Freshwater is one of the world’s most valuable resources for the survival of all ecosystems but with human population growth freshwater ecosystems have been increasingly under pressure.
Professor Guy Woodward of Imperial College, London describes food webs as complex systems that can be broken down into its simpler components. Therefore, when one component is under some environmental stress, the whole food web is affected. By understanding food web relationships, they can be used as biosensors to predict the impacts of pressures like climate change and acidification.
The DURESS project (Diversity of Upland Rivers for Ecosystem Service Sustainability) assesses the role of biodiversity on how key ecosystem services are delivered. The project has monitored river systems in the UK recording the effects of acidification on fish species, in particularly trout. They found that an increase in acidity decreases the biodiversity resulting in trophic cascades, in the favour of meso-predators.
Although, Woodwood suggested that chemical recovery could make freshwater systems more vulnerable to dramatic changes.
Ultimately the effects on the ability of a species to be replaced by another depends on whether they are a more generalist species or more specialist.
Woodwood also described 4 scenarios for the future of upland freshwater ecosystems:
- Agricultural Intensification – with increased use of insecticides knocking out the middle of food webs, decreasing the species diversity of invertebrates.
- Enhanced ecosystem management – regular water quality measurements
- Business as usual – cease improvement actions and continue agricultural processes
- Abandonment – enabling natural processes to resume and rewilding opportunities
As a conservationist, I really enjoyed how Woodwood took an apparently complex system and described how each trophic link is connected. So if a scenario arises where one link was damaged the effects on other links could be predicted enabling environmental managers to mitigate any impacts.
I would like to take a more freshwater ecosystem pathway, in particular reintroductions, in my career. This seminar also gave me another perspective into how possible Eurasian beaver reintroductions could act as a buffer for agricultural pollutants entering lentic systems.
In conclusion, the seminar made me consider that sometimes small problems can have a great effect when on a large scale whilst having potentially simple solutions.