Climate change-driven habitat degradation is rapidly reshaping coastal seascapes, yet the ecological consequences of habitat fragmentation for marine megafauna remains poorly understood. We investigated the influence of seagrass configuration on the movements and habitat use of green turtles (Chelonia mydas) in Shark Bay, Western Australia, where an unprecedented marine heatwave caused seagrass loss and fragmentation. We analysed satellite tracking data from 20 turtles over 4,213 tracking days (mean ± SE = 210.63 ± 24.4 days) in combination with high-resolution habitat mapping across an area of ~7,000km2.
Green turtle foraged over larger areas when seagrass edge exposure and patch shape complexity was high. Edge effects had a substantial influence on the distribution of green turtles, with green turtles exhibiting a negative response to seagrass edges and limiting use of non-seagrass habitats further from edges. However, the strength of this response varied with environmental and temporal context.
Our findings demonstrate the importance of habitat configuration for green turtles, and indicate that fragmentation is likely to alter the functional value and connectivity of foraging habitats. Accounting for habitat configuration into models of space and habitat use can improve understanding of how specialised megafauna utilise their environment and strengthen conservation planning in rapidly changing coastal ecosystems.