Mismatch of thermal optima between performance measures, life stages and species of spiny lobster

Michael Oellermann,Gretta T Pecl,Alistair J Hobday,Quinn P Fitzgibbon,Samantha Twiname,Chris G Carter

doi:10.1038/s41598-020-78052-4

Abstract

In an ocean warming hotspot off south-east Australia, many species have expanded their ranges polewards, including the eastern rock lobster, Sagmariasus verreauxi. This species is likely extending its range via larval advection into Tasmanian coastal waters, which are occupied by the more commercially important southern rock lobster, Jasus edwardsii. Here, thermal tolerances of these lobster species at two life stages were investigated to assess how they may respond to warming ocean temperatures. We found that the pattern, optimum and magnitude of thermal responses differed between performance measures, life stages and species. Sagmariasus verreauxi had a warmer optimal temperature for aerobic scope and escape speed than J. edwardsii. However, J. edwardsii had a higher magnitude of escape speed, indicating higher capacity for escape performance. There were also differences between life stages within species, with the larval stage having higher variation in optimal temperatures between measures than juveniles. This inconsistency in performance optima and magnitude indicates that single performance measures at single life stages are unlikely to accurately predict whole animal performance in terms of life-time survival and fitness. However, combined results of this study suggest that with continued ocean warming, S. verreauxi is likely to continue to extend its distribution polewards and increase in abundance in Tasmania.

Highlights

In an ocean warming hotspot off south-east Australia, many species have expanded their ranges polewards, including the eastern rock lobster, Sagmariasus verreauxi
Our experiments show that thermal pattern, optima and magnitude of response vary between multiple performance measures, life stage and species and highlights that a single measure of performance does not predict whole organism performance[14,19,20,34]
S. verreauxi had warmer temperature performance optima for metabolic rates and escape speeds tested for pueruli and juveniles respectively, J. edwardsii had higher magnitudes of response for escape speeds

Summary

Introduction

In an ocean warming hotspot off south-east Australia, many species have expanded their ranges polewards, including the eastern rock lobster, Sagmariasus verreauxi. The pace at which species alter their distribution occurs at different velocities, likely changing their interaction with other species, with ramifications for food webs and potentially widespread modifications of ecosystems[7,8,9,10]. Thermal performance curves map changes of a particular performance measure (e.g. metabolism, growth) against changes in temperature to derive a species’ optimal or suboptimal temperatures for these specific measures[14,15,16,17] This approach is useful for ectothermic organisms whose body temperature and associated body functions are directly affected by ambient temperature[12,15]. Using thermal performance curves will help identify how individual species react to changes in ocean temperatures and potentially inform at what temperature the outcomes of species interactions may alter

Methods

Results

Discussion

Conclusion