Behavioural Responses of Cerastoderma edule as Indicators of Potential Survival Strategies in the Face of Flooding Events

Tiago Verdelhos,Pedro Anastácio,João Carlos Marques,Helena Veríssimo

doi:10.3390/app11146436

Abstract

According to climate change scenarios the incidence of extreme events, such as flooding, is expected to increase worldwide. In the current climate change context, understanding behavioural responses of marine species to such stressors is essential, especially for species of high ecological and economic interest such as bivalves, which can be quite useful for future management and conservation actions. In this study, a laboratory experiment using different salinity conditions was undertaken to assess potential behavioural responses of cockles (Cerastoderma edule), as a survival strategy facing low-salinity stress during riverine flood events. Results showed consistent patterns of burrowing/emergence of cockles facing salinity variation: with high salinities the individuals were observed buried in the sediment; when salinity decreased, organisms were observed to actively emerge, and when salinity was <10, cockles were found exposed at the sediment surface. These behavioural changes may be a strategy for the survival of this species in response to flooding: once at the sediment surface, hydrodynamics may transport organisms towards areas that are more suitable

Highlights

This work aimed to evaluate C. edule’s burrowing/emergence patterns when subjected to salinity variations, observing if the individuals: (a) burrow in the sediment at higher salinity; (b) emerge with decreasing salinity; (c) re-burrow when salinity increase; (d) show consistent behaviour when salinity variation is repeated
Cerastoderma edule exhibited a burrowing vs. emergence pattern when subjected to salinity variations: (a) at the initial experimental salinity (= 20) individuals burrowed in the sediment, quite swiftly in some cases; (b) they displayed an emerging response during decreasing salinity trend; (c) specimens showed a burrowing response in the course of salinity increment; (d) when salinity variations were repeated the same behavioural responses were observed, their magnitude was higher on the 1st salinity variation cycle when compared to the 2ndcycle
In the Mondego estuary, increased mortality of the common cockle C. edule and the peppery furrow shell Scrobicularia plana was observed during flooding events, impacting the population structure and dynamics of these bivalves [8,43,44]

Summary

Introduction

The increasing occurrence and intensity of extreme climatic events (e.g., floods, droughts and heat waves) often lead to abrupt changes in temperature, salinity and hydrodynamic conditions [1]. This results in impacts on organisms (e.g., physiological processes, behaviour, and mortality), leading to changes in population abundance, community structure and ecosystem functioning [2]. Since this trend is expected to continue, further impacts on aquatic ecosystems are predictable [3,4]

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