A novel method to assess effects of chemical stressors on natural biofilm structure and function

Abstract

SUMMARY1. The regulation and management of chemical contaminants rarely use community-and ecosystemlevel endpoints, partly due to a lack of suitable methods. To overcome this limitation, we propose contaminant exposure substrata (CES), an adaptation of the widely used nutrient-diffusing substratum method, to assess responses of biofilm communities to chemical contaminants in situ. 2. We describe methods for using CES to assess effects on biofilm biomass, community structure, process rates, biofilm-consumer interactions and biofilm chemistry. We also provide equations to calculate the flux of soluble chemicals from CES and describe an approach to compare contaminant dose in CES assays to the contaminant dose encountered by biofilms in polluted surface waters. 3. Data from four case studies demonstrate that CES can detect impairment of biofilm structure and function. 4. The adaptability, simplicity and cost-effectiveness of CES make them valuable tools to assess community-and ecosystem-level responses to contaminants, suggesting potential for routine use and incorporation of data generated from such assays into contaminant regulation and management.

Urban stream microbial communities show resistance to pharmaceutical exposure

“…, Costello et al. ). Caffeine (df = 1, 52; F = 6.59; P < 0.05), cimetidine (df = 1, 51; F = 7.02; P < 0.05), and ciprofloxacin (df = 1, 52; F = 12.76; P < 0.05) all significantly reduced biofilm respiration across all sites, whereas diphenhydramine had a marginal effect (df = 1, 52; F = 3.34; P = 0.07).…”

“…We used CES (Rosi-Marshall et al 2013, Costello et al 2016 to measure the responses of biofilms in each of the four streams to caffeine, cimetidine, ciprofloxacin, and diphenhydramine. This contaminant exposure method allowed us to test the effects of drugs on the structure and function of microbial communities in situ.…”

“…, Costello et al. ) to experimentally expose biofilms in the same four streams to four drugs (caffeine, the antibiotic ciprofloxacin, and the antihistamines cimetidine and diphenhydramine) and measured both the ecological function (as respiration) and the bacterial community composition (based on high‐throughput sequencing of 16S rRNA genes) of biofilms. Functional resistance and changes in composition were assessed based on comparisons to control substrates not exposed to drugs.…”

“…1). We also used contaminant exposure substrates (CES; Rosi-Marshall et al 2013, Costello et al 2016 to experimentally expose biofilms in the same four streams to four drugs (caffeine, the antibiotic ciprofloxacin, and the antihistamines cimetidine and diphenhydramine) and measured both the ecological function (as respiration) and the bacterial community composition (based on highthroughput sequencing of 16S rRNA genes) of Fig. 1.…”

Net methylmercury production in 2 contrasting stream sediments and associated accumulation and toxicity to periphyton

“…The exposure design of the present study followed that of Costello and colleagues , which was adapted from prior investigations using nutrient‐diffusing substrates . Sandy, low‐organic (1% loss on ignition, acid volatile sulfide [AVS] = 0.4 μmol/g dry wt) sediment was collected from Sugar Creek (Sugarcreek Township, OH, USA) and fine‐grained, organic‐rich (17% loss on ignition; AVS = 4.8 μmol/g dry wt) sediment from Warden Ditch (Fairborn, OH, USA).…”