Facing predation risk in aquatic systems: differential response of zooplankton and habituation to the false alarm

MARÍA FLORENCIA GUTIERREZ; VICTORIA ANDRADE; NOELIA FANTÓN; ANA MARÍA GAGNETEN

FUNDAMENTAL AND APPLIED LIMNOLOGY

E SCHWEIZERBARTSCHE VERLAGS

Lugar: Stuttgart; Año: 2016

1863-9135

In aquatic systems, alarm signals (physical and chemical) favor early detection of predators and promote the development of antipredation behaviors in preys. However, further studies are needed to understand how different the antipredation behavior can be among different species coexisting in a natural assembly. In this work, we conducted an indoor experiment with a zooplankton assemblage from a natural subtropical system to experimentally analyze their evasion behavior when exposed to an enclosed visual predator. We aimed to assess whether such behavior is different depending on the species within the assemblage and if they habituate to the alarm signals released by the predator after certain period without receiving any real attack. Ostracods, cladocerans and copepod nauplii evaded the predator but differed in the magnitude of the response as well as in the response time. The evasion behavior was not maintained in time and most organisms returned to an even distribution as time passed, suggesting that zooplankters may habituate to the alarm signals. Adult copepods and copepodites (here analyzed together) did not evade the fish but showed an almost homogeneous distribution over time. Rotifers moved over the time, but independently of the presence of fishes. Differential responses to the same alarm signals may contribute to determine the spatial distribution of zooplankton in natural aquatic ecosystems.