Abstract
Seagrass meadows are highly productive and ecologically important ecosystems. Their leaves attenuate water flow, trap sediment from the water column; their roots stabilize and aerate the surrounding sediments. Seagrasses serve as nurseries and, in some cases, food for marine mammals, sea turtles, waterfowl and invertebrates (Hemminga and Duarte 2000; Kenworthy et al. 2006). Worldwide they are declining, in large part due to increasing pressure from anthropogenic impacts, such as nutrient enrichment, dredging, and shoreline modification (Short and Wyllie-Echeverria 1996; Orth et al. 2006.
Seagrasses in the genus Phyllospadix, also known as “surfgrasses,” differ from others in that they inhabit exposed, rocky shore intertidal and subtidal environments (den Hartog 1970, Phillips and Meñez 1988). Like other seagrasses, Phyllospadix spp. play an important role in coastal ecosystems. P. scouleri and P. torreyiprovide nursery habitat and food for the California spiny lobster, Panulirus interruptus, (Castaneda-Fernandez de Lara et al. 2005a, 2005b) and P. scouleri is critical foraging habitat for the endangered East Pacific green turtle, Chelonia mydas on the Pacific side of the Baja Peninsula (Lopez-Mendilaharsu et al. 2005). Recent work suggests that the surfgrass P. iwatensis provides structure to trap and retain allochthonous subsidies such as algal drifts and subtidal sea urchins (Hori 2006).
While human impacts to Phyllospadix spp. from sewage outfalls (Littler and Murray 1975) and oil spills (Foster et al. 1988) have been shown, the burial responses of Phyllospadix spp. have not been evaluated. Surfgrasses are likely to be impacted by beach nourishment and shoreline protection projects that place sand either directly or indirectly onto surf grass beds. Since the roots and rhizomes of Phyllospadix spp. attached to rocks are normally exposed, their responses to sediment burial may differ from other seagrasses whose roots and rhizomes are normally covered with sediments.