Food webs and energy flow in seagrass ecosystems Seagrass systems are highly productive (both primary and secondary) Primary production a function of light and nutrient availability

From Dennison et al. 1993 Yet, in many seagrass ecosystems, herbivory on seagrass is limited and relatively few species include seagrasses as a major

part of their diet (sea turtles, manatee, geese, some urchins, some fish, some amphipods...).

http://www.int-res.com/articles/meps2004/279/m279p045.pdf The reason is that seagrasses are fibrous (structural carbohydrate; high C:N ratio) and contain compounds that are difficult to metabolize (especially phenolic compounds that may act as an anti-fouling defense). Paradox of the seagrass ecosystem: How can secondary production (i.e. consumer production) be high if few species are consuming seagrass tissue? Seagrass epiphytes may contribute more than one-third to the total above ground biomass and 30% to combined seagrass/epiphyte productivity. Epiphytes appear to provide a more assimilable food source for animals such as snails that were previously assumed to be 'detritivores'. But in some locations, megaherbivores (dugongs, sea turtles, and large fish)

http://journal.frontiersin.org/article/10.3389/fmars.2014.00028/full Studies suggest that high densities of megagrazers can degrade seagrass ecosystems.

Given that many of the megaherbivores are endangered species, what does this suggest about our understanding of energy flow in seagrass systems? Could What about the loss of the top predators of megaherbivores (e.g. tiger sharks)? Do they affect energy flow?

http://journal.frontiersin.org/article/10.3389/fmars.2014.00028/full So, what would a food web/energy diagram look like for a seagrass ecosystem? Where in relation to a coral reef might herbivory be most intense if herbivory is a slow process that exposes herbivores to predators?