California Cooperative Oceanic Fisheries Investigations

1. Chl samples are drawn on all rosette bottles tripped from ~200m to surface; sampling on a standard 20-bottle cast usually starts at #7 (sample vol is ~140mls).  For shallow stations, all the bottles may be sampled; noontime prodo casts may have extra bottles to sample; duplicate depths are usually skipped.  Refer to the electronic sample log to verify which bottles to sample or ask the watchleader.

2.  Drawing from the middle valve, add ~20mls, cap loosely, shake then dump; three rinses.  Double-check the sample bottle number matches the rosette bottle number (often).

3.  Chl samples are volumetric so after rinsing, fill it completely, cap loosely, tap the bottle gently against the rosette frame to dislodge any small bubbles then top-off, cap tightly, invert the bottle – if you see a bubble, top-off and check again. Squeezing the sides of the bottle can change the sample volume and create a persistent bubble; cup the bottle in your palm during the final fill to minimize this problem.

4. Once all the chlorophylls have been drawn, draw the LTER water samples such as HPLCs.  The sample volume will vary with chlorophyll concentration so with the LTER watchleader for bottle size and sample depths.

5. Again, all bottles are rinsed three times then fill completely.

6. Once samples are drawn, fill out sample tags or forms, then initial the sample log.

7. When filtering chlorophylls: take the chlorophyll sample form from the clipboard along with the chlorophyll samples to the chl van to filter ASAP.  The prodo experiment filtrations in the evening may delay the filtrations so ask to be notified when the chl van is available.

• Retrieve an empty nutrient rack from the lab fridge if needed and record the color key on the sample log sheet.
• Tubes are inverted when empty and should not be turned over until filled
• Never touch the inside of the cap or tube since residue from your fingers can contaminate the sample – soap contain phosphates.  If unavoidable – rinse several times.
• Nutrients are normally drawn from the middle valve – fill the tube with ~25mls, cap loosely, shake then dump.  Repeat three times.
• Double check the tube number matches the rosette bottle number.
• Fill the tube completely then flick out several mls so the sample reaches the base of the neck/threads.  Cap tightly.
• Draw one sample per rosette bottle (except on the surface bottle).  If tube 24 is not needed, draw a duplicate surface sample.
• Once all the nutrient samples are drawn:
  • Carefully tip the nutrient rack until you can see the sample through the cap of each tube – if a tube is empty and not inverted, double-check the sample log and fill if necessary.
  • fill out a sample label (from the sample log clipboard) with the time, your initials, total number of samples
• Wrap the label around tube #1 and carefully re-insert into rack – be sure to include the extra surface sample to the sample count by listing it as “+1”
  • return the filled rack to the nutrient fridge right away.
  • add your initials to the bottom of the sample log’s nutrient column

Common mistakes are empty tubes that shouldn’t be; missing duplicate surface sample; contaminated samples; and duplicate draws – two sample tubes filled from the same bottle

•  The sample bottle number should ALWAYS match the rosette bottle number – check and double-check this during the sample drawing process.  If you ever have any doubt about the sample, dump it and start over.
• The sample bottles are stored inverted – they should not be turned over until the sample has been taken.  If you need to step away from sampling for any reason and have not filled the sample bottle, return it to the case inverted.
• The bottles should never be stored empty so as the old sample is dumped, use it to rinse any salt that may have crystallized on the threads, thimble, and cap.
• Salt samples are usually drawn from the bottom valve. Fill the bottle with ~40mls of seawater, cap loosely, shake then dump, rinsing the threads and thimble.  Repeat – you should rinse the bottle 3 times; the dumping of old sample does not count as a rinse.
• The last fill should be done without interruption until overflowing, filling the bottle completely; pour ~10ml out over the thimble, place it firmly in the bottle and cap.  The caps are brittle and should be tightened gently. If they crack, retrieve a replacement from the spares Ziploc, keeping the thimble in place.  See photo for optimal fill height.
• Salts are taken from all closed rosette bottles unless directed otherwise.
• Sample bottles are fragile – carefully place them back in the correct slot.  If you drop one on deck or into the case and crack the glass, replace the cracked bottle from the spares case, adding the bottle number.  Redraw the sample.
• Once all the salts are taken:
  • fill out a sample label (on the sample log clipboard) with the time, your initials, total number of samples Place the label in a plastic sleeve and into the box of samples
  • take into the lab, adding it to the end of the “salt box queue”; bring out an empty case for next station.
  • add your initials to the bottom of the sample log’s salt column.

• Common mistakes are duplicate draws; samples returned to the case out of sequence (common when more than one person is drawing salts); missing thimble insert; not enough air (can crack the bottle as it warms and not allow the analyst to load the sample); too much air (can shift the salinity value or not give the analyst enough sample to measure); and cracked or broken bottles (drops).