Sunday, 3 June 2012

Santa Cruz Long-Toed Salamander



The Santa Cruz long-toed salamander (Ambystoma macrodactylum croceum) is an endangered subspecies of the long-toed salamander, which is found only close to a few isolated ponds in Santa Cruz County and Monterey County, California. It has a black body, broken yellow or orange irregular striping along its spine, and a tail fin well designed for swimming. Like other mole salamanders it is found near pools or slow moving steams; this creature has a very secretive lifestyle, making it difficult to find.


Comparison with the Common Long-toed Salamander

The Santa Cruz long-toed salamander has a range separate with the more common long-toed salamander. Whereas the range of the long-toed salamander is from Tuolumne County north, the Santa Cruz long-toed salamander is found only near a few isolated ponds in Santa Cruz and Monterey counties. Like other long-toed salamanders, its belly is sooty to dark brown, and it has tubercles on its feet. The Santa Cruz long-toed salamander has an irregular broken yellow stripe on its back, whereas the common long-toed salamander has a more regular yellow vertical stripe. Both species have twelve or thirteen costal grooves visible from the side. The Santa Cruz long-toed salamander has a measurable degree of mitochondrial DNA genetic distance from the 'coastal' or 'western' subspecies of long-toed salamander. The genetic relationship, however, is still unclear as more evidence is needed from additional genes and individuals (Thompson and Russell 2005).
In both species, eggs are laid singly near the water surface on rushlike spikes, but sometimes in small clusters at the base of logs or sticking to vegetation in the deeper parts of a pond. Hatching larvae are approximately ten millimeters long, and in their first summer, they grow to 50 to 100 millimeters. But the Santa Cruz long-toed salamander is generally considered the smaller species. The precise times of migration for both species, to and from the breeding ponds, occur during periods of sustained nighttime rainfall.

Valencia Lagoon, the modern discovery site

On December 2, 1954 the Santa Cruz Long-toed Salamander was discovered in Valencia Lagoon by R.W. Russell and James Anderson. This small seasonal lagoon clogged with cattails in Aptos, California, measured only about 30 meters by 150 meters (100 feet by 500 feet) at that time. Caltrans filled half of the lagoon with a widening of State Route 1 in the year 1968. The next study of Valencia Lagoon occurred in 1974 by Earth Metrics, whose staff examined the lagoon to develop further migration strategies to allow the creature to better breed and migrate; that study also called for the permanent protection of Valencia Lagoon, which was later effected when the State of California purchased the lagoon. Hogan's study also noted the adverse effects of siltation that were occurring in Valencia Lagoon from the highway embankment erosion created by widening of Route 1; it was reasoned that the siltation should decrease once the vegetation became re-established on these slopes and allow the habitat to improve; moreover, the Earth Metrics study derived additional mitigation for the county of Santa Cruz to follow in considering any further discretionary actions around Valencia Lagoon. Another mitigation breeding area in the same drainage along Bonita Road was set aside as a protected area.

Life cycle

Most of this salamander's adult life is spent in upland Coast Live Oak forest in small animal burrows during the long dry season (May to October) in coastal California. Once winter rains have soaked the soil and filled ephemeral streams, both males and females migrate up to two kilometers to breeding ponds that exist only in winter. In January, the males arrive at the ponds first, in time to prepare for a night time courtship. When the male and female have completed their courtship, the male deposits a packet of sperm, called the spermatophore, in the water, which the female retrieves and uses to fertilize her eggs. She may lay the eggs singly or in loose clusters of six to eight eggs in shallow water five to eight centimeters deep.
Neither parent tends the eggs, which hatch into tadpoles in March and metamorphose into adult salamanders when the pond begins to dry out. The tadpoles commonly eat small copepods. Predators that eat long-toed salamander larvae include aquatic invertebrates, garter snakes, and other vertebrates (California's Wildlife, 1988). Other species of salamander tadpoles (larvae) compete with those of the long-toed salamander.
The breeding ponds of most species of long-toed salamanders completely dry up during the dry season. It's likely that year-round ponds harbor frogs, fish and other aquatic predators that eat young salamanders, and the salamanders therefore prefer ephemeral ponds. Most species of long-toed salamanders migrate up into nearby forests and do not spend any time near the breeding pond once they have metamorphosed and the pond is dry. But A. m. croceum juveniles often spend their first summer close to the breeding pond in a rodent burrow or rock fissure, only later migrating uphill into the forest. This may be because A. m. croceum breeding ponds retain water all summer.

Outlook for this species

Ambystoma macrodactylum croceum is designated as an endangered species by both the State of California and the Federal Government; however, its limited range and fragile specialized habitat place severe restrictions to the viability of this species. There is no definitive population estimate for the Santa Cruz Long-toed Salamander; however, the numbers are deemed to be quite small. Further disturbance of its limited habitat could lead to this species' extinction (Bury, 1972).