Fine-scale conditions across mangrove microhabitats and larval ontogeny contributes to the thermal physiology of early stage brachyurans (Crustacea: Decapoda)

L D Vorsatz; P Pattrick; F Porri

doi:10.1093/conphys/coab010

Fine-scale conditions across mangrove microhabitats and larval ontogeny contributes to the thermal physiology of early stage brachyurans (Crustacea: Decapoda)

Conserv Physiol. 2021 Mar 16;9(1):coab010. doi: 10.1093/conphys/coab010. eCollection 2021.

Authors

L D Vorsatz^{1

2

3}, P Pattrick^{1

2

4}, F Porri^{1

2}

Affiliations

¹ Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa.
² South African Institute for Aquatic Biodiversity (SAIAB), Makhanda 6139, South Africa.
³ The Swire Institute of Marine Science and the Division of Ecology and Biodiversity, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong SAR.
⁴ South African Environmental Observation Network, Elwandle Coastal Node, Port Elizabeth 6070, South Africa.

Abstract

Most marine ectotherms require the successful completion of a biphasic larval stage to recruit into adult populations. Recruitment of larvae into benthic habitats largely depends on biological interactions and favourable environmental conditions such as the inescapable diurnal thermal and tidal exposures. Hence, assessing how different taxa metabolically respond to variations in temperature is imperative to understand the community and ecosystem dynamics at both local and global scales. The present study aimed to investigate the effects of acute temperature variation on the physiology of stage-specific brachyuran larvae collected from different microhabitats at two mangrove forests in South Africa. Results indicate that the conditions within microhabitats, which larvae experience, likely influence their physiology, based on respirometry, to short-term acute temperature exposures. Furthermore, the larval thermal optimum shifted ontogenetically to become increasingly eurythermic as individuals developed from stage I zoea through to megalopa. Mangrove crab larvae in their early stages are hence increasingly vulnerable to acute temperature exposures, which could be particularly harmful to the persistence of populations if thermally stressful events increase in magnitude and frequency.

Keywords: Development; habitat complexity; larvae; mangroves; respirometry; vulnerability.