Dataset: Growth rates of Trichodesmium erythraeum GBRTRLIN201 and Synechococcus WH8012 from phosphate-manipulation laboratory culture experiments

Culturing Methods

Synechococcus WH8012 and Trichodesmium erythraeum GBRTRLIN201 were isolated from the Sargasso Sea and the North Great Barrier Reef Lagoon, respectively (Waterbury et al. 1986; Bell et al. 2005). Thermal performance curves were established by stepwise acclimation of stock cultures from 28 °C to target temperatures, with approximately 3–4 days of acclimation between sequential transfers to minimize transient stress responses. Synechococcus was grown from 15 to 34 °C and Trichodesmium from 20 to 34 °C, both at 2–3 °C intervals. Triplicate cultures were grown in 0.2 µm-filtered, microwave-sterilized artificial seawater under a range of phosphate concentrations (0, 0.1, 0.2, 0.4, 0.7, 1, 2, 5, and 10 µM). In addition to phosphate, 100 μM nitrate, 10 μM phosphate, and 125 nM Fe-25 μM EDTA were added. Light was provided at ~40 µmol photons m⁻² s⁻¹ (Synechococcus) and ~150 µmol photons m⁻² s⁻¹ (Trichodesmium) on a 12:12 h light: dark cycle. Cultures were maintained in batch culture, and measurements were conducted at the exponential growth phase. 

Physiological Analyses

Growth rate. Daily growth rates were determined from in vivo chlorophyll a fluorescence measured with a Turner Designs 10-AU fluorometer. Specific growth rates were calculated as µ = ln[N(T1)/N(T0)] / (T1– T0). Maximum specific growth rates (µmax) and half-saturation constants (K1/2) were determined by fitting growth rates to the Monod equation.