PERI-FIX 2021

PERI-FIX (Fe Incubation eXperiment) was the first experiment conducted using the Pelagic Ecosystem Research Incubators (PERIcosms) for SCOPE (PERI-SCOPE). The goal of PERI-FIX is to manipulate the supply of N:P:Fe to a natural, oligotrophic community in order to see how nutrient supply ratios affect community composition and nitrogen fixation over the course of several weeks. Seawater was collected from the oligotrophic North Pacific Subtropical Gyre near Hawaii (21.08920 N, 158.07428 W), and incubated in twenty-four 113 L PERIcosm tanks at the University of Hawaii Marine Center (21.31657 N, 157.87588 W) for 29 days. Treatments were named for the nutrients added, which included a no-addition control (C), added P at a rate of 9.3 nM each day (P), added N at a rate of 150 nM each day (N), added Fe at a rate of 1nM each day (F), and all combinations therein (PF, NF, NP, NPF).