Catching Up with Scientific Diving at USC Dornsife: Surfgrass Monitoring at Catalina

By Christine Sur and Laura Wang

Note: Before we join the new group of students training for the 2012 Micronesia Expedition we will catch up with several of the USC scientific divers and see what they have been working on over the past year.

Southern California Bight and Channel Islands Map. (Image courtesy of NOAA)

Living in a high density, urban setting such as Los Angeles can be tough for an outdoor enthusiast. However, roughly 30 miles southwest of downtown lies Santa Catalina Island, which offers one of the most spectacular environments that Southern California has to offer. The island is home to a variety of endemic plants and animals, and boasts a coastline that is teaming with marine life. As part of the Channel Islands archipelago, the vast majority of the terrestrial and marine environments on Catalina are safeguarded under state and federal regulations. Most notably, Catalina is home to several protected marine areas, which are designed to safeguard and conserve marine life and habitats.

Recently, we helped establish a monitoring project to investigate the density and abundance of coastal surfgrass (Phyllospadix torreyi) in the Blue Cavern State Marine Conservation Area adjacent to the USC Wrigley Marine Science Center on Catalina Island.

Surfgrass meadow off Santa Catalina Island. Phyllospadix torreyi is an annually flowering angiosperm and is common among sandy subtidal habitats in the Southern California coastal region. (Photo by Jim Haw)

Known as a foundation species, surfgrass provides an important refuge for both juvenile and adult organisms. It is a useful indicator of ecosystem health as surfgrass meadows help stabilize sediments and filter nutrients from the water column. Overall, P. torreyi is fairly resilient to disturbance events (e.g., storm events, human activities), however, given the irregular patterns of recruitment in this species, large-scale recovery efforts have been difficult.

Surprisingly, little is known about the spatial patterns and variability of P. torreyi found living in the Blue Cavern Marine Protected Area, which was designated as a no-take marine reserve nearly 25 years ago. With few published scientific data sets to build upon, we were confronted with the challenge of designing and implementing a monthly data collection methodology that could ensure replicable results over the long term.

Point-intercept-transect survey of P. torreyi in the Blue Cavern Marine Protected Area. The percent coverage of surfgrass is recorded on a monthly basis along six separate, 50-meter transect lines. (Photo by Christine Sur)

In the end, we decided to implement a series of benthic transects that cover the area in which P. torreyi is found. Additionally, we deployed underwater sensors to record daily information on subsurface temperature and light at the study site. Since the project began in September 2011, our methodology has proven to be an effective means to evaluate the baseline health of this surfgrass population.

With ongoing surveys of this population of P. torreyi and other associated organisms, our goal is to provide a more complete understanding of natural and anthropogenic impacts on surfgrass communities. For example, in the case of P. torreyi, little is known about the patterns of seed dispersal in this species, which in turn, has hindered the ability of resource managers to accurately predict the growth of a given population.

This can contribute to future problems surrounding governance by making it difficult to pinpoint what needs to be conserved or protected. Moreover, anthropogenic impacts such as changes to water quality and sediment load can affect the growth of a specific surfgrass population. Collectively, these data can provide valuable insight on the breadth and depth of human impacts within a localized region.

Example of temperature and light data recorded over 6-day period (Nov 10-16, 2012) in P. torreyi meadow off Catalina Island. Black line indicates subsurface water temperature (F); blue line is measure of underwater light intensity (lumens per square foot)

In summary, the experience we gained from this project has been valuable. For example, we conducted independent research, practiced our science diving skills, and will present these data at the annual meeting of the Southern California Academy of Sciences in May 2012. Additionally, seeing that the project may have very real policy implications is exciting. While we were always passionate about the environment, the past several months of research have made us certain that we want futures in environmental science and policy.

About the Authors: Christine Sur (left) and Laura Wang are seniors in the USC Dana and David Dornsife College of Letters, Arts and Sciences, and will graduate this May with a BS and BS/MA in Environmental Studies, respectively.? Both learned science diving as part of the 2010 USC Guam and Palau program.? Christine will be pursuing a Ph.D. in Marine Ecology and Laura will be a policy intern at the White House Council on Environmental Quality.

Editor?s note: Scientific Research Diving at USC Dornsife is offered as part of an experiential summer program offered to undergraduate students of the USC Dana and David Dornsife College of Letters, Arts and Sciences. This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island and throughout Micronesia. Students investigate important environmental issues such as ecologically sustainable development, fisheries management, protected-area planning and assessment, and human health issues. During the course of the program, the student team will dive and collect data to support conservation and management strategies to protect the fragile coral reefs of Guam and Palau in Micronesia.

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