GROWTH RESPONSE OF ANTARCTIC PHYTOPLANKTON TO IRON ENRICHMENT (18th Symposium on Polar Biology)

• Main Authors: タケダ シゲノブ, ワタナベ ケンタロウ, Shigenobu TAKEDA, Kentaro WATANABE
• Format: Report
• Language: English
• Published: Proceeding 1997
• Subjects: Antarctic; Southern Ocean; Antarc*; Polar Biology; Proceedings of the NIPR Symposium on Polar Biology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=5336; http://id.nii.ac.jp/1291/00005336/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=5336&item_no=1&attribute_id=18&file_no=1

Laboratory culture experiments were conducted with marine phytoplankton isolated from the Southern Ocean to determine the growth responses to iron enrichment. Batch cultures of ten diatom clones and two Phaeocystis clones were grown under various total iron concentrations (0.1-10.1 nM) using trace metal clean techniques. These Antarctic phytoplankton clones responded to iron enrichment by increasing their growth rates. When growth rates are plotted against the total iron concentration on a semilogarithmic graph, the growth curves may be grouped into three patterns. Odontella weissflogii showed a linear increase with total iron. Chaetoceros dichaeta (clone AA-B-40 and C-21), Chaetoceros hendeyi, Nitzschia sp. 1 and sp. 4, Phaeocystis sp. 1 and sp. 2 showed hyperbolic increase with total iron from 0.1 nM. Corethron criophilum, Nitzschia sp. 2, sp. 3, and sp. 5 showed hyperbolic increase with total iron from 0.2 nM, or a sigmoid pattern. There was no clear difference in their growth response to iron enrichment between isolates from the open ocean and marginal ice waters. The dependence of growth rates on cell volume size was also insignificant. Our results suggest that Antarctic phytoplankton may respond differentially and significantly to changes of iron level even within the natural fluctuation in the Southern Ocean.