Agricultural practices alter function and structure of macroinvertebrate communities in Patagonian piedmont streams

HORAK, CRISTINA NATALIA; ASSEF, YANINA ANDREA; GRECH, MARTA GLADYS; MISERENDINO, MARÍA LAURA

HYDROBIOLOGIA

SPRINGER

Año: 2020 vol. 847 p. 3659 - 3676

0018-8158

The intensification of agricultural practices is impacting on Piedmont streams in Patagonia and concern exists regarding the integrity of aquatic ecosystems. This study investigated changes in water quality, habitat and riparian condition, and macroinvertebrate community attributes at three small streams during high- and low-water periods. The upper reaches of streams consisted of well-conserved riparian forest where agricultural impact was minimal, while different production systems affected lower stream-reaches. Significant changes in water quality were indicated by increases in nutrient levels, conductivity, total suspended solids, and bacteria (E. coli) at spatial scale. These were mostly associated with livestock, pasture, and horticulture production, though the most severe impacts on in-stream habitat and riparian ecosystem occurred at sites with livestock productions. A gradient of disturbance was highlighted by Canonical Community Ordination and macroinvertebrates were grouped accordingly. Among the metrics measured, EPT richness, number of insect families, density of tolerant taxa, abundance of collector-gatherers, and total invertebrate density displayed significant responses to water quality. The overriding stressor explaining community changes with regard to intolerant taxa (EPT) was ammonium. Mitigation measures should be directed towards reducing livestock intrusion on streams and riparian areas, maintenance and restoration of buffer zones, and regulation of application of fertilizers.