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Wednesday, April 03, 2013

Secretive and Endangered Amphibian Is One of Malibu’s Most Unusual Residents

• California Newts Are Species of Special Concern but Continue to Face Survival Challenges Despite Protections

BY SUZANNE GULDIMANN

The California newt, Taricha torosa, is the largest of the five members of the salamander family that live in the Malibu area, growing to a length of eight inches, but this robust orange and yellow amphibian is seldom seen.
 California newts are  born in water, where they developing gills, legs and and finally lungs during a tadpole-like larval phase.
The larva then become air-breathing and terrestrial, spending summer and autumn on land in leaf litter, where it hunts for small invertebrates.
However, during mating season in the winter and spring, this secretive amphibian returns to the water.
The California newt is a California species of special concern. In the Santa Monica Mountains it is only found in and around the most pristine creeks and seasonal pools.
Malibu residents usually encounter the California newt during the amphibian’s terrestrial phase, when individuals occasionally find their way into a house or turn up under a plant pot in the garden.
On land they hide under leaf litter, where they hunt for small insects, worms and slugs. During their aquatic phase, they keep out of sight in the shade of stones or under floating leaves. Larval newts can easily be mistaken for frog tadpoles.
Although they have neither claws nor teeth capable of biting anything tougher than slugs, California newts have a highly effective defense mechanism. When they are threatened they secrete a powerful neurotoxin that can incapacitate and even kill most potential predators. Known as tarichatoxin or tetrodotoxin, this biological weapon is the same neurotoxin found in pufferfish.
The toxin can enter the body through cuts or broken skin, reportedly causing a burning sensation followed by numbness. Research indicates that the toxin shows promise as a potential local anesthetic-but is only thought to be fatal in humans when ingested. Poisoning incidents are extremely rare and several species of Taricha are sold as pets.
California newts traditionally only have a couple of natural predators. Garter snakes have a high tolerance to the toxin and prey on adult newts.
The larvae of some species of dragonfly and caddisfly consume newt eggs and newt larvae. Adult newts will also sometimes consume their own larvae.
While tarichtoxin protects California newts from most predators, it doesn’t apparently deter invasive species that include crawfish, bullfrogs and mosquito fish from eating eggs and larvae. The crawfish also has a a reputation for attacking adult newts.
Tarichtoxin is also no protection against the two biggest threats to newts: habitat loss and pollution.
“They need clean water,” National Park Service ecologist Katy Delaney told the Malibu Surfside News during a recent watershed press tour. “You only find them in the cleanest water,” she said.
Delaney is part of an NPS amphibian monitoring program and participates in the water project advocacy organization Heal the Bay’s Stream Team monitoring program.
According to Delaney, many newt ponds and stream pools used for breeding have been destroyed for development, or impacted by sedimentation caused by construction, wildfires and agriculture. The remaining habitat is increasingly impacted by non-native species.
“The best way to protect native amphibians is to keep exotic predators out,” Delaney said.
“Once mosquito fish and crayfish enter a stream it’s difficult to get rid of them.”
A brief prepared for the NPS states. “In 2003, Pepperdine [University] researchers launched a project to remove crayfish from Trancas Creek. Their efforts have helped amphibian populations rebound, but ongoing removal will be required.”
Research indicates that, while California newt habitat is increasingly fragmented and impacted by human activities, the amphibian’s decline in Southern California began at the end of the last Ice Age and its chance of continued survival in the drier and hotter climate predicted for the future is increasingly slim, research indicates.
In the mythology of several California Native American cultures, salamanders have the power to protect the purity of the water they live in.
This unusual amphibian is still an indicator of stream health and its presence remains a good omen.

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