[OANNES Foro] Sub-lethal effects of off-road vehicles (ORVs) on surf clams on sandy beaches

[Raul Sanchez Scaglioni]

Journal of Experimental Marine Biology and Ecology
Volume 380, Issues 1-2, 15 November 2009, Pages 113-118 
doi:10.1016/j.jembe.2009.09.009     

Copyright © 2009 Elsevier B.V. All rights reserved.


Sub-lethal effects of off-road vehicles (ORVs) on surf clams on sandy beaches 


 
Natalie Shepparda, Kylie A. Pitta, ,  and Thomas A. Schlacherb, 


aAustralian Rivers Institute – Coast and Estuaries and Griffith School of Environment, Gold Coast Campus, Griffith University, QLD 4222, Australia
bUniversity of the Sunshine Coast, Faculty of Science, Health and Education; Maroochydore DC, QLD-4558, Australia

Received 6 May 2009;  
revised 7 September 2009;  
accepted 7 September 2009.  
Available online 3 October 2009. 



Abstract
Ecological impacts of vehicle traffic are a significant environmental management issue on many sandy shores. Impacts usually focus on lethal effects of vehicles to organisms, but sub-lethal effects which could reduce the fitness of macrofauna populations are equally possible but unknown. Consequently, we measured changes in body condition and burrowing performance of the beach clam Donax deltoides subjected to vehicle traffic on sandy shores in eastern Australia. Body mass index of clams on beaches open to traffic was 16% lower, but gonadosomatic index and relative valve thickness were not consistently linked to vehicle access to beaches. By contrast, off-road vehicles significantly impaired the burrowing performance of clams. After experimental exposure to ORV traffic (30 passes) and dislodgement from the sediment, the time taken for clams to re-bury into the sand doubled irrespective of the vehicle weight used. Because burrowing is such a critical
 function in the behavioural repertoire of sandy beach animals, the traffic-induced changes to organisms' performance found in this study may increase mortality by causing displacement to less favourable habitats by swash, and by intensifying the risk of predation and desiccation. When assessing the ecological impacts of vehicles on beach fauna, it is thus important to consider both lethal and sub-lethal effects.

Keywords: Body condition; Burrowing; Donax deltoides; Human impacts; Recreational ecology; Sandy shores


      
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