The interacting effects of anthelmintic residues and exposure-delay on four ecosystem functions supported by dung beetles.

<p>Measures of dung removal (A), primary productivity (B), feeding activity (C) and soil compaction (D), are shown as a function of species richness and perturbation with the anthelmintic ivermectin. Relationships between each function and the timing of exposure are plotted along with 95% confidence intervals at each level of anthelmintic exposure. Light-grey-filled circles with unbroken lines represent anthelmintic-free controls, grey-filled circles with dotted trend lines represent low exposure (125 ppm), and dark-grey-filled circles with dashed trend lines represent high exposure (500 ppm).</p

Dung beetle survival as a function of anthelmintic exposure.

<p>Dung beetle survival was not significantly affected by anthelmintic exposure. Means (bars) are calculated using the number of adult <i>Aphodius fossor</i> dung beetles entering emergence traps at the end of the experiment (Phase 3). Means are grouped based on the exposure-delay. Bars represent treatment means with standard errors.</p

Quantifying immediate and delayed effects of anthelmintic exposure on ecosystem functioning supported by a common dung beetle species

<div><p>Dung beetles (Coleoptera: Scarabaeoidea) support numerous ecosystem functions in livestock-grazed pastures. Exposure to veterinary anthelmintic residues in livestock dung can have lethal and sublethal effects on dung beetles, and can reduce rates of dung removal, but the immediate and longer-term consequences for other dung beetle mediated functions have rarely been studied. We investigated the consequences of anthelmintic exposure on survival of the dung beetle <i>Aphodius fossor</i> and its delivery of four ecosystems functions that underpin pasture production: dung removal, soil fauna feeding activity, primary productivity, and reduction of soil compaction. We tested whether anthelmintic exposure had immediate or delayed effects on these functions individually and simultaneously (i.e., ecosystem multifunctionality). We found no evidence that ivermectin residues had a lethal effect on adult beetles. For dung removal, we found a significant interaction between the timing of exposure and functioning: while dung removal was impaired by concurrent exposure to high levels of ivermectin, functioning was unaffected when beetles that had been exposed previously to the same concentration of anthelmintic later interacted with untreated dung. Other ecosystem functions were not affected significantly by anthelmintic exposure, and there was no evidence to suggest any persistent impact of anthelmintic exposure on ecosystem multifunctionality. While anthelmintic residues remain a significant threat to dung beetle populations, for adult beetles, we found no evidence that residues have detrimental consequences for ecosystem functioning beyond the immediate point of exposure.</p></div

The relationship between the exposure timing of the anthelmintic ivermectin and ecosystem multifunctionality.

<p>Relationships between exposure timing and multifunctionality at control (A), low (B) and high (C) levels of anthelmintic exposure. Thresholds span between 10–87% of the observed maxima. Confidence Intervals (95%) surrounding the slope estimates indicate whether the intervals contain zero. In no case did we find any evidence of a strong loss or gain of multifunctionality associated with anthelmintic exposure.</p

Schematic of the experimental design.

<p>All dung beetles used within the experiment were moved through a series of three enclosures, spending one week in each Phase. Black dung indicates the period of the experiment when the anthelmintic was added (or not added in the controls) to dung. All ecosystem functions were measured during the final part of the experiment (Phase 3). To manipulate the time between exposure and measurement of functioning, beetles were exposed to ivermectin (except in the controls) during either Phase 1, Phase 2, or Phase 3, which corresponded to ‘exposure-delays’ of two-weeks prior to (A), one-week prior to (B), or concurrently alongside (C) the enclosure where functions were measured (Phase 3). The experiment was replicated with high anthelmintic residues (500 ppb ivermectin), low anthelmintic residues (125 ppb ivermectin), or controls without anthelmintic. Enclosures used for Phase 1 and Phase 2 were fully sealed, while enclosures used for Phase 3 were open at the bottom, and dug into the soil to allow free colonisation by soil invertebrates.</p

Summary of linear models describing the relationship between exposure-delay (Delay), and the concentration of anthelmintic residues (Residues) in cattle dung.

<p>Summary of linear models describing the relationship between exposure-delay (Delay), and the concentration of anthelmintic residues (Residues) in cattle dung.</p

Appendix E. Changes in herbivore abundance and biomass through time in response to temperature and nitrogen addition.

Changes in herbivore abundance and biomass through time in response to temperature and nitrogen addition

The effect of concurrent ivermectin exposure on four ecosystem functions supported by the dung beetle <i>Aphodius fossor</i>.

<p>Each panel shows a different ecosystem function: dung removal (A), primary productivity (B), feeding activity (C), and soil compaction (D). Bars represent treatment means with standard errors. In panel A, sharing of lowercase letter labels indicate that differences between treatment means are not significant, at a level of: α = 0.05.</p

Appendix H. Changes in herbivore individual body mass through time in response to temperature and nitrogen addition.

Changes in herbivore individual body mass through time in response to temperature and nitrogen addition

Appendix G. Changes in abundance of the three most common herbivore species through time and in response to temperature and nitrogen addition.

Changes in abundance of the three most common herbivore species through time and in response to temperature and nitrogen addition