Tracing dissolved organic matter (DOM) from land-based aquaculture systems in North Patagonian streams.
Chile is the second largest producer of salmonids worldwide. The first step in the production of salmonids takes place in land-based aquacultures. However, the effects of the discharge from these aquacultures on stream dissolved organic matter (DOM) content, molecular composition and degradability are unknown. The aim of this study was thus to investigate the inputs of anthropogenic DOM from land-based aquaculture to the predominantly pristine river systems of North Patagonia. We hypothesized, that i) DOM exported from land-based aquaculture mainly consists of protein-like fluorescence (tyrosine and tryptophan) released from fish feces and food remains, and that ii) this DOM is highly degradable and therefore rapidly turned-over within the receiving streams. In the North Patagonian region we conducted a screening of ten land-based aquacultures and an intensive sampling campaign for one aquaculture. This was combined with longitudinal transects and a degradation experiment in order to couple the composition of DOM exported from land-based aquacultures to its degradability in streams. We measured dissolved organic carbon (DOC) concentration by high-temperature catalytic oxidation and DOM composition by fluorescence spectroscopy and parallel factor analysis. In the effluent of the ten screened aquacultures and in the repeated sampling of one aquaculture, we consistently found an increase of DOC concentrations and a dominance of protein-like fluorescence. The protein-like fluorescence rapidly disappeared downstream of the aquacultures, and in the degradation experiment. 21% of the DOC export from the repeatedly sampled aquaculture resulted from food addition and 76% from fish production. We conclude that large amounts of degradable DOM are exported from land-based aquacultures. This probably has strong effects on the ecological structure and function of North Patagonian streams, and similarly affected streams worldwide.
Instituto de Ciencias Marinas y Limnológicas, Laboratorio de Bioensayos y Limnologia Aplicada, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile. Electronic address: jorge.nimptsch@uach.cl.
Jorge
J
Nimptsch
Instituto de Ciencias Marinas y Limnológicas, Laboratorio de Bioensayos y Limnologia Aplicada, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
Stefan
S
Woelfl
Instituto de Ciencias Marinas y Limnológicas, Laboratorio de Bioensayos y Limnologia Aplicada, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
Sebastian
S
Osorio
Instituto de Ciencias Marinas y Limnológicas, Laboratorio de Bioensayos y Limnologia Aplicada, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
Jose
J
Valenzuela
Helmholtz Centre for Environmental Research - UFZ, Central Water Analytics & Chemometrics, Brückstraße 3a, 39114 Magdeburg, Germany.
Paul
P
Ebersbach
Helmholtz Centre for Environmental Research - UFZ, Central Water Analytics & Chemometrics, Brückstraße 3a, 39114 Magdeburg, Germany.
Wolf
W
von Tuempling
Laboratorio de Bioindicadores, Servicio Agrícola y Ganadero, Región de la Araucanía, Casilla 16-D, Temuco, Chile.
Rodrigo
R
Palma
Escuela de Ciencias Ambientales, Laboratorio de Ecotoxicología y Monitoreo Ambiental, Universidad Católica de Temuco, Casilla 15-D, Temuco, Chile; Escuela de Acuicultura, Facultad de Recursos Naturales, Universidad Católica de Temuco, Casilla 15-D, Temuco, Chile.
Francisco
F
Encina
Escuela de Acuicultura, Facultad de Recursos Naturales, Universidad Católica de Temuco, Casilla 15-D, Temuco, Chile.
David
D
Figueroa
Helmholtz Centre for Environmental Research - UFZ, Department of River Ecology, Brückstraße 3a, 39114 Magdeburg, Germany.
Norbert
N
Kamjunke
Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark.
Daniel
D
Graeber
D017756:Aquaculture; D002244:Carbon / Q000032:analysis; D002677:Chile; D004784:Environmental Monitoring / Q000379:methods*; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D014874:Water Pollutants, Chemical; D002244:Carbon
Aquaculture; Dissolved organic matter; Fish farms; Fluorescence spectroscopy; Organic contamination