Manchester Day 21

We’re officially halfway through our pH treatment window!

Laura and I did the following today:

  • Water chemistry sampling: 1L grab samples and bottle samples
  • I siphoned fecal matter out of tanks while Laura rinsed the Olys with freshwater
  • Cleaned filters
  • Bleached algal lines
  • Modification to procedure: 20 mL of bleach into 6 L of water, then run a full bucket of freshwater through to ensure bleach is completely washed through lines
  • Laura installed a water alarm in the large header tank, but the water is so turblent in there that it doesn’t work the way we want it to
  • Moved probes between tanks

When cleaning oysters, I found a completely dead (not mostly dead C. gigas in Tank 3. I could tell it was dead because it was gaping even when out of the water.


Figure 1. Dead oyster from tank 3 (left) next to another alive oyster (right). Oysters that are dead will continue to gape out of the water when compared with their living counterparts.

We also found a couple of fat and happy polychaete worms on a few oysters. My hands were really wet at the time so I couldn’t snap a picture, but I did manage to get a photo of another baby anemone I found on an oyster. I’m not sure where these polychaetes came from, since we thoroughly cleaned the oysters last week.


Figure 2. Baby anemone found on an oyster. This is the second anemone I have found.

PSRF upped the feeding to 500 mL of Reed’s Shellfish Diet per day (roughly 2 billion cells per milliliter spread out between six culture tanks and the two larger C. gigas tanks on the bottom). The tanks were a little too dark and we think the extra algae might be modifying water chemistry. We asked them to drop it down to 450 mL Shellfish Diet daily, and we’ll be monitoring pH to ensure the treatment tank pH doesn’t increase too much.

We saw today that the pH in the low pH tanks was hovering closer to -33 mV when they’ve been around -28 mV previously. Additionally, our water temperatures today were higher than I’ve seen before. I think this might be due to the space heater in the dry lab. It’s really powerful and might be changing the water temperature of our grab samples. From now onwards, we will unplug the space heater in the dry lab while taking water chemistry and standard curve measurements.

Things I need to do by Monday:

  • Update chemistry data spreadsheet
  • Get PSRF to poison samples while Laura and I are at NSF
  • Write up a protocol for Grace and Olivia to follow on 3/29
Written on March 8, 2017