Dear Marmam community, On behalf of my co-authors, I am pleased to share our new paper in Science of the Total Environment: Gilbert, L., Spitz, J., Chevallay, M., & Jeanniard-du-Dot, T. (2025). Predator-mediated nutrient transfers and recycling in ecosystems: Fine-scale variation in the contribution of Antarctic fur seals (Arctocephalus gazella) on and around the Kerguelen Islands. Science of The Total Environment, 975, 179195. The article is open access and can be found here: https://doi.org/10.1016/j.scitotenv.2025.179195 Abstract: Waters on the Kerguelen Plateau are characterised by a high productivity and unique nutrient dynamics compared to the surrounding Southern Ocean. They support large populations of amphibious marine predators such as seabirds and marine mammals, which participate in nutrient recycling at sea and nutrient transfers from sea to land on their colonies. This study investigates the contribution of Antarctic fur seals (Arctocephalus gazella) to the biological recycling of 15 essential and 5 non-essential nutrients on and around the Kerguelen Islands during their four-month breeding season. Nutrient concentrations of 59 fur seal scats from two colonies were examined and used to determine faecal nutrient output from lactating females using a bioenergetic model. We evidenced individual variability in the multi-nutrient composition of fur seal scats, with different types of potential fertilisers. Colony differences in scat compositions resulted in multi-nutrient release levels that did not simply reflect colony abundances. This suggests that estimating predators' nutrient release based on averages (diets, prey or faecal nutrient contents) likely overlooks important fine-scale spatial variability in their contributions. Collectively, fur seals deposit up to 628 kg (95 % CI [548–710]) of phosphorus (limiting on land), 46.4 [39.8–53.2] kg of iron (limiting at sea), and 5.9 [5.2–6.8] g of lead (toxic to most organisms). At sea, fur seal defecation could trigger locally significant enrichment events. On land, fur seal faecal nutrient deposition is spatially concentrated in coastal colonies where phosphorus deposition is in the range of global crop fertiliser use. We argue that the role of marine predators in the local nutrient dynamics of the Kerguelen area should not be overlooked, and that fine-scale variability in the nutrient input by such marine predators is important to consider in any local nutrient dynamic study. I would also like to share another recently published paper that does not focus on marine mammals but examines the multi-nutrient composition of a range of potential fish prey in the Kerguelen area. Data on the nutrient composition of prey is scarce in most environments (especially when considering multiple nutrients), whereas it is a key input data for studying the contribution of marine mammals to nutrient recycling, with other potential uses including studies on nutrition and exposure to contaminants. This article is also open access and the reference, DOI link and abstract are given below: Gilbert, L., Jeanniard-Du-Dot, T., Cherel, Y., & Spitz, J. (2025). Major and trace nutrient concentrations in sub-Antarctic forage fish around the Kerguelen Islands: All are not equal for nutrient recycling by top predators. Journal of Experimental Marine Biology and Ecology, 586, 152097. https://doi.org/10.1016/j.jembe.2025.152097 Abstract: While the nutrient content of forage species is crucial to study how marine top predators release nutrients in their waste (faeces and urine) and possibly facilitate nutrient recycling at lower trophic levels of the food webs, it is poorly documented in many ecosystems. Here, we analyse the concentrations of five major nutrients, eight essential trace nutrients, and four non-essential nutrients in 34 mesopelagic and demersal forage fish species from the Kerguelen Plateau area (Southern Indian Ocean). This biogeochemically singular region benefits from natural iron (Fe) fertilisation and is an oasis for marine life in the high nutrient low chlorophyll Southern Ocean. Its nutrient dynamics have been subject to intense research for decades, but the contribution of the biota remain unexplored. Local forage fish were found to be significantly heterogeneous in their absolute nutrient concentrations, and in their relative nutrient content. Using hierarchical clustering, we showed that some species were enriched in nutrients found in limited concentrations in Southern Ocean surface waters, such as Fe and manganese (Mn), whereas others were enriched in nutrients likely limiting primary productivity in terrestrial ecosystems, such as phosphorus (P) or calcium (Ca). These fish species could be major contributors to these nutrients' biological cycling in different ecosystems when consumed by predators. This functional typology further demonstrates that prey are not interchangeable. The consumption of one or another prey species modulates not only the ability of the predator to meet its requirements and exposure to contaminants, but also predator-mediated nutrient recycling. This work provides valuable baseline knowledge that can be used in studies of nutrition, nutrient dynamics, and contaminant transfer. It also paves the way for the inclusion of predator-prey relationships in local biogeochemical studies to help unravel the complex processes at work in this unique ecosystem. Both datasets (multi-nutrient content of fish and Antarctic fur seal scats) are available on a dedicated Open Science platform, links are provided in the articles. Please feel free to reach out with any comment or questions. Best, Lola Gilbert, Post-doc researcher at Centre for Biological Studies of Chizé (CEBC) & La Rochelle University lola.gilbert@univ-lr.fr / lola.gilbert@lilo.org