Sea Turtles in the Urban River
Crush may have almost stolen the show in "Finding Nemo," and with good reason. Green sea turtles are true nomads of the water, able to make a home in waterways around the world, including -- surprisingly -- the most urban of places like the San Gabriel River in Long Beach.
Rumored to live for more than a century and very mobile, these endangered creatures are also quite enigmatic, posing more questions to researchers than they answer.
"We know some things about this species. They are circumglobal creatures. The ocean is their habitat," says Eric Zahn of Tidal Influence, which works with Los Cerritos Wetlands in the hopes of providing a conducive environment for these creatures in the future restored wetland, "Without putting a camera and swimming around and following them for years and years, we don't know what sea turtles do -- except when they go ashore. Trying to figure out what's happening with this anomalous population is a big challenge."
But every mystery has its Sherlock Holmes and Dr. Watson.
In this case, Doctors Watson, in the form of about thirty regular volunteers to the San Gabriel River Sea Turtle Monitoring Project, a partnership between the Aquarium of the Pacific in Long Beach, the National Oceanic and Atmospheric Administration (NOAA) Fisheries, and the Los Cerritos Wetlands Authority.
Every first Saturday of the month, volunteers roll out of their warm beds into the foggy mouth of San Gabriel River in Long Beach. Meeting at 8:30 a.m., these dedicated volunteers are greeted with a fortifying cup of coffee and the familiar faces of other volunteers.
By 9 a.m. precisely, these volunteers are spread in pairs of threes across ten stations along the San Gabriel Bike trail between Pacific Coast Highway and 7th Street, their eyes trained toward the water in the hopes of sighting a precious green sea turtle.
"Sightings are very unpredictable," says Cassandra Davis-Ramon, who along with her partner, Barbara, have been helping run the citizen program for the past three years. "It can be slow and long, but it can also be short, instant and easy to miss. It all depends on what the turtle decides to do at one time." Volunteers really need to concentrate, counting how many turtles are actually present to the best of their ability. At 9:30 am, the exercise is over and no other sightings are counted, to retain consistency in the data.
It may seem like a simple counting exercise to the untrained, but the citizen science effort has been helping researchers figure out some answers to these mysterious questions by giving them "a 30-minute snapshot of what's going on," says Dan Lawson of NOAA Fisheries, who receives the citizen science reports. He also fields other efforts to monitor these anomalous green sea turtle population. He is the Sherlock of the equation.
Lawson says that these green sea turtles are quite baffling. "Prior to this, we thought green sea turtles only came as far north as San Diego Bay." To find a population in an urban river further north was a shock. Though data is still being collated to prove anything, researchers think the warmer waters generated by the power plants near the San Gabriel River have attracted the green sea turtle population here. The power plants use the waters of San Gabriel River to cool its operations, generating warmer water in the river. This creates an attractive Jacuzzi for these green sea turtles.
Eventually, however, those power plants are going to cease operations. "What are the turtles going to do in response? We don't know," says Lawson. "We're not expecting them to just pick up and leave, but there will be some changes in behavior." This is why research is crucial.
The green sea turtles are part of the local flavor of Long Beach. "Bikers, surfers and residents are all very protective of the turtles," says Kim Thompson of the Aquarium of the Pacific, co-principal on the San Gabriel River green sea turtle citizen science monitoring project. "When they see us on the river, they always ask what we're doing with the turtles."
In fact, it was through a local that NOAA discovered this population. Lawson says that NOAA had always been aware that there were occasional sea turtles (not necessarily green ones) that accidentally find themselves in the area. "We thought they were just occasional visitors, when the water was warm." But a when a couple of recreational fisherman reported that they kept seeing sea turtles every time they fished. Their report finally became the blip NOAA needed home into this population.
"Here we are at the regional office right in Long Beach and we weren't even aware of them. Sure enough when we crossed the bridge and walked down near the San Gabriel River, we saw a turtle pop its head up," recounts Lawson. "Every time we went to the river, we saw turtles. We pretty much have a year-round resident group. We just don't know if they're the same turtles every year."
This discovery also led the NOAA to launch a capture, tagging, and tracking program for sea turtles complementing the citizen science program. According to Lawson, researchers are trying to answer a number of questions by employing different methods. They want to know if these are the same turtles they see every year, what areas of the river they're using, why they're attracted to those spots, and if there are other nearby spots that they'd be attracted to.
So far, there have been a few answers, says Zahn. "We know they're here all-year round and they use a majority of the river until it turns into cement. We can confidently say they're all juveniles between 0 to 30 years old and that they're active anytime of day. We know where they're most active, but we don't know why there."
Answers will soon be even more valuable as the San Gabriel power plants cease operation and warm waters will cease to flow at San Gabriel River. Researchers and locals are hoping that with the data they're able to gather, future revitalization efforts, particularly at the nearby future site of the Los Cerritos Wetlands, will be able to entice these creatures to stay.
"Our best guess is that because they can sense the warm water from the power plants, they're attracted to go there. We think if we do it right, we could make a wetland habitat that will be safe for these turtles, that will offer shelter and food, so that when these power plants stop emitting warm water they could find another home here," says Zahn. "We don't want to lose these turtles, they're our mascot."
