Updated: Dec 14, 2019
Mountain freshwater ecosystems and the biota they provide habitat for are highly threatened by human activities. In these ecosystems, amphibians are keystone species. They impact nutrient dynamics, influence the cycling of nutrients and energy flows between freshwater and terrestrial systems, and control populations of pest insects. Tadpoles are primary consumers, altering algal biomass, community composition and sedimentation, whereas adults prey on invertebrate communities and deposit energy-rich eggs that are consumed by many species.
This video produced by P³ summarizes the tough life of amphibians and their unsure future under climate change and human impact.
The text spoken in the short film:
Mountains are important for recreation and the livelihood of billions of people by providing many different services to humanity, as e.g. clean drinking water.
Amphibians are critical species for mountain ecosystems and are highly susceptible to the currently occurring environmental change. Generally, amphibians/THEY are very tough species, being able to survive under so extreme conditions as found in alpine freshwater ecosystems. There temperatures are generally low and growth seasons usually short. The common frog Rana temporaria arrives very early at breeding sites, the lakes just have unmelted and water temperature is just above 4°C. This species produces an important amount of eggs. The outer layer of these egg clutches protect the inner ones from frost and low temperatures, allowing those eggs to develop faster. Most of the egg jelly envelop of these clutches is also the first energy source for tadpoles, giving them a kick-start into their tough live.
Once they leave the egg clutch behind, tadpoles are eating machines, gracing on biofilm, algae etc. and looking for the warmest spots in the lake to take in energy from the sun. Their only aim: get as big as possible so that they reach metamorphosis fast and become the biggest possible froglet. A bigger tadpole will lead to bigger adults and will give a higher survival chance to the whole population.
Naturally, life is already quite tough for amphibians in alpine lakes. Many of the eggs will either never hatch, tadpoles will die due to too low temperatures or are eaten by naturally occuring predators. Fish are not naturally occurring in alpine lakes, but they feed on eggs as well as on tadpoles. They also induce stress making tadpoles spend energy tadpoles would need to become the biggest possible froglet.
Then, there is a less visible threat – pathogens. Tadpoles might just be getting close to their aim to become the biggest possible froglet before the pathogens kills these young frogs.
Live is tough for a frog, but it has become much tougher since humans induced changes even to remote areas.
We, P³, investigate these changes and the impact on frogs and other biota. Find information on our adventures here