Restoring seagrass beds: Some new approaches with Ruppia maritima L. (Widgeon-grass)

Durako, Michael; Shup, Judith; Andress, Carmen; Tomasko, David

Experimental seagrass plantings were conducted in three artificially created ponds in central Sarasota Bay. Planting units were produced from locally collected Ruppia maritima (Widgeon-grass) that had been clonally micropropagated in vitro. Explants used to produce the planting units were rhizome segments containing five short-shoot nodes. Explants were propagated axenically in sucrose-enriched media supplemented with the cytokinin 2-isopentyl adenine (2iP). Culture conditions resulted in high rates of node production and branching: nodes and branches exhibited doubling times of less than two weeks. We used a new planting technique in which the micropropagated plants were placed in biodegradable cotton-mesh bags that contained river-rock ballast in three configurations. This technique protected and anchored the fragile planting units prior to rooting. Leaves and roots rapidly grew through openings in the cotton-mesh bags, and plants became rooted before the bags decomposed (about two months). Survival of the plants in Pond No.1 ranged from 60 to 97 percent after three to five months and was greatest in planting units with rock ballast secured to the bag corners. Survival ranged from 15 to 63 percent in Pond No. 2, which had less tidal flushing, rockier sediments, and a persistent accumulation of macroalgae. No planting units survived in Pond No.3, seemingly because of unsuitable sediments and disturbance by humans. Plants expanded rapidly, and areal coverage doubled approximately every month. These preliminary results indicate that Widgeon-grass produced through micropropagation may be suitable for planting in situ. In addition, the use of the cotton-bag technique enhances establishment and survival of this structurally fragile species. Abstract provided by author.