| Summary: | Maintenance and Update Frequency: notPlanned Statement: 5.3.1. Experimental conditions Experimental conditions are described in detail in Ericson et al. (2018b). Briefly, krill were collected from the Southern Ocean (66-03°S, 59-25°E and 66-33°S, 59-35°E) on the RSV Aurora Australis, using a mid-water trawl net. They were held in shipboard aquaria using standard husbandry methods (see King et al. 2003) and transported to the Australian Antarctic Division Krill Aquarium in Tasmania. For ocean acidification experiments, five 300L tanks were equilibrated to five pCO2 levels; 400 μatm pCO2 (pH 8.1 control treatment), 1000 μatm pCO2 (pH 7.8), 1500 μatm pCO2 (pH 7.6), 2000 μatm pCO2 (pH 7.4) and 4000 μatm pCO2 (pH 7.1). Seawater temperature of all tanks was held at 0.5ºC (± 0.2). Seawater chemistry for the duration of the experiment is reported in Supplementary Material in Ericson et al. (2018b). Observational units (CO2 treatment tanks) could not be replicated, due to the large tank size required to achieve the best possible animal husbandry for this pelagic species, and the limited space and resources available for these large tanks over such a long-term study. Tanks were inspected daily, and there was no visual evidence to suggest that tank effects were confounding our experimental results. Two hundred krill were randomly assigned to each tank on the first day of the experiment (25th January 2016), and reared in these pCO2 treatments until the experiment ended on the 12th December 2016. Light was controlled in the laboratory to mimic the seasonal Southern Ocean light regime (66°S, 30m depth) and krill were fed six days per week with a microalgal diet of the Antarctic species Pyramimonas gelidicola (2 x 104 cells mL-1), and Reed Mariculture Inc. (USA) cultures of Thalassiosira weissflogii (8.8 x 103 cells mL-1), Pavlova lutheri (4.5 x 104 cells mL-1) and Isochryisis galbana (5.5 x 10 cells mL-1). 5.3.2. Sample collection and lipid extraction Krill were sampled from the pCO2 treatment tanks in experimental weeks 1, ...
|
|---|