Can Biomarkers Respond Upon Freshwater Pollution?-A Moss-Bag Approach

Simple Summary Pollution of the aquatic environment is a well-known problem with a long history. Monitoring water quality relies on biota in order to provide adequative assessment and management of the water bodies. Among the different biological indicators applied, aquatic macrophytes, and particularly mosses, are in direct relationship with the environment and their use as biomonitors is well documented. In the current study, we made an attempt to apply new fast, reliable and comprehensible methods for water pollution control. Three reservoirs were selected for the following reasons: (i) they were polluted with hazardous substances (heavy metals and organic material) and (ii) they are used for fish farming and irrigation and their water quality directly affects human health. Moss-bags with the selected biomonitor Fontinalis antipyretica were exposed in the reservoirs for a period of 30 days and molecular, chemical and micromorphological markers were studied. All biomarkers tested appeared to be sensitive to the pollution. This research provided a basis for further studies on selected biomarkers towards standardization. Moss-bags were applied to study the effect of contamination in three standing water bodies in Bulgaria (Kardzhali, Studen Kladenets and Zhrebchevo Reservoirs), the first two with old industrial contamination and the last polluted with short-chain chlorinated paraffins (SCCPs). Fontinalis antipyretica Hedw. collected from background (unpolluted) site was placed in cages for a period of 30 days. The present study examined whether inorganic and organic pollution detected with moss-bags resulted in corresponding differences in molecular, chemical and micromorphological markers. Suppressed large subunit of ribulose-1,5-bisphosphate carboxylase (rbcL) expression was assessed in moss-bags from two of the reservoirs, contaminated with heavy metals. There was a decrease of the total phenolic content (TPC) in the moss-bags, which provides a basis for further studies of the chemical content of aquatic mosses. Fontinalis antipyretica also showed a response through leaf micromorphological characteristics. In the all three reservoirs, an increase of the twig leaf cell number was recorded (p <= 0.01 for Kardzhali and p <= 0.001 for Studen Kladenets and Zhrebchevo reservoirs), as well as of the stem leaf cell number in Zhrebchevo Reservoir (p <= 0.001). On the contrary, the width of the cells decreased in the studied anthropogenically impacted reservoirs. All three studied groups of biomarkers (molecular, chemical and micromorphological) appeared to be sensitive to freshwater pollution. The results achieved indicated that rbcL gene expression, TPC, cell number and size are promising biomonitoring tools.

Automated summary

The study utilized moss-bags to monitor water quality in three reservoirs in Bulgaria. It found that mosses were sensitive to pollution in terms of molecular, chemical, and micromorphological markers, providing a basis for further standardized research on biomonitoring.