Leatherbacks Swimming In Silico: Modeling and Verifying Their Momentum and Heat Balance Using Computational Fluid Dynamics

Abstract

As global temperatures increase throughout the coming decades, species ranges will shift. New combinations of abiotic conditions will make predicting these range shifts difficult. Biophysical mechanistic niche modeling places bounds on an animal’s niche through analyzing the animal’s physical interactions with the environment. Biophysical mechanistic niche modeling is flexible enough to accommodate these new combinations of abiotic conditions. However, this approach is difficult to implement for aquatic species because of complex interactions among thrust, metabolic rate and heat transfer. We use contemporary computational fluid dynamic techniques to overcome these difficulties. We model the complex 3D motion of a swimming neonate and juvenile leatherback sea turtle to find power and heat transfer rates during the stroke. We combine the results from these simulations and a numerical model to accurately predict the core temperature of a swimming leatherback. These results are the first steps in developing a highly accurate mechanistic niche model, which can assists paleontologist in understanding biogeographic shifts as well as aid contemporary species managers about potential range shifts over the coming decades.

Predicted distributions and abundances of the sea turtle ‘lost years’ in the western North Atlantic Ocean

“…Our predictions of turtle distributions could be also applied as inputs to a suite of other modeling approaches that would benefit from increased detail on the proportion of hatchling cohorts that experience different environmental conditions or anthropogenic disturbances. For instance, combining our movement model with a mechanistic model of heat and momentum balance (Dudley et al 2014) and dynamic energy budget model (Marn et al 2017, Stubbs et al 2019) could improve estimates of how changes in the distributions of oceanic-stage turtles influence growth, survival and reproductive output in individual turtles. Aggregating such information by year classes could then feed into population dynamics (Warden et al 2015), stock assessment (Gallaway et al 2016) or ecosystem (Gruss et al 2018) models to determine the potential influences on population abundance, age-structure and resiliency.…”

Functional morphology and hydrodynamics of plesiosaur necks: does size matter?

“…Hydrodynamics is the study of moving fluids that are practically incompressible, and in the context of swimming performance has been explored for various aquatic taxa including extant marine mammals (Fish and Rohr, 1999;Fish et al, 2008;Segre et al, 2016), extant and extinct fish (Lauder and Madden, 2006;Borazjani and Sotiropoulos, 2010;Fletcher et al, 2014;Kogan et al, 2015;Van Wassenbergh et al, 2014Fish and Lauder, 2017), and leatherback turtles (Dudley et al, 2014).…”

“…The rapidly developing methods in virtual paleontology can help us visualise and analyse fossils digitally much easier and quicker than previously, and the methods have changed the way we study fossil specimens (Davies et al, 2017). CFD is one of many ways to perform virtual paleontology and is a relatively inexpensive method to visualise hydrodynamic flow modelling in 3D (Sutton et al, 2017) and has been used for several types of studies in paleontology (Liu et al, 2015;Rahman et al, 2015aRahman et al, , 2015bDynowski et al, 2016;Rahman, 2017;Rahman and Lautenschlager, 2017) and biology (Dudley et al, 2014;Van Wassenbergh et al, 2014Kogan et al, 2015;Beckert et al, 2016;Bradney et al, 2016;McHenry et al, 2016).…”

Flipper strokes can predict energy expenditure and locomotion costs in free-ranging northern and Antarctic fur seals

“…As most of the metabolic cost of foraging comes from the cost of transport 6 (i.e., the energy needed to move a unit of mass over a distance, usually expressed in J/m or in J/kg/m), count and amplitude of ‘stride’, ‘wingbeats’, and ‘stroke’ rates (in the case of marine animals) have been proposed as proxies of energy expenditure in a wide range of species 7 8 9 10 . Several methods such as video images 7 11 12 or acoustic recordings 13 can be used to record these stroke rates in aquatic animals, but they do not allow the intensity or amplitude of strokes to be estimated. More recently, acceleration that can characterize both frequency (i.e.…”