Abstract Detail

Ecophysiology

Schwarz, Arthur [1], Thorhaug, Anitra [2], Berlyn, Graeme [3].

Hurricane effects on restored seagrass corridors in Texas.

Storm track maps from 100 years of data (NOAA) show clustered hurricane “hotspots” in the Gulf of Mexico (GOM), and that hurricanes are increasing in number. In the past decade, the negative impact of hurricanes in Texas has included private property, residences, shoreline erosion, and agricultural losses, as well as to public infrastructure, including collapsed coastal roads, bridges and damage to water-front structures. Estuarine shorelines in Texas are chiefly sediments accreted from riverine and GOM sources, and are easily eroded. During industrial development of the last century, coastal Texas lost 70% of its seagrass (Pulich, 1998). We have sought to mitigate seagrass losses by restoring a series of nearshore estuarine corridors with the seagrass Halodule wrightii on sites from Texas’ south (Laguna Madre) to it’s north (Galveston Bay). Hurricanes of various intensities and durations followed our seagrass restorations. A similar process of change occurred at each site. Intact seagrass meadows had a shoaling effect on waves and sea level increase during hurricane events such that these shorelines to remain largely intact. Proximate shorelines barren of seagrass had differing results. Site 1 in S. Galveston Bay, a restored seagrass area (244 x 37 m), underwent storms Harvey, Laura, and Delta. Galveston site the shoreline eroded 0.2m during each storm, with 0.5m total. Well-developed intertidal salt-marshes lost from 3 m to 0.1 m of shoreline with vegetative structures including roots carried away in the waves. Wave shoaling by naturally-occurring seagrass meadows were similar to restored seagrass. Whereas the barren control shoreline eroded many meters. Under severe wave action, seagrass blades naturally detach from rhizomes at an incision point, enabling the rhizomes and roots to remain in the sediment. Rapid regrowth of Halodule wrightii leaf blades created a dense seagrass meadow within 1.5 month. Animal recolonization occurred rapidly after blade regrowth so that animals returned to their former densities. A very similar process occurred to the Aransas/St. Charles Bay two restoration sites: small movement of shoreline, rapid recovery of seagrass density, and recolonization of animals. Predator Island in North Laguna Madre (restored spring 1999), also underwent this process (Hurricanes Brett in 1999, and Harvey in 2017), although regrowth and recolonization after the 2021 Hurricane Hanna was slower.

1 - Southwestern Adventist University, Biological Sciences, 214 Woodlawn Dr., Keene, TX, 76059, United States
2 - Greater Caribbean Energy and ENvironment Foundation, 1359 SW 22 Ter Apt 1, Miami, FL, 33145, United States
3 - Yale University, School Of Foresty & Evironmental Studies, Marsh Hall-360 PROSPECT ST, New Haven, CT, 06511, United States

Keywords:
Seagrass shoaling
seagrass restoration
Seagrass stabilization of shorelines
Halodule wrightii stabilization of shorelines
Halodule wrightii restoration shorelines Texas .

Presentation Type: Oral Paper
Number: EPH2005
Abstract ID:345
Candidate for Awards:None