Investigating the Sub-Acute Responses of Lemna Minor, Pseudokirchneriella Subcapitata, Euglena Gracilis and Anodonta Grandis to Tributyltin-Hydride and Atrazine in Freshwater
thesisposted on 2023-01-23, 15:35 authored by Christopher J.E. Pearce
Freshwater resources exist in limited quantities and are subject to increasing demands due to the consumption by residential, commercial and industrial uses. There are concerns that the widely used chemical analysis of drinking water does not deliver timely results. This study examines the efficacy of developing a holistic, multi-organism early-warning biomonitoring technology to assess aquatic toxicity. Sensitive indicator species such as Lemna minor, Pseudokirchneriella subcapitata, Euglena gracilis, and Anodonta grandis have been selected due to their specific behavioural and short-term biochemical responses in the identification of classes of contaminants in aquatic environments. Tributyltin, an antifouling agent in paints used on boats and atrazine, an herbicide widely used on agricultural crops, are evaluated in increasing concentrations to identify behavioural changes in these organisms. These graded responses, upon implementation in models, will warn water treatment operators of incoming contaminants and help identify the nature of the stressor. All organisms displayed some sensitivity to selected concentrations of the two test chemicals. The normal growth rate of L. minor dramatically declined with exposure to TBT (100.0 mg/L) and atrazine (500.0 g/L). Monitoring the biochemical changes, dissolved oxygen production, and also the growth rate, cell counts, of P. subcapitata showed significant effects to similar concentrations of TBT (100.00 g/L) and atrazine (500.00 g/L). The aquatic protest, E. gracilis, alters its cell morphology in the presence of low concentrations of TBT (10.0 g/L) and atrazine (50.0 g/L). Respiration patters of the bivalve, A. grandis, was directly influenced by the two chemicals, TBT (1.0 mg/L) and atrazine (50.0 mg/L). This study demonstrates that biological assessments of water samples deliver a rapid, realistic representation of the surrounding aquatic environment conditions.