Paleoecological evidence for decadal increase in phytoplankton biomass off northwestern Australia in response to climate change

• Published in: Ecology and evolution Vol. 8; no. 4; pp. 2097 - 2107
• Main Authors: Yuan, Zineng, Liu, Dongyan, Keesing, John K., Zhao, Meixun, Guo, Shixin, Peng, Yajun, Zhang, Hailong
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.02.2018; John Wiley and Sons Inc; Wiley
• Subjects: Alkanes; Aquaculture; Biomarkers; Biomass; Climate change; Coastal waters; Cygnet Bay; diatom; dinoflagellate; Dinoflagellates; Ecosystems; Glycerol; Grain size; Lipids; Microorganisms; Ocean temperature; Ocean warming; Original Research; Paleoecology; Phytoplankton; Plankton; Principal components analysis; Proxies; Rainfall; River discharge; River flow; Rivers; Sea surface temperature; Sedimentation & deposition; Sediments; Sterols; TEX 86 H; Australia; ocean warming; diatom; Cygnet Bay; dinoflagellate; biomarkers; TEX86H
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.3836

Ocean warming can modify the phytoplankton biomass on decadal scales. Significant increases in sea surface temperature (SST) and rainfall in the northwest of Australia over recent decades are attributed to climate change. Here, we used four biomarker proxies (TEX86 index, long‐chain n‐alkanes, brassicasterol, and dinosterol) to reconstruct approximately 60‐year variations of SST, terrestrial input, and diatom and dinoflagellate biomass in the coastal waters of the remote Kimberley region. The results showed that the most significant increases in SST and terrestrial input occurred since 1997, accompanied by an abrupt increase in diatom and dinoflagellate biomasses. Compared with the results before 1997, the average TEX86H temperature during 1997–2011 increased approximately 1°C, rainfall increased 248.2 mm, brassicasterol and dinosterol contents increased 8.5 and 1.7 times. Principal component analysis indicated that the warming SST played a more important role in the phytoplankton increase than increased rainfall and river discharge. An abrupt increase in phytoplankton occurred since the 1990s, accompanied by significant increases in temperature and terrestrial input. Warming temperature played a more important role for the decadal phytoplankton increase than rainfall. Applicability of TEX86H biomarker proxy for SST off northwestern Australia was validated.