DOI: 10.5061/dryad.280gb5n0n
title: Data from: Microcystins bioaccumulate but do not biomagnify in an experimental aquatic food chain

description: Microcystins-common hepatotoxins produced by cyanobacteria—have been
 detected in a wide range of organisms, though research examining the
 trophic transfer of microcystins and whether microcystins bioaccumulate or
 biomagnify in food webs has generated contradictory results. Here, we
 explored the trophic transfer of microcystins from the herbivorous water
 flea, Daphnia pulex, to the predatory larvae of a damselfly, Enallagma sp.
 We tested the hypotheses that microcystins transfer from the tissue of
 herbivorus zooplankton to that of predatory invertebrates and that these
 toxins biomagnify across trophic levels. We also assessed the relative
 contribution of toxin transfer from the gut and tissue of Daphnia pulex to
 Enallagma sp. We found that microcystins are effectively sequestered in
 the tissue of Daphnia pulex, and that these sequestered toxins are then
 transferred to the tissue of Enallagma sp. The contribution of gut
 contents to toxin transfer was negligible. Contrary to the pattern
 predicted by biomagnification, we found that the concentration of
 microcystins decreased with increasing trophic levels. Our results support
 the hypothesis that microcystins can be transferred trophically, but do
 not support the hypothesis that microcystins biomagnify from lower to
 higher trophic levels. Conversly, we observe biodilution in this system.
 These results have consequences for the impact of microcystins across
 trophic levels in a changing world with increasing intensity and duration
 of harmful algal blooms.
description: This dataset includes measurements of microcystin in three
 trophic levels in an experimental aquatic foodweb. Data were collected as
 described in associated manuscript. Microcystins were measured using the
 MMPB technique. Final concentration of microcystin per dry weight (mg) for
 each sample is reported in column labeled ngMC/mgTL. As described in the
 associated manuscript, in one of the five trials, microcystins were
 detected in <em>Microcystis</em> but not in the grazing
 <em>Daphnia</em>. Data from this trial have been omitted from
 the dataset, as they were not used in the reported analysis.
 This R script includes all steps for reproducing figures and
 statistical tests using the associated dataset.
description: # Data from: Microcystins bioaccumulate but do not biomagnify in an
 experimental aquatic food chain
 [https://doi.org/10.5061/dryad.280gb5n0n](https://doi.org/10.5061/dryad.280gb5n0n) ## Description of the data and file structure This dataset includes measurements of microcystin in three trophic levels in an experimental aquatic food web including *Microcystis*, *Daphnia*, and *Enallagma*. The data were used to test for biomagnification, toxin transfer route, and trophic transfer efficiency across trophic levels. Data were collected as described in associated manuscript. Microcystins were measured using the MMPB technique. Final concentration of microcystin per dry weight (mg) for each sample is reported. ### Files and variables #### File: Data\_29Oct24.csv **Description:**  ##### Variables * Algae: One of two values:* Microcystis* (toxic algae) or* Scenedesmus* (non-toxic algae) * Daphnia gut: Describes whether gut of *Daphnia *was full (including algae) or clear * Enallagma gut: Describes whether gut of *Enallagma *was full (including algae) or clear * Treatment: Treatment code incorporating information from three columns: Algae, *Daphnia* gut, and *Enallagma* gut. These treatment codes were used in the analysis in attached R script. * Rep: Trial number (2, 3, 4, or 5) * Density_cells/mL: Density of algae in cells/ml in trial * ng MC/Daph: Amount of microcystin (in ng) per *Daphnia* individual * No.Daphnia Eaten: Number of *Daphnia* consumed by* Enallagma* in corresponding trial * MCEnall_ng/Enall:  Amount of microcystis per* Enallagma* indicidual * ngMC/mgTL: Concentration of microcystin (in ng) per dry weight (in mg) * Trophic Level: One of three values indicating trophic level upon which measurements were made: 1 (algae), 2 (*Daphnia*), or 3 (*Enallagma*) Further notes: 1. 'NA' values indicate that a measurement was not made. For example, if the treatment was 'Microcystis', measurements were only made on Microcystis and not Daphnia. For that reason, 'ng MC/Daph' would have an 'NA' value. 2. 'BDL' indicates 'below detection limit', which was 0.2 ng/mL #### File: Bioaccumulation\_29Oct24.R **Description:** This R script includes all steps for reproducing figures and statistical tests using the associated dataset. ## Code/software Analysis was completed using attached R script. Versions of R and loaded packages: 1. R version 4.2.2 2. rstatix_0.7.2 3. cowplot_1.1.1 4. ggplot2_3.5.1 5. tidyverse_2.0.0 6. forcats_1.0.0 ## Access information No other publicly accessible locations of the data.