DOI: 10.5061/dryad.ngf1vhhwj
title: Data from: Freshwater ecological quality assessment of the gold mining Mashcon watershed, Cajamarca - Peru

description: These data were generated to investigate the aquatic community gradients
 across different types of anthropogenic impacts (reference, mining, rural
 and urban) and Andean environmental gradients (headwaters, midstream and
 downstream) in the Mashcon watershed.  The
 macroinvertebrates' taxa abundance and abundance of traits modalities
 serve as biological values. The latter in combination with abiotic
 measurements of the freshwater habitats (i.e. physicochemical water
 quality and hydromorphology) constitute the ecological data. The values
 were obtained from river sediments (macroinvertebrates collection), water
 samples for laboratory analyses, field protocols and in-situ water quality
 measurements at 40 sites, wherein 6 were downstream of the gold mine’s
 artificially recharged headwaters, 8 sites at near-pristine headwaters
 tributary streams, 14 sites at midstream rural areas and 12 sites at
 downstream urban areas (sample grouping information is shown in the
 Field_protocol.xlsx file).
description: Freshwater macroinvertebrates were collected
 with a standardized kick-sampling method, by simultaneously kicking and
 sweeping the river substrate using a hand-net (frame size 20 × 30 cm; mesh
 size 500 µm) to sample as many microhabitats as possible, and for 5
 minutes at each location (Acosta et al., 2008). Macroinvertebrates were collected from the
 substrate samples and stored in 75% ethanol. The taxa were counted and
 identified at the family level by an expert taxonomist, except for the
 Acari subclass. The level
 of taxonomic resolution was selected for being sufficient to detect
 environmental and biodiversity gradients of freshwater macroinvertebrates
 communities (Mueller et
 al., 2013). The
 macroinvertebrate taxa counts were complemented with traits information.
 Eight traits were selected according to the availability of databases of
 sufficient taxonomic resolution and suited to Andean ecosystems. Traits of
 macroinvertebrates were obtained from Tomanova et al.
 (2008), Tomanova and Usseglio-Polatera
 (2007) and Tachet et al. (2000). These consisted of five biological (maximal
 body size, food source, body form and respiration) and three ecological
 (mobility and attachment to substrates, feeding habits, saprobity and pH
 preferendum) traits. A traits matrix was created containing the
 modalities’ aﬃnity scores for 43 taxa (supplementary ‘taxa-to-trait.xlsx’
 file). Six families (Blephariceridae, Chordodidae, Curculionidae,
 Gripopterygidae, Hyalellidae and Hydrobiosidae) were excluded due to
 lacking traits information. A fuzzy coding procedure was applied to estimate
 the weighted traits abundance, allowing multiple affinities for certain taxa.
 For example, Baetidae feeds by scraping fine particulate organic matter,
 microphytes and microinvertebrates from surfaces, but it is also able to
 feed on deposited debris sometimes. Thus, considering the modalities ‘x’,
 ’y’ and ‘z’ for a given trait, and supposing there are 100 individuals of
 a taxon, and knowing that this taxon has an aﬃnity of 3 for modality ‘x’,
 1 for modality ‘y’ and no aﬃnity for modality ‘z’; then the modality ‘x’
 was given an abundance of 75 counts, modality ‘y’ 25 counts, and modality
 ‘z’ 0 counts. In addition, a dominant-trait coding procedure was applied
 to the initial traits matrix, disregarding the non-dominant trait
 modalities. In the above-mentioned Baetidae example, modality ‘x’
 dominates the others, thus the dominant-trait approach assigns 100 counts
 for modality ‘x’. If more than one modality were equally dominant in a
 taxon, the affinity scores had to be assigned by equal fractions totaling
 1, allocating equal counts to the equally dominant modalities. In both
 quantification methods, the abundance per sampling site was estimated by
 adding up the modality counts from each taxon.
 Physicochemical measurements of temperature,
 conductivity, pH, turbidity, chlorophyll-a and dissolved oxygen (DO%) were
 taken using YSI® multiparameter probes. Hach-Lange® laboratory test kits
 were used for measuring chemical oxygen demand (COD), phosphorus, nitrate,
 nitrite and ammonium. Sulphates were measured with Hach® SulfaVer® 4 kits.
 Filtered (0.45 µm) freshwater samples were collected in 50 ml falcon
 tubes, and acidiﬁed to 1% HNO3 for dissolved metal analyses. The latter
 step was repeated without filtering for total metal analyses. A Thermo
 Fisher Scientiﬁc® iCAP 6000 ICP-OES® was used to measure concentrations of
 barium, copper, manganese and zinc. Geocoordinates and altitude were
 recorded using a Garmin eTrex® HC series GPS.