Swimming for your life: locomotor effort and oxygen consumption during the green turtle (Chelonia mydas) hatchling frenzy

Abstract

SUMMARY Swimming effort and oxygen consumption of newly emerged green turtle Chelonia mydas hatchlings was measured simultaneously and continuously for the first 18 h of swimming after hatchlings entered the water. Oxygen consumption was tightly correlated to swimming effort during the first 12 h of swimming indicating that swimming is powered predominantly by aerobic metabolism. The patterns of swimming effort and oxygen consumption could be divided into three distinct phases: (1) the rapid fatigue phase from 0 to 2 h when the mean swim thrust decreased from 45 to 30 mN and oxygen consumption decreased from 33 to 18 ml h–1; (2) the slow fatigue phase from 2 to 12 h when the mean swim thrust decreased from 30 to 22 mN and oxygen consumption decreased from 18 to 10 ml h–1; and(3) the sustained effort phase from 12 to 18 h when mean swim thrust averaged 22 mN and oxygen consumption averaged 10 ml h–1. The decrease in mean swim thrust was caused by a combination of a decrease in front flipper stroke rate during a power stroking bout, a decrease in mean maximum thrust during a power stroking bout and a decrease in the proportion of time spent power stroking. Hence hatchlings maximise their swimming thrust as soon as they enter the water, a time when a fast swimming speed will maximise the chance of surviving the gauntlet of predators inhabiting the shallow fringing reef before reaching the relative safety of deeper water.

Variation in body condition during the post-moult foraging trip of southern elephant seals and its consequences on diving behaviour

“…However, numerous studies have highlighted strong and linear relationships between locomotion effort and oxygen consumption for a broad range of taxa (see Schmidt-Nielsen, 1972;Mayhew, 1977;Booth 2009). Furthermore, in a recent study on post-breeding SES females, Genin et al (A.G., G.R., J.J., B.P., N. El Skabi, J.V.-G. and C.G., unpublished) found that surface interval duration, related to the number of breaths taken, was highly correlated to the dive duration and the overall swimming effort of the previous dive.…”

Locomotor activity during the frenzy swim: analysing early swimming behaviour in hatchling sea turtles

“…During the swim frenzy, hatchlings usually alternate between bouts of a high thrust production, lift-based movement of the fore-flippers, the 'power stroking' gait, and bouts of a lower thrust production 'dog paddling' gait in which alternate movement of all four flippers in a paddle-like motion produces dragbased thrust (Salmon and Wyneken, 1987;Wyneken and Salmon, 1992). Power stroking bouts typically last between 2 and 20s and are interspersed with short periods of dog paddling (1-5s), when hatchlings surface to breathe (Salmon and Wyneken, 1987;Burgess et al, 2006;Booth, 2009) (Fig.1). Power stroke rates and oxygen consumption are highest immediately after the hatchlings enter the water and decline as the swim frenzy progresses (Salmon and Wyneken, 1987;Wyneken and Salmon, 1992;Burgess et al, 2006;Booth, 2009;Ischer et al, 2009).…”

“…Power stroking bouts typically last between 2 and 20s and are interspersed with short periods of dog paddling (1-5s), when hatchlings surface to breathe (Salmon and Wyneken, 1987;Burgess et al, 2006;Booth, 2009) (Fig.1). Power stroke rates and oxygen consumption are highest immediately after the hatchlings enter the water and decline as the swim frenzy progresses (Salmon and Wyneken, 1987;Wyneken and Salmon, 1992;Burgess et al, 2006;Booth, 2009;Ischer et al, 2009). As power stroking bouts become less intense, dog paddling bouts become longer and resting periods may increase over time (Burgess et al, 2006).…”

“…As power stroking bouts become less intense, dog paddling bouts become longer and resting periods may increase over time (Burgess et al, 2006). Booth showed that swimming effort in green turtle Chelonia mydas (Linnaeus 1758) hatchlings can be divided into three phases: (a) rapid fatigue, from 0 to 2h; (b) slow fatigue, from 2 to 12h; and (c) sustainable swimming effort, from 12 to 18h (Booth, 2009). The decrease in swimming effort is the result of a decrease in power stroke rate during power stroking bouts, a decrease in the proportion of time spent power stroking and a decrease in thrust produced per power stroke (Booth, 2009).…”

“…Booth showed that swimming effort in green turtle Chelonia mydas (Linnaeus 1758) hatchlings can be divided into three phases: (a) rapid fatigue, from 0 to 2h; (b) slow fatigue, from 2 to 12h; and (c) sustainable swimming effort, from 12 to 18h (Booth, 2009). The decrease in swimming effort is the result of a decrease in power stroke rate during power stroking bouts, a decrease in the proportion of time spent power stroking and a decrease in thrust produced per power stroke (Booth, 2009). Other studies have shown that there are intraspecific (Wyneken et al, 2008) and inter-specific (Wyneken and Salmon, 1992;Jones et al, 2002;Jones et al, 2007) differences in sea turtle hatchling swimming behaviour.…”