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Introduction
Freshwater environments are habitat to at least 10% of the global biodiversity, corresponding to c. 126 000 species (Dudgeon et al. 2006, Strayer & Dudgeon 2010). This biodiversity is even more remarkable given that fresh waters cover only 0.8% of the Earth’s surface (Acreman et al. 2020). Nevertheless, threats to fresh waters have become more intense in recent decades, making this environment one of the most threatened in the world, with a sharp decline occurring in its biodiversity (Dudgeon et al. 2006, Vörösmarty et al. 2010, Reid et al. 2019). Pollution and wastewater discharge are major drivers of biodiversity loss and, consequently, great efforts are necessary to understand the negative effects of these factors on the aquatic community and its conservation (Reid et al. 2019, Barros et al. 2020). Harmful effects also reach humans who are strictly dependent on inland waters, from the more basic needs such as water and food supplies to more complex uses such as industry. Hence, conserving freshwater environments is of utmost urgency.
Inland aquatic ecosystems could benefit from protected areas (PAs), which are crucial to biodiversity conservation globally (Abell et al. 2007, Gaston et al. 2008). PAs can minimize anthropogenic pressures such as land conversion, fragmentation, habitat loss, hunting and logging (Grignolio et al. 2011, Feng et al. 2021, Yang et al. 2021). However, the effectiveness of PAs at protecting aquatic biodiversity has been questioned, and PAs’ potential to protect fresh water needs strengthening (Hermoso et al. 2016, Acreman et al. 2020). In addition, there is a lack of consideration by policymakers for freshwater ecosystems in PA design and management, providing only incidental protection to rivers, creeks, streams and wetlands within their borders (Herbert et al. 2010, Thieme et al. 2012, Quenta-Herrera et al. 2022). Recent studies having highlighted pesticide, pharmaceutical and personal care product contamination inside PAs, raising global concern regarding the influence of these compounds even in highly preserved regions (Elliot & VanderMeulen 2017, Bradley et al. 2021). For example, Bradley et al. (2020) recorded 80 different bioactive compounds in freshwater samples from five PAs in the USA. Sources of threats to water systems in PAs may be diverse, such as visitation (Weissinger et al. 2018), agriculture and land conversion in surrounding areas (Battaglin et al. 2016,...