Oral Paper

         Physiology

A plan for large scale restoration of damaged seagrass communities.

Presenting Author
Arthur Schwarz
Description
The global area occupied by seagrass has been estimated at 191,000 km2 with 7% loss per year (Waycott et al, 2006). Industrialized coastal areas around the world have experienced major losses of seagrass from urbanization, dredging for navigational channels and ports, release of damaging effluent, and direct land fill. Seagrass loss has far exceeded restoration of damaged areas. In coastal Texas, large areas have experienced all such degradation in estuaries that were once rich seagrass beds. This coastline is one of the worlds’ major fossil fuel refining complexes. A major study of the loss of Texas seagrass (Pulich, 1999) showed only 30% seagrass remaining, with some estuaries having far less. Small scale restoration of seagrass has occurred along the coast of Texas for three decades. We are building a systematic effort to create a Texas State plan for restoring seagrass and its services on a larger scale. The major ecological services seagrasses provided include enhanced water clarity, fisheries nursery habitat, food-webs for endangered species, shoreline stability, and mineral cycling. Various areas offer restoration of differing services. We are beginning with the third largest Texas estuary,  Matagorda Bay, which has received the least attention for it’s seagrass. We have begun by selecting degraded sites where critical services could potentially be restored. We next filtered these sites based on where we believe restoration will be most beneficial throughout the 1,093 km2 expanse of the bay. The precise shoreline elevation and configuration are being confirmed by coastal shoreline surveys. A series of over 1,200 plugs of seagrasses will be planted in spring. Past seagrass restorations, including our own, ranging from south (Padre Lagoon) to north (Galveston Bay) has shown that plugs of Halodule wrightii establish most successfully. Restored seagrass beds along shorelines in three locations from Galveston Bay to Corpus Christi Bay have showed high resilience and persistence of the shoreline during hurricanes, while marshes without associated seagrass along the shoreline were more likely to sustain damage or wash away.  All our restorations resulted in recolonization of animal communities within months. The water clarity is improved with the presence of seagrass as sediment is trapped among the stems, rhizomes and roots. Blue carbon sequestration was higher than natural seagrass growing in the vicinity (Thorhaug, 2017). Our plan is to restore various types of sites and monitor the return ecological services. Generally, the estuaries have relatively high flow of surface water from large catchment areas flowing into the bay. The eastern sides of Texas bays have barrier islands with infrequent passes to the Gulf of Mexico. Thus, there are varying types of sites, which will be ranked for priority of restoration efforts.