Scaling of activity space in marine organisms across latitudinal gradients

Unifying models have shown that the amount of space used by animals (e.g.,
activity space, home range) scales allometrically with body mass for
terrestrial taxa; however, such relationships are far less clear for
marine species. We compiled movement data from 1,596 individuals across 79
taxa collected using a continental passive acoustic telemetry network of
acoustic receivers to assess allometric scaling of activity space. We
found that ectothermic marine taxa do exhibit allometric scaling for
activity space, with an overall scaling exponent of 0.64. However, body
mass alone explained only 35% of the variation with the remaining
variation best explained by trophic position for teleosts and latitude for
sharks, rays, and marine reptiles. Taxon-specific allometric relationships
highlighted weaker scaling exponents among teleost fish species (0.07)
than sharks (0.96), rays (0.55), and marine reptiles (0.57). The
allometric scaling relationship and scaling exponents for the marine
taxonomic groups examined were lower than those reported from studies that
had collated both marine and terrestrial species data derived using
various tracking methods. We propose that these disparities arise because
previous work integrated summarised data across many studies that used
differing methods for collecting and quantifying activity space,
introducing considerable uncertainty into slope estimates. Our findings
highlight the benefit of using large-scale, coordinated animal
biotelemetry networks to address cross-taxa evolutionary and ecological
questions.