The sea urchin – the ultimate herbivore and biogeographic variability in its ability to deforest kelp ecosystems

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1 Biology Department, University of Massachusetts Boston, Boston, Massachusetts, United States
2 Lavan University, Quebec City, Canada
3 School of Earth & Environmental Sciences, University of Adelaide, Adelaide, Australia
4 Department of Statistics, University of Auckland, Auckland, New Zealand
5 School of Biological Sciences, University of Auckland, Auckland, New Zealand
6 Centro i-mar, Universidad de Los Lagos, Puerto Montt, Los Lagos, Chile
7 Moss Landing Marine Laboratories, Moss Landing, California, USA
8 Biogeography Branch, NOAA National Ocean Service, Silver Spring, Maryland, USA
DOI
10.7287/peerj.preprints.174v1
Published
Accepted
Subject Areas
Ecology, Marine Biology
Keywords
kelp, urchin, top-down control
Licence
This is an open access article, free of all copyright, made available under the Creative Commons Public Domain Dedication. This work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.
Cite this article
Byrnes JE, Johnson LE, Connell SD, Shears NT, McMillan SM, Irving A, Buschmann AH, Graham MH, Kinlan BP. 2013. The sea urchin – the ultimate herbivore and biogeographic variability in its ability to deforest kelp ecosystems. PeerJ PrePrints 1:e174v1

Abstract

Barren rocky seafloor landscapes, denuded of almost all life by ravenous sea urchins, liberated from their predators, stands as one of the iconic images of trophic cascades in Ecology. While this paradigm has been cited in nearly every temperate rocky reef ecosystem across the globe, there is widespread disagreement as to its generality. Given their biology, sea urchins are clearly one of the ocean’s strongest herbivores in many systems, but where will their impact be strongest? Here we perform a global meta-analysis of sea urchin-kelp relationships in the field. We find that sea urchins appear to be able to control kelp abundances in any system where they can achieve high densities. Furthermore, their ability to create large-scale long-lasting barrens appears to be limited to biogeographic regions where they can achieve high consumptive potential. Based on the literature, we outline a conceptual model that examines when and where sea urchins should be able to have a strong regulating impact on kelp forest ecosystems. We suggest that many elements of global change may shift the balance of forces regulating sea urchin consumptive potential in these ecosystems. Given their ability to have strong impacts on temperate rocky reefs, these drivers need to be considered in concert with their effect on sea urchins when attempting to predict future change to marine ecosystems.

Supplemental Information

Supporting Online Materials Table 1

Data used for the kelp-urchin abundance meta-analysis. Full references are included in the Supplementary References. Data from the Channel Islands National Park Service Kelp Forest Monitoring Project are labeled KFM. Data from the Partnership for Interdisciplinary Study of Coastal Oceans are labeled PISCO.

DOI: 10.7287/peerj.preprints.174v1/supp-1

Supporting Online Table 2

Data used for the urchin consumption meta-analysis. Methods for extrapolation beyond consumption rates of individuals are described in methods, with equations included in the spreadsheet.

DOI: 10.7287/peerj.preprints.174v1/supp-2

Supporting Online Materials 1 & 2

References for Table 1 and Supporting Online Materials Table 1

DOI: 10.7287/peerj.preprints.174v1/supp-3