This study suggests that the effects on urban water systems in the Netherlands could provide lessons for management – for example, restricting boat traffic in canals may improve underwater habitat, say researchers.
Noting that the period of COVID-19 restrictions provided a unique opportunity for studying human-ecosystem interactions, and that healthy urban aquatic ecosystems are positive for human wellbeing, researchers in the Netherlands looked at the impacts of changes in human demand for different water-based ecosystem services during the COVID-19 anthropause.
They reported that some shifts in human activities caused positive changes for water-based ecosystems (such as reduced fishing pressure) while others had negative impacts (such as an increase in disinfectants reaching surface waters). In the study they focused on four aspects of interaction from the period following 15 March 2020, when strict measures came into force including social distancing and episodic closing of schools and non-essential businesses.
Analysing boat-traffic data from Amsterdam’s ‘Digital Canal’ programme, in which boats are fitted with trackers, they found that recreational boating was much reduced – largely due to the suspension of international tourism. Data on water transparency from the Amstel, Gooi and Vecht water authority's monitoring programme showed that this reduced boat traffic led to clearer canal water (less suspended solid matter) compared to previous years. The resulting increase in light penetration permitted aquatic plants to establish – thereby improving the ecosystem service of habitat.
Meanwhile, as outdoor physical activities were not restricted in the Netherlands, an increase in recreational fishing, use of bathing waters and national parks, posed risks of heightened ecosystem degradation. While there was a perceived increase in demand for such recreational activities, the researchers noted, the level of change can only be inferred from proxy data. Using this approach, the researchers found that sales of fishing licenses increased compared to the previous four years; and that there were more Google searches for ’swimming outside' and the names of national parks containing wetlands or open-water systems.
The researchers highlight that an increase in angling at a limited number of locations could negatively affect fish stocks, or lead to a rise in unsanctioned practices such as self-stocking of angling or bait fish, which can affect food-web dynamics. Higher demand for wild swimming, meanwhile, may lead to swimming at locations not monitored under the EU Bathing Directive, potentially exposing swimmers to pathogens. The researchers assert that greater pollution of waters, for instance with personal protective equipment or microplastics, may also occur with more human use. Noise pollution from higher visitor numbers could disturb fish, birds and mammals in national parks, and increase physical wear of pathways.
The researchers suggest that it would be useful to set boundaries for utilising water systems, in order to avoid compromising vital functions. For example, designating boating pathways could conserve some areas for habitat development – which this research shows can develop quickly when permitted. They add that enacting intermittent periods of restricted access in canals to promote ecosystem recovery – for example during spring growth periods – could also promote this. Limiting the number of bathers using an area might be another course of action to reduce human impacts, or operating rotational access to bathing, fishing and scenic water systems, they say.
Insights from the anthropause should be disseminated to provide management lessons, conclude the researchers, while monitoring of effects of any new measures can offer further knowledge. New practices informed by these studies should be implemented quickly, seizing recent positive perceptions and valuation of ecosystems, to foster more environmentally-conscious communities and support mutually beneficial outcomes for society and nature.
