Serving many masters at once: importance of ecosystem services in (novel) lakes

Abstract

Gravel and sand are essential for construction and are therefore mined continually around the world. These mining activities have resulted in the creation of numerous gravel or sand quarry lakes. In the Netherlands alone, over 500 quarry lakes can be found. In-depth research towards understanding the ecology of these man-made small deep (quarry) lakes is still lacking. Often located near or in residential areas, quarry lakes are in many instances the primary aquatic system people interact with. The ecosystem services these man-made lakes can provide are rarely quantified or qualified, however, local citizens ask various services to be supplied of these systems. Which services can be provided by a freshwater ecosystem depends to a large extent on the ecological quality of that ecosystem. In this thesis we propose a framework to enable water managers to assess the ability of a specific quarry lake to provide specific services based upon their ecological quality. For each ecosystem service we determined threshold values based upon available scientific literature, an extensive field survey or expert knowledge. This system can also be used to determine the bandwidth of specific environmental parameters needed to supply a specific service. Furthermore, we focused on the biodiversity of macrophytes which can be found in quarry lake ecosystems. We compared the macrophyte diversity and water quality of 51 quarry lakes in the Province of Noord-Brabant (the Netherlands) to the surrounding shallow water bodies. Quarry lakes are clearer, nutrient poorer and contain macrophyte species not found in the surrounding shallow waterbodies. Oligotrophic quarry lakes contribute disproportionality to the regional macrophyte species pool and should therefore be protected from anthropogenic activities that can impact these unique novel ecosystems. In the second part of this thesis we focus on the importance of including stakeholders in water management and aquatic environmental research. We describe the results for a questionnaire distributed among European citizens about water awareness. Our results showed that the amount of daily water use and effect of climate change and detrimental habits such as feeding ducks, were greatly underestimated among respondents. However, 85% of our participants indicated an interest in participating in research to understand and improve their local water quality. One effective way of including stakeholders in local water management is to start citizen science projects. To exemplify this, we adapted the TBI, a highly standardized methodology for determining soil decomposition, for use in lakes. A citizen science project was organized to test the aquatic TBI in 40 European natural and quarry lakes, located in four climate zones, ranging from oligotrophic to hypereutrophic systems. By providing standardized protocols, a website, as well as meetings, we show that collecting scientifically relevant data can go hand in hand with increasing scientific and environmental literacy in participants. Active participation by all stakeholders in the process of addressing viable options for quarry lakes is vital for inclusive water management. The lessons learned from quarry lakes can be applied in the decision process concerning the use, quality and services to be demanded from aquatic systems worldwide.