A Comparison of Mechanical and Manual Seagrass Planting Techniques at Three Sites in Tampa Bay
Until recently, all seagrass restoration was accomplished by labor-intensive, hand-planting methods. However, James Anderson, president of Seagrass Recovery, Inc., has developed a vessel to mechanically plant bare-root bundles of seagrass. Using a vessel Anderson named "Jeb," the mechanical installation speeds the seagrass planting process and requires fewer man-hours than hand-planting techniques. This method potentially allows the habitat to be restored at a lower cost per acre than by hand-planting procedures.
Although mechanical seagrass planting is promising, the pros and cons of this technique have not been fully determined. Additionally, the growth and survival of mechanically transplanted seagrasses has never been compared to that of seagrass installed using more traditional hand-planting techniques.
Jeb is a 30-foot aluminum pontoon boat that has been modified to allow seagrasses to be planted in a semi-automated fashion. Two aluminum planting wheels containing plant injecting nozzles can be raised and lowered through an open well in the center of the boat. Workers feed units into each planting nozzle as the planting wheel turns. When the planting nozzle penetrates the sediment, the planting unit is released from the wheel at the down position and inserted into the sediment.
Shoalgrass (Halodule wrightii) was planted at three locations in the Tampa Bay area of Florida (Feather Sound, Apollo Beach, Shell Island) during June and early July 2002 using Jeb. At the same time, adjacent plots were planted with Shoalgrass using three hand-planting techniques (staple, peat pot, and rubber band units). Fifteen 50m x 10m plots were established at each planting site. Planting treatments were randomly assigned to the various plots (three plots using each technique at each site, plus three control plots to evaluate natural recruitment).
Using all planting techniques at every planting site will enable us to separate site-specific successes and failures from method-linked ones. Seagrass cover in transplant plots will be determined using Braun-Blanquet cover/abundance analysis conducted semi-annually for at least three years. Videotaping will also be used to establish a permanent visual record of the progression of seagrass cover.