Photo: Jeffrey Blum on Unsplash
Even before COVID-19, freshwater ecosystems and fish populations were subject to high exploitation pressures and varied threats. And yet these threats could change in the long term as a result of the pandemic, scientists suggest in a paper published in Biological Conservation.
Positive and negative impacts – often two sides of the same coin
1. Invasive species
Invasive species, for example, are considered one of the most significant drivers of aquatic biodiversity decline. Reductions in travel will also diminish the unintended introduction of such species, but only in the short term. As the economy recovers, the pace of invasions will increase again. To make matters worse, COVID-19 has led to significant budget reductions for controlling the spread of invasive species all over the world; not only monitoring and regulatory measures, but also scientific programmes have been reduced in many places.
2. Fragmentation of freshwater systems
Another example cited by the scientists is the fragmentation of freshwater ecosystems due to the construction of dams. There has in fact been a slowdown in construction activities. However, if regions prioritise economic recovery post-pandemic, regulations and environmental protection measures could be side-stepped and controversial projects pushed forward faster than ever – especially in countries where environmental issues played a subordinate role even before the pandemic. Environmental issues and funding for restoration projects could be deferred or held back.
3. Fisheries
In the commercial fisheries, pressure on fish stocks declined temporarily during the lockdown. In many cases, markets have collapsed, especially in direct marketing. However, interruptions to other food production sectors and income losses may lead communities to rely more heavily on freshwater fisheries as a food source, especially in developing and emerging countries. The researchers are also concerned about a reduction in monitoring capacity. At the same time, the pandemic has generated a noticeable increase in recreational angling interest in many regions. This may even have increased fishing pressure, particularly on many small lakes and river sections. In contrast, recreational fishing participation has declined in tourist areas, especially during periods of lockdown. This is likely to have a positive impact on fish populations.
4. Climate change
The finding with regard to climate change is similarly ambivalent: although the decrease in global emissions could reduce climate impacts in the short term, the timescale of these reductions is too short to reverse damaging trends. The decisive factor will therefore be whether economic recovery efforts follow a return to “business as usual”, or instead, embrace the implementation of new climate policies that drive shifts to clean energy.
Looking to the future
For these and other reasons, the researchers conclude that the state of freshwater ecosystems and fish stocks is unlikely to be any better in five years than it is today. Prioritisation of economic and societal recovery in the post-pandemic phase could accelerate and compound existing threats, and compromise conservation and fisheries management activities. This dynamic is particularly likely in developing regions, whereas in Europe, for example, the EU Water Framework Directive and the Biodiversity Strategy will probably mitigate many of the threats.
Actions taken during the pandemic will also cause longer-term negative impacts: disruptions in monitoring and research programmes, and interrupted education and training create data and knowledge gaps.
The experts recommend adapting management measures and policy decisions now to ensure that biodiversity is preserved for the benefit of humankind and aquatic ecosystems. In practical terms, this means reviewing and effectively shaping environmental regulations; integrating large-scale restoration and monitoring programmes into economic stimulus packages; and preventing a return to high emission levels. They also call for a rigorous examination and assessment of the impacts on fish biodiversity as lockdowns are lifted.
