Dear MarMamers

We would like to share our new open access article that measures the metabolic contribution of digestion in the bottlenose dolphin (https://doi.org/10.1242/jeb.251474). This study quantified the heat increment of feeding (HIF), the metabolic cost of digestion, in eight common bottlenose dolphins using breath-by-breath respirometry. After consuming standardized fish meals (1659–2658 kcal), metabolic rate rose by ~37% above fasting levels and peaked ~60 min post-feeding, returning near baseline within two hours. Scaled to a full day, digestion increased daily metabolic needs by ~8.2% of basal metabolic rate, indicating a moderate energetic impact comparable to other marine mammals. These findings provide the first multi-individual estimate of HIF in dolphins, refining bioenergetic models and improving predictions of prey requirements and energetic vulnerability in wild populations

Title: Heat increment of feeding in the common bottlenose dolphin (Tursiops truncatus) contributes moderately to field metabolic rate estimates

Authors: Koliopoulou, I., DeRuiter, S.L. Altimiras, J., Larsson, J., Arenarez, J., Rosen, D.  Fahlman, A.

doi: https://doi.org/10.1242/jeb.251474

Abstract: Digestion elevates metabolism through the heat increment of feeding (HIF) – the energy expended on mechanical and biochemical processes after eating. Quantifying this cost is essential for bioenergetic models that predict energy flow and prey requirements in populations. Using breath-by-breath respirometry, we measured oxygen consumption (V̇ O2) in eight common bottlenose dolphins (Tursiops truncatus) before and after feeding standardized meals (1659–2658 kcal of capelin and herring). Metabolic rate rose by ∼37% above resting levels, peaking 60 min after feeding before returning to baseline within 2 h. When scaled across the day, digestion increased daily metabolic needs by ∼8.2% of basal metabolism, similar to values reported for Steller sea lions (Eumetopias jubatus) and harbour seals (Phoca vitulina), where HIF contributes 4–10% of daily energy expenditure. This study provides the first multi-individual estimate of HIF in dolphins and suggests that the energetic cost of digestion is a moderate contribution to overall daily metabolism, refining energetic models and improving prey requirement estimates for cetaceans in the wild.