Co-dynamics of Symbiodiniaceae and bacterial populations during the first year of symbiosis with Acropora tenuis juveniles

Fourteen colonies of A. tenuis were collected from Geoffrey Bay, Magnetic Island and transported to the National Sea Simulator Facility (SeaSim) at the Australian Institute of Marine Sciences (AIMS). Corals were maintained in outside aquaria prior to the spawning event

Once larvae were competent to settle (7 days postspawning) preconditioned terracotta tiles crustose coralline algae (CCA) were introduced to induce settlement. Larvae were left to settle for 11 days. Settlement on each tile was assessed visually, and tiles containing juveniles were strung onto stainless steel rods in groups of 15 separated by PVC spacers.

Nineteen days postspawning, 240 tiles, each with 40–200 juveniles, were transported to Magnetic Island and deployed at two sites at Magnetic Island (Geoffrey Bay and Nelly Bay) respectively, at a depth of approximately 6.

Fluorescent microscopy was used to confirm the absence of Symbiodiniaceae cells prior to field deployment. Juveniles were sampled from tiles on the 19th of each month from 8:30 to 10:30 a.m. where conditions allowed, where between 6 and 17 juveniles were photographed at each time point. As juveniles began to present more complex branching patterns, 3D modelling was then employed to capture the geometries and estimate surface area. Surface area measurements were matched with Symbiodiniaceae cell counts and DNA extractions for each juvenile.

The age of juveniles at each sampling time point was as follows:

T1 – 40 days
T2 – 71 days
T3 – 11 days
T4 – 129 days
T5 – 167 days
T6 – 194 days
T7 – 316 days
T8 – 380 days

See Quigley et al (2020) for full details.