Climate-Resilient Diets for Gilthead Sea Bream: Can Sustainable Feeds Keep Pace with Warming-Driven Growth Acceleration?2026-06-30
As Mediterranean aquaculture faces rising temperatures and more frequent thermal stress events, one key question is becoming increasingly relevant: can sustainable diets not only maintain performance, but also support the accelerated growth observed under warmer conditions? In our latest study from the Nutrigenomics and Integrative Fish Biology Group, developed within the framework of the Complementary Programme in Marine Sciences ThinkInAzul and published in Frontiers in Physiology, we show that climate-resilient feed formulations can sustain strong performance even in a context where warming is already shortening production cycles and accelerating gilthead sea bream growth in the western Mediterranean.
Our work builds on a clear production reality. Long-term temperature records at the IATS-CSIC facilities revealed a progressive warming trend, and the warmest recent production cycles were associated with faster growth up to harvest size. In particular, the 2022 cohort showed the fastest growth among the evaluated cycles, indicating that elevated temperatures were linked to accelerated growth while overall growth efficiency remained largely stable.
Within this climate-relevant context, we evaluated three dietary strategies in gilthead sea bream (Sparus aurata): a plant-based commercial-like control diet, a formulation based on processed animal proteins and salmon oil by-products (PAP), and an alternative formulation including insect proteins, microbial biomass, and algal oil (ALT). Remarkably, all three diets supported similarly strong growth performance, with fish growing from juvenile size to around market size under unusually warm summer conditions, while preserving liver and intestinal tissue integrity throughout the trial.
This is an important message for Mediterranean aquaculture: sustainable diets can support productive performance even under warming-driven growth acceleration. In other words, reducing dependence on traditional marine ingredients does not necessarily imply a penalty in growth or tissue health when diets are properly formulated. But the most interesting result goes beyond performance alone. Although growth outcomes were very similar across dietary groups, the fish did not reach those outcomes through the same biological route.
Fish fed the ALT diet showed lower basal stress-axis activity, more proactive behavioural responses following confinement, and enhanced intestinal transcriptional activity — all features consistent with greater resilience to common farming stressors. By contrast, the PAP diet was associated with a down-regulation of liver and white muscle transcriptomes, suggesting a potential physiological trade-off that could affect cold adaptation later in the production cycle.
This is precisely why the concept of climate-resilient diets must go beyond feed formulation alone. If warming conditions can accelerate growth, we also need to understand what kind of physiology supports that growth, whether resilience is being improved or compromised, and how dietary ingredients reshape metabolism, stress regulation, and tissue function under climate pressure.
To address that complexity, this study applied an integrative omics-informed framework, combining targeted gene expression profiling in liver, white skeletal muscle, and anterior intestine with plasma biomarkers, histology, and behavioural phenotyping. This approach allowed us to move beyond classical performance indicators and capture the deeper biological signatures associated with each dietary strategy.
More broadly, this work reinforces the value of combining nutrigenomics, multi-tissue transcriptomics, microbiome-oriented thinking, and functional phenotyping to evaluate the next generation of aquafeeds. It is no longer enough to ask whether fish grow well; we also need to understand how they grow, which metabolic and immune pathways are activated, how stress responsiveness is modulated, and how the host interacts with its associated microbiota as a functional holobiont.
The key message is clear: low-trophic and circular-economy feed ingredients can sustain growth, tissue health, and welfare under warming scenarios — and they may do so even in production contexts where rising temperatures are already driving accelerated growth. But their real value only becomes visible when assessed through integrated omics approaches capable of revealing the biological mechanisms behind performance.
