Dozens of frog, salamander and other amphibian species disappeared from parts of Latin America in the 1980s to 2000s. The decline in these species not only disturbs the ecological balance, but also has direct health consequences for people in the regions, according to a new study: According to a research team led by Michael Springborn from the University of California in Davis in the journal Environmental Research Letters reportedamphibian extinctions in Costa Rica and Panama led to a spike in malaria cases.
From the early 1980s to the mid-1990s, the fungus Batrachochytrium dendrobatidis (Bd) spread in Costa Rica. The pathogen attacks the skin of amphibians and thus impairs their biological function. The disease caused by the fungus, chytridiomycosis, usually leads to the death of the infected animals. The fungus spread from Costa Rica and caused a mass die-off of amphibians in neighboring Panama in the 2000s. According to the researchers, the pathogen led to the extinction of at least 90 amphibian species worldwide and the decline of more than 400 other species.
According to Springborn and team, the development in Central America shows that the biological diversity of an ecosystem can also be important for human well-being. The starting point of the research work was the observation that after the extinction of many amphibians in Costa Rica and Panama, significantly more people fell ill with malaria than usual in both countries health care on malaria cases.
A salamander larva can eat up to 400 mosquito larvae per day
According to the team, their results show a connection between the time and place of the spread of the fungus and the time and place of the increase in malaria cases. After amphibian populations had declined in the studied regions of Costa Rica and Panama, the number of cases of malaria increased dramatically in the following years: by 0.76 to 1.1 cases per 1000 inhabitants. During this phase, the total number of diseases per 1000 inhabitants was 1.5 in Costa Rica and 1.1 in Panama.
The researchers explain this “substantial proportion” by the fact that amphibians play a key role in the food web because they eat mosquitoes – including those species that transmit diseases such as malaria to humans. For example, a salamander larva can eat up to 400 mosquito larvae per day, write Springborn and colleagues.
However, the amphibian die-off probably does not only lead to more malaria cases. Studies had already shown that the decline in frog species in particular is also drastically decimating snake populations in the region. According to one study, at least 30 species of snakes have become extinct as a result.
According to the researchers, this shows how important it is to protect ecosystems and preserve biological diversity. Even the extinction of a single animal species can trigger a chain reaction. “Stable ecosystems support all possible aspects of human well-being, for example the regulation of processes that are important for the prevention of diseases,” Springborn is quoted as saying in a statement from his university. Springborn and colleagues also warn of the consequences of the unregulated international trade in wild animals. In this way, pathogens such as the Bd fungus could spread worldwide, promote the extinction of animal species – and thus have unforeseen consequences for humans.