Bioaccumulation and ecotoxicological responses of juvenile white seabream (Diplodus sargus) exposed to triclosan, warming and acidification. (February 2019) - Maulvault, Ana Luísa
Abstract: Triclosan (TCS) is a synthetic microbial compound widely used in the formulation of various personal care products. Its frequent detection in marine ecosystems, along with its physical and chemical properties, suggest that TCS can be highly persistent, being easily bioaccumulated by biota and, therefore, eliciting various toxicological responses. Yet, TCS's mechanisms of bioaccumulation and toxicity still deserve further research, particularly focusing on the interactive effects with climate change-related stressors (e.g. warming and acidification), as both TCS chemical behaviour and marine species metabolism/physiology can be strongly influenced by the surrounding abiotic conditions. Hence, the aim of this study was to assess TCS bioaccumulation and ecotoxicological effects (i.e. animal fitness indexes, antioxidant activity, protein chaperoning and degradation, neurotoxicity and endocrine disruption) in three tissues (i.e. brain, liver and muscle) of juvenile Diplodus sargus exposed to the interactive effects of TCS dietary exposure (15.9 μg kg −1 dw), seawater warming (ΔTºC = +5 °C) and acidification (Δ p CO2 ∼ +1000 μatm, equivalent to ΔpH = −0.4 units). Muscle was the primary organ of TCS bioaccumulation, and climate change stressors, particularly warming, significantly reduced TCS bioaccumulation in all fish tissues. Furthermore, the negative ecotoxicological responses elicited by TCS were significantly altered by the co-exposure to acidification and/or warming, through either the enhancement (e.g. vitellogenin content) or counteraction/inhibition (e.g. heat shock proteins HSP70/HSC70 content) of molecular biomarker responses, with the combination of TCS plus acidification resulting in more severe alterations. Thus, the distinct patterns of TCS tissue bioaccumulation and ecotoxicological responses induced by the different scenarios emphasized the need to further understand the interactive effects between pollutants and abiotic conditions, as such knowledge enables a better estimation and mitigation of the toxicological impacts of climate change in marine ecosystems. Graphical abstract: Highlights: TCS was primarily bioaccumulated by fish muscle, followed by liver and brain. Climate change significantly reduced TCS bioaccumulation in all fish tissues. TCS and TCS + acidification increased LPO and inhibited HSP70/HSC70 synthesis. AChE activity was inhibited by TCS alone or combined with both abiotic stressors. VTG content was further diminished by TCS co-exposed with both abiotic stressors. Abstract : Warming and acidification decreased TCS tissue bioaccumulation. TCS ecotoxicological effects were influenced by temperature and p CO2 levels.