Herbivory in Seagrass Meadows: an Evolving Paradigm

In the past few decades, we have learned much about the factors that regulate the productivity of seagrass-dominated ecosystems, especially those at low latitudes. Here, we update our previous assessments of the importance of seagrass-herbivore interactions, focusing on recent studies that have examined (1) the diversity of herbivores feeding on live seagrass leaves; (2) the factors that determine the ability of seagrasses to respond to herbivore damage; (3) how potential chemical deterrents, and structural defenses, in seagrass leaves influence herbivore consumption; (4) how climate-driven changes in herbivore identity might change grazing intensity in temperate seagrasses; (5) the effects of herbivory on pollen, flowers, fruits, and seeds of seagrasses; and (6) the effects of human removal of seagrass megaherbivores and the top-down effects of overfishing top predators on seagrass consumption. We also identify important gaps in our understanding of the broadly defined topic of herbivory in seagrass-dominated ecosystems. Specifically, we suggest that future studies should consider focusing on increasing our understanding of herbivore foraging strategies, quantifying the impact of herbivory on seagrass reproductive biology, including effects on the fates of flowers, fruits, and seeds and documenting the commonness of compensatory responses and chemical defenses to grazing. Studies of the roles of the nutritional content (as measured by C/N/P ratios), in determining herbivore feeding preferences, remain fertile grounds for future studies, as do additional experiments to quantify the relative roles of top-down and bottom-up factors in determining seagrass abundance and energy fluxes in seagrass meadows.

Automated summary

This study provides an update on the factors regulating the productivity of seagrass-dominated ecosystems, focusing on seagrass-herbivore interactions and highlighting areas for future research to fill gaps in understanding herbivory behavior in seagrass ecosystems.