SeaHARRE-3 : the third SeaWiFS HPLC Analysis Round Robin Exercise History 2 previous SeaHARRE exercises, coordinated by S. Hooker (NASA) and LOV:  1999: PROSOPE: mainly mesotrophic; 4 labs (Ref: Hooker et al, 2000; Claustre et al. 2003)  2002: BENCAL: mainly eutrophic waters; 8 labs. Agreement between labs: 7% for TChla; 21% for other pigments. “ Well within the primary 35% accuracy objective for remote sensing validation purposes ” Scientific Objectives SeaHARRE-3 ● Application to extremely low Chlorophyll a concentrations ● All participating labs are working on improvement of different methodologies and instrumentation for lower detection limits, better resolution (>1) and higher precision (99%). ● 8 Participating labsParticipating labs ● Organisers: S. Hooker, H. Claustre, L. Van Heukelem, J. Ras

Methods and measurements to be made Sampling: –Water will be collected at 24 sites and at various depths and trophic conditions. –For oligotrophic and mesotrophic waters: in situ pump with 293 mm diameter GF/F filter.in situ pump –CSIRO (L. Clementson) is building a punch for cutting out more than 60 replicates from a single filter. –For eutrophic waters (and for regular pigment sampling): 24 post filtration system; positive pressure (to be built). –On board filtration will require thorough mixing of water to maintain homogeneity. Measurements : –HPLC measurements by 8 different labs. Each lab receives 24 batches of 3 replicates. Other tests will be carried out on remaining replicates

Sampling Water volumes: –For in situ sampling (in collaboration with the IAEA team): Usually 1h pumping of about 800 L is equivalent to about 6 L on a 25 mm GF/F filter. –For on board filtering (also concerns regular pigment sampling) Water volume is variable according to Chlorophyll a concentration. First, this will be determined by Turner Fluorimetry (P. Raimbault) providing an estimate of the volume of water to filter for pigments. A whole CTD cast will be required to collect 24 replicates (long stations only). Limits of detection of the HPLC method are being improved: maximum volume may vary between 2.8 and 5.6 L per sample in oligotrophic conditions. Minimum volume can reach 0.25 L in eutrophic waters. Technical requirements: Enough time for in situ pumping (about 1 hour) Safe transport of samples to their various destinations (Europe, North America, South Africa, Australia). Any ideas?

Regular sampling for phytoplankton pigments 2 CTD casts per day (up to 12 depths): 1 in the morning, 1 at midday. (In all cases the midday cast must be maintained). A surface sample will be taken every time in situ optical measurements will be made (Pump? Bucket?). Necessary water volume per sample: as mentioned before, this depends on result of the Turner fluorimetry measurement. ☼

Participating labs  Laboratoire d’Océanographie de Villefranche – H. Claustre, J. Ras  Horn Point Laboratory (USA)– L. Van Heukelem  Marine Coastal Management (South Africa) – Ray Barlow  CHORS (USA) – Chuck Trees  University of Hawaii (USA) - R. Bidigare  JRC (Italy) – J.F. Berthon  CSIRO (Australia) – L. Clementson  ?

In situ pump GF/F filter after filtration Variation coefficient of replicates: 4 to 7.6%