Response of Ocypode quadrata to storm waves on an urbanized sandy beach

Fernanda Ramos Fernandes De Oliveira,Leonardo Querobim Yokoyama

doi:10.1590/2675-2824069.20-339frfo

Fernanda Ramos Fernandes De Oliveira, Leonardo Querobim Yokoyama

Open Access

https://doi.org/10.1590/2675-2824069.20-339frfo

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Abstract

Extreme climate events cause major disturbances to the fauna of sandy beaches. For abiotic-controlled species, storm waves play a significant role in controlling populations. Considering the projected increase in the frequency of extreme climate events and the consequential influence on benthic macrofauna, there is a need to adjust the time-scale of observations. In this context, we conducted weekly monitoring of the ghost crab Ocypode quadrata on an urbanized sandy beach in southeast Brazil to evaluate the effect of storm waves on population dynamics. The effect of storm wave events was not as strong as expected, but two of the 8 registered storm events provoked an increase in density of O. quadrata. Although not significant, after events 4-5, the population suffered a decrease in density and burrows were concentrated in the upper supralittoral, probably because of contiguous effect of habitat reduction by trampling and the storm waves. It is probable that the combination of storm wave events in conjunction with urbanization could have prevented the population recovery by reducing the overall recruitment or even causing mortality or migration towards safer areas. Multi-factor approaches are needed to better understand the dynamics of O. quadrata in urbanized beaches, however, our study showed that weekly monitoring allowed us to record subtle variations in population dynamics that would go unregistered with other approaches but might reveal long-term changes.

Highlights

Coastal urbanization is one of the major threats to sandy beaches (Schlacher et al, 2007)
Over the 17 months, we identified 8 storm wave events (SWE) at Satélite Beach: 3 occurred during the last three months of 2016 and 5 were distributed throughout 2017 (Fig. 2)
High densities were observed at the beginning of the monitoring, on September 05th and October 17th 2016 (Fig. 2); a decrease in density occurred after SWE 4 and 5 and, with the exception of an increase on October 10th 2017, densities remained low (< 0.002 inds/m2) throughout 2017

Summary

Introduction

Coastal urbanization is one of the major threats to sandy beaches (Schlacher et al, 2007) This dynamic and fragile ecosystem has been degraded due to disorderly coastal occupation and tourism (Blankensteyn, 2006), with negative consequences for biodiversity (Scherner et al, 2013). Submitted: 13-May-2020 Approved: 21-March-2021 Associate Editor: Abilio Soares-Gomes regimes, promotes beach accretion and/or erosion, and alters the benthic community (Walker et al, 2008). Another result of coastal urbanization is the adoption of management actions such as beach cleaning and nourishment, which alters the characteristics of the sediment, with major consequences for the biota (Peterson et al, 2000; Hobbs et al, 2008). Species inhabiting sandy beaches sensitive to anthropogenic and climatic impacts are

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