SeaHARRE-3 : the third SeaWiFS HPLC Analysis Round Robin Exercise

History2 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 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. – 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.

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Participating labs

Laboratoire d’Océanographie de Villefranche – H. Claustre, J. RasHorn Point Laboratory (USA)– L. Van HeukelemMarine Coastal Management (South Africa) – Ray BarlowCHORS (USA) – Chuck TreesUniversity of Hawaii (USA) - R. BidigareJRC (Italy) – J.F. BerthonCSIRO (Australia) – L. Clementson?

In situ pump

GF/F filter after filtration

Variation coefficient of replicates: 4 to 7.6%