ORCID

Abstract

Magnesium is essential to numerous biological processes in many species. Including protecting intracellular pH and ATP concentrations during temperature and anoxia stress. Extracellular [Mg2+] is tightly regulated in many, but not all crustaceans. There is evidence that extracellular [Mg2+] content may be open to environmental influence such as temperature. The alteration of extracellular [Mg2+] in decapod crustaceans in response to temperature has been proposed, with individuals exposed to low temperature often displaying an increase in extracellular [Mg2+]. However, data, supporting or refuting this hypothesis, are sparse and drawn mainly from temperate and sub-polar studies. Therefore, the aim of this study was to determine if extracellular [Mg2+] increased at low temperature, indicating a disruption of [Mg2+] regulation for tropical crab species that do not typically experience large temperature fluctuations. Three species of Christmas Island land crabs were exposed to environmental (25 °C) and reduced (6 °C) temperatures for 60–90 min (depending on species). Haemolymph was sampled every 30 min and concentrations of Mg2+, and other key ions (Ca2+, K+, Cu2+, and Na+) quantified. Contrary to our prediction, all species displayed extracellular [Mg2+] resilience to temperature, exhibiting either the absence of evolved physiological mechanisms, or presence of tight regulatory abilities. There were, however, small but significant changes in concentrations of some of the other measured ions. We conclude that the alteration of extracellular [Mg2+] in response to acute reduced temperature is not a ubiquitous function in crustaceans as there is little support from the three tropical Christmas Island land crabs investigated.

Publication Date

2026-05-27

Publication Title

Comparative Biochemistry and Physiology -Part A : Molecular and Integrative Physiology

Volume

318

ISSN

1095-6433

Acceptance Date

2026-05-26

Deposit Date

2026-06-19

Funding

We thank the Park Manager and staff of Parks Australia, Christmas Island, for their logistical assistance, hospitality and enthusiasm for this work. This work was conducted under permits granted by the Australian Government Environment Protection and Biodiversity Conservation Regulations 2000 (permit numbers AU-COM2011-125 , PS2011_011 , and Turner_PCrab_Physiology_14/07/2011-30/06/2012 ). The British Ecological Society (Small Ecological Project Grant: 3682/4548 ) and the Journal of Experimental Biology (Company of Biologists Travelling Fellowship) are thanked for providing funding to L.M.T., and the University of Plymouth for providing funding to K.N.G.T. to complete this work. Funding has been provided by The British Ecological Society (Small Ecological Project Grant: 3682/4548) and the Journal of Experimental Biology (Company of Biologists Travelling Fellowship) to L.M.T., and a University of Plymouth Studentship for K.N.G.T. to complete this work.

Keywords

Crustacean, Extracellular magnesium, Ionic regulation, Temperature, Tropical land crabs

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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