Evaluation of the aquatic bryophyte Fontinalis antipyretica for laboratory and field toxicity studies

Fontinalis antipyretica is an ecologically important aquatic moss in boreal streams. Bioassays using this species provide information of effects at the base of the food chain. The present study assessed toxicological effects to F. antipyretica, firstly of the positive controls copper and 3,5- dichlorophenol (3,5-DCP) in separate laboratorial bioassays, and secondly of ecologically relevant pollutants during autumn in a catchment area dominated by agriculture in a field study. The laboratorial studies assessed effects of five concentrations of copper sulphate (CuSO4, 0- 300 μM) and 3,5-DCP (0-9 mg/L) for exposure up to 21 days. This included determination of suitable mode of actions (MoAs) including maximal PS II efficiency (Fv/Fm), pigment concentration and production of reactive oxygen species (ROS), and the adverse outcomes (AO) greenness index (GI) and growth, and toxic effects on these endpoints. Copper caused clear concentration and time-dependent responses for inhibition of GI, Fv/Fm, pigment concentration, and production of ROS. 3,5-DCP caused clear concentration and time-dependent responses for inhibition of GI, Fv/Fm, and pigment concentration, additionally to weak responses for growth. Optimal exposure time was typically 7-14 days for most endpoints; however, 21 days were needed for growth. The field study assessed effects of environmentally relevant concentrations of pollutants and stressors of the test stream Skuterudbekken, compared to a reference stream with little pollution. Moss tissue was deployed from Skut 1 (located upstream of sedimentation ponds) and Skut 2 (located downstream of sedimentation ponds and European route 18) back into their respective location and additionally to the reference stream. The study additionally included comparison of native and deployed moss in the test stream, and moss sampling for endpoint analysis was done after exposure for up to 14 days. Chemical and physical conditions of streams were monitored during the exposure study. The results indicated no clear deployment status, site or time-dependent responses caused by pollution. However, site-specific negative responses on growth, Fv/Fm, and production of ROS were observed in Skut 2, possibly caused by high water discharge combined with fragmenting of F. antipyretica due to the time of year. Overall, F. antipyerica demonstrated to be a suitable study species for bioassays, with limitations including difficulties in obtaining sterile moss cultures for laboratorial assays and short life cycle period for obtaining ideal growth conditions