SCCF Marine Lab, ‘Ding’ Darling survey seagrass in wildlife refuge
SCCF Marine Lab staff, with the assistance of J.N. “Ding” Darling National Wildlife Refuge biologists Joe Stack and Rachel Krauss, surveyed the seagrass resources of the wildlife refuge.
Through a cooperative grant with the U.S. Fish & Wildlife Service from May 2011 through October 2012, SCCF (Sanibel-Captiva Conservation Foundation) teamed together with Refuge staff to monitor water quality and aquatic habitat within the Refuge, providing information which can be used to focus management efforts.
As was readily apparent during the surveys, many sea creatures use the seagrass as critical habitat. During the surveys, the team was circled by sharks, bullied by manatees and constantly poked and prodded by various types of shellfish, crabs and other “notorious man eaters.”
To survey seagrasses, the team donned mask and snorkel to count and identify seagrass over a 100-meter distance at 10 separate sites within the Refuge. They also noted the amount of algae or other organisms growing on the seagrass blades (fouling) along with number of shoots, percent coverage, sediment type and water depth. This is done every six months at locations throughout the refuge to provide a long-term record of habitat quality.
When the data is analyzed over time, changes in seagrass health can be detected which may be related to water quality conditions or other management concerns, such as hypersalinity or the seasonal draw downs of water for shorebirds.
During the 2011 surveys, the team found five different species of seagrass surviving in conditions ranging from clear colorless water to cloudy, dark water with lots of algae growing over the seagrass. Looking at all the data together, along with long-term water quality data, can give us a better understanding of the long term stability of seagrass habitats and relationships with wading birds or other marine life, like the bay scallop.
The once plentiful bay scallop requires seagrass habitat in all stages of its life cycle to provide shelter, structure for settlement, and to aid in successful food uptake. Bay scallop populations almost disappeared from the local area in the 1970s due to poor water quality (some blame the 1963 construction of the Sanibel Causeway).
SCCF has been studying local bay scallop populations since 2003 with Florida Fish & Wildlife Conservation Commission scientists (FWC). Several small-scale restoration attempts around the Refuge in 2004 were initially successful but red tide in 2005 led to high mortality of bay scallops throughout the Southwest Florida coast. Successful restoration of scallops depends on healthy seagrass habitats. SCCF, the refuge, and area fishermen intend to establish a large local bay scallop population in Tarpon Bay where the seagrass habitat is healthy and diverse.
Just like when you were a kid and looked down and saw how many creatures lived within the grass at your feet, when we survey seagrass we also realize that this habitat provides a place where many creatures need to live. Monitoring the health of our seagrass resources is essential to protecting them and the creatures that depend on them.