Water samples for chlorophyll extraction were collected from the mesocosms via a 5 L Niskin. Chlorophyll samples were filtered in triplicate through a 25mm Glass Fiber Filter (GFF), and immediately extracted in 6 mL of ethanol for 12-18 hours in the dark at room temperature. After extraction, filters were removed from the sample, and the fluorescence of the sample was read on a Turner AU10. The sample was then acidified with 1 drop of 10% HCL and re-read on the same instrument. The fluorometer was calibrated prior to using with a chlorophyll standard purchased from Sigma.
Mesocosm treatments are as follows:
P-limited: N:P added in a 60:1 ratio during the first 3 days of the experiment, no shading
Redfield: N:P added in a 16:1 ratio during the first 3 days of the experiment, no shading
Shaded: N:P added in a 16:1 ratio during the first 3 days of the experiment, top shaded of the mesocosm added on May 20, 2017
Ambient: no nutrients added, no shading
Samples were taken from either 1m, 5m, or from sediment from settling cones. Samples were noted in the Sample Depth (m) column.