Incidencia de los herbívoros sobre la fanerógama marina Posidonia oceanica en la reserva marina de Tabarca, España

Abstract

Annual changes in grazing on Posidonia oceanica have been studied in the Marine Reserve of Tabarca (Spain). The main grazer is the fish Sarpa salpa, while isopods and the sea urchin Paracentrotus lividus have lower importance. Grazing by S. salpa decreases with depth and, in the shallow meadow, overgrazing causes the death of some shoots. Factors that control yearly changes in leaf apex condition are: the appearance of new leaves, leaf age that increases the possibility of leaf break by hidrodynamism or grazing, and the senility and shedding of older leaves. Overgrazing must be considered in the management of marine protected areas where grazers could increase their populations considerably