Biologists Study Climate Change At Huntington Beach WetlandsPublished: September 15, 2011
A yearlong experiment at the Brookhurst wetlands in Huntington Beach may lead to better understanding of potential effects of global climate change.
Anastasia Shippey, a biological sciences master’s student at CSULB who is studying in the lab of Professor Christine Whitcraft, is mimicking effects of changes in temperature and moisture on plants and small organisms such as snails and worms that live in the 67-acre wetland.
This research is among several collaborative projects between CSULB faculty and students along with members of the Huntington Beach Wetlands Conservancy, funded by several grants from the National Oceanic and Atmospheric Administration (NOAA).
Marshes like these perform a number of important natural functions. Their landforms and plants help control tidal flow to inland areas and they’re an ideal environment for a host of creatures. Wetlands often serve as nurseries for commercially important fishes as well as nesting sites for a variety of birds. However, decades of coastal development cut off normal tidal flow and severely degraded the wetlands, which is why NOAA and the Huntington Beach Wetlands Conservancy have undertaken multi-million dollar restoration efforts.
“The idea that started Anastasia’s project is that we’re spending all this money on restoration and planting to achieve very targeted goals, but we do it under the assumption of what we know about climate today,” Whitcraft explained. “The prediction is that future climate will be different than today and we can predict some of this change (increased temperature) while other aspects (rainfall) are unknown. Under those scenarios of climate change, it would be nice to know, how do plants grow, how do invertebrates respond and how do food webs function?
“This project specifically mimics predicted climate change scenarios to understand how a marsh restoration and planting can work under altered climate conditions,” she continued. “We know that temperatures are going to increase. The best estimates of the lowest increase are about 2 degrees Celsius for Southern California. That’s a conservative estimate of how much it would change. So, we designed a treatment that increases temperature. The precipitation outlook isn’t as well understood. It could be extended drought that occurs or it could be increased storms and flooding, or some combination thereof, so the dry periods would be drier and the wet periods would be wetter.”
In April, Shippey installed more than 60 boxes made of plastic pipe around plants, which will remain for one year. Some of the boxes just are frames to serve as reference treatments; others have white greenhouse plastic wrapped on four sides but are open at the top, and some have tops covered as well. “In order to mimic an increase in temperature, we wrapped greenhouse plastic around all four sides, which captures more sunlight and moisture,” Shippey explained. “In order to mimic a decrease in precipitation, we put a piece of the greenhouse plastic across the top.”
They also installed rain gauges to check localized rainfall. “Mainly, it’s the variability of the precipitation,” she said. “Not knowing if we’re going to get more rain in summer, we wanted to be sure we covered our wet season, which typically in this region runs from about December to February.
“With our standard monitoring at Brookhurst, we saw that after the planting there, there was an increase in precipitation that winter and we started to see recovery almost immediately,” Shippey noted. “Typically in a salt marsh, when you do a restoration that includes active planting, it’s about five years before you really see recovery resembling what we consider to be a more natural marsh, which is something that’s less impacted by human influence.
“With that recovery happening so quickly, I was wondering if one of the mechanisms involved in that was that increase in natural precipitation as opposed to human-assisted. The conservancy has sprinkler systems to give an initial amount of water to help the plants grow. But, if natural precipitation increases, does that help the plant even more? That was my initial question—was that the reason? But when you start looking into climate change, nothing is that simple.”
Shippey periodically visits the site to record progress on the study and will prepare a final report next year. She hopes her work will benefit both local projects as well as restoration efforts elsewhere.
“Brookhurst was an unusual situation because they already had some plant cover, so it offered an opportunity to see restoration trajectories on a shorter time scale,” she pointed out. “We saw some recovery—not functionally equivalent—on a six-month to one-year time scale, which was really exciting. It advocates that maybe getting plant cover in your marshes quickly is a good idea.
“But, active planting programs involve a lot of expense. The conservancy has invested in a nursery construction, contractors and volunteers to do the plantings, and in watering systems,” Shippey continued. “So, understanding how well the planting regimes work under climate change or under certain conditions could maybe benefit in getting those plantings funded or even deciding if you should do an active planting versus a passive restoration where the plants just recruit themselves.”
“The conservancy has been very receptive to the idea of adaptive management—that they can use their monitoring data and science information to feed back into their next restoration as well as into their management of the marsh,” Whitcraft added. “They’ve been working with NOAA to be really proactive about the management of the marshes. When they see something change, they evaluate whether it’s a positive or negative change toward the restoration goals and they’ve adapted the plan, which isn’t always done elsewhere.”