Factors modulating herbivory patterns in Cymodocea nodosa meadows

Rocío Jiménez‐Ramos,Juan J. Vergara,Luis G. Egea,Fernando G. Brun

doi:10.1002/lno.11749

Rocío Jiménez‐Ramos, Juan J. Vergara + Show 2 more

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https://doi.org/10.1002/lno.11749

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Abstract

AbstractIn coastal marine food webs, seagrass‐grazer interactions play a fundamental role in ecological processes by regulating the structure and functioning of plant communities. Therefore, assessing the strength of these seagrass‐grazer links and identifying the mechanisms that regulate these relationships are crucial to increasing our understanding of community and ecosystem structure and dynamics. Herbivory on the temperate seagrass Cymodocea nodosa was evaluated in four locations with contrasting abiotic and biotic factors (i.e., depth; meadow size; seagrass shoot density, productivity, and leaf traits; and herbivore presence) using cross‐transplantation experiments carried out once per season to account for seasonal variation. Patterns of feeding rates on C. nodosa meadows showed high temporal variability, with peaks occurring in spring and summer. Results indicate that between 46.59% and 74.08% of the annual leaf production is lost to herbivory at the locations sampled in this study. Herbivory rates increased with higher nitrogen content and shoot density for all types of consumers (mesograzers, fishes, and sea urchins). This work highlights the need to integrate the abiotic and biotic factors modulating herbivory patterns, particularly in a foundation species like C. nodosa, for which changes in plant traits and grazer abundance may trigger trophic cascades with far‐reaching consequences for associated species.

Highlights

Seagrasses are considered to be foundation species that host communities with high biodiversity in coastal areas (Heck et al 2003)
The highest shoot densities in C. nodosa meadows were recorded at ST, with the maximum values occurring during summer (630.12 Æ 29.12 shoot m−2)
Palatability patterns in Cymodocea nodosa leaves C. nodosa showed different leaf traits depending on season and location. This plasticity is in agreement with previous findings by De los Santos et al (2013), who observed this capacity to thrive under a range of hydrodynamic forces through adaptation of leaf traits

Summary

Introduction

Seagrasses are considered to be foundation species that host communities with high biodiversity in coastal areas (Heck et al 2003). Most of them exhibit selective feeding, according to leaf nutritional quality (i.e., nitrogen content; McGlathery 1995; Cebrián and Lartigue 2004) leaf structural composition and design (i.e., carbon and fiber contents, biomechanical properties; De los Santos et al 2013), and the presence of chemical deterrents (i.e., phenolic compounds; Vergés et al 2007, Prado and Heck 2011). Such leaf properties determine tissue palatability, which can be defined as plant susceptibility to consumption by herbivores (Heady and Child 1994). This study was conducted in shallow meadows of Cymodocea nodosa using in situ seasonal manipulative crosstransplantation experiments across a gradient of locations ranging from sheltered to open waters in Cádiz bay, which were inhabited by different dominant herbivore species (mesograzers, fish, and sea urchins)

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