What scares a mussel? Changes in valve movement pattern as an immediate response of a byssate bivalve to biotic factors

Anna Dzierżyńska-Białończyk,Jarosław Kobak,Łukasz Jermacz,Joanna Zielska

doi:10.1007/s10750-019-04007-0

Anna Dzierżyńska-Białończyk, Jarosław Kobak + Show 2 more

Open Access

https://doi.org/10.1007/s10750-019-04007-0

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Journal: Hydrobiologia	Publication Date: Jul 10, 2019
Citations: 26	License type: open-access

Affiliation: Nicolaus Copernicus University

Abstract

Responsiveness to biotic factors is crucial for the survival of sessile aquatic animals. They cannot escape from danger, but developed a number of defences against predation, usually delayed in time. We checked the initial defence of the freshwater byssate zebra mussel, Dreissena polymorpha, associated with valve gaping. We tested the effect of chemical signals: fish predator scent (the roach Rutilus rutilus), conspecific alarm cue and a mixture of both, as well as a mechanical stimulus: the presence of an amphipod (Dikerogammarus villosus) mechanically irritating mussels. The alarm cues and amphipod presence made mussels spend more time with closed/narrowly open valves, which can be related to decreasing detection probability by reduced infochemical excretion and/or protecting soft tissues in the presence of an imminent threat. In contrast, reactions to the predator scent alone were much weaker. Moreover, the fish scent mixed with alarm substance induced weaker responses than the alarm substance alone. Thus, the fish infochemical might mask the presence of the alarm cue components, potentially benefiting the predator. A variety of defences exhibited by mussels demonstrates the importance of the predation cue type (direct/indirect, chemical/mechanical, originating from conspecifics/predators/mixed) for the behaviour of sessile animals.

Highlights

Aquatic sessile species are ecologically and economically important as ecosystem engineers, fouling community members and nuisance for submerged equipment (Khalaman, 2001; Sousa et al, 2009)
We examined the following response variables: (1) Average valve gaping during the experiment; (2) Percentage of time spent by mussels with: (i) widely open valves ([ 80% of the maximum valve gaping) (ii) narrowly open valves (\ 20%) and (iii) totally closed valves; (3) Number of valve opening movements
Average valve gaping during the experiment varied from 2 to 72% (Fig. 2) and significantly depended on experiment duration and on the cues (General Linear Model: Table 1A)

Summary

Introduction

Aquatic sessile species are ecologically and economically important as ecosystem engineers, fouling community members and nuisance for submerged equipment (Khalaman, 2001; Sousa et al, 2009). Depending on evolutionary constraints and predator hunting modes, they can more strongly adhere to the substratum (Shin et al, 2008; Cheung et al, 2009), reduce feeding rates (Naddafi et al, 2007), develop harder shells (Czarnołeski et al, 2006), produce toxins (Hill et al, 2005) and/or select sheltered sites during their mobile phase of life (Bryan et al, 1998; Dahms et al, 2004) These responses may vary depending on the quality of the predation cue, ranging from predator kairomones (depending on their diet and hunger level) to alarm substances produced by wounded conspecifics (indicating a more direct danger: a currently foraging predator) (Smee & Weissburg, 2006; Large et al, 2012; Jermacz et al, 2017). Prey reactions vary with time, different measures being induced immediately after the detection of predation cues and during the chronic exposure to predator pressure (Reimer & Tedengren, 1997; Turner et al, 2006)

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