Freshwater macroinvertebrate traits assessment as complementary to taxonomic information for mining impact detection in the northern Peruvian Andes

Abstract

Aim:We studied the distribution of freshwater macroinvertebrate taxa and traits to distinguish ecological gradients among the mining-controlled and natural headwaters, and rural and urban economic activity influences.Location: In 2016's dry season, macroinvertebrate samples were collected at 40 locations in the Mashcon watershed, northern Peruvian Andes. Six locations were in the headwaters directly influenced by mining, eight near-pristine tributary headwaters, 14 agricultural locations at midstream and 12 urban locations downstream.Methods: Eight traits (five biological and three ecological) were selected according to data availability, and modalities scores were assigned using the weighted and the dominant-trait approaches. The traits relative abundances and abiotic conditions were compared among watershed sections. The ecological interpretability of the ungrouped data was verified with a distance-based redundancy analysis. Results:The high-altitude mining section had fewer taxa types and abundance, and distinct body forms distributions and prevalent body sizes in macroinvertebrate communities, relatable to the control of the mining headwaters. Physiological and ecological traits (respiration, mobility and attachment, food sources, feeding habits, saprobity and pH preferenda) differed among traits quantification approaches and were less informative at high altitudes. The ecological conditions from the near-pristine tributaries recovered in the vegetated midstream section, to again be affected in the downstream urban section.Main Conclusions: Our results suggest the presence of ecological impairment despite the excellent physicochemical quality of the water discharged by the mine. The obtainment of autecological information at a higher taxonomic resolution, e.g. for ubiquitous taxa like Acari and Chironomidae, would be needed to advance the freshwater quality assessment of ecologically and hydrogeochemically complex Andean mining ecosystems.

Freshwater Management Discourses in the Northern Peruvian Andes: The Watershed-Scale Complexity for Integrating Mining, Rural, and Urban Stakeholders

“…Moreover, a 2012 study in the Mashcon watershed found that human dietary intakes of arsenic, cadmium, and lead were higher closer to the mine than downstream [ 8 ]. Another study found excellent physicochemical water quality in the RG upstream section but also ecological impairment in contrast to the natural headwaters [ 10 ]. Today, the GORE, JUM, SENAMHI, and a rural interviewee acknowledge that freshwater management is a much more complex challenge beyond mining impacts.…”

“…In the northern Peruvian Andes, the Yanacocha mine (MYSRL) exploits gold and silver ores at the headwaters of four watersheds, wherein two (Mashcon and Chonta) are sub-basins of the Amazon and the other two (Rejo and Honda) drain into the Pacific Slope [ 6 ]. Assessments downstream of the mine have found both positive (e.g., landowners increased income) [ 7 ] and negative impacts (e.g., human intake of heavy metals, land use planning lobbying, freshwater ecological impairment, and decreased phreatic level) [ 6 , 8 , 9 , 10 ]. Studies with no focus on mining, yet located in the MYSRL influence area, have reported anthropogenic pressures from logging, farming, and water abstraction for drinking and irrigation.…”

Biological traits, geographic distributions, and species conservation in aquatic ecosystems

“…Several papers in this special issue provide practical examples on the use of trait‐based approaches for impact, risk, and vulnerability assessment. In one example, Mercado‐Garcia et al (2022) assess the impact of mining in a watershed on the functional changes of freshwater macroinvertebrate assemblages in the northern Peruvian Andes. They find clear ecological impairment (less macroinvertebrate diversity and changing phenotypic trait composition) of parts of the watershed impacted by mining relative to those that are not.…”

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management

“…Traits in tropical countries are understudied and therefore little is known about the responses of macroinvertebrate traits towards flow velocity, turbidity, and accumulated impacts of human activities in these regions [ 20 ]. These environmental variables are particularly important, as studies have indicated that flow velocity, sedimentation, and multiple stressors strongly affect macroinvertebrate traits [ 21 , 22 , 23 , 24 ]. Although a few studies investigated the effect of flow velocity and sedimentation on macroinvertebrate traits, most are implemented in temperate regions or mesocosms [ 21 , 25 , 26 , 27 ].…”