For seven years, Christine Whitcraft has been tracking the fate of restored coastal wetlands in Huntington Beach step by step, from dry and empty lots to thriving ecosystems, in order to understand what it takes to reach the finish line. Now, she is ready with an answer.
Whitcraft and her team found that community composition, the relative abundance of different species, is the gold standard for determining whether a restored wetland has achieved ecological resilience.
“There are benefits to having a more diverse community composition,” says Whitcraft. “Having a community composition that has multiple species with the same function, the same role in the food web, provides an element of resilience to the system.” Resilient wetlands are better able to survive disasters like drought, invasive species or pollution.
Whitcraft also looked at wetlands with high species richness and individual abundance, but found these did not provide the same level of resilience as community composition.
This means that restoring a healthy wetland is a lot like assembling a winning football team. It’s not enough to have one player for each position on the field, or high “species richness.” A team needs multiple linebackers, receivers and substitute players. Neither is it useful to have hundreds of running backs on hand – high “individual abundance” – if you don’t have a quarterback. Winning teams have the right number of the right players, a healthy community composition.
Results from this project with student co-authors are in preparation for submission to two journals, Restoration Ecology and Marine and Coastal Fisheries.
Hurry up and wait
It wasn’t easy for Whitcraft find her research sites in Southern California. Just half of the original coastal wetlands remain, and many are degraded.
So when she heard of plans to restore tidal flow to Brookhurst Marsh in Huntington Beach, Whitcraft knew she had to move fast. A rapid response grant from California Sea Grant got her started on the first three months of monitoring before tidal water was returned to Brookhurst in 2008. Since then, she has been using restoration sites managed by the Huntington Beach Wetlands Conservancy to look for the point where work crews could claim “mission accomplished” and devote precious time and funding to the next project.
Whitcraft’s team found that the fish community in the restored wetlands in Huntington Beach could reach high species richness and individual abundance within just a few months, yet it took years to achieve the community composition found in an relatively undisturbed wetland.
“One of the key challenges of managing these systems is that the different components of these wetlands are going to come back on different time scales,” says Whitcraft. “And it’s going to depend on your starting conditions.”
For example, at a restoration site in Mission Bay, San Diego, wetland recovery occurred over ten years. Huntington Beach, which had existing plant cover, has seen recovery of certain groups like algae and fish in less than five years.
After decades of decline, Southern California wetlands expanding through restoration, partnerships
Whitcraft hopes her research can help other wetland restorations, and is sharing her findings through her role on the Science Advisory Panel of the Southern California Wetlands Recovery Project (SCWRP), which advises dozens of wetland restoration sites on the Southern California coast.
While restoration work means that Southern California’s wetlands have been slightly increasing in terms of area, the quality can vary. “Projects tend to be evaluated on a project by project basis.”
SCRWP’s challenge to restoration managers is to share knowledge more efficiently and work together on developing best practices and high quality standards. Whitcraft says the group promotes the inclusion of goal setting, monitoring, adaptive management and regional coordination – a key feature to, say, protecting bird migration corridors.
“People are doing really cool things,” says Whitcraft. “Working on a regional scale, we can get that in the hands of public land managers and landowners who can benefit from the information.”