Phytoplankton species composition under Fe and Mn limitation in the Drake Passage

• Main Authors: Balaguer, Jenna, Koch, Florian, Hassler, Christel S, Trimborn, Scarlett
• Format: Dataset
• Language: English
• Published: PANGAEA 2021
• Subjects: co-limitation; Phytoplankton composition; Priority Programme 1158 Antarctic Research with Comparable Investigations in Arctic Sea Ice Areas; Southern Ocean; SPP1158; trace elements; Arctic; Antarctic; Drake Passage; Antarc*; Phytoplankton; Sea ice
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.935868; https://doi.org/10.1594/PANGAEA.935868

This study highlights the importance of manganese (Mn) next to iron (Fe) for growth of specific Southern Ocean phytoplankton groups. Two Fe-Mn bottle amendment experiments with two natural phytoplankton communities were performed during Polarstern expedition PS97 in 2016 in the Drake Passage. At two locations, sea water was pumped (using trace metals clean techniques) from 25m depth and used to fill polycarbonate bottles after having passed through a cleaned 200 μm mesh (removing large grazers). The Control treatment was the sampled seawater without any trace metals addition while the other three treatments were enriched with either FeCl3 alone (0.5 nM; +Fe treatment) or MnCl2 alone (1 nM; +Mn treatment) or both trace metals together (+FeMn treatment). All treatments were done in triplicate 2,5L PC bottles. All incubation bottles were maintained at 30 μmol photons m-2 s-1 under a 16:8 (light:dark) hour cycle at 1 ̊C. After on average 15 days, samples for chlorophyll a content, flow cytometry and light macroscopy were taken in order to detect FeMn co-limitation effect on species composition. In addition to the two experiments, 9 in situ stations of PS97 were also sampled for dissolved Fe, dissolved Mn as well as photophysiology and to complete this dataset, data from PS112 (2018) were also used. The results showed that only some members of the phytoplankton community were Fe-Mn co-limited, with the biogeochemical important diatom group Fragilariopsis and one subgroup of picoeukaryotes.