Periodic Reporting for period 1 - LEOTHREAT (Assessment of the threat of metal exposure to lions (Panthera leo) in East Africa)
Reporting period: 2023-10-01 to 2025-12-31
Across East Africa, lions are exposed to multiple pressures, including habitat loss, prey decline, human–wildlife conflict and other environmental changes. Pollution has also been identified as a potential threat, but very little is known about contaminant exposure in free-ranging lions or about the pathways through which pollutants may move from the environment to large carnivores.
With the support of the Marie Skłodowska-Curie Actions programme, LEOTHREAT investigated whether metal exposure could represent an overlooked risk for lions in East Africa. The project focused on lions and their ecosystem in areas potentially influenced by mining activities and in less impacted reference areas. Its main objectives were to assess metal exposure in lions, evaluate possible links with blood plasma clinical-chemical parameters, test whether lion hair can be used as a non-invasive biomonitoring matrix, and investigate exposure routes through prey, soil, vegetation, water and stable isotope information.
During the project, the contaminant scope was also expanded by adding PFAS and Total Oxidizable Precursor Assay analyses to the Tanzanian samples. Overall, LEOTHREAT aims to generate baseline information, improve biomonitoring tools for large carnivores, and provide evidence that can support future research and conservation-oriented monitoring in East African protected areas.
With the support of the Marie Skłodowska-Curie Actions programme, LEOTHREAT investigated whether metal exposure could represent an overlooked risk for lions in East Africa. The project focused on lions and their ecosystem in areas potentially influenced by mining activities and in less impacted reference areas. Its main objectives were to assess metal exposure in lions, evaluate possible links with blood plasma clinical-chemical parameters, test whether lion hair can be used as a non-invasive biomonitoring matrix, and investigate exposure routes through prey, soil, vegetation, water and stable isotope information.
During the project, the contaminant scope was also expanded by adding PFAS and Total Oxidizable Precursor Assay analyses to the Tanzanian samples. Overall, LEOTHREAT aims to generate baseline information, improve biomonitoring tools for large carnivores, and provide evidence that can support future research and conservation-oriented monitoring in East African protected areas.
LEOTHREAT carried out fieldwork in Uganda and Tanzania. In Uganda, samples were collected from 8 lions in Queen Elizabeth National Park, together with prey and environmental samples along a potential exposure gradient from the Kilembe mining area. The Ugandan samples have not yet reached NTNU because of unresolved export and shipment issues, so their analytical work remains pending.
In Tanzania, samples were collected from 29 lions in Serengeti National Park, together with prey, soil, vegetation and water samples. The field strategy had to be adapted to the real distribution of lions during the expedition, which was strongly influenced by seasonal prey movements. Most samples were therefore obtained in the southeastern part of Serengeti, where lion availability was higher during the field campaign.
The main analytical work was completed for the Tanzanian dataset. Metals were analyzed in lion whole blood, lion hair, lion feces, prey hair and muscle, soil, vegetation and water. Blood plasma clinical-chemical parameters were also analyzed in lion plasma, and stable isotopes were analyzed in lion hair. These results provide the first core dataset of the project and support the interpretation of metal exposure, physiological status and trophic ecology in Serengeti lions.
The first results indicate generally low metal concentrations in the sampled Serengeti lions and their environment. Blood plasma clinical-chemical parameters were within reported physiological ranges, and metal concentrations were generally lower than those reported for other terrestrial carnivores. Therefore, the Tanzanian dataset is currently interpreted as a low-metal-contamination or reference dataset. This limits the assessment of strong pollution-related effects in Tanzania, but provides valuable baseline information for future comparison with more impacted areas.
The project also advanced the evaluation of lion hair as a non-invasive biomonitoring matrix and generated the basis for future comparison between hair and internal exposure matrices. In addition, PFAS and TOPA analyses were added to the Tanzanian samples, expanding the project beyond metals and opening a new research line on emerging persistent pollutants in East African lions.
In Tanzania, samples were collected from 29 lions in Serengeti National Park, together with prey, soil, vegetation and water samples. The field strategy had to be adapted to the real distribution of lions during the expedition, which was strongly influenced by seasonal prey movements. Most samples were therefore obtained in the southeastern part of Serengeti, where lion availability was higher during the field campaign.
The main analytical work was completed for the Tanzanian dataset. Metals were analyzed in lion whole blood, lion hair, lion feces, prey hair and muscle, soil, vegetation and water. Blood plasma clinical-chemical parameters were also analyzed in lion plasma, and stable isotopes were analyzed in lion hair. These results provide the first core dataset of the project and support the interpretation of metal exposure, physiological status and trophic ecology in Serengeti lions.
The first results indicate generally low metal concentrations in the sampled Serengeti lions and their environment. Blood plasma clinical-chemical parameters were within reported physiological ranges, and metal concentrations were generally lower than those reported for other terrestrial carnivores. Therefore, the Tanzanian dataset is currently interpreted as a low-metal-contamination or reference dataset. This limits the assessment of strong pollution-related effects in Tanzania, but provides valuable baseline information for future comparison with more impacted areas.
The project also advanced the evaluation of lion hair as a non-invasive biomonitoring matrix and generated the basis for future comparison between hair and internal exposure matrices. In addition, PFAS and TOPA analyses were added to the Tanzanian samples, expanding the project beyond metals and opening a new research line on emerging persistent pollutants in East African lions.
LEOTHREAT goes beyond the current state of the art because contaminant exposure in African terrestrial apex predators remains poorly studied. To our knowledge, the project generated the first dataset combining metal exposure and blood plasma clinical-chemical parameters in free-ranging East African lions. This provides new baseline information for a species of high ecological and conservation value.
The project also contributes to the development of non-invasive biomonitoring tools. By analyzing lion hair together with internal matrices from the same animals, LEOTHREAT provides the basis for evaluating whether hair can be used to assess metal exposure in lions. This is important because repeated blood sampling in protected large carnivores is difficult, costly and invasive.
Another novel aspect is the integrated design of the project. LEOTHREAT did not only measure metals in lions; it also included prey, soil, vegetation, water, stable isotope information and physiological indicators. This approach helps link contaminant exposure with possible exposure routes and animal health.
The inclusion of PFAS and TOPA analyses further expanded the project beyond the original focus on metals. This may open a new research line on emerging persistent pollutants in African lions and other large carnivores.
The project also contributes to the development of non-invasive biomonitoring tools. By analyzing lion hair together with internal matrices from the same animals, LEOTHREAT provides the basis for evaluating whether hair can be used to assess metal exposure in lions. This is important because repeated blood sampling in protected large carnivores is difficult, costly and invasive.
Another novel aspect is the integrated design of the project. LEOTHREAT did not only measure metals in lions; it also included prey, soil, vegetation, water, stable isotope information and physiological indicators. This approach helps link contaminant exposure with possible exposure routes and animal health.
The inclusion of PFAS and TOPA analyses further expanded the project beyond the original focus on metals. This may open a new research line on emerging persistent pollutants in African lions and other large carnivores.