COMPENSATORY GROWTH IN OCEANIC LOGGERHEAD SEA TURTLES: RESPONSE TO A STOCHASTIC ENVIRONMENT

By K. Bjorndal, A. Bolten, T. Dellinger, Cláudia Delgado, H. Martins. 2003

167 citations recorded by the source corpus.

Compensatory growth (CG, accelerated growth that may occur when an organism that has grown at a reduced rate as a result of suboptimal environmental conditions is exposed to better conditions) is considered an adaptation to variable en- vironments. Although documented thoroughly under captive conditions, CG has rarely been studied in wild populations. In their first years of life, oceanic-stage loggerhead sea turtles (Caretta caretta) have relatively little control over their geographic position or movements and thus have an extremely stochastic lifestyle with great variation in food availability and temperature. This environmental variation results in variable growth rates. We evaluate somatic growth functions of oceanic-stage loggerheads from the eastern Atlantic based on skeletochronology that allowed us to assign age and cohort to each individual. We demonstrate CG in these turtles based on three different analytical approaches: changes in coefficients of variation in size-at-age, generalized additive model regression analyses of somatic growth, and linear regression of age-specific growth rates. As a result of CG, variation in size-at-age in these juvenile loggerheads is substantially reduced. Thus, size is a better predictor of age than expected based on variation in growth rates. CG decreases with age, apparently as loggerheads gain greater control over their movements. In addition, we have evaluated for the first time in wild sea turtles the time-dependent nature of somatic growth by distinguishing among age, year, and cohort effects using a mixed longitudinal sampling design with assigned-age individuals. Age and year had significant effects on growth rates, but there was no significant cohort effect. Our results address critical gaps in knowledge of the demog- raphy of this endangered species.

Subfields: Ecology, Nature and Landscape Conservation

View Paper: https://www.semanticscholar.org/paper/8c1855327bd76553c5f281adf95330b537b1a5f9

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Ecology

1. Bj Godley
2. AC Broderick
3. K. Bjorndal
4. M. Chaloupka
5. A. Bolten
6. Lucy A. Hawkes
7. G. Hays
8. Larisa Avens

In Nature and Landscape Conservation

1. Bj Godley
2. M. Chaloupka
3. K. Bjorndal
4. A. Bolten
5. AC Broderick
6. G. Hays
7. Larisa Avens
8. Lucy A. Hawkes

Citations in the corpus

• Hawksbill sea turtles in seagrass pastures: success in a peripheral habitat (2010, background): “4b, similar to the pattern for loggerheads exhibiting compensatory growth (Bjorndal et al. 2003).”
• Quantifying multiple threats to endangered species: an example from loggerhead sea turtles (2011, background): “In reality, this shift occurs over a range of ages from 7 to 12 years (Bjorndal et al. 2000, 2003).”
• The diet composition of immature loggerheads: Insights on trophic niche, growth rates, and fisheries interactions (2009, background): “Immature, oceanic-stage loggerhead turtles (Caretta caretta) in the North Atlantic Ocean exhibit compensatory growth, a process by which individuals exhibit ‘catchup’ growth during periods of high resource abundance or improved environmental conditions to compensate for previous periods of scarce or”
• Polymodal foraging in adult female loggerheads (Caretta caretta) (2010, background): “Juvenile loggerheads recruit to neritic foraging areas at sizes between 46 and 64 cm curved carapace length, after about 7‐12 years in oceanic habitats ( Bjorndal et al. 2000, 2003 ).”
• Estimation of age at maturation and growth of Atlantic green turtles (Chelonia mydas) using skeletochronology (2010, background): “recaptured tagged loggerheads (Bjorndal et al. 2003), but has yet to be validated in the humeri of Atlantic green turtles.”
• Foraging ecology of oceanic-stage loggerhead turtles Caretta caretta (2009, background): “Although much has been learned about this oceanic life stage in the eastern Atlantic (Bolten 2003), which lasts from 7 to 12 yr (Bjorndal et al. 2003), the loggerheads’ diet remains poorly quantified.”
• Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio‐temporal perspective (2016, background): “Compensatory growth and growth responses to periods of limited feeding followed by ad libitum feeding have been demonstrated in juvenile sea turtles (Bjorndal et al. 2003, Roark et al. 2009).”