September 22, 2014

Drought, Dogs and Crayfish

 

PHOTO BY ROSI DAGIT

Drought, Dogs and Crayfish

From left, Jason Fannon, Maya Demontreux, Susan Nissman, Stacy Sledge and Tanya Starcevich with the winning posters in front of the Topanga Library.

On Wednesday, May 28, the Topanga Library was covered with posters created by fifth graders from Topanga Elementary School, students from the Topanga Mountain School and Topanga Youth Wildlife Project.

The contest asked students to design posters to help educate beach visitors about how dogs on the beach can lead to bacterial exceedances, while reflecting the creativity and passion of our students.

The Judges—Stacy Sledge and Tanya Starcevich of the Topanga Town Council; Susan Nissman, Sr. Deputy for Supervisor Yaroslavsky; and Lucie Kim, representing the LA County Department of Beaches and Harbor (LACDBH); and Watershed Steward Project members, Lizzy Montgomery and Crystal Garcia—closely examined each poster. After much deliberation, first place went to Slater Anton, second place to Maya Demontreux and third place to Jason Fannon. The posters will be made into signs and posted at Topanga Beach by LACDBH to help with public outreach efforts.

The meeting highlighted the collaboration of local students with UCLA undergraduates under the direction of Dr. Jenny Jay.

The Topanga Town Council provided “Adopt a Dolphin” kits donated by the Ocean Conservation Society as prizes. With the kits, students can follow the adventures of a local dolphin online, while cuddling up with a soft dolphin pillow pet.

On Friday, May 30, the judges presented the prizes to the students at morning assembly.

STUDENT SCIENTISTS

As part of their Service Learning class with Dr. Jay, the UCLA undergrads assisted the local students with data collection and analysis during a field trip to Topanga Beach on Friday, May 2.

The research effort involved students collecting and testing sand samples for a reservoir of bacteria living in the sand, and how that might contribute to the bacteria counts in the ocean.

Working with their UCLA mentors, the local students developed hypotheses, collected samples, analyzed the data and wrote up their conclusions. The research posters were presented at a field day at UCLA on May 16.

TOPANGA SOURCE IDENTIFICATION STUDY

This educational element is part of a larger Topanga Source Identification Study, which began in 2013 and will conclude in October 2014. The RCDSMM continues to work with Dr. Jay and others to identify sources of bacterial contamination at Topanga Beach and make recommendations to reduce those problems.

Preliminary study results outline the impacts of the drought on Topanga Creek and highlight ways to reduce the stress on our creek. In addition to the lack of rainfall, what makes this drought even more challenging than in the past is that there is an increased number of hot days and fewer individuals remaining in the endangered fish population.

Portions of Topanga Creek that have not been dry since the early 1990s are already without water. This forces all the aquatic species into sharing refugia pools that are fed by seeps and springs. Numbers of native frogs, newts and fishes are low this year compared to past years throughout the creek.

With the hottest months ahead of us, we need to do everything we can to prevent pollution from getting into the creek and from taking water out of the creek. Several strategies were discussed: recycling pool water for irrigation, reducing water use in washing dishes, taking shorter showers and using shower water to flush toilets, and using clever strategies for reusing washing machine grey water for irrigation.

DOG POOP ON THE BEACH

Dr. Vanessa Thulsiraj, a postdoctoral fellow in Dr. Jay’s lab provided a more technical update of the bacterial source studies. Based on the preliminary results, the bacteria are generated either within Topanga lagoon or at the beach. Using molecular markers, it appears that gulls, dogs and humans all share some responsibility. The most interesting pattern observed is that during the summer months, when there is more activity at the beach, the dog contribution is less. During the winter months, the contribution increases significantly. Clearly, dog poop on the beach contributes to the bacterial problem.

Like all the beaches in southern California, Topanga Beach got fairly good grades from the Heal the Bay Beach Report Card for 2013-2014, compared to previous years when it made the Beach Bummer list among the 10 worst beaches.

The challenge is to develop strategies to improve beach water quality when the rains return. The RCDSMM and UCLA teams are investigating several possible solutions, but by far the most important is to restore the function of Topanga lagoon, so that it changes from a source of bacteria to a solution for recycling and naturally cleansing the water.

CRAYFISH REMOVAL PROJECT

A presentation of the Crayfish Removal Project by Crystal Garcia and Lizzy Montgomery traced the initial introduction in 2000 of crayfish into Topanga Creek to at least one local looking for a steady source of fishing bait. Other introductions may have followed.

There have been examples of releasing non-native species into the creek throughout the mountains, but Topanga was one of the last creeks to be invaded. Working with student volunteers from the Topanga Wildlife Youth Project and Calvary Christian School, more than 400 crayfish have been hand-captured and removed since September 2013.

The Topanga Wildlife Youth Project students have contributed to the outreach effort by developing a website and ecozine (www.topangawildlife.org

), and actively participate in hands-on efforts to learn about local ecosystems.

The weekly effort by student volunteers resulted in more than 1,000 hours of fishing and allowed comparison of the 200-meter reach where crayfish were removed, with another 200-meter reach where they remained. Crystal and Lizzy analyzed data collected not only with student help, but also during snorkel surveys and annual stream surveys.

In addition to the drought impacts, the crayfish are also wreaking havoc in the creek. Comparison of aquatic bug numbers and species suggests that crayfish are using that food source and changing the community composition of the bugs. The number of newts and newt egg masses has plummeted as the crayfish population has exploded. The snorkel team even rescued a newt being attacked by crayfish in April.

Unfortunately, the crayfish have taken advantage of the low flow and warmer water to spread throughout the creek and crayfish invasions of drought-time Mediterranean wetlands are currently occurring on a global scale. It is not realistic to think we can remove them all, even though the RCDSMM has a special permit to supervise the hand-removal effort. No traps and no fishing are allowed in the creek.

So, what to do? Pray for rain this winter! Monitoring in Trancas Creek by Dr. Lee Kats of Pepperdine University has shown that crayfish get washed out in big storm events and that is the time to really put effort into removal. Meanwhile, we can continue with our small effort and hope that Topanga Creek remains resilient enough to recover. We hope to share the final results of all this research in the fall.

Become a Topanga Creek Stream Team volunteer and join 150 of your friends to help with creek cleanups, water quality testing, crayfish and invasive plant removal and other creek adventures. To get on the listserve, e-mail Rosi at rdagit@rcdsmm.org.­­­­­­