Thermal tolerance of the zoea I stage of four Neotropical crab species (Crustacea: Decapoda)

Adriana P Rebolledo,Rachel Collin

doi:10.3897/zoologia.35.e14641

Abstract

. Although larval stages are often considered particularly vulnerable to stressors, for many marine invertebrates studies of thermal tolerance have focused on adults. Here we determined the upper thermal limit (LT50) of the zoea I of four Caribbean crab species (Macrocoelomatrispinosum, Aratuspisonii, Armasesricordi, and Minucarapax) and compared their thermal tolerance over time and among species. The zoea from the subtidal species M.trispinosum and tree climbing mangrove species A.pisonii had a lower thermal tolerance, 35 and 38.5 °C respectively, than did the semiterrestrial A.ricordi and M.rapax. In all four species tested, the estimates of thermal tolerance depend on the duration of exposure to elevated temperatures. Longer exposures to thermal stress produce lower estimates of LT50, which decreased by ~1 °C from a two- to a six-hour exposure. Crab embryos develop on the abdomen of the mother until the larvae are ready to hatch. Therefore, the thermal tolerances of the embryos which need to coincide with the environmental conditions experienced by the adult stage, may carry over into the early zoea stage. Our results suggest that semiterrestrial species, in which embryos may need to withstand higher temperatures than embryos of subtidal species also produce larvae with higher thermal tolerances. Over the short term, the larvae of these tropical crab species can withstand significantly higher temperatures than those experienced in their marine habitat. Longer term rearing studies are necessary to determine the temperature at which chronic exposure has a negative impact on embryonic and larval survival.

Highlights

Environmental temperature influences the physiology and ecology of marine organisms across all the stages of their complex life cycles (Storch et al 2009, 2011, Hammond and Hofmann 2010, Byrne 2011)
There is little information on the temperature tolerance and safety factors of tropical species, since most studies have focused on temperate species (e.g. Anger et al 2003, Storch et al 2009, 2011, Weiss et al 2009, Fowler et al 2010, Schmalenbach and Franke 2010, Schiffer et al 2014, Tepolt and Somero 2014), and few have focused on determining their upper thermal limit (e.g. Ravaux et al 2016)
Upper thermal limit (UTL) of the zoea I stage of four Neotropical crab species, as the first step to determine their vulnerability to environmental warming

Summary

Introduction

Environmental temperature influences the physiology and ecology of marine organisms across all the stages of their complex life cycles (Storch et al 2009, 2011, Hammond and Hofmann 2010, Byrne 2011). Available information on tropical marine species suggest that they are generally more tolerant of heat than are temperate species, adults may live closer to their upper thermal limits, reducing their safety factors and making them especially susceptible to increases environmental temperatures (Somero 2010, Nguyen et al 2011, Madeira et al 2012). Upper thermal limit (UTL) of the zoea I stage of four Neotropical crab species, as the first step to determine their vulnerability to environmental warming.

Results

Conclusion