40-54% of total), whereas pico phytoplankton contribute 14-25%. Uncertainties: The model is calibrated mainly from data derived from stratified, oligotrophic regions, and therefore its applicability to the Shelf Seas remains uncertain. The photosynthetic efficiency of some size classes may differ in Shelf Sea environments compared to the open ocean, especially in the nano class, which represents a large diversity of phytoplankton groups both in terms of trophic status and photo-physiology. Other studies in Shelf Seas have shown that micro have lower photosynthetic rates than nano phytoplankton, which contrasts the calibration of the published models. There is also a lack of appropriate in situ data to validate these size fractionated PP models. Currently, model accuracy assessment is done using 14C based photosynthesis-irradiance (PE) parameters and filter pad absorption coefficients (aph) of the total biomass, and then partitioning this into constituent sizeclasses using diagnostic phytoplankton pigment markers. This can lead to discrepancies between size classes, since some diagnostic pigments can be shared by groups in different sizes. When applying such models to long term ocean colour satellite data, different satellite missions cover different time periods. There is therefore a need to merge ocean colour data from a number of different sensors. The application of these merged products to models of phytoplankton size class biomass and production, remain to be tested and validated. Research Questions and Objectives: This studentship will address four principal research questions: Q1 Are existing models of size fractionated PP accurate for the UK shelf seas and when applied to merged ocean colour data? Obj1 If the existing models do not prove to be accurate, the student will develop a new model using the new data collected. Q2 What is the magnitude of the difference between size fractionated 14C PE parameters, aph and Chla and those derived from diagnostic pigment markers? Obj2. The student will measure size fractionated PE parameters, Chla and aph over a 1 yr cycle at the Western English Channel Observatory and on dedicated SSB cruises. This data will be used to validate or calibrate existing and new models. Q3. What are the long term spatial and temporal changes in micro, nano and pico PP in the UK shelf seas? Obj3. The most accurate satellite model will be used to produce a time series for the UK shelf seas. Variability in the 3 size fractions will be analysed in contrasting in contrasting areas. Q4. How does size-class production in the UK Shelf Seas compare with that on the Scotian Shelf? Obj4. Trends in micro, nano and pico phytoplankton PP in the UK shelf will be compared with the Scotian Shelf, to illustrate the potential significance of the UK shelf.
- NERC Reference:
- NE/L00013X/1
- Grant Stage:
- Completed
- Scheme:
- DTG - directed
- Grant Status:
- Closed
- Programme:
- SSB Studentship
This training grant award has a total value of £89,656
FDAB - Financial Details (Award breakdown by headings)
| Total - Fees | Total - RTSG | Total - Student Stipend |
|---|---|---|
| £16,210 | £16,815 | £56,632 |
If you need further help, please read the user guide.