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Front. Environ. Sci. | doi: 10.3389/fenvs.2019.00125

Adaptation of Red Sea Phytoplankton to Experimental Warming Increases Their Tolerance to Toxic Metal Exposure

  • 1Red Sea Research Center, King Abdullah University of Science and Technology, Saudi Arabia
  • 2Guangzhou University, China

Our recent study has demonstrated the rapid adaptation of the Red Sea phytoplankton to ocean warming, with associated constraints of physiological performance. However, the possible tradeoff between thermal adaptation and the organism’s tolerance to other environmental drivers in a warmer future scenario remains understudied. Here, we designed an evolutionary selection environment where the Red Sea diatom Chaetoceros tenuissimus was adapted to ambient (26 oC) and warming (30 oC) temperature scenarios for over 2000 generations. These strains were subsequently exposed to a range of copper (Cu) dose over three assay temperatures (26 oC, 30 oC, and 35 oC), to assess whether the adaptation to experimental warming is accompanied by a reformed tolerance to toxic pollutants. Most previous studies on Cu toxicity in marine phytoplankton were conducted within a small range of temperature (20−25 oC), indicating the need for further assessments to reveal the potential complex interactive effects between pollutants and more significant warming in the future. The acute Cu toxicity was estimated in terms of reduction in cell abundance (cells mL−1), growth rate (μ) and PSII photosynthetic efficiency (Fv/Fm), with 48 h median effective concentration values (EC50) varying from 2.22−20.19 μg L−1. We found a statistically significant interaction between assay temperature, selection temperature, and Cu doses in all the criteria tested. However, under extreme warming scenario (35 oC), the Cu sensitivity was significantly reduced, indicating cumulative antagonistic effects between these factors. Adaptation of phytoplankton to higher temperatures may help maintain their heavy metal tolerance, although a shift in temperature during the tests clearly altered their sensitivities. We conclude that selection for warming having made cells more resistant to Cu at the selection temperature in comparison to ambient-adapted population tested at 26 ºC. However, in warming-adapted cells, this was traded off against cupper resistance at 26 ºC.

Keywords: Red Sea, Phytoplankton, Chaetoceros tenuissimus, warming, adaptation, copper toxicity, Fv/Fm

Received: 06 May 2019; Accepted: 16 Aug 2019.

Edited by:

Andrew Hursthouse, University of the West of Scotland, United Kingdom

Reviewed by:

Victoria Lopez-Rodas, Complutense University of Madrid, Spain
C.-Elisa Schaum, Universität Hamburg, Germany  

Copyright: © 2019 Kottuparambil, Jin and Agusti. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Sreejith Kottuparambil, Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, 23955, Makkah, Saudi Arabia, sreejithkottuparambil@gmail.com