Deformities in amphibians

Question 1

Widespread appearance singe

Answer 1

mid1990s

Question 2

Severity has increased to

Answer 2

15-90% of population

Question 3

Causes

Answer 3

trematode infections
Chemical contaminants

Question 4

Ribeiroia ondatrae trematodes

Answer 4

exposure as adults has little impact on health-> exposure to high levels as tadpoles increases risk of limb deformities (80-100%)

Question 5

Ribeiroia ondatrae trematodes life cycle

Answer 5

infected snails release free-swimming stage that invades developing limbs of tadpoles-> parasites encyst just below skin, typically near hind limbs-> water birds eat infected amphibians-> they release eggs of parasite within their feces-> become infectious to a new crop of snails

Question 6

Infects how many amphibian species

Answer 6

30
consist mostly of species that breed in still-standing waters like lakes
more common in juveniles-adults tend to not live to reproductive age
fast growing species more susceptible

Question 7

Clinical signs

Answer 7

limb malformation->hindlimb more common
abnormal skin webbing

Question 8

Chemical Contaminants

Answer 8

Pesticides, heavy metals, acidification, fertilizers

Question 9

Pesticides

Answer 9

19k-20k different pesticides currently OK’d by EPA
higher potential exposure and increased in-animal concentrations when obtained from water sources
causes metabolic changes
excessive cortisol levels
damages reproductive system
immunosuppression

Question 10

Heavy metals and acidification

Answer 10

metal disrupt many body functions and balances-> oral deformities, increased metabolic rate, lowered larval/tadpole survival, permanent organ damage from toxicosis
-acidification can affect amphibian growth and development->low pH arrests embryo development-> high pH trap embryo inside egg capsule
-work synergistically

Question 11

Fertilizers

Answer 11

high enough nitrate concentrations cause death and developmental anomalies
sources enter aquatic ecosystems through agricultural runoff, livestock, precipitations and effluents from industrial and human waste->ammonia more toxic
Causes: reduced feeding activity, difficulty swimming or ability to complete righting reflex, deformities, endocrine system disruption, reduced hatching success, skewed sex ratio