Green Crab Experiment Part 7

Treatment Days 8 through 10

Day 8

  • Protocol for today
    • Performed TTR for seven randomly selected crabs in a tank. Sexed, gauged color, measured, and weighed each sampled crab, then labelled each crab with a number. Based on weight (20-30 g), we selected crabs for respirometry.
    • Acclimated three selected crabs for one hour
    • Measured oxygen consumption. The goal was to measure consumption until the chambers reached 75-80% oxygen.
    • Removed crabs from the respirometry chambers. Resealed the chamber and measured background respiration for 20 minutes. Empty chambers and wipe down with 70% ethanol.
    • Use refractometer to get salinity measurement for acclimation tank
    • Notes
    • Usually set up acclimation for one tank while performing TTR for the next tank
    • T3: Recalibrated probe 2
    • T4: 2 dead crabs. 1 male, blue-green, 1 female, orange, open abdomen
    • Warm temperatures seem to be speeding up molt cycle
  • Tank order
    • T6
    • T3
    • T2
    • T5
    • T1
    • T4
  • Salinity
    • T1/T4: 35
    • T2/T5: 36
    • T3/T6: 34
  • Checked ammonia concentrations in all tanks
    • T1: 1.0
    • T2: 0
    • T3: 8.0
    • T4: 2.0
    • T5: 0
    • T6: 8.0
  • Performed water change, cleaned, and added 1/2 tsp conditioner to T1, T3, T4, and T6
  • Fed crabs 1/4 tsp in cold and ambient tanks, 3/8 tsp in warm tanks after respirometry

Day 9

  • Checked ammonia concentrations in all tanks
    • T1: 1.0
    • T2: 0.5
    • T3: 8.0
    • T4: 4.0
    • T5: 0.5
    • T6: 8.0
    • Carolyn: High ammonia concentrations in warm tanks consistent with what she experienced, continue doing water changes and monitoring. As long as crab behavior doesn’t change it’s probably fine
  • Cleaned all tanks, performed water change for T3 and T6, and added 1/2 tsp conditioner to T1, T3, T4, and T6
  • Replaced aquarium filters on all tanks
  • No mortalities
  • Fed all tanks 1/4 tsp
  • T6 temperature holding closer to 29-30ºC on heater probes. Increased set point to 33ºC and reduced Hd and Cd to 0.2ºC. Will see if that stabilizes temperature and confirm with HOBOs

Day 10

  • Checked ammonia concentrations in all tanks
    • T1: 1.0
    • T2: 0.5
    • T3: 8.0
    • T4: 4.0
    • T5: 0.5
    • T6: 8.0
  • Cleaned all tanks, performed water change for T3 and T6, and added 1/2 tsp conditioner to T1, T3, T4, and T6
  • No mortalities
  • Fed ambient and warm tanks 1/4 tsp, cold tanks 1/8 tsp
    • Saw T3 and T6 crabs eat!
  • Got HOBO data
    • Adding tank to the left of T1 (in front of 10ºC line) seems to insulate it and reduce variation between T1 and T4
    • T3 and T6 holding 31-32ºC, attempted to reduce some variation within tanks by setting Hd and Cd to 0.2ºC on all heaters. Back heaters set at 33ºC, T6 front 33ºC, T3 front 32ºC
    • yrv_3, yrv_9, yrv_10 low battery (cold tanks)
  • T6 temperature holding closer to 29-30ºC on heater probes. Increased set point to 33ºC and reduced Hd and Cd to 0.2ºC. Will see if that stabilizes temperature and confirm with HOBOs
  • T3: one crab on top, T6: four crabs on top. Patched small hole in T6 mesh that allowed crabs to sit between mesh and glass lid

Going forward

  1. Continue with experiment
  2. Check HOBOs and replace low battery loggers
  3. Update protocols
  4. Organize project repository and datasheets
Written on July 14, 2022