Seagrass-Watch Magazine Issue 47 - March 2013 | Page 7

Boating & USA seagrass Florida Article by W. Judson Kenworthy, Margaret O. Hall, Manuel Merello & Giuseppe Di Carlo Photography by W. Judson Kenworthy, Anne F. Glasspool, Charles Costello & Bermuda Zoological society Motorised watercraft operation is one of the most popular recreational and commercial activities that humans pursue in the coastal environment. During the past several decades rapid growth in coastal populations accompanied by surging affluence and expanding commercial development has led to more and larger vessels operating in close proximity to seagrass meadows. Growth in the economic value of the commercial and recreational boating industries has far surpassed many traditional uses of the coastal zone, placing significant pressure on seagrass resources. This pressure is certain to escalate even more in the future, thus resource managers are concerned about the potential ecological consequences of vessel operation in seagrass ecosystems. Surveys and applied scientific research have demonstrated the impacts of boating on seagrass ecosystems and the need for more attention to responsibly manage boating activities(1,2,3,4). Here we discuss some of the most significant impacts vessels have on subtropical/tropical seagrass ecosystems and review surveys and scientific studies that have documented these impacts. We also briefly discuss methods to mitigate and restore vessel damage, and some potential solutions to the boating issues. The Problem Motorised vessels can impact seagrasses indirectly by affecting water and sediment quality (chemical contamination), sediment re-suspension (turbidity), and wave turbulence (substrate and shoreline erosion)(2). Construction and maintenance of docks, piers and overwater structures can directly impact seagrass meadows by intercepting light and shading the plants(5). Anchor damage Scar formed from an anchor mooring chain in a shallow Thalassia testudinum meadow. Dragging an anchor through a meadow, or excavating seagrass with an anchor mooring chain can also injure seagrass meadows. These injuries are most notable in locations where the primary means for securing vessels are mooring fields instead of docks. AG MARCH 2013 7