Enhanced wetland on UCSC’s Coastal Science Campus will benefit threatened frogs

Construction of a seasonal pond within an existing wetland area in the Younger Lagoon Natural Reserve will create potential aquatic breeding habitat for the California red-legged frog

California red-legged frog
The California red-legged frog is a threatened species that uses both aquatic and upland habitats. (Photo by John Bradley, USFWS)
plant propagation in greenhouse
Younger Lagoon Reserve staff and student employees are propagating native wetland species such as Juncus effusus (common rush) at the UCSC Greenhouse in preparation for planting on the enhanced wetland site. (Photo by Vaughan Williams)

The California red-legged frog is a threatened species that has been found on the UC Santa Cruz Coastal Science Campus, but has not been known to breed there successfully. That may soon change with the construction of a small pond designed to enhance an existing seasonal wetland and provide potential breeding habitat for the native frog.

The wetland enhancement project will be located near the railroad corridor in the upper terrace area of the Coastal Science Campus, north of McAllister Way, and it is within the Younger Lagoon Natural Reserve. Construction is expected to begin in mid-September and will be followed by replanting of the area to restore native vegetation around the pond.

“This project fits in seamlessly with our restoration program for the terrace lands that are now part of the reserve,” said Elizabeth Howard, director of Younger Lagoon Natural Reserve. “The enhanced habitat will also create new opportunities for research, education, and outreach activities around the California red-legged frog.”

As part of the Coastal Long Range Development Plan (CLRDP) for the Coastal Science Campus approved by the California Coastal Commission in 2009, 47 acres of terrace lands were added to the Younger Lagoon Natural Reserve. The terrace lands had been farmed for nearly 70 years, and the reserve’s restoration efforts include removing non-native invasive plants, restoring native plants, creating more diverse habitats, and protecting and enhancing wetland areas.

The upper terrace wetland enhancement project will create an area for water to pool seasonally and remain longer on the site. It is designed to rely on existing natural water sources, including rainfall and surface runoff, with no permanent structures to add or remove water, and will continue to naturally drain towards Younger Lagoon.

“We are trying to enhance and restore the natural hydrology of the site,” said UCSC Natural Reserves Director Gage Dayton.

The campus has explored the potential for improving aquatic habitat for the California red-legged frog in the upper terrace as part of a suite of Coastal Science Campus projects since 2014. The restoration project has been made possible through a partnership between UCSC, the U.S. Fish and Wildlife Service (USFWS), U.S. Department of Agriculture Natural Resource Conservation Service (NRCS), and the Resource Conservation District of Santa Cruz County (RCD). Construction costs are being funded by the USFWS Local Coastal Program and RCD, which is overseeing the design and construction of the pond, while UCSC is responsible for replanting and ongoing maintenance as part of the reserve’s wetland restoration program.

The restoration program involves many UCSC students, who will be helping to collect seeds and propagate native plants, plant the site after construction of the pond, and monitor and maintain it over the years. “The enhanced wetland will also create new opportunities for students to do research projects and have learning experiences up close with this protected species,” Howard said.

The California red-legged frog uses both aquatic and upland habitats. Dayton said adult red-legged frogs have been found in the upper terrace area for a long time. For successful breeding, however, the frogs require ponds or other aquatic habitat. The eggs are laid in water and the larvae (tadpoles) remain in the water until they mature into adult frogs. The adults then move into terrestrial habitat for the remainder of the year.

“We understand that frogs have been moving onto the reserve from nearby aquatic habitat sites and then going back during the breeding season,” Dayton said. “The native plant restoration work we’ve been doing is creating better terrestrial upland habitat for the frogs, and we hope that the upper terrace wetland enhancement project will create successful aquatic breeding habitat which would then be connected to other breeding populations in the area. It’s another piece of the puzzle that not only helps our goals for the reserve but can also help this threatened species.”