New article on nutrient concentrations in minke whale faeces
Dear Colleagues, On behalf of my co-authors I am pleased to present our recently published paper: Freitas, C., Gundersen, K., Lindblom, L., Biuw, M., Haug, T., 2023. Nutrient concentrations in minke whale faeces and the potential impact on dissolved nutrient pools off Svalbard, Norway. Progress in Oceanography, 210, 102927. Abstract: There is increasing interest in assessing the impact of whales on nutrient and carbon cycling in the ocean. By fertilising surface waters with nutrient-rich faeces, whales may stimulate primary production and thus carbon uptake, but robust assessments of such effects are lacking. Based on the analysis of faeces collected from minke whales (n = 31) off Svalbard, Norway, this study quantified the concentration of macro and micronutrients in whale faeces prior to their release in seawater. Concentrations of the macronutrients nitrogen (N) and phosphorous (P) in minke whale faeces were 50.1 ± 10.3 and 70.9 ± 12.1 g kg−1 dry weight, respectively, while the most important micronutrients were zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu). By combining measured faecal nutrient concentrations with estimated prey-consumption and prey-assimilation rates, we calculate that the current population of approximately 15, 000 individuals in the small management area (SMA) of Svalbard defecates daily 7 ± 1.4 tonnes (t) N and 10 ± 1.7 t P during summer. The molar ratio of N:P in minke whale faeces was 1.6:1, meaning that N was proportionally limiting, when compared to average elemental ratios of 16:1 in phytoplankton. In case of no N limitation in surface waters at that time, the release of elemental P through defecation in surface waters has the potential to stimulate 407 ± 70 t of carbon per day during summer as new or regenerated primary production in the SMA of Svalbard. This amounts to 0.2 to 4 % of daily net primary production in this region. This study provides the first assessment of nutrient concentration in whale faeces prior to their dissolution in sea water. Further research, namely on the amount of N released via urine and seasonal changes in excreted nutrients, is needed to better assess the full potential of whale nutrient additions to dissolved nutrient pools in surface waters at regional and global scales. The article is freely available at: https://www.sciencedirect.com/science/article/pii/S0079661122001860 Kind regards, Carla Carla Freitas Institute of Marine Research, Norway
Dear Colleagues, On behalf of my co-authors I am pleased to present our recently published paper: Freitas, C., Skogen, M. D., Sigurðsson, G. M., Biuw, M., Haug, T., Lindblom, L., & Gundersen, K. (2025). Impact of baleen whales on ocean primary production across space and time. Proceedings of the National Academy of Sciences, 122(43), e2505563122. doi:10.1073/pnas.2505563122 The article is freely available at: https://www.pnas.org/doi/10.1073/pnas.2505563122 Abstract Primary production in the ocean is a fundamental process that supports marine food webs and global carbon sequestration. This process depends on nutrients that are often limited in surface waters. Whales are known to release essential elements such as nitrogen, phosphorus, and iron, yet the extent of their contribution to ocean primary production remains unclear. Here, we present daily estimates of nutrient input by baleen whales in high-latitude feeding grounds (Nordic and Barents Seas), based on multielement analyses of feces and urine. We then used end-to-end ecosystem models to assess the impact of these nutrients on primary production. We found that nitrogen is primarily excreted via urine, whereas phosphorus and trace elements are mainly released through feces. Ecosystem models indicate that baleen whales, including minke, fin, sei, humpback, blue, and bowhead whales, support annual and seasonal net primary production, with varying impacts across space and time. While the annual effects are modest (<2%) in most areas, the greatest impacts (up to 10%) occur during summer stratification and in offshore areas far from other nutrient sources. These increases in primary production have cascading effects on the food web, driving rises in mesozooplankton biomass. This study highlights the ecological significance of nutrient cycling by whales and underscores the value of integrating whale nutrient data into ecosystem modeling to assess the broader impacts of whales on marine productivity. Significance Whales have long been suggested to enhance ocean productivity by recycling essential nutrients, yet their quantitative impact on primary production has remained uncertain. Our study quantifies nutrient release via feces and urine by baleen whales in high-latitude feeding grounds and evaluates its impact on primary production using ecosystem models. Results indicate that whales enhance ocean productivity, particularly in offshore regions where nutrients are scarce, leading to cascading effects on the food web. These findings highlight the ecological importance of whale-mediated nutrient cycling and emphasize the role of whale populations in sustaining productive and resilient marine ecosystems. Kind regards, Carla Carla Freitas Institute of Marine Research, Norway
Dear Colleagues, On behalf of my co-authors I am pleased to share our recently published article: Eide, S., Rikardsen, A. & Freitas, C. Comparative diving patterns of two minke whales (Balaenoptera acutorostrata) and two fin whales (Balaenoptera physalus) in Northern Norway. Anim Biotelemetry 13, 40 (2025). https://doi.org/10.1186/s40317-025-00432-2 Abstract Background Common minke whales (Balaenoptera acutorostrata) and fin whales (Balaenoptera physalus) are important and abundant top predators in the North Atlantic marine ecosystem. Despite this, information on their diving behavior in this area is scarce. Such knowledge is essential for understanding their role in the marine ecosystem, both as top predators on fish and large zooplankton, and as fertilizers of nutrients to phytoplankton through their excretions. To study their diving behavior in this area, we satellite-tagged two minke whales and two fin whales at the coast of Northern Norway. Results The whales were tracked for 5–11 days, displaying both area-restricted search (assumed feeding) and transit behavior, as quantified by first passage time analyses. Minke whale dives lasted 2.0–11.8 min (mean ± sd, minke 1: 4.5 ± 1.3 min; minke 2: 4.4 ± 1.1 min) and reached depths of 20–250 m (minke 1: 62.9 ± 40.8 m; minke 2: 128.7 ± 66.8 m). Fin whale dives were significantly longer, lasting 2.4–25 min (fin 1: 6.6 ± 1.8 min; fin 2: 9.6 ± 3.1 min), but the dive depths were within the same depth range as the minke whales, reaching depths of 20–275 m (fin 1: 129.8 ± 23.0 m; fin 2: 98.9 ± 58 m). While foraging simultaneously during summer in a large and deep fjord, both species showed similar depth preferences (mainly 120–160 m), possibly targeting the same resources. However, the fin whale exhibited significantly longer dives (6.5 ± 1.6 min) compared to the minke whale (4.4 ± 1.1 min). For both species, square-shaped dives were significantly more common during assumed feeding, while V-shaped dives were more frequently observed during transit. Conclusions Despite the limited sample size and deployment duration, this study provides valuable insight into the currently limited understanding of the diving behavior of minke and fin whales in high-latitude feeding grounds of the North Atlantic. Kind regards, Carla Carla Freitas Institute of Marine Research, Norway
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Brandt, Carla Freitas