Wrack Removal as Short-Term Disturbance for Talitrus Saltator Density in the Supratidal Zone of Sandy Beaches: an Experimental Approach

Abstract

A distinctive feature of sandy beaches is the stranded wrack, which represents a key element in the maintenance of their biodiversity and ecosystem function. However, these materials are commonly removed from beaches worldwide. In October-November 2012, a field experiment following an M-BACI design was conducted to assess the effect of wrack removal on sandhopper populations on two sandy beaches on the Atlantic southwest coast of Spain. The beaches, Levante (36°33′N, 6°13′W) and Cortadura (36°28′N, 6°15′ W) differed in their morphodynamics (dissipative and intermediate, respectively) and in the dominant wrack sources (seagrasses vs. macroalgae). Wrack removal diminished the density of the sandhopper, Talitrus saltator, a dominant species in the supratidal zone especially under wrack, but the difference between impacted and control plots was shortlived (several days). Juvenile sandhoppers appeared more sensitive to this disturbance than adults, although this was found only at Levante. This study highlights the adaptability of this sandhopper to a single wrack removal event and shows that the magnitude of the effect is likely dependent on the particular characteristics of individual beaches. The consequences of frequent wrack removal from these beaches on sandhopper populations remain to be determined.

An Impact Assessment of Beach Wrack and Litter on Beach Ecosystem Services to Support Coastal Management at the Baltic Sea

“…A low increase in potential (+1) revealed its function as an additional hard structure for new habitats of marine organisms (Kiessling et al 2015 ). Other studies indicate that beach wrack (potential and flow: +3) support a rich supralittoral fauna (Defeo et al 2009 ) and emphasize their high importance as habitat and food source for dominant species at sandy beaches, e.g., sandhoppers (Ruiz-Delgado et al 2016 ; Pelletier et al 2011 ). Pest and disease control (RM4) was moderately impacted by beach wrack on their service potential and flow (both +2).…”

Zonation of macrobenthos across a mesotidal sandy beach: Variability based on physical factors

“…Wrack also signifies greater availability of food and provides shelter from predation (Dugan et al, 2003;Lewis et al, 2007;Barreiro, 2013). Particularly, it has been studied that a wrack removal diminished the density of the sandhopper Talitrus saltator, a dominant species in the supralittoral zone of sandy beaches, showing the important role of wrack as food or refuge for talitrid amphipods (Ruiz-Delgado et al, 2015). It is likely that the low and inconstant supply of wrack in the coastal area of these beaches could be the reason for the absence of talitrid amphipods or other species on the supralittoral zone of the beach.…”

The role of inputs of marine wrack and carrion in sandy‐beach ecosystems: a global review

“…Wrack biomass can range over 1–4 orders of magnitude across locations within a region (Tarr & Tarr, 1987 ; Dugan et al ., 2003 , 2011 ; Barreiro et al ., 2011 ; Liebowitz et al ., 2016 ; Holden et al ., 2018 a ; Reimer et al ., 2018 ; Schooler et al ., 2019 ). Similarly, standing stock may show temporal variation from no visible accumulation to tens or thousands of grams dry mass per square metre, within hours to days (Ruiz‐Delgado et al ., 2016 b ; Vieira et al ., 2016 ), and across years (Barreiro et al ., 2011 ; Revell, Dugan & Hubbard, 2011 ; Jiménez et al ., 2015 ; Liebowitz et al ., 2016 ; Holden et al ., 2018 a ). Wrack dynamics are principally influenced by the input, accumulation, and export of material.…”