The Los Cerritos Wetlands at the mouth of the San Gabriel River
The estuary environment where we find the sea turtles was not always an urban waterway. Before the power plants were built, and before the levees were constructed, the mouth of the San Gabriel River was primarily a wetland environment. Some of these wetlands are in the process of being rebuilt, next to where our citizen scientists are conducting their study, in order to restore native habitat for local species.
Is it possible that the Pacific Green Sea Turtles will spend time in restored wetlands? Our observation program may be able to determine the effect of habitat restoration on the sea turtles as we observe their surfacing patterns over the years to come.
Restoring the wetlands
The Los Cerritos Wetlands Stewardship Program is working to restore 66 acres of wetlands owned by the Los Cerritos Wetlands Authority. These wetlands occupy habitat in two cities, Long Beach and Seal Beach, and two counties, Los Angeles and Orange. The program’s ongoing restorative activities have included removing non-native plants, collecting seeds from rare plants for later use, and collecting trash.
Restoration focuses on non-native weed removal and rare native plant conservation. These events are led by trained naturalists and local educators, offering a great opportunity for local citizens to learn more about the Los Cerritos Wetlands, while getting hands-on involvement with the restoration.
Is it possible that the Pacific Green Sea Turtles will spend time in restored wetlands? Our observation program may be able to determine the effect of habitat restoration on the sea turtles as we observe their surfacing patterns over the years to come.
Restoring the wetlands
The Los Cerritos Wetlands Stewardship Program is working to restore 66 acres of wetlands owned by the Los Cerritos Wetlands Authority. These wetlands occupy habitat in two cities, Long Beach and Seal Beach, and two counties, Los Angeles and Orange. The program’s ongoing restorative activities have included removing non-native plants, collecting seeds from rare plants for later use, and collecting trash.
Restoration focuses on non-native weed removal and rare native plant conservation. These events are led by trained naturalists and local educators, offering a great opportunity for local citizens to learn more about the Los Cerritos Wetlands, while getting hands-on involvement with the restoration.
The Pacific Green Sea Turtles have made this urban watershed their home
The urban ocean setting affects both the environment and behavior of the Pacific Green Sea Turtles that spend time in the mouth of the San Gabriel River.
The San Gabriel River is warmer due to anthropogenic (human) influences
The turtles are directly affected by the power plants using once-through cooling, which can increase the water temperature up to 25° F, creating a more comfortable temperature range for these sea turtles.
The once-through cooling used by the power plants is not the only reason the San Gabriel River water is warmer. The San Gabriel River, like the Los Angeles river, was channelized for flood control in . Before reaching the last 3.5 miles of soft-bottom river where the sea turtles can be found, the water in the San Gabriel River travels for ten miles through a concrete channel, where sunlight heats the river water as it continues downstream (read more about the river's history and construction in The San Gabriel River: Past and Present, from the Los Angeles Department of Public Works' San Gabriel Corridor Master Plan).
Why do the turtles need warmer water?
Pacific Green Sea Turtles are one species which require warmer waters in order to avoid cold-stunning when the water temperature drops too low, which can cause lethargy and even death. Cold-stunned turtles are most often found in the Northeast United States, where sea turtles can become trapped by temperature shifts at the end of summer. Cold-stunned turtles are most often found stranded in Cape Cod, Massachusetts, due to the temperature patterns in the Northeast in September - October, but sea turtles in the Pacific Ocean are also susceptible to cold-stunning.
How do other human actions affect the San Gabriel River and the sea turtles?
Although warmer water from the flood channel and the power plants has a small benefit for the sea turtles, there are many ways that the urban environment is dangerous to the sea turtles and other animals which live in the San Gabriel River.
What will happen when once-through cooling stops?
The river temperature will lower near the power plants, but scientists hypothesize that the sea turtles in the river may still stay in the San Gabriel River. Ongoing observation of the wildlife - especially the pacific green sea turtle citizen science program - will be important in measuring the effects of shutting down the power plants' once-through cooling systems.
Ready to learn more about once-through cooling?
