Golden Frog Extinction Outline Draft #1

This topic submitted by Britton Windeler ( windelbd@miamioh.edu) at 4:30 PM on 3/26/05.

Miami has 100s of acres of beautiful Natural Areas which lend themselves to research projects! (Quicktime movie~4 mb). On the same walk, I spotted my first garter snake of the spring! In another 1 mb quicktime movie, a pair of mallard ducks lands in Harkers Run in Bachelor Woods

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Golden Toad (Bufo periglenes) Introduction
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The Extinction of the Golden Toad (class=SpellE>Bufostyle='font-family:Arial'> periglenes) style='font-family:Arial;font-style:normal;mso-bidi-font-style:italic'>–
Symptom of a Worldwide Crisis

 

src="Golden%20Toad%20Outline_files/image002.jpg" v:shapes="_x0000_i1025">

 

 

style='mso-list:Ignore'>I.        
Habitat

style='mso-list:Ignore'>A.     
Golden toads occupied a few square miles in the class=SpellE>Monteverde Cloud Forest Reserve in northern w:st="on">Costa Rica

style='mso-list:Ignore'>B.     
Habitat occurred at about 2000 m ASL

style='mso-list:Ignore'>C.     
Golden toads were thought to live under fallen
leaves and moss

style='mso-list:Ignore'>1.      
Sightings of golden toads were limited to about
one week per year, when they came out to breed

 

style='mso-list:Ignore'>II.      
Mating habits

style='mso-list:Ignore'>A.     
forstyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'> a
week in April every year, thousands of these brilliant toads gathered in pools
in a breeding orgy.

style='mso-list:Ignore'>1.      
The golden toad is renowned for its
brilliant color- it is the only known species of toad that is not gray or brown

style='mso-list:Ignore'>2.      
Golden toads displayed extreme sexual dimorphismstyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>a)      
Males- golden

style='mso-list:Ignore'>b)     
Females- range from olive to dark brown
or black, spotted with scarlet

style='mso-list:Ignore'>3.      

Males outnumbered females about 8 to 1

style='mso-list:Ignore'>B.     
Mating would occur near temporary water
pools

style='mso-list:Ignore'>1.      
Unable to differentiate gender, males
would clasp anything that moves

style='mso-list:Ignore'>a)      
Males possessed a special vibration
signal to relay gender, and disengage other males

style='mso-list:Ignore'>b)     
Inadvertent coupling with other species
of frogs could occur, lasting for days

style='mso-list:Ignore'>2.      
Males would remain attached to females
in
amplexus until the female laid eggsstyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>a)      
Females would lay approx. 200 to 400 eggsstyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>b)     
After hatching- larvae remain in water
for five weeks before metamorphosis into their terrestrial form

 

style='mso-list:Ignore'>III.     
Decline/Extinction

style='mso-list:Ignore'>A.     
Discovered in 1964

style='mso-list:Ignore'>B.     
The April breeding frenzy was the only
time that the toads were ever observed

style='mso-list:Ignore'>C.     
In 1987, more than 1500 golden toads
were observed during the breeding period

style='mso-list:Ignore'>D.    
1988 and 1989- onle
one toad was observed

style='mso-list:Ignore'>1.      
The reserve also had several captive
frogs, but they died of unknown causes in the mid 1980’s.

style='mso-list:Ignore'>2.      
Other species of amphibians declined at
this time also

style='mso-list:Ignore'>E.     
1992- the
golden toad was pronounced almost certainly extinct, as the last one had been
sighted in 1989.

 

style='mso-list:Ignore'>IV.   
Reasons for decline

style='mso-list:Ignore'>A.     
Climactic

style='mso-list:Ignore'>1.      
1986-1987 El Nino resulted in the
lowest rainfall on record at Monteverde 2

style='mso-list:Ignore'>2.      
Low rainfall could have caused chemical
pollutants to become concentrated in breeding pools

style='mso-list:Ignore'>3.      
Changing climate alters the patterns of
temperature, mist, and rainfall, causing cloudbanks to form at increasing
elevations, and compressing the possible range for cloud forests.style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>B.     
Pollutants

style='mso-list:Ignore'>1.      

For many pesticides, there isn’t
sufficient data regarding its negative effect on amphibians.style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>a)      
Atrazine is probably the most widely used
herbicide in the world and one of the most common contaminants in ground and
surface waters.

style='mso-list:Ignore'>b)     
atrazine induced class=SpellE>hermaphroditism at concentrations of only 0.1 ppb (Hayes et
al. 2002) when administered throughout larval development of African clawed
frogs

style='mso-list:Ignore'>c)      
Most water sources in the w:st="on">United States,
including rainwater, have been found to exceed that concentrationstyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>d)     
This concentration is 30 times less than the US
EPA-mandated drinking water standard.5

style='mso-list:Ignore'>e)      
10–92%
of male leopard frogs in different regions of the w:st="on">United States show class=SpellE>gonadal
abnormalities such as retarded development and class=SpellE>hermaphroditism

style='mso-list:Ignore'>C.     
Ultraviolet radiation

style='mso-list:Ignore'>1.      
solar ultraviolet (UV) B radiation (of
wavelength 280-320 nm) damage in the declines of R. cascadae
and B. boreas boreas in w:st="on">Oregonstyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>2.      
Blaustein and Wake
(1995) have recently suggested that UV exposure impairs immune function, making
the larvae more susceptible to infection by the fungus Saprolegnia,
which naturally occurs in lakes and ponds.

style='mso-list:Ignore'>D.    
Fungal
skin infections

style='mso-list:Ignore'>1.      

