Seagrass Restoration and Monitoring
Transcript( music playing ) Hello. My name is Michelle Tongue. I am a Biologist working in the Damage Recovery Program under the Division of Resource Management at Biscayne National Park. Today we’ll be talking about seagrass restoration and monitoring that is done here in the park. I hope you enjoy the video clip and at the end be sure to hear what you can do to help protect our underwater resources. Biscayne National Park encompasses 173,000 acres of the waters between Miami and Key Largo. The park was created in 1968 and includes mangrove, seagrass, coral reef, and hardwood hammock resources as well as shipwrecks and other historic sites. The park is responsible for preserving and protecting these rich resources and providing recreational opportunities for the public. The need for seagrass restoration and monitoring is tied to the amount of boat traffic in Biscayne National Park. The park is 95% water, and over the years, an increasing number of boats are using the park for all types of recreation, such as fishing, snorkeling and scuba diving. ( bubbling ) Increased boat traffic translates into more boaters running aground in shallow water and damaging park resources. Causes for these groundings can vary from inexperienced captains or engine failure, ( sound of an engine faltering ) to, loss of visibility in bad weather. ( sound of thunders ) ( music playing ) The Damage Recovery Program is part of the Division of Resource Management at Biscayne National Park. When boats run aground and damage shallow seagrass beds and coral reefs, we assess that damage and choose the best options for restoration. Our goal in restoration is to take actions so that the resources can recover to pre-injury conditions as soon as possible. There are several types of injuries that can be caused when a boat runs aground in seagrass habitat. Prop scarring, blowholes and berms are most common. Propeller scars are long trenches in the seagrass bed made by a boat’s propellers. Blowholes are deep holes that are formed when a boat operator attempts to free the boat using its engines. The sediment excavated from a blowhole, or even from a deep propeller scar, forms piles that are called berms. ( gentle music playing ) When boats run aground in seagrass habitat, they often excavate sediment and leave seagrass roots and rhizomes exposed in the water column. Seagrass rhizomes grow horizontally and need to be surrounded by sediments to grow. When the rhizomes are exposed at a grounding site, the plants cannot grow back into the injured area. ( gentle music playing ) ( motor running ) To restore these injuries, the first thing we do is place sediment into blowholes and deep propeller scars to return the seafloor to its original grade. This stabilizes the substrate to prevent further erosion, and prepares the area for colonization by seagrasses. Sediment for fill, usually fine limestone sand, is obtained from a local quarry. This sediment is transported to the restoration site on a shallow draft barge and then placed into the injury either in burlap sacks, or as loose fill using a clamshell bucket. Coastal sediments in South Florida are nutrient-limited, which means that certain nutrients important to plant growth are in low supply. We try to provide a fertilizer source at our restoration sites to help the seagrasses recover more quickly. After filling the injury sites, bird stakes are placed in the restoration areas to encourage roosting of waterfowl. Bird stakes are constructed of PVC support poles with treated wood blocks attached atop the poles. While birds are perched on the stakes, their droppings provide a regular source of natural fertilizer to the seagrass beds below the stake. We leave the bird stakes in place for about 18 months, to allow the nutrients to accumulate in the sediments. After that time, the bird stakes are removed and used again at another site. Sometimes, we transplant seagrasses that have been harvested from donor areas into the restoration sites. This helps to stabilize the sediments and more quickly increase seagrass cover at the restoration site. Both Individual seagrass plants and seagrass plugs can be used as transplants. Individual plants are carefully removed from the sediments, and then bundled into planting units for transplanting. Seagrass plugs that are thick enough to contain the rhizome mat and surrounding sediments are collected using a hand trowel or coring device. The harvested plants and plugs are then secured in the restoration site with a sod staple to help keep them in place. Once the sediment levels have been returned to match the area around the injury and bird stakes and or transplanted seagrasses have been installed, it is important to monitor the success of the restoration. We monitor our restoration sites regularly for five years to document the recovery process. We usually monitor a site twice a year for the first two years after restoration, and then annually for years 3, 4 and 5. ( music playing ) Our definitions of restoration success are based on project objectives. For blowholes and deep scars, our objective is to restore topographic elevation- in other words, to fill the hole. Success is measured by the stability of the backfilled material. Over the 5 year monitoring period, we monitor erosion of the fill and consider a project successful if there is less than 10cm loss during that time. When we place bird stakes and transplant seagrasses into an injury site, our objective is to encourage seagrass recruitment by providing a fertilizer source and to increase overall seagrass cover. Success is measured by the survival and expansion of the transplants, and also by overall increasing seagrass cover. Seagrass coverage is measured during each monitoring event using visual assessment methods. Comparing changes in seagrass coverage within the restored site with changes in an undisturbed area outside of the injury allows us to assess seagrass recolonization. For each of our monitoring events we use a computer program to give us the location of a specific number of points within each injury and surrounding reference area. At each point we place a square quadrat made out of PVC and measure the abundance of algae, seagrasses, sponges, corals and any other living organisms within the quadrat area. Each item is then given a score based on the area it takes up within the quadrat, and that number is recorded on the data sheet. We also collect water temperature and salinity measurements using a handheld water quality meter and take photos of the injury and reference areas at each site. Once all the data is collected it gets entered into a database and then analyzed statistically. The seagrass monitoring data we collect allows us to track the success of our restoration efforts and modify our techniques in order to get the best results from our work. We use it to plan for future projects and estimate how long it will take for the injured areas to recover to the health and productivity levels that existed before the injury occurred. We strive to protect and restore damaged seagrass habitat because it plays a very important role in the health of our oceans. Seagrasses serve as a nursery ground to many commercially important species of fish and crustaceans; they also stabilize coastal sediments, and improve water clarity by trapping sediment particles in the water column. Seagrass ecosystems are also extremely important in cycling nutrients, and in capturing energy from sunlight and transferring it to other organisms higher up the food chain. ( music playing ) There are things YOU can do to help protect seagrass habitat. Know where you are going before you set out for a trip on your boat! Use up-to-date nautical charts to plan where you are going AHEAD OF TIME. Identify the shallow areas which you need to be aware of during your trip, and know when the tides are low so you don’t get caught in a shallow area during the low tide. Make sure you have someone on your boat to be a look-out for shallow areas, waterway markers and other vessels. When you are anchoring, be sure you place your anchor in an area that does not have seagrass, if possible, and when you pull up your anchor, be careful not to bring up clumps of seagrass and sediment. Please visit www.nps.gov/bisc for more information and for help in planning your visit to Biscayne National Park. I am Michelle Tongue and I thank you for watching! ( upbeat music playing ) ( music ends )
Seagrass Restoration and Monitoring in Biscayne National Park. Hosted by Michelle Tongue.