Amphibians: Indicators of Environmental Conditions . Michael Ellefson Joe Ryan. Why a good indicator?. Amphibians breath through their skin, which allow toxins/chemicals to be absorbed into their body. Salamander Population Decline Rising levels of Acid Deposition
Amphibians: Indicators of Environmental Conditions
Salamander Population Decline
Rising levels of Acid Deposition
Rising levels of Pesticides (TPT in particular)
Rising occurrences of Viruses (Particularly RRV ATV)
Rise in levels of Heavy Metals (Particularly Cadmium)
Decline in Frog Populations
Rising occurrences of Parasites (Particularly Ribeiroia)
Rising levels of Pesticides (Particularly Atrozine and Methoprene)
Tennessee State University Study showed that TPT made natural killer cells in humans to become powerless in their fight against tumors and viral onslaughts
TPT and Salamanders
Study showed TPT causes mortality and lower feeding rates in the Streamside Salamander (Ambystoma barbouri)
Lower feeding rates cause the salamanders to metamorphosis later in life, making the age of sexual maturity later
Eggs exposed to 5 ug/L of TPT were killed 93% of the time
Eggs exposed to 1 ug/L didn’t have any mortality, but decreased their feeding rate
Professor James Petranka’s study compared the number of salamanders in habitats left untouched by humans to habitats that had had extensive logging of trees
Of the estimated salamander population in North Carolina, 80% were found in streams passing through undisturbed forests, while 20% were found in streams that were next to developed land.
The dramatic difference is thought to be caused by fertilizer runoff which increases the pH in the waterways
Petranka estimates that 14 million salamanders a year were killed in North Carolina alone because of habitat destruction
Low concentrations occur naturally in environment
Manure plants, metal refineries, and pesticides used on farms are major sources of cadmium increase
Cadmium poses sever implication for humans
It causes diarrhea, stomach pains, severe vomiting, weakened bones, infertility, damage to central nervous system, damage to immune system, psychological disorders, and possibly DNA damage or cancer development
LD-50 occurs at 227.3 mu g/L Cd in less than 10 days and 193.1 mu g/L Cd in less than 24 hours in salamander eggs
During Metamorphosis, these concentrations account for stunted growth in the limbs
At levels of 12.8 mu g/L Cd, no mortalities were recorded, nor were any restrictions on growth
Ultraviolet radiation has been known to disturb amphibian development by causing damage to the immune system and causing genetic disorders. This has been getting worse with the decline of the ozone layer.
Ultraviolet rays can kill amphibian embryos, larvae, and cause serious eye damage in frogs. However, this does not explain the deformities.
Pesticide pollution was put forth as a possible solution because Retinoid, which is similar to the pesticide methoprene, plays an important role in amphibian development, even in hind limb development. However, they could not reporduce this with methoprene.
More recently, an endocrinologist from Berkeley, Tyrone Hayes, targeted atrazine as a possible culprit.
Atrazine is a weed killer. It has been shown to chemically castrate and feminize male frogs.
Many deformed frogs came from atrazine contaminated water.
Atrazine has also been known to weaken frogs immune systems, making them more vulnerable to parasites.