To Eat or Not to Eat: the Importance of Starvation on Behavioral Bioassays

Abstract

Behavioral endpoints are important parameters to assess the effects of toxicants and other stressors on natural ecosystems. The relevance of these parameters has caused a rise in their use in aquatic ecotoxicology. However, abiotic and biotic parameters may interact causing changes in the behavioral responses. Among those parameters, starvation of animals is a factor that is usually applied in ecotoxicological short-term bioassays. This could alter animal behavior, along with the toxicant. Therefore, the study of the effects of starvation on baseline behaviors of invertebrates is a relevant issue. This study assessed the behavior of the aquatic snail Potamopyrgus antipodarum under a combination of four treatments: (1) animals normally fed (control treatment), (2) starved animals, (3) animals normally fed and exposed to a high conductivity, and (4) starved animals exposed to a high conductivity. The behavior activity of snails was monitored for 14 days. Results show that animals of the second treatment (starved animals) increased their activity. On the contrary, animals of the third and fourth treatments reduced their activity. Animals from the control treatment showed an activity in between starved animals and animals exposed to high conductivity (both starved and normally fed). These results show that starvation increases the snail activity, but under another environmental stressor (i.e., high conductivity), this trend was reversed. The influence of starvation on behavior should be taken into account in the development of behavioral bioassays.