Seagrass herbivory: evidence for the continued grazing of marine grasses

Unlike the majority of marine plants, seagrasses are believed to experience little damage from the feeding activities of marine herbivores. Based on o ur previous work, plus a review of the literature, we suggest that this par adigm significantly underestimates the importance of seagrass herbivory in nearshore environments. In this review, we provide evidence from over 100 p ublications, showing that grazing on seagrasses is widespread in the world' s oceans. Overwhelmingly, reports of grazing on seagrasses are based on obs ervations, laboratory measurements, and bioenergetic calculations. To date, few field experiments have been conducted to evaluate the importance of se agrass grazing in the nearshore environment. Of these, even fewer have cons idered the possibility that herbivores may stimulate rates of primary produ ction of the role of belowground nutrient reserves in determining the impac ts of grazers on seagrasses. We contend that the currently accepted view th at herbivory plays a minor role in the energetics of seagrass habitats need s to be reexamined by measuring seagrass responses to grazer induced tissue losses in controlled field manipulations. Only then will we be able to det ermine the importance of the seagrass-grazing pathway in marine food webs.