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Facilitation of an invader by a native habitat-former increases along interacting gradients of environmental stress

Citation

Uya, M and Bulleri, F and Wright, JT and Gribben, PE, Facilitation of an invader by a native habitat-former increases along interacting gradients of environmental stress, Ecology, 101, (4) Article e02961. ISSN 0012-9658 (2020) [Refereed Article]


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Copyright Statement

© 2019 by the Ecological Society of America

DOI: doi:10.1002/ecy.2961

Abstract

Native habitat‐forming species can facilitate invasion by reducing environmental stress or consumer pressure. However, the intensity of one stressor along a local gradient may differ when expanding the scale of observation to encompass major variations in background environmental conditions. In this study, we determined how facilitation of the invasive porcelain crab, Petrolisthes elongatus, by the native tube‐forming serpulid, Galeolaria caespitosa, varied with environmental gradients at local (tidal height) and larger (wave exposure) spatial scales. G. caespitosa constructs a complex calcareous matrix on the underside of intertidal boulders and we predicted that its positive effects on P. elongatus density would increase in intensity with shore height and be stronger at wave‐sheltered than wave‐exposed locations. To test these predictions, we conducted two experiments. First, we determined the effects of serpulid presence (boulders with live or dead serpulid matrix vs. bare boulders) at six shore heights that covered the intertidal distribution of P. elongatus. Second, we determined the effects of serpulid presence (present vs. absent), shore height (high vs. low) and wave exposure (sheltered vs. exposed) on crabs across six locations within the invaded range in northern Tasmania, Australia. In Experiment 1, the presence of serpulids (either dead or alive) enhanced P. elongatus densities at all shore heights, with facilitation intensity (as determined by a relative interaction index; RII) tending to increase with shore height. In Experiment 2, serpulids facilitated P. elongatus across shore heights and wave exposures, although crab densities were lower at high shore levels of wave‐sheltered locations. However, the intensity of crab facilitation by serpulids was greater on wave‐sheltered than on wave‐exposed shores, but only at the high shore level. This study demonstrates that local effects of native habitat‐formers on invasive species are dependent on prevailing environmental conditions at larger spatial scales and that, under more stressful conditions, invaders become increasingly reliant on positive interactions with native habitat‐formers. Increased strength of local‐scale facilitation by native species, dampening broader scale variations in environmental stressors, could enhance the ability of invasive species to establish self‐sustaining populations in the invaded range.

Item Details

Item Type:Refereed Article
Keywords:biological invasion, environmental stress, facilitation, intertidal boulder field, Petrolisthes elongatus, positive interactions
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Marine and estuarine ecology (incl. marine ichthyology)
Objective Division:Environmental Management
Objective Group:Marine systems and management
Objective Field:Assessment and management of benthic marine ecosystems
UTAS Author:Wright, JT (Associate Professor Jeffrey Wright)
ID Code:143167
Year Published:2020
Web of Science® Times Cited:7
Deposited By:Ecology and Biodiversity
Deposited On:2021-03-03
Last Modified:2021-05-20
Downloads:6 View Download Statistics

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