Pharmaceuticals suppress algal growth and microbial respiration and alter bacterial communities in stream biofilms

Abstract

Pharmaceutical and personal care products are ubiquitous in surface waters but their effects on aquatic biofilms and associated ecosystem properties are not well understood. We measured in situ responses of stream biofilms to six common pharmaceutical compounds (caffeine, cimetidine, ciprofloxacin, diphenhydramine, metformin, ranitidine, and a mixture of each) by deploying pharmaceutical-diffusing substrates in streams in Indiana, Maryland, and New York. Results were consistent across seasons and geographic locations. On average, algal biomass was suppressed by 22%, 4%, 22%, and 18% relative to controls by caffeine, ciprofloxacin, diphenhydramine, and the mixed treatment, respectively. Biofilm respiration was significantly suppressed by caffeine (53%), cimetidine (51%), ciprofloxacin (91%), diphenhydramine (63%), and the mixed treatment (40%). In autumn in New York, photosynthesis was also significantly suppressed by diphenhydramine (99%) and the mixed treatment (88%). Pyrosequencing of 16S rRNA genes was used to examine the effects of caffeine and diphenhydramine on biofilm bacterial community composition at the three sites. Relative to the controls, diphenhydramine exposure significantly altered bacterial community composition and resulted in significant relative increases in Pseudomonas sp. and decreases in Flavobacterium sp. in all three streams. These ubiquitous pharmaceuticals, alone or in combination, influenced stream biofilms, which could have consequences for higher trophic levels and important ecosystem processes.

Effects of flow intermittency and pharmaceutical exposure on the structure and metabolism of stream biofilms

“…The DGGE fingerprinting analyses revealed that the structure of bacteria community was also altered (Fig. 3), in the way already observed in other studies Yergeau et al, 2012;Rosi-Marshall et al, 2013). The algal growth rate decreased, as well as algal biomass, algal taxa richness, and the community composition.…”

“…Since pharmaceutical compounds are designed to be pharmacologically active in human or animals, they may have long-term effects on non-target aquatic biota, such as stream biofilms. Their presence may induce changes in microbial species composition, which may in turn influence ecosystem function (Yergeau et al, 2012;Proia et al, 2013a;Rosi-Marshall et al, 2013). Stream biofilms integrate algae, cyanobacteria, bacteria, protozoa and fungi embedded in a polysaccharide matrix (Lock, 1993).…”

One-Time Addition of Nano-TiO2 Triggers Short-Term Responses in Benthic Bacterial Communities in Artificial Streams

“…Each data point represents the community from one stream on one sampling date TiO 2 treatment, suggesting that they were all sensitive to nano-TiO 2 and that all bacterial orders recovered after 3 weeks. The lack of change in community composition that was observed in the current study was unexpected, as previous studies have shown that a variety of chemical stressors, ranging from heavy metals [48] to antimicrobial compounds [49,50], and pharmaceuticals [51] can cause shifts in the taxonomic composition of benthic bacterial communities. Nano-TiO 2 has also been shown to alter bacterial community composition in terrestrial soils [52][53][54] and activated sludge [55], although these effects were observed at nano-TiO 2 concentrations 50 to 100 times higher than were used in the current study.…”

Pharmaceuticals and personal care products alter the holobiome and development of a medically important mosquito

“…Kołodziejska et al (2013) demonstrated that antibiotic contaminates commonly released from fisheries reduced growth of green algae (Scenedesmus vacuolatus) and duckweed (Lemna minor), as well as viability of the crustacean Daphnia magna. Rosi-Marshall et al (2013) showed the stimulant, caffeine, significantly reduced respiration rates of stream biofilms, but had no effect on their bacterial composition. They also showed that an antihistamine, diphenhydramine, caused both a reduced respiration rate and a significant change in the bacterial community of the biofilms.…”