Extreme temperature impairs growth and productivity in a common tropical marine copepod

Nam X Doan,Hung Q Pham,Torkel Gissel Nielsen,Mary S Wisz,Minh T T Vu,Khuong V Dinh

doi:10.1038/s41598-019-40996-7

Abstract

Shallow, tropical marine ecosystems provide essential ecosystem goods and services, but it is unknown how these ecosystems will respond to the increased exposure to the temperature extremes that are likely to become more common as climate change progresses. To address this issue, we tracked the fitness and productivity of a key zooplankton species, the copepod Pseudodiaptomus annandalei, acclimated at two temperatures (30 and 34 °C) over three generations. 30 °C is the mean temperature in the shallow water of the coastal regions in Southeast Asia, while 34 °C simulated a temperature extreme that occurs frequently during the summer period. For each generation, we measured the size at maturity and reproductive success of individuals. In all three generations, we found strong negative effects of warming on all measured fitness-related parameters, including prolonged development time, reduced size at maturity, smaller clutch sizes, lower hatching success, and reduced naupliar production. Our results suggest that P. annandalei are already exposed to temperatures that exceed their upper thermal optimum. Increased exposure to extreme temperatures may reduce the abundance of these tropical marine copepods, and thus reduce the availability of resources to higher trophic levels.

Highlights

Shallow, tropical marine ecosystems provide essential ecosystem goods and services, but it is unknown how these ecosystems will respond to the increased exposure to the temperature extremes that are likely to become more common as climate change progresses
In the F1 and F2 generations, P. annandalei showed no difference in naupliar development time between 30 °C and 34 °C (Fig. 1a–d)
The nauplii development time of the F3 generation was similar to the F1 and F2 generations, but the copepodite stages lasted longer, and they reached the maturity on day 9 at 30 °C and day 10 at 34 °C (Fig. 1e,f)

Summary

Introduction

Tropical marine ecosystems provide essential ecosystem goods and services, but it is unknown how these ecosystems will respond to the increased exposure to the temperature extremes that are likely to become more common as climate change progresses To address this issue, we tracked the fitness and productivity of a key zooplankton species, the copepod Pseudodiaptomus annandalei, acclimated at two temperatures (30 and 34 °C) over three generations. Elevated temperature increased fitness over multiple generations in high latitude zooplankton[28], but reduced the reproductive success of a coral reef damselfish Acanthochromis polyacanthus[29] It remains relatively unknown how tropical coastal marine organisms, especially those at the base of the marine food web such as copepods, will be affected by extreme warming, across generations. We documented how warming affects key fitness-related traits of copepods as the secondary producers including the development time, size at maturity of males and females, the clutch size, the hatching success and the naupliar production

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Conclusion