The composition and abundance of phytoplankton after spring bloom in the Arctic Svalbard fjords

Seongjun Bae, Haryun Kim, Seung Il Nam, Keun Hyung Choi, Tae Wook Kim, Sung Tae Yun, Hye Seon Kim, Tae Hoon Kim, Dukki Han, Young Ho Ko, Ju Hyoung Kim, Young Kyun Lim, Joo Myun Park

Research output: Contribution to journalArticlepeer-review

Abstract

Glacial melting and massive spring blooms caused by global warming have significantly altered the environmental conditions in the Svalbard fjords of the European Arctic. These changes included reduced salinity (the gradient of salinity from inner to outer fjords, ranging from 23 to 34 PSU), stratification of the water column, increased turbidity (>135 FTU), low nutrient conditions (0.06–1.13 μM PO4, 1.19–3.54 μM NO3, 1.19–3.54 μM NH4+, and −2.1 to 0.9 N*), reduced light penetration, and release of organic matter, resulting in changes in the structure and composition of the phytoplankton. Our study, conducted in Isfjorden, van Mijenfjorden/Bellsund, and Hornsund of Svalbard in early August 2019, observed the dominance of cryptophytes in the phytoplankton composition after the spring bloom. Our results show a different phenomenon from the previous diatom/dinoflagellate dominance in the late 1970s and the early 2020s. Changes in phytoplankton composition can be explained as follows. (1) The excessive consumption of nutrients during spring bloom and the reduction of nutrient mixing in the water column stratification due to glacier melting has formed nutrient-depleted conditions, providing favorable conditions for the small-sized phytoplankton that easily find nutrients. (2) A wide range of salinities has created beneficial conditions for cryptophytes, capable of controlling osmotic stress against various salinities, of surviving compared to diatoms and dinoflagellates. (3) Finally, the influx of organic matter into fjords due to glacier melting can increase turbidity and decrease light availability; therefore, cryptophytes with mixotrophic metabolisms could be more viable than diatoms with only autotrophic metabolisms. In summary, the dynamic environmental conditions after enhanced spring bloom and glacier melting will further alter phytoplankton compositions and, in turn, influence food webs at higher tropical levels in European Arctic fjord ecosystems.

Original languageEnglish
Article number107970
JournalEstuarine, Coastal and Shelf Science
Volume275
DOIs
Publication statusPublished - 2022 Sep 30

Keywords

  • Cryptophyceae
  • Diatom
  • Dinophyceae
  • Glacier melting
  • Phytoplankton
  • Svalbard fjords

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

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