Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (Scenedesmus obliquus) and a consumer (Daphnia magna)

Abstract

The effects of a commercially available anionic surfactant solution (FFD-6) on growth and morphology of a common green alga (Scenedesmus obliquus) and on survival and clearance rates of the water flea Daphnia magna were studied. The surfactant-solution elicited a morphological response (formation of colonies) in Scenedesmus at concentrations of 10–100 μl l−1 that were far below the No Observed Effect Concentration (NOEC) value of 1,000 μl l−1 for growth inhibition. The NOEC-value of FFD-6 for colony-induction was 3 μl l−1. Daphnia survival was strongly affected by FFD-6, yielding LC50–24h and LC50–48h of 148 and 26 μl l−1, respectively. In addition, clearance rates of Daphnia feeding on unicellular Scenedesmus were inhibited by FFD-6, yielding a 50% inhibition (EC50–1.5h) at 5.2 μl l−1 with a NOEC of 0.5 μl l−1. When Daphnia were offered FFD-6-induced food in which eight-celled colonies (43 × 29 μm) were most abundant, clearance rates (~0.14 ml ind.−1 h−1) were only 25% the rates of animals that were offered non-induced unicellular (15 × 5 μm) Scenedesmus (~0.56 ml ind.−1 h−1). As FFD-6 concentrations in the treated food used in the experiments were far below the NOEC for clearance rate inhibition, it is concluded that the feeding rate depression was caused by the altered morphology of the Scenedesmus moving them out of the feeding window of the daphnids. The surfactant evoked a response in Scenedesmus that is similar to the natural chemically induced defensive reaction against grazers and could disrupt the natural information conveyance between these plankton organisms.

A review of potential methods for zooplankton control in wastewater treatment High Rate Algal Ponds and algal production raceways

“…The FFD-6 drastically depressed the feeding and survival rates of D. magna. The LC 50 -24 h and LC 50 -48 h were respectively 148 μl/L and 26 μl/L [248].…”

Multiple stressor effects of predation by rotifers and herbicide pollution on different Chlamydomonas strains and potential impacts on population dynamics

“…Whereas no significant differences in feeding rates could be detected for diuron-and paraquat-exposed compared with control algae, pre-exposure to S-metolachlor reduced feeding by rotifers in a dose-dependent manner (Fig. A similar correlation between feeding rates and particle size was also observed for green algae exposed to the anionic surfactant FFD-6 and the predator D. magna, indicating that chemical effects on particle size might be a more general mechanism for how toxicants can interact with such food webs [27]. This finding shows that S-metochlor-treated algae are indeed less palatable for rotifers.…”

“…Several studies have investigated the influence of predation on pesticide tolerance in freshwater cladocerans [6,[15][16][17], amphibians [18][19][20], and insects [21][22][23]. One example of chemicalinduced tolerance to predation was recently presented by Lürling et al for the green alga Scenedesmus obliquus: the anionic surfactant FFD-6 induced a response in the alga that protected it from being grazed by the water flea D. magna [27]. However, most of the studies investigated predation stress only by adding chemical signals released by predators into the environment.…”

A novel protocol for assessing aquatic pollution, based on the feeding inhibition of Daphnia magna

“…The inhibition of feeding has been applied by several authors to assess the possible ecotoxicological effects of different contaminants, such as metals (Flickinger et al, 1982;Ferrando and Andreu, 1993) and pesticides (Fernandez-Cassalderrey et al, 1994). Hartgers et al (1999) and Lürling et al (2011) found that the clearance rate of Daphnia magna using artificial beads is a more sensitive endpoint than an acute lethal test. Alterations in the feeding and digestive behaviour of daphnids as endpoints were compared by De Coen and Janssen (1998) and , where ingestion rate was assessed using fluorescent microbeads and measuring fluorescence.…”