DOI: 10.6073/pasta/4c86334144db175da8fcb514e3f563a5
title: Pharmaceutical effects on biofilm functioning quantified via contaminant exposure substrates presented in Rosi et al. 2018.

description: An ongoing component of the Baltimore urban long-term ecological research (LTER) project (Baltimore Ecosystem Study, BES) is the use of the watershed approach and monitoring of stream water quality to evaluate the impacts of multiple chemical stressors on urban stream ecosystem functioning within Baltimore. The LTER research has focused on the Gwynns Falls watershed, which spans a gradient from highly urban, urban-residential, and suburban zones. In addition, a forested watershed serves as a reference. The long-term sampling network includes four longitudinal sampling sites along the Gwynns Falls mainstem, as well as several small (40-100 ha) watershed within or near the Gwynns Falls, providing data on water quality in different land use zones of the watersheds. Each study site is continuously monitored for discharge and is sampled weekly for water chemistry. Those data are available elsewhere on the BES website. 
      
      
          We are interested in studying the effects of pharmaceuticals and personal care products (PPCPs) on stream biofilm functioning within urban streams. We constructed and deployed contaminant exposure substrates (CES) in four streams within the greater Baltimore, Maryland, USA area to measure the responses of biofilms in each of the four streams to caffeine, ciprofloxacin, cimetidine, diphenhydramine, and no PPCPs.  
      
      
          We incubated CES for 2 weeks in the four different streams, with five replicate CES for each treatment being randomly placed on plastic L-bars within each stream. After the two-week deployment, we used the light-dark incubation approach to estimate gross primary production and community respiration via change in dissolved oxygen (DO) for biofilms colonizing substrates (either cellulose sponges to select heterotrophic biofilms or fritted glass disks to select for autotrophic biofilms) topping each CES. 
      
      
          This dataset includes all of the raw data for the light-dark incubations used to calculate gross primary production and community respiration for the various CES treatments at different sites. A subset of these data were used to estimate the effects of PPCPs on community respiration that is presented in the following publication:
      
      
          Rosi, E.J., H.A. Bechtold, D. Snow, M. Rojas, A.J. Reisinger, and J.J. Kelly. 2018. Urban stream microbial communities show resistance to pharmaceutical exposure. Ecosphere 9(1):e02041. doi: 10.1002/ecs2.2041
      
      
          Each stream studied in this dataset is a core BES monitoring stream, and additional water chemistry and hydrology data are available elsewhere on the BES data portal.
      
      
          Codes and abbreviations
      
          1 - GwynnsRun - Gwynns Run at Gwynns Falls - Urban
      
          2 - GwynnsFalls - Gwynns Falls at Carroll Park - Urban
      
          3 - DeadRun - Dead Run at Krome Avenue - Urban
      
          4 - GwynnsBrook - Gwynns Falls at Gwynnbrook Avenue (Delight) - Suburban
      
      
          Column,Column Name,Variable-if different than Column Name (units)
      
          A,cup,identifier for CES cup replicate
      
          B,site, Site
      
          C,compound, Treatment - can be one of: Ciprofloxacin, Cimetidine, Caffeine, Control, or Diphenhydramine
      
          D,substrate, substrate topping the CES used to select for either autotrophic or heterotrophic biofilms - can be either Cellulose (heterotrophic) or Fr. Glass (autotrophic)
      
          E,light, light treatment for the incubation, either light (used to estimate NPP and GPP) or dark (used to estimate CR)
      
          F,o2.init, initial dissolved oxygen (DO) concentration of incubation water (mg O2/L)
      
          G,o2.final, final DO concentration after CES incubation has completed (mg O2/L)
      
          H,t.start, start time for the incubation - time when incubation vials were filled and closed (HH:MM:SS)
      
          I,t.end, end time for the incubation - time when incubation vials were opened and o2.final was measured (HH:MM:SS)
      
          J,blank.o2.init, initial DO concentration of incubation water used for blank incubation vials (no CES substrate) that are used to correct for water column activity (mg O2/L)
      
          K,blank.o2.final, final DO concentration of water in blank incubations that are used to correct for water column activity (mg O2/L)
      
          L,blank.t.start, start time for the blank incubations (HH:MM:SS)
      
          M,blank.t.end, end time for the blank incubations (HH:MM:SS)
      
      
          Methods: 
      
      
          We used CES 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 PPCPs on the structure and function of microbial communities in situ. CES consisted of 30-mL polyethylene cups filled with a 2% (by weight) agarose gel amended with caffeine, ciprofloxacin, cimetidine, diphenhydramine, or no pharmaceutical. The concentration of PPCP in each cup was 0.05 mol/L. Each cup was capped with either a cellulose sponge cloth or a fritted glass disk to promote colonization by heterotrophic and autotrophic biofilms, respectively. Five replicate CES of each PPCP treatment and an additional control treatment were secured to the stream bottom on plastic L-bars, with treatments and replicates arranged randomly. CES were deployed for two weeks in March 2012. After deployment, CES were collected and transported to the laboratory on ice.
      
      
          We used the light-dark incubation approach to estimate GPP and CR from the different substrates for each CES. Each substrate was placed ina  50-mL centrifuge tube and each tube was filled with filtered stream water with known initial DO concentration. Each tube was capped underwater to remove all air bubbles and was incubated in the light and dark for 2-4h for each light treatment. We included blank tubes, which were filled with filtered stream water only, to correct for changes in background DO. After the 2-4h incubation period, we measured the final DO concentration in each of the tubes. These incubation data are what are included in this dataset. To calculate GPP and CR, standard light-dark DO incubation methods can be followed. For example, see:
      
      
          Tank, J.L., A.J. Reisinger, and E.J. Rosi. 2017. Ch. 31: Nutrient limitation and uptake. In Methods in Stream Ecology Vol 2: Ecosystem Function (3rd Edition), eds: G.A. Lamberti and F.R. Hauer. Academic Press, San Diego, CA, USA.