Update on Olympia oyster temp/feeding experiment
Olympia oyster experiment is running well out at Manchester. Quick recap:
- Question: how do temperature & food availability during winter (or during “pre-conditioning”) impact Olympia oyster gonad quality, and subsequent larval survival through metamorphosis?
- Approach: precondition oysters in 4 groups, high/low temperature (~7C & ~10C) + high/low food availability (need from PSRF!) for 6 weeks and 12 weeks. Monitor gonad for evidence of resorption, maturation, via histology throughout (every 2-3 weeks); also collect and samle oysters from Mud Bay on same schedule to compare gonads in experiment to wild. Condition oysters up to 18C, monitoring gonad development via histology, and freeze 1/2 of gonad for lipid/glycogen/protein content. Spawn, collect & count larvae. Rear larvae in small static silos separated by day (~family). Measure survival to juvenile stage. Preserve subsample of larvae immediately upon collection from broodstock for lipid content (need to know how many/mass is necessary).
- Side experiment: larval trials! Subject larvae to various stressors, measure mortality rate: salinity, heat, pH - Erin Horken (PSRF) may help with this project.
- 1,700 Olympia oysters were collected from Mud Bay in Dyes Inlet on November, 6th 2017. The next day they underwent standard intake procedure (scrubbing, rinsing with fresh water, 1-hour freshwater+bleach soak to kill epibionts), then were acclimated to hatchery conditions in flow-through tanks (ask PSRF: feeding rate during this acclimation period?)
- On November 30th, subsample were sacrificed for histology (n=20) and DNA samples (n=100, including 20 used for histology) (DNA collected for PSRF’s purposes)
- 1,600 oysters were randomly sorted into 32 bags of 50, volume displacement of each bag was measured.
- The 32 bags were randomly sorted into 8 50L tanks (4/tank), for the following 4 treatments:
* A1 & A2: Low food, low temp
* B1 & B2: Low food, high temp
* C1 & C2: High food, low temp
* D1 & D2: High food, high temp
* Used recirculating chiller/heater to regulate temperature in 50L reservoirs, which then distributed SW to culture tanks.
- Temperature was gradually (1C/day) adjusted acheive ~7C & ~10C starting on December 1st.
- Animals were cleaned 3x per week, and checked for morts
- Half of the animals were removed at week 6 for spawning - PSRF managed this phase. They have been collecting and counting all larvae, but not rearing/monitoring survival.
- I will manage the 12-week treatment groups.
- See my Feb. 27th post for more detail on terminating the treatments and moving groups to conditioning/spawning buckets.
- Below are temperature plots from the Avtech system. I also have HOBO data loggers recording temperature on half of the buckets (one logger per treatment replicate), AND out at Mud Bay.
Temperatures from November 30th -> March 15th, when they reached 18C, the temperature used to induce spawning and rear larvae. The spikes correspond to cleaning events where the probes recorded temperature while they were out of the water
Here’s a closer look at temperatures during the conditioning phase
Written on March 15, 2018