DOI: 10.5061/dryad.zw3r2288p
title: Reduced genetic diversity of freshwater amphipods in rivers with increased levels of anthropogenic organic micropollutants

description: Anthropogenic chemicals in freshwater environments contribute majorly to
 ecosystem degradation and biodiversity decline. In particular,
 anthropogenic organic micropollutants (AOM), a diverse group of compounds
 including pesticides, pharmaceuticals, and industrial chemicals, can
 significantly impact freshwater organisms. AOM were found to impact the
 genetic diversity of freshwater species, however, the degree to which AOM
 cause changes in population genetic structure and allelic richness of
 freshwater macroinvertebrates remains poorly understood. Here, the impact
 of AOM on the genetic diversity of the common amphipod Gammarus pulex
 (Linnaeus, 1758) (clade E) was investigated on a regional scale. The
 site-specific AOM levels and their toxic potentials were determined in
 water and G. pulex tissue sample extracts for 34 sites along six
 rivers impacted by wastewater effluents and agricultural run-off in
 central Germany. Population genetic parameters were determined for G.
 pulex from the sampling sites by genotyping 16 microsatellite loci.
 Genetic differentiation among G. pulex from the studied rivers was
 strongly associated with geographic distance between sites, but also with
 differences in site-specific concentrations of AOM. Thus, genetic
 diversity parameters of G. pulex were found to be related to site-specific
 AOM levels; allelic richness was significantly negatively correlated to
 levels of AOM in G. pulex tissue (p &lt; 0.003) and was reduced by up
 to 22% at sites with increased levels of AOM. This was seen despite a
 positive relationship between allelic richness and the presence of
 waste-water effluent. In addition, the inbreeding coefficient of G. pulex
 from sites with toxic AOM levels was up to 2.5 times higher than in G.
 pulex from more pristine sites. These results indicate that AOM levels
 commonly found in European rivers significantly contribute to changes in
 the genetic diversity of an ecologically relevant indicator species.
description: AOM concentrations in water
 and <em>G. pulex</em> tissue samples were analyzed by
 a Thermo Ultimate 3000
 liquid chromatography
 (LC) system coupled
 with a quadrupole-orbitrap high-resolution mass
 spectrometer
 (HRMS;
 Thermo QExactive
 Plus).
 To quantify AOM in the samples, raw data from the LC-HRMS analysis were
 converted into the .mzML format using ‘ProteoWizard v3.0.18265’.
 The peak list for each
 batch was generated by MZmine v2.32. The list was annotated for 523 compounds from water samples and
 497
 compounds from
 <em>G. pulex</em> tissue samples and corrected for blanks. The analyzed compounds comprised AOM with a wide spectrum of hydrophobicity and
 application
 categories including
 pesticides,
 pharmaceuticals, and
 household and industrial
 chemicals known to regularly occur in central-European
 rivers. To assess population genetic structure and
 genetic diversity parameters of <em>G.
 </em><em>pulex</em>, 16 microsatellite loci were
 genotyped in a total of
 931 individuals from the different sampling
 sites (10–30 individuals
 per site). Genomic DNA was
 extracted from pereopods of each individual using the DNeasy Blood &
 Tissue kit (Qiagen,
 Hilden, Germany). DNA
 integrity was checked on an agarose gel, followed by DNA concentration
 quantification using a NanoDrop spectrophotometer (NanoDrop Technologies
 Inc.). Microsatellite loci were amplified and genotyped on 20 (Holtemme River sites) to up to 30 (all other sites) <em>G. pulex</em>
 DNA
 samples.
description: Supplementary table S3. List of concentrations of compounds detected in
 water samples from every
 site in
 ng/L, with information on
 types of application (Type), and minimal detection limits (MDL) of the detected
 compounds. Supplementary table S4. List of concentrations of compounds detected in
 amphipod tissue
 samples from every site
 in ng/g wet
 tissue, with information
 on types of applications (Type), and minimal detection limits (MDL) of the detected
 compounds. Tab_microsat_all_sites. Table in genepop format
 with <em>Gammarus pulex</em> microsatellite genotypes of 16
 loci from six rivers and 34 sites in Central Germany. Genotypes are are
 listed for the Altenau River (A1-A5), the Eine River (E1-E6), the Holtemme
 River (H1-H6), the Parte River (P1-P5), the Saale River (S1-S5), and the
 Wipper River (W1-W7). Six zeros are listed when no value was
 available.