Table 1.
Culture treatments for Acropora kenti and Acropora spathulata, including stocking density, turnover, UV sterilization (Steril.), and surface agitation.
Fig 1.
Culture tank design and experimental overview.
A) A diagram of a 500 L culture tank highlighting the culture treatments: (1. UV sterilization, 3. air-driven surface agitation) and tank features (2. Angled inlets generating circular rotation, 4. Aeration delivered to the bottom of the tank, 5. Cylindrical mesh filter on outlet, 6. Water sample outlet, 7. Standpipe to set operational height). Water flow is indicated using blue arrows, air flow is indicated using grey arrows. B) A visual representation of the six combinations of culture treatments used for each species (see Table 1). Unique symbols are used to denote air-driven surface agitation and UV sterilization as depicted in A). The tank color indicates the tank turnover (i.e., flowrate) with darker blue indicated 0.6 vol. hr-1. The pink, orange, and dark orange circles represent a larval density of either 0.3, 1.0, or 2.0 larvae mL-1 stocking density, respectively.
Table 2.
Statistical results comparing culture responses across different culture treatments over time.
Fig 2.
Temporal patterns in larval cultures.
A) Larval survival (proportion of target stocking density) for A. kenti and A. spathulata in different culture treatments. B) Larval size (area mm2). C) Proportion of larvae with normal morphologies (i.e., round or elongated). Columns distinguish coral species. Larval stocking densities are represented using different colors, tank turnover treatments have dashed or solid lines, and the surface agitation treatment is denoted with triangles. Points represent means and SE.
Fig 3.
Selected nitrogen water quality parameters and bacterial abundance for A. spathulata and A. kenti in different culture treatments: A) nitrite and (; µM) B) nitrate (
; µM), and C) particulate nitrogen (µM); D) particulate carbon (µM) and E) bacterial abundance measured from a subset of treatments using ddPCR (cells mL-1).
The gray band in E indicates the mean ± SE of bacterial abundance from local reef samples. Columns distinguish coral species. Larval stocking densities and UV sterilization are represented using different colors, tank turnover treatments have solid or dashed lines, and the surface agitation treatment is denoted with triangle symbols. Points represent means and error bars represent SE. Blue lines represent values in the incoming seawater before (dark blue) and after UV sterilization (light blue). The black vertical line indicates when zygotes were added.
Table 3.
Linear model results for water quality characteristics of larval cultures.
Table 4.
Permutational analysis of variance (PERMANOVA) results of microbial communities in A. kenti and A. spathulata larval cultures. Predictors include the day of culture, water turnover (0.2 or 0.6 vol. hr-1) and their interaction. P-values ≤0.05 are indicated in bold.
Fig 4.
Dynamics of microbial community diversity and composition in culture water.
A) Faith’s phylogenetic diversity (PD) of the bacterial community from 16S rDNA sequencing. The culture treatments are indicated in purple while the source seawater is indicated in blue. The low turnover (0.2 vol. hr-1) treatment is indicated using purple dashed lines while the high turnover (0.6 vol. hr-1) treatments is indicated with purple solid lines. Points represent means and error bars represent SE. The vertical black line represents when larvae were added to the culture tanks. B and C) Ordinations by principal coordinates analysis of the microbial communities between 0.2 and 0.6 × hr-1 turnover treatments for A. spathulata and A. kenti, respectively. Point locations represent the relative community composition of a particular culture treatment on each day of culture (indicated using numbers). Low turnover is indicated using open purple circles and high turnover is indicated using solid purple symbols. Blue asterisks indicate the community composition of the source seawater. X and Y axes are the first and second principal coordinates, respectively.
Fig 5.
Genus-level microbial community composition in the culture water for A. kenti (A) and A. spathulata (B).
Every panel depicts the composition of up to 3 culture tanks for each sampling Day and turnover treatment. Each bar represent relative abundance of genera that exceeded 10% relative abundance in any coral species, turnover treatment, or sampling day. Citreicella, Cognatishimia, and Donghicola belong the class Alphaproteobacteria while the other genera belong to the Gammaproteobacteria. ‘Other’ includes all other genera as well as three unidentified taxa with >10% relative abundance but that could not be identified to genus-level.