Toxicity of Benzalkonium Chloride on Monoalgal Cultures and Natural Assemblages of Marine Phytoplankton

Abstract

The current widespread use of benzalkonium chloride (BAC) in different cleaning and disinfecting products led us to investigate its potential toxic effect on phytoplankton. To this aim, different physiological variables were monitored to detect toxicity of four ecologically relevant concentrations of BAC (15-200 μg l −1 ) on batch cultures of the microalgae Isochrysis galbana and Chaetoceros gracilis, and on a coastal phytoplankton assemblage. Fluorescence variables measured by fast repetition rate fluorometry, specifically variable fluorescence (F v ), were the most suitable to be used as endpoint among all the variables recorded (biomass, growth rate, size structure, and species composition). Calculated effective concentrations from F v data provided evidences of higher sensitivity in the natural assemblage at short exposure times (natural assemblage-EC 50 [24 h]= 36.4 μg l −1 vs. monoalgae-EC 50 [24 h]>120 μg l −1 ). Despite these differences, standard monoalgal laboratory toxicity tests provided comparable estimates of safe concentrations for microalgae in the environment. Assessed EC 10 fall within the range of BAC concentrations reported in the literature for different effluents.

Toxicity of Synthetic Surfactants to the Marine Macroalga, Ulva lactuca

“…With regard to algae, it appears that amphiphiles interfere with the phospholipid bilayer and bind with or denature membrane proteins, thereby altering the organisation, stability and permeability of the membrane (Cserháti et al 2002). Once inside the cell, surfactants may affect thylakoid organisation and chlorophyll synthesis, and are able to interact electrostatically or hydrophobically with enzymes and other bioactive molecules, resulting in their malfunction or a reduction in their activity (Walker and Evans 1978;Lürling 2006;Pérez et al 2009). Lack of measurable toxicity displayed by SDS over the concentration range studied implies limited interactions with cell membranes and/or intracellular, bioactive macromolecules of U. lactuca.…”

“…Because of their ability to withstand moderately polluted conditions and accumulate many contaminants, Ulva species are considered to be useful biomonitors and important test organisms in ecotoxicological studies (Haritonidis andMalea 1999, Lee andWang 2001;Han et al 2009;Masakorala et al 2008;Turner et al 2009). We used chlorophyll a fluorescence quenching as a noninvasive measure of toxicity in our experiments because of its ease of measurement and sensitivity with respect to algal-surfactant interactions (Pérez et al 2009;van Wijk et al 2009). …”

Use of Fast Repetition Rate Fluorometry on Detection and Assessment of PAH Toxicity on Microalgae

“…Light conditions influence the fluorescence response (Petersen and Kusk 2000) as well as the photodegradation of PAHs (in contrast to the parental PAHs' effect, degradation products may affect F v /F m ). Among the other monitored fluorescence variables, and taking into account that no differences on sensitivity were found among F 0 , F m and F v , the latter was chosen in accordance to previous studies of sensitivity to other toxicants (Pérez et al 2009;Perez et al, submitted;Pérez et al, in preparation). Deleterious effects of Nap, Phe and Flu were recorded on both GR and F v (Figs.…”

“…Furthermore, fluorescence is proving to be more sensitive than classical endpoints due to its sublethal but ecologically relevant character (i.e. Gensemer et al 1999;Pérez et al 2006;Pérez et al 2009;Pérez et al, in preparation).…”

“…Every fluorescence variable is linked to different steps of the fluorescence induction or the photosynthetic electron-transport flow; thus, when used in bioassays, different sensitivity among variables could be expected. Aiming at selecting a simple, relevant and sensitive fluorescence variable, the response of minimal fluorescence (F 0 ), maximum fluorescence (F m ), variable fluorescence (F v ) and potential photochemical efficiency of photosystem II (PSII) (F v /F m ) is being monitored in bioassays with toxicants showing potential different toxic mechanisms or associated to different matrices: copper as trace metal (Pérez et al 2006, Pérez et al, in preparation), benzalkonium chloride as cationic surfactant (Pérez et al 2009), sediment contaminated with fuel (Mariño-Balsa et al 2003), and, in this work, polycyclic aromatic hydrocarbons (PAHs).…”