Cool barnacles: Do common biogenic structures enhance or retard rates of deterioration of intertidal rocks and concrete?

Coombes, M. A., Viles, H. A., Naylor, L. A. and La Marca, E. C. (2017) Cool barnacles: Do common biogenic structures enhance or retard rates of deterioration of intertidal rocks and concrete? Science of the Total Environment, 580, pp. 1034-1045. (doi: 10.1016/j.scitotenv.2016.12.058)

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Sedentary and mobile organisms grow profusely on hard substrates within the coastal zone and contribute to the deterioration of coastal engineering structures and the geomorphic evolution of rocky shores by both enhancing and retarding weathering and erosion. There is a lack of quantitative evidence for the direction and magnitude of these effects. This study assesses the influence of globally-abundant intertidal organisms, barnacles, by measuring the response of limestone, granite and marine-grade concrete colonised with varying percentage covers of Chthamalus spp. under simulated, temperate intertidal conditions. Temperature regimes at 5 and 10 mm below the surface of each material demonstrated a consistent and statistically significant negative relationship between barnacle abundance and indicators of thermal breakdown. With a 95% cover of barnacles, subsurface peak temperatures were reduced by 1.59 °C for limestone, 5.54 °C for concrete and 5.97 °C for granite in comparison to no barnacle cover. The amplitudes of short-term (15–30 min) thermal fluctuations conducive to breakdown via 'fatigue' effects were also buffered by 0.70 °C in limestone, 1.50 °C in concrete and 1.63 °C in granite. Furthermore, concentrations of potentially damaging salt ions were consistently lower under barnacles in limestone and concrete. These results indicate that barnacles do not enhance, but likely reduce rates of mechanical breakdown on rock and concrete by buffering near-surface thermal cycling and reducing salt ion ingress. In these ways, we highlight the potential role of barnacles as agents of bioprotection. These findings support growing international efforts to enhance the ecological value of hard coastal structures by facilitating their colonisation (where appropriate) through design interventions.

Item Type:Articles
Additional Information:Rock and concrete used in this study originate from a project supported by a Great Western Research and Environment Agency funded PhD project [Science Project SC060096, Coombes, 2011b]. The current experimental work was supported by the Esmée Fairbairn Foundation, UK [Grant no. 10-1180]. The sponsors had no role in the study design and collection, analysis and interpretation of data.
Glasgow Author(s) Enlighten ID:Naylor, Dr Larissa
Authors: Coombes, M. A., Viles, H. A., Naylor, L. A., and La Marca, E. C.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Science of the Total Environment
ISSN (Online):1879-1026
Published Online:22 December 2016
Copyright Holders:Copyright © 2017 Elsevier
First Published:First published in Science of the Total Environment 580:1034-1045
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
642561Bioprotection: an overlooked aspect of biodiversity on coastal rocks and structuresLarissa NaylorThe Esmee Fairbairn Foundation (ESMEEF)10-1180SCHOOL OF GEOGRAPHICAL & EARTH SCIENCES