Water Quality and Socio-Economic Indicators are Linked in a Tropical Watershed: Emerging Implications for the Sustainable Management of Waterscapes

Abstract

Human societies rely on water to fulfill multiple needs. Paradoxically, our dependency on water has brought fundamental changes to freshwater ecosystems that may manifest as abrupt transitions in water quantity and quality indicators associated with conditions that can no longer fulfill human needs. Of particular concern amidst a time of environmental changes are tropical streams and their linked riparian zones, particularly in islands, given their role in the provisioning of water-derived ecosystem services. Focusing on a watershed that has become a key player in the water economy of Puerto Rico we investigated the spatiotemporal variation of water quality and socio-economic indicators, including links between them. The analyses of two unique datasets showed that 1) water quality indicators exhibited three distinctive behaviors, 2) in a small number of stations biological and chemical variables tended to decrease over time, 3) socio-economic indicators were spatially discontinuous, and 4) water quality and socio-economic indicators were related in counter-intuitive ways yet scale became a critical factor revealing the nature of the relationships. Our results raise questions about the causes underlying the observed variability in water quality and socio-economic conditions, the resilience of tropical watersheds, and ultimately the sustainable delivery of water-derived ecosystem services.