Land diets and warm water rewire gene activity in farmed gammarids

Scientists have mapped how two simple levers of aquaculture husbandry—what gammarids eat and how warm their water is—leave measurable fingerprints on gene activity in the amphipod crustacean Gammarus locusta. The study, published in Frontiers in Aquaculture, assembled a new reference transcriptome for the species and used differential gene expression analysis to compare animals raised on terrestrial plant-based feeds against a marine control diet, and animals held across a gradient of temperatures from 5 to 20 degrees Celsius. The work is framed around a practical goal: gammarid biomass is emerging as a candidate for producing high-nutritional-value feed ingredients that could replace marine ingredients currently derived from wild-capture fisheries.

The study's author list includes researchers affiliated with the Spanish National Research Council (CSIC) in Madrid, the Centro Interdisciplinar de Investigação Marinha e Ambiental at the Universidade do Porto, and the Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung in Bremerhaven. In the first, animals were fed either a marine Fucus sp. control diet or two alternative terrestrial diets based on carrot and coconut. In the second, rearing temperature was varied across four levels—5, 10, 15 and 20 degrees Celsius—while the researchers tracked how transcript abundance changed. Because the species lacked a well-established genomic resource, the team first built a newly assembled reference transcriptome, which then served as the backbone for identifying genes involved in lipid and fatty acid metabolism, ecdysis and development.

The diet experiment produced a clear molecular signal. According to the authors, the alternative terrestrial diets were related with shifts in transcript abundance for key genes involved in fatty acid catabolism and transport. In practical terms, the authors report that animals fed plant-derived terrestrial ingredients, rather than the marine Fucus sp. control diet, were related with shifts in transcript abundance for genes involved in fatty acid catabolism and transport. The authors frame this as relevant because optimising culture conditions, such as diet composition, is described as essential to maximise both biomass yield and nutritional quality of gammarid ingredients intended to replace marine ingredients derived from wild-capture fisheries.

The temperature experiment told a more cautionary story. According to the authors, elevated rearing temperatures were associated with the upregulation of neuroendocrine and metabolic transcripts that parallel accelerated growth rates. The abstract does not report growth-rate data itself; it states only that the upregulated transcripts parallel accelerated growth rates. The authors also report that these elevated rearing temperatures coincide with reduced long-term survival. The abstract presents this as an association: elevated temperatures were associated with upregulated neuroendocrine and metabolic transcripts that parallel accelerated growth rates yet coincide with reduced long-term survival.

The authors describe the findings as providing novel candidate molecular markers for evaluating gammarid physiological status. Using a newly assembled reference transcriptome, the authors performed differential gene expression analysis to identify genes involved in lipid and fatty acid metabolism, as well as ecdysis and development. In this study, the newly assembled reference transcriptome made it possible to pinpoint specific candidate genes tied to lipid and fatty acid metabolism under dietary change, and to neuroendocrine and metabolic pathways under thermal change. The authors state that the findings provide novel candidate molecular markers for evaluating gammarid physiological status, offering an exploratory framework to aid the optimisation of sustainable culture practices for aquaculture feed applications.

The framing of the study is explicitly exploratory. The authors describe their findings as offering an exploratory framework to aid the optimisation of sustainable culture practices for aquaculture feed applications, not as a validated production protocol. The authors describe the findings as an exploratory framework; the abstract reports associations between culture conditions and transcript abundance and does not report performance data for the terrestrial diets as finished feed ingredients. The authors position the study as offering an exploratory framework to aid the optimisation of sustainable culture practices for aquaculture feed applications, rather than as a validated production protocol.

Even so, the strategic logic is straightforward. The authors note that gammarids and their biomass are emerging as promising candidates for the production of high-nutritional-value ingredients to replace marine ingredients derived from wild-capture fisheries. The abstract does not provide additional detail on gammarid biomass sources beyond this framing. The study evaluated the transcriptomic responses of Gammarus locusta to alternative terrestrial diets (Carrot and Coconut vs. marine Fucus sp. control) and to thermal gradients (5, 10, 15, and 20 °C), identifying candidate molecular markers tied to these culture conditions.

The article's keywords include environmental regulation, alongside differential gene expression, Gammarus locusta, lipid metabolism and transcriptome assembly. In the temperature experiment, elevated rearing temperatures were associated with the upregulation of neuroendocrine and metabolic transcripts, and the authors report that these coincide with reduced long-term survival. In the diet experiment, the alternative terrestrial diets were related with shifts in transcript abundance for key genes involved in fatty acid catabolism and transport. Keywords associated with the article—differential gene expression, environmental regulation, Gammarus locusta, lipid metabolism and transcriptome assembly—reflect that dual focus on a molecular technique and the two environmental variables most amenable to control in a culture facility.

The authors present the findings as novel candidate molecular markers for evaluating gammarid physiological status. The study used a newly assembled reference transcriptome, which the authors describe as a resource for identifying genes involved in lipid and fatty acid metabolism, as well as ecdysis and development. The authors describe the study as offering an exploratory framework to aid the optimisation of sustainable culture practices for aquaculture feed applications.

Subject of Research: Transcriptomic responses of the amphipod Gammarus locusta to alternative terrestrial diets and rearing temperatures for aquaculture feed applications

Article Title: Transcriptomic analysis and differential gene expression of the effects of diet and temperature in Gammarus locusta fed alternative terrestrial feeds

Article References: Ribes-Navarro, A., Machado, A. M., Alberts-Hubatsch, H., Navarro, J. C., Castro, L. F. C., & Monroig, Ó. (2026). Transcriptomic analysis and differential gene expression of the effects of diet and temperature in Gammarus locusta fed alternative terrestrial feeds. Frontiers in Aquaculture, 5, Article 1947571. https://doi.org/10.3389/faquc.2026.1947571

Image Credits: AI Generated

DOI: 10.3389/faquc.2026.1947571

Keywords: Gammarus locusta, transcriptomics, differential gene expression, aquaculture, fatty acid metabolism, lipid metabolism, ecdysis, temperature, terrestrial diets, feed ingredients, sustainable aquaculture, amphipods