Do natural disturbances have significant effects on sandy beach macrofauna of Southeastern Brazil?

Leonardo Lopes Costa,Phillipe Mota Machado,Ilana Rosental Zalmon

doi:10.3897/zoologia.36.e29814

Abstract

The role of morphodynamic features such as grain size, swash climate and wave action on the macrofauna of beaches are well-known. However, few studies have investigated natural disturbances as potential drivers of temporal community variations. In southeastern Brazil, we sampled the intertidal macrofauna of two sandy beaches to test whether seasonal disturbances as the frequency of storm wave events (SWE) and rainfall have significant influence on their composition and abundance. The macrofauna assemblage differed significantly between the rainy and the dry seasons, but rainfall was not the main driver of community changes, although both beaches are in the vicinity of extensive river plumes. Actually, SWE explained most macrofauna richness overtime, with positive effects. Our results point to the importance of learning more about the effects of poorly studied disturbances on macrofaunal communities, and based on them we strongly recommend including these seasonal phenomena when monitoring sandy beaches.

Highlights

Morphodynamics play a key role in determining the structure of the benthic macrofauna, which is mainly structured by physical features such as grain size, wave action and tide (Defeo and Mclachlan 2005)
The influence of morphodynamic features on the macrofauna of sandy beaches is usually modulated by differences in grain size and swash climate (Defeo and Mclachlan 2005)
Our results showed that morpho and hydrodynamics factors might not be single drivers of macrofaunal richness and density overtime at a local scale (Veloso and Cardoso 2001)

Summary

Introduction

Morphodynamics play a key role in determining the structure of the benthic macrofauna, which is mainly structured by physical features such as grain size, wave action and tide (Defeo and Mclachlan 2005). Dissipative and undisturbed beach populations may be controlled by ecological interactions (e.g., density-dependent mechanisms) (Defeo and Mclachlan 2005). Other environmental conditions are thought to be important drivers of the community structure of the macrofauna, including temperature (Taylor and Mclachlan 1980), food availa bility (Bergamino et al 2013), and natural disturbances such as storms (Harris et al 2011, Machado et al 2016, Corte et al 2017) and rainfall (Lercari and Defeo 1999, 2015)

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