Upload
mgray11
View
279
Download
0
Tags:
Embed Size (px)
DESCRIPTION
2013 International Symposium on Ranaviruses by Danna Schock
Citation preview
Amphibian ranavirus dynamics in an industrially altered landscape
Danna M. Schock2nd International Symposium on Ranaviruses
Knoxville TN, 27-29 July 2013
Map from the Washington Post
Fort McMurray, AlbertaOilsands, boreal forest, big money & big politics
RV dynamics like prevalence& frequency of outbreaks
Habitat characteristics, Wetland classification
Contaminant levels in amphibian tissues and breeding ponds
Population biology & biomarkers of (chronic) stress
Proximity to disturbancesCan wood frogs be used to monitor ecosystem health in the oil sands?
Establishing field sites – 2012 & 2013
1)Wood frogs breeding at the site
2)In close proximity to air monitoring stations
3)Geographically representative of the landscape*
4)Safe to work
Priority placed on identifying wetlands suitable for long-term monitoring of the oil sands region of Alberta.
Atmospheric deposition and pulses of contaminants into amphibian breeding ponds in the spring
Photo: Dave Cooper, Calgary Herald
Snow sampling March 2013
wood frogs boreal chorus frogs
Canadian toads
Ranaviruses detected widely in wood frogs
12/27 (44%) sites positive at least once from 2010 – 2013
Positive wetlands from Fort Resolution to Fort McMurray
● PCR and/or characteristic lesions and carcasses (~2,200 samples still to screen, including most samples from 2013)
Ranaviruses detected widely in wood frogs
Ranavirus-related die-offs at remote sites (helicopter access only) and highly disturbed sites
Die-offs take place last week of June/first week of July
● irrespective of type of site
● irrespective of spring thaw
Ranaviruses detected widely in wood frogs
The majority of carcasses are tadpoles Gosner stages 37 - 40
All positives sequenced to date are FV3-like
● MCP4/5 primers
● but see Schock et al. 2008 Copeia re “hidden” variability of northern isolates
● additional characterization in progress by J. Brunner
Data collectedBasic information• Species• Snout-Vent-Length• Gosner stage (tadpoles), weight (terrestrials)• Physical abnormalities
Tissue samples• toe/tail clips (several times/year, screen for
RV, Bd)• lethal whole body, once/year, screen for
contaminants and evidence of stress
Water quality• pH & conductivity (handheld meters)• In-depth analysis (3x per active season)
including hardness, and 26 metals, 74 PAH, and 60 NA
Narratives of 3 wetlands
• Jetliner – loss of entire age class
• Tower Road – repeated die-offs, no apparent change in population biology (yet?)
• Gateway – why hasn’t ranavirus been detected here (yet)?
Results – an evolving story
Distribution of mass of terrestrial wood frogs in 2013 at 6 intensively studied sites.
Mass (g)
Jetliner
# o
f in
div
iduals
Jetliner
Jetliner
Wood frog egg masses at Jetliner May 2011
Jetliner Pond
Mass (g) of terrestrial wood frogs 2011 - 2013
2011
2013
2012
# o
f in
div
iduals
Mass (g)
Distribution of mass of terrestrial wood frogs in 2013 at 6 intensively studied sites.
Mass (g)
Tower Road
# o
f in
div
iduals
Tower Road
Tower Road
Distribution of mass of terrestrial wood frogs in 2013 at 6 intensively studied sites.
Mass (g)
Gateway
# o
f in
div
iduals
Gateway
Gateway
Size at metamorphosis is another indication of population health
Snout-vent length (mm) of Gosner Stage 44 wood frogs in 2013
F5,159 = 17.287, P < 0.01aa
b
A role for environmental transmission?
Unrelated 2011 lab study:
Only wood frog tadpoles in reference wetland water and aged tap water became infected.
FV3: apparently “killed” by something in the OSPM water?
Tadpoles in the OSPM water: 85%+ survival Gateway
A role for invertebrates in ranavirus transmission?
• Impede transmission by scavenging carcasses quickly?
• Facilitate transmission or persistence – leeches ?