The
underlying cause of the decline of many amphibians could be due to a fungal
disease known as chytridiomycosis.
style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>a)      
Initial
diagnosis is difficult - occasional abnormal epidermal sloughing and
ulceration, or hemorrhage in the skin were the only gross lesions encountered
and these were rare (Fig. 1).4

style='mso-list:Ignore'>b)     
Diagnosis
is usually only possible through examination of a freshly preserved carcass
under an electron microscope.

style='mso-list:Ignore'>c)      

The
result of this type of infection is skin damage, leading to skin thickening and
eventual suffocation and/or dehydration

 

style='mso-list:Ignore'>V.     
Reasons
for Concern

style='mso-list:Ignore'>A.     
Frogs
and toads are extremely sensitive indicators of environmental changes
style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>1.      

Uptake
of oxygen and water through their skin can increase concentrations of
pollutants

style='mso-list:Ignore'>2.      
The
life cycle of frogs and toads exposes them to water and airborne contaminants
style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>B.     
Tadpoles
eat aquatic plants

style='mso-list:Ignore'>C.     
Adults
eat potentially disease-carrying insects

style='mso-list:Ignore'>D.    
Amphibians
are a vital part of the food web for many other species of animals
style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>E.     
The
Costa Rican government has adopted a policy towards sustainable class=GramE>agriculture which
includes the promotion of Integrated Pest
Management (IPM) and non-chemical crop protection. At the same time, pesticides
remain exempt from taxes and duties, which inevitably increases
their use. 6

style='mso-list:Ignore'>F.     
Research
at Costa Rica’s National University shows that in 1993 about 18% of all
pesticide imports (by volume) were in the World Health Organisation
toxicity classification categories Ia, extremely
hazardous, or Ib, highly hazardous(2). 6
style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>G.    
In class=GramE>1993 the banana sector accounted for 57% of all pesticides
sales, despite occupying less than 10% of w:st="on">Costa Rica’s agricultural area.style='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>H.     
a case of massive sterilization of approximately
1,500 workers in Costa Rica,
due to the exposure to a toxic pesticide called DBCP, applied in large
commercial banana plantations

 

style='mso-list:Ignore'>VI.   
Implications for amphibians worldwidestyle='mso-bidi-font-size:10.0pt;mso-bidi-font-family:Arial;color:black'>

style='mso-list:Ignore'>A.     

According
to the IUCN Red List of Threatened Species, at least 1,856 amphibian species class=GramE>are threatened
with extinction, representing 32 percent of
all species.

style='mso-list:Ignore'>B.     
This is considerably higher than the comparable
figures for birds (12 %) and mammals (23%), the only other groups for which
comprehensive global assessments have been completed. style='mso-tab-count:2'>

 

 

 

Working Bibliography

 

Sarkar, class=SpellE>Sahotra (1996). Ecological Theory and
Anuran Declines.
Biosciencestyle='font-family:Arial;mso-bidi-font-family:"Times New Roman";font-style:
normal;mso-bidi-font-style:italic'>,
46style='font-family:Arial;mso-bidi-font-family:"Times New Roman";font-style:
normal;mso-bidi-font-style:italic'> (3), 199-208.

 

 

Pounds JA, Crump ML. (1994). class=GramE>Amphibian declines and climate disturbance: the case of the style='font-family:Arial;mso-bidi-font-family:"Times New Roman";mso-bidi-font-weight:
bold;font-style:normal;mso-bidi-font-style:italic'>golden
style='mso-bidi-font-style:normal'> toad and the harlequin frog.
Conservation Biology, style='mso-bidi-font-style:normal'>8, 72-85.

 

class=GramE>Blaustein w:st="on">AR, Wake DB, Sousa
WP.
(1994). Amphibian declines: judging stability, persistence, and
susceptibility of populations to local and global extinctions. style='mso-bidi-font-style:normal'>Conservation Biology, 8, 60-71.

 

Daszak, P., Cunningham, A.A. & Hyatt, A.D. “Amphibian Chytridiomycosis and Emerging
Infectious Diseases of Wildlife.”
Accessed via the web address href="http://www.vet.uga.edu/ivcvm/2000/Daszak/Daszak.htm">http://www.vet.uga.edu/ivcvm/2000/Daszak/Daszak.htmstyle='mso-spacerun:yes'> Viewed March 25, 2005.

 

Hayes, T., class=SpellE>Haston, K., Tsui, M., Hoang,
C.H., and Vonk, A. “
class=articletitle>Atrazine-Induced Hermaphroditism
at 0.1 ppb in American Leopard Frogs (Rana class=SpellE>pipiens): Laboratory and Field Evidence.” class=GramE>Environmental
Health Perspectives
, 111 (4).class=medium-normal>

 

Agneclass=GramE>, S. and Waibel, H. (1997). class=GramE>“Pesticide Policy in w:st="on">Costa Rica.” style='mso-bidi-font-style:normal'>Pesticides News 36, 8-10.class=medium-normal>

 



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