Energetic Costs of Foraging in Degraded Seascapes and Long-Term Impacts on Marine Populations

Abstract

Marine seascape degradation alters habitat structure and resource distribution, potentially imposing
strong energetic constraints on marine organisms. This study aimed to quantify how seascape
degradation influences foraging energetics, metabolic performance, and energy balance, and to
evaluate how individual energetic constraints scale up to affect population-level survival. The research
was done at the marine locations along coastal regions with a gradient of seascape degradation. Habitat
condition was measured based on a composite degradation index that involved habitat complexity,
prey density, turbidity, and nutrient load. Two marine species representing contrasting trophic roles
were examined. Field energy expenditure was estimated using tri-axial accelerometry corrected to
oxygen consumption, whereas standard and active metabolic rates were measured using respirometry.
Telemetry, accelerometry, and prey calorimetry were used to measure foraging behavior, energy
intake, and net energy gain. The relationship between degradation, the energetics, and the survival
was measured using linear mixed-effects and generalized linear models, and the model performance
was measured using the R2, RMSE, and MAE. Habitat degradation was linked with drastic changes
in habitat complexity and prey density, and a rise in turbidity and nutrient load. The degradation
elevated the metabolic rates strongly and reduced the aerobic scope (p < 0.001). In poor habitats, the
amount of daily energy expenditure rose significantly, with the foraging expense consuming up to
51.9% of total energy expenditure. High degradation caused a more than 60% decline in net energy
gain by predators and 70% by consumers. The model fits were good (R2= 0.740.81) and the
probability of survival grew nonlinearly with individual energy reserves, varying between 0.42 and
0.91 in the 25th percentile of energy reserves. The destruction of seascapes enhances the cost of
energy, lowers foraging efficiencies, and limits demographic survival. These results demonstrate the
role of energetic balance as a central mechanistic relationship between habitat degradation and
population-level responses with significant implications for marine conservation and habitat
restoration.