Three Decades of Changing Nutrient Stoichiometry from Source to Sea on the Swedish West Coast

Over the past three decades, freshwater ecosystems along the Swedish west coast have undergone significant shifts in macronutrient stoichiometry, moving further from the Redfield Ratio—a benchmark for balanced nutrient ratios—and becoming increasingly carbon-rich while depleted in nitrogen (N) and phosphorus (P). This trend, observed across 20 lakes and watercourses ranging from headwaters to river mouths, is driven by declines in inorganic N and total P, alongside rising organic carbon (C), likely influenced by reductions in atmospheric deposition and land cover changes. Notably, lakes act as buffers against C increases, while decreases in inorganic N are most pronounced under arable land cover. The study also identifies a consistent decline in phosphorus concentrations in small forest lakes—a phenomenon termed 'oligotrophication'—highlighting complex, unexplained ecological changes. These findings suggest that long-term nutrient shifts may contribute to detrimental changes in adjacent coastal ecosystems, offering critical insights for managing aquatic systems in Europe and North America.

Peacock, M., Futter, M. N., Jutterström, S., Kothawala, D. N., Moldan, F., Stadmark, J., & Evans, C. D. (2022). Three Decades of Changing Nutrient Stoichiometry from Source to Sea on the Swedish West Coast. Ecosystems, 25(8), 1809–1824. https://doi.org/10.1007/s10021-022-00798-x