Articles | Volume 13, issue 13
Research article
11 Jul 2016
Research article |  | 11 Jul 2016

A 150-year record of phytoplankton community succession controlled by hydroclimatic variability in a tropical lake

Kweku Afrifa Yamoah, Nolwenn Callac, Ernest Chi Fru, Barbara Wohlfarth, Alan Wiech, Akkaneewut Chabangborn, and Rienk H. Smittenberg

Abstract. Climate and human-induced environmental change promote biological regime shifts between alternate stable states, with implications for ecosystem resilience, function, and services. While these effects have been shown for present-day ecosystems, the long-term response of microbial communities has not been investigated in detail. This study assessed the decadal variations in phytoplankton communities in a ca. 150 year long sedimentary archive of Lake Nong Thale Prong (NTP), southern Thailand using a combination of bulk geochemical analysis, quantitative polymerase chain reaction (qPCR) and lipid biomarkers techniques including compound-specific hydrogen isotope analysis as a proxy for precipitation. Relatively drier and by inference warmer conditions from ca. 1857 to 1916 Common Era (CE) coincided with a dominance of the green algae Botryococcus braunii, indicating lower nutrient levels in the oxic lake surface waters, possibly related to lake water stratification. A change to higher silica (Si) input around 1916 CE was linked to increased rainfall and concurs with an abrupt takeover by diatom blooms lasting for 50 years. These were increasingly outcompeted by cyanobacteria from the 1970s onwards, most likely because of increased levels of anthropogenic phosphate and a reduction in rainfall. Our results showcase that the multi-proxy approach applied here provides an efficient way to track centennial-scale limnological, geochemical and microbial change, as influenced by hydroclimatic and anthropogenic forcing.

Short summary
Predicting the effects of changing climate on microbial community shifts on longer timescales can be challenging. This study exploits the power of combining organic geochemistry, molecular microbial ecology, and geochemistry to unravel trends in microbial community induced by climatic variability. Our results show that climate-induced variability on decadal timescales can trigger changes in both lake trophic status and phytoplankton communities.
Final-revised paper