Low level off-road vehicle (ORV) traffic negatively impacts macroinvertebrate assemblages at sandy beaches in south-western Australia

Abstract

Off-road vehicle use is arguably one of the most environmentally damaging human activities undertaken on sandy beaches worldwide. Existing studies focused on areas of high traffic volumes have demonstrated significantly lower abundance, diversity and species richness of fauna in zones where traffic is concentrated. The impact of lower traffic volumes is unknown. This study aimed to investigate the impacts of relatively low-level vehicle traffic on sandy beach fauna by sampling invertebrate communities at eight beaches located in south-western Australia. We found that even low-level vehicle traffic negatively impacts the physical beach environment, and consequently, the ability of many species to survive in this habitat in the face of this disturbance. Compaction, rutting and displacement of the sand matrix were observed over a large area, resulting in significant decreases in species diversity and density, and measurable shifts in community structure on beaches that experienced off-road vehicle traffic. Communities at impact sites did not display seasonal recovery as traffic was not significantly different between seasons. Given a choice between either reducing traffic volumes, or excluding ORV traffic from beaches, our results suggest that the latter would be more appropriate when the retention of ecological integrity is the objective.

Impact of vehicles on benthic macrofauna on a subtropical sand beach

“…We also revealed a high number of samples with no invertebrates in all periods, especially in the most impacted sector and at the upper levels of the beach, likewise observed by Schlacher, Richardson, et al (2008) and Davies et al. (2016), suggesting that this impact is continuous throughout the time, with peak events in the summer, not allowing the recovery of the fauna. Furthermore, we observed that vehicle traffic did not show differences between the levels of the beach, different from the results found by Schlacher and Thompson (2007) and Davies et al.…”

“…Besides to the physical changes, vehicle traffic also causes several impacts on biota of these ecosystems, altering the composition and abundance of birds (Borneman, Rose, & Simons, 2016; Schlacher, Nielsen, & Weston, 2013), dune vegetation (Thompson & Schlacher, 2008), insects (van Dam & van Dam, 2008), sea turtles (Antworth, Pike, & Stiner, 2006; Nester, 2006), and mainly benthic macrofauna (Davies, Speldewinde, & Stewart, 2016; Lucrezi & Schlacher, 2010; Sheppard, Pitt, & Schlacher, 2009). Benthic macrofauna have been continually studied because they play a key role in coastal areas and are potentially vulnerable to impact on beaches (McLachlan & Defeo, 2017a, 2017b).…”

“…The pioneering studies that evaluated vehicle traffic impacts on benthic assemblages of sandy beaches showed little damage, low mortality rates, and even high tolerance by intertidal macrozoobenthos for passing cars (van der Merwe & van der Merwe, 1991; Wolcott & Wolcott, 1984). More recent studies showed the great importance of beach management through conservation of macrofauna, once highly negative impacts on organisms have been reported (Davies et al., 2016; Schlacher, Richardson, et al, 2008; Schlacher, Thompson, & Walker, 2008). Thus, in order to assist in future management plans of beaches, our study is the first to investigate vehicular impacts on the macrofauna assemblage in different areas and periods of Cassino Beach.…”

Local scale processes drive long‐term change in biodiversity of sandy beach ecosystems

“…The lack of planktonic larval stages and the low dispersal abilities of some adult invertebrates (Table 2a) make wrackassociated species especially sensitive to anthropogenic impacts that directly affect their populations or the abundance of wrack subsidies that provide food and shelter . Removal or disturbance of wrack resources has been shown to strongly impact wrack-associated taxa and diversity (Dugan et al, 2003;Llewellyn & Shackley, 1996) (Davies, Speldewinde, & Stewart, 2016;Schlacher & Thompson, 2008). At two of our study beaches that were subject to intense ORV traffic during the 1970s, biodiversity increased across the survey periods likely in response to the elimination of ORV disturbance more than 15 years before our 2009-11 surveys.…”

“…Despite a result of higher or no change in overall adjusted species richness values at these beaches, wrack‐associated richness had declined by greater than 20% at all but one groomed beach in 2009–11 compared to the 1970s. Similarly, ORVs can severely impact wrack as well as dune vegetation and biota (Davies, Speldewinde, & Stewart, ; Schlacher & Thompson, ). At two of our study beaches that were subject to intense ORV traffic during the 1970s, biodiversity increased across the survey periods likely in response to the elimination of ORV disturbance more than 15 years before our 2009–11 surveys.…”