title: Influence of rice field agrochemicals on the ecological status of a tropical stream.
abstract: Many tropical countries contain a high density of protected ecosystems, and these may often be bordered by intensive agricultural systems. We investigated the chemical and ecological status of a stream connecting an area with conventional rice production and a downstream protected nature reserve; Mata Redonda. Three sites were sampled: 1) an upstream control, 2) in the rice production area and 3) a downstream site in Mata Redonda. We sampled benthic macroinvertebrates and pesticides in water and sediments along with supporting physical and chemical data. Pesticide concentrations in water exceeded current safety thresholds at sites 2 and 3, especially during the rainy season, and sediment associated pesticide concentrations exceeded current safety thresholds in three of six samples. Importantly, the highest predicted pesticide toxicity in sediments was observed at site 3 in the Mata Redonda confirming that the nature reserve received critical levels of pesticide pollution from upstream sections. The currently used macroinvertebrate index in Costa Rica (BMWP-CR) and an adjusted version of the SPecies At Risk index (SPEAR) were not significantly correlated to any measure of anthropogenic stress, but the Average Score Per Taxon (ASPT) index was significantly correlated with the predicted pesticide toxicity (sumTUD.magna), oxygen concentrations and substrate composition. Our results suggest that pesticide pollution was likely involved in the impairment of the ecological status of the sampling sites, including site 3 in Mata Redonda. Based on our results, we give guidance to biomonitoring in Costa Rica and call for increased focus on pesticide transport from agricultural regions to protected areas.
authors.affiliation: Aarhus University, Department of Bioscience, Vejlsøvej 25, 8600 Silkeborg, Denmark. Electronic address: jr@bios.au.dk.
authors.forename: Jes Jessen
authors.initials: JJ
authors.lastname: Rasmussen
authors.affiliation: University of Copenhagen, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Emilie Marie
authors.initials: EM
authors.lastname: Reiler
authors.affiliation: Centro de Investigación en Contaminación Ambiental, Ciudad Universidad de Costa Rica Universitaria Rodrigo Facio, San José, Costa Rica.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Carazo
authors.affiliation: Centro de Investigación en Contaminación Ambiental, Ciudad Universidad de Costa Rica Universitaria Rodrigo Facio, San José, Costa Rica.
authors.forename: Jessie
authors.initials: J
authors.lastname: Matarrita
authors.affiliation: Centro de Investigación en Contaminación Ambiental, Ciudad Universidad de Costa Rica Universitaria Rodrigo Facio, San José, Costa Rica; Escuela de Biología, Ciudad Universitaria Rodrigo Facio, San José, Costa Rica.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Muñoz
authors.affiliation: University of Copenhagen, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.
authors.forename: Nina
authors.initials: N
authors.lastname: Cedergreen
mesh_terms: D016573:Agrochemicals / Q000032:analysis / Q000633:toxicity*; D000818:Animals; D003364:Costa Rica; D004784:Environmental Monitoring / Q000379:methods*; D007448:Invertebrates / Q000145:classification / Q000254:growth & development; D012275:Oryza; D010575:Pesticides / Q000032:analysis / Q000633:toxicity; D045483:Rivers / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D016573:Agrochemicals; D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: Ecological quality indices; Macroinvertebrates; Pesticides; Protected areas; Risk assessment; Tropical streams