Pharmaceuticals and personal care products (PPCPs) are ubiquitous in aquatic environments, yet little is known regarding impacts of PPCPs on ecological processes. Selective serotonin reuptake inhibitors (SSRIs), a specific type of PPCP, act as anti-depressants by altering the levels of serotonin in the brain. In aquatic ecosystems, SSRIs can accumulate in invertebrates, affecting aggression and foraging behavior. Impacts of SSRIs on crayfish behavior are particularly interesting as crayfish exhibit increased aggression in response to SSRIs. Furthmore, crayfish and are commonly found in anthropogenically-influenced environments where SSRIs and other PPCPs are commonly found. We were interested in the question: How does a common SSRI influence the effect of crayfish on stream ecosystem functions? Using a fully-crossed artificial stream experiment, we tested the impacts of a common SSRI, citalopram, crayfish, and the SSRI-crayfish interaction on stream ecosystems. We used a Y-shaped flume experiment to quantify the effects of SSRIs on crayfish behavior and food/conspecific preference. Furthermore, we quantified the interacting effects of SSRIs and crayfish on a variety of ecosystem functions (nitrogen uptake, gross primary production) within artificial streams.
Results/Conclusions
The flume experiment showed that SSRIs impacted crayfish behavior: crayfish exposed to SSRI’s peeked out of shelters and emerged from shelters more quickly than non-exposed crayfish (p=0.016). Furthermore, control crayfish spent more time in the conspecific section of the flume than SSRI crayfish (p=0.013) whereas SSRI crayfish spent more time in the food section of the flume (p=0.042). Whole-stream metabolism was not affected by either SSRIs or crayfish, but we did observe a marginal effect of crayfish increasing ecosystem respiration occurring in the water column (p=0.093). Furthermore, crayfish reduced whole-stream nitrate uptake (p=0.05), but there was no significant direct or interactive effect of SSRI’s on stream ecosystem functions. These results show that crayfish can directly alter ecosystem functions within artificial streams, and that SSRIs may indirectly affect ecosystem processes by altering organismal behavior, supporting the claim that PPCPs are ecological disrupting compounds with a range of sublethal effects.