Assessment of the independent and combined effects of copper and polycyclic aromatic hydrocarbons on gametogenesis and sporophyte development of the kelp Lessonia spicata (Phaeophyceae, Ochrophyta)

Abstract

AbstractCoastal shores near the industrial park of Quintero Bay in central Chile exhibit increasing concentrations of copper (Cu) and polycyclic aromatic hydrocarbons (PAHs), well above international standards. This raises concern about their combined toxic effects on early development stages of kelps. Accordingly, we aimed to assess more accurately the independent and combined effects of Cu and PAHs on gametogenesis and sporophyte development in the kelp Lessonia spicata from central Chile by in vitro cultivation. Independent Cu and PAH trials were performed using increasing nominal concentrations of Cu and PAHs in the ranges 0.8–200 µg L−1 and 0.05–100 µg L−1, respectively. Cu and PAH median effective concentrations (EC50) on gametogenesis and early sporophyte formation were calculated using DRC in the R environment. Then, combined EC50 Cu + PAH trials were conducted to determine their effects on gametogenesis and sporophyte formation. Cu EC50 values on gametogenesis and sporophyte formation were up to three orders of magnitude lower than EC50 reported previously on spore germination in kelps. The gametogenesis (EC50 = 1.39 µg L−1) was more sensitive to Cu than sporophyte formation (EC50 = 11 µg L−1). Inversely, sporophyte formation (EC50 = 0.04 µg L−1) was more sensitive to PAHs (EC50 = 0.11 µg L−1). Considering the entire exposure period, the combined EC50 Cu + PAH exposure was the most harmful and rapid for L. spicata microscopic stages, especially the synergistic effect on early sporophytes. This highlights the need to acquire an integrated knowledge of the seasonal variation of pollutants and their combination on highly intervened coasts.