The San Gabriel River is warmer due to anthropogenic (human) influences
The turtles are directly affected by the power plants using once-through cooling, which can increase the water temperature up to 25° F, creating a more comfortable temperature range for these sea turtles.
The once-through cooling used by the power plants is not the only reason the San Gabriel River water is warmer. The San Gabriel River, like the Los Angeles river, was channelized for flood control in . Before reaching the last 3.5 miles of soft-bottom river where the sea turtles can be found, the water in the San Gabriel River travels for ten miles through a concrete channel, where sunlight heats the river water as it continues downstream (read more about the river's history and construction in The San Gabriel River: Past and Present, from the Los Angeles Department of Public Works' San Gabriel Corridor Master Plan).
Why do the turtles need warmer water?
Pacific Green Sea Turtles are one species which require warmer waters in order to avoid cold-stunning when the water temperature drops too low, which can cause lethargy and even death. Cold-stunned turtles are most often found in the Northeast United States, where sea turtles can become trapped by temperature shifts at the end of summer. Cold-stunned turtles are most often found stranded in Cape Cod, Massachusetts, due to the temperature patterns in the Northeast in September - October, but sea turtles in the Pacific Ocean are also susceptible to cold-stunning.
How do other human actions affect the San Gabriel River and the sea turtles?
Although warmer water from the flood channel and the power plants has a small benefit for the sea turtles, there are many ways that the urban environment is dangerous to the sea turtles and other animals which live in the San Gabriel River.
- Pollution - Anything that ends up in a gutter in Los Angeles can end up in the San Gabriel River or Los Angeles River. For a county with over ten million people in 2013, that results in a lot of trash and runoff (US Census). Chemicals, fertilizers, pesticides, and trash can enter the river through the storm drains, and pollution from urban runoff is heaviest after a rain (Ngo, Schwanemann, Sompramotjit, & Landon-Stevens, 2009). Plastic bags, bottles, discarded sports balls, and even metal shopping carts are often seen in the river by volunteers.
- Invasive species - Fish and other marine life that has escaped from farming or residential containment can introduce disease or take over native habitat and food sources. Even turtles can be invasive. In Southern California watersheds, red-eared sliders released by pet owners threaten the habitats and health of native California western pond turtle (U.S. Geological Survey, 2014).
- Fishing and Poaching -
What will happen when once-through cooling stops?
The river temperature will lower near the power plants, but scientists hypothesize that the sea turtles in the river may still stay in the San Gabriel River. Ongoing observation of the wildlife - especially the pacific green sea turtle citizen science program - will be important in measuring the effects of shutting down the power plants' once-through cooling systems.
Ready to learn more about once-through cooling?
Continue Exploring
Our next section for suggested reading covers the use of once-through cooling and its effects on the river.
References
Ngo, C., Schwanemann, K., Sompramotjit, S., & Landon-Stevens, L. (2009). Water quality testing of the Los Cerritos Channel and San Gabriel River. Retrieved from http://issuu.com/kjena/docs/2009_report-chemhydro?e=6086987/8821504
LADPW. (2006). The San Gabriel River Past and Present. The San Gabriel River Corridor Master Plan, 29-43. Retrieved from http://ladpw.org/wmd/watershed/sg/mp/docs/SGR_MP.pdf
United States Census Bureau. (2014, July 8). Los Angeles County QuickFacts from the US Census Bureau. Retrieved August 08, 2014.
U.S. Geological Survey. (2014). Nonindigenous Aquatic Species Database. Gainesville, Florida. Retrieved August 16, 2014.
LADPW. (2006). The San Gabriel River Past and Present. The San Gabriel River Corridor Master Plan, 29-43. Retrieved from http://ladpw.org/wmd/watershed/sg/mp/docs/SGR_MP.pdf
United States Census Bureau. (2014, July 8). Los Angeles County QuickFacts from the US Census Bureau. Retrieved August 08, 2014.
U.S. Geological Survey. (2014). Nonindigenous Aquatic Species Database. Gainesville, Florida. Retrieved August 16, 2014.