A new biological indicator of extremely degraded habitats in areas of agricultural industry in Poland

The intensification of livestock production causes extreme environmental degradation, requiring effective bioindicators for monitoring. This study proposes Haematococcus pluvialis as a novel bioindicator of pollution from industrial farms. The research presented in this study constitutes the first investigation of this kind in Poland and in the European Union to characterize the habitat of H. pluvialis in rainwater and surface waters, and the first in the world to provide such a comprehensive description of the threshold environmental conditions for the occurrence of this alga across different types of aquatic environments. Research conducted at two locations with high farm density monitored precipitation, surface, ground, and well waters. We analyzed physicochemical parameters and H. pluvialis occurrence frequency using advanced statistical methods. Results identified industrial farms as the primary pollution source, with extreme nutrient concentrations (total nitrogen exceeded standards up to 96-fold). H. pluvialis occurred exclusively in surface and precipitation waters within specific thresholds: pH 7.5-8.5, conductivity 1.0-1.5 mS/cm-1, phosphates 0.5-2.0 mg/L-1, and ammonium nitrogen <10 mg/L-1. The absence from groundwater relates to light limitation and soil filtration. We demonstrate H. pluvialis as an effective bioindicator of extreme degradation from industrial animal farming, with defined tolerance ranges enabling practical environmental monitoring.