Ontogeny and ecological significance of metabolic rates in sea turtle hatchlings

Brittany Imlach,T Todd Jones,Christopher R Gatto,Richard D Reina

doi:10.1186/s12983-022-00451-2

Brittany Imlach, T Todd Jones + Show 2 more

Open Access

https://doi.org/10.1186/s12983-022-00451-2

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Abstract

BackgroundSea turtle hatchlings must avoid numerous predators during dispersal from their nesting beaches to foraging grounds. Hatchlings minimise time spent in predator-dense neritic waters by swimming almost continuously for approximately the first 24 h post-emergence, termed the ‘frenzy’. Post-frenzy, hatchling activity gradually declines as they swim in less predator-dense pelagic waters. It is well documented that hatchlings exhibit elevated metabolic rates during the frenzy to power their almost continuous swimming, but studies on post-frenzy MRs are sparse.ResultsWe measured the frenzy and post-frenzy oxygen consumption of hatchlings of five species of sea turtle at different activity levels and ages to compare the ontogeny of mass-specific hatchling metabolic rates. Maximal metabolic rates were always higher than resting metabolic rates, but metabolic rates during routine swimming resembled resting metabolic rates in leatherback turtle hatchlings during the frenzy and post-frenzy, and in loggerhead hatchlings during the post-frenzy. Crawling metabolic rates did not differ among species, but green turtles had the highest metabolic rates during frenzy and post-frenzy swimming.ConclusionsDifferences in metabolic rate reflect the varying dispersal stratagems of each species and have important implications for dispersal ability, yolk consumption and survival. Our results provide the foundations for links between the physiology and ecology of dispersal of sea turtles.

Highlights

Sea turtle hatchlings must avoid numerous predators during dispersal from their nesting beaches to foraging grounds
Sea turtle hatchlings have high mortality rates compared to other reptiles because of high predation rates during their prolonged dispersals [4, 5]
Overall variation in metabolic rates with activity level, behavioural stage and species Hatchling mass and test temperatures for each species and location are reported in Tables 1 and 2, respectively

Summary

Introduction

Sea turtle hatchlings must avoid numerous predators during dispersal from their nesting beaches to foraging grounds. Hatchlings minimise time spent in predator-dense neritic waters by swimming almost continuously for approximately the first 24 h post-emergence, termed the ‘frenzy’. Post-frenzy, hatchling activity gradually declines as they swim in less predator-dense pelagic waters. Sea turtle hatchlings have high mortality rates compared to other reptiles because of high predation rates during their prolonged dispersals [4, 5]. During the frenzy, hatchling swimming activity can be broken into three phases: the rapid fatigue phase when oxygen consumption is initially high and quickly declines; followed by the slow fatigue phase when oxygen consumption rates continue to drop, but at a slower rate; and lastly the sustained effort phase when oxygen consumption is relatively stable [7].

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