Effects of a range-expanding sea urchin on behaviour of commercially fished abalone.

Elisabeth M A Strain,Craig R Johnson,Russell J Thomson

doi:10.1371/journal.pone.0073477

Elisabeth M A Strain, Craig R Johnson + Show 1 more

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https://doi.org/10.1371/journal.pone.0073477

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Journal: PloS one	Publication Date: Sep 20, 2013
Citations: 25	License type: CC BY 4.0

Affiliation: University of Bologna, University of Tasmania

Abstract

BackgroundGlobal climate change has resulted in a southerly range expansion of the habitat modifying sea urchin Centrostephanus rodgersii to the east coast of Tasmania, Australia. Various studies have suggested that this urchin outcompetes black-lipped abalone (Haliotis rubra) for resources, but experiments elucidating the mechanisms are lacking.Methodology/Principal FindingsWe outline a new framework involving experimental manipulations and Markov chain and Pareto modelling to examine the effects of interspecific competition between urchins and abalone and the effect of intraspecific competition in abalone, assessed as effects on behaviour. Manipulations of abalone densities had no detectable effect on urchin behavioural transitions, movement patterns or resightability through time. In contrast, additions of urchins resulted in abalone shifting microhabitats from exposed to sheltered positions, an increase in the proportion of mobile abalone, and declines in abalone resightability through time relative to controls without the urchins. Our results support the hypothesis of asymmetrical competitive interactions between urchins and abalone.Conclusions/SignificanceThe introduction of urchins to intact algal beds causes abalone to flee and seek shelter in cryptic microhabitat which will negatively impact both their accessibility to such microhabitats, and productivity of the abalone fishery, and will potentially affect their growth and survival, while the presence of the abalone has no detectable effect on the urchin. Our approach involving field-based experiments and modelling could be used to test the effects of other invasive species on native species behaviour.

Highlights

Global climate change is resulting in the poleward range expansion of many marine species [1,2,3,4]
There were no detectable effects of the translocation procedures or of interspecific competition on the percentage of urchins resighted through time (f1, 8.328 = 1.238, p.0.05)
We examined the effects of interactions between the range-expanding long spined sea urchin (Centrostephanus rodgersii) and the commercially fished black-lipped abalone (Haliotis rubra) on their behaviour, movement and local abundances

Summary

Introduction

Global climate change is resulting in the poleward range expansion of many marine species [1,2,3,4]. The paucity of information about the nature and effects of interactions between many range expanding and native species limits understanding of potential impacts of range expansions on marine ecosystems, and hinders efforts to prioritise management responses [8]. The establishment of the species is of particular concern because of its ability to catastrophically overgraze productive and diverse algal beds, and maintain an alternative and stable bare rock barrens habitat [15], resulting in local declines in the abundances of commercially fished black-lipped abalone (Haliotis rubra) [13]. Global climate change has resulted in a southerly range expansion of the habitat modifying sea urchin Centrostephanus rodgersii to the east coast of Tasmania, Australia. Various studies have suggested that this urchin outcompetes black-lipped abalone (Haliotis rubra) for resources, but experiments elucidating the mechanisms are lacking

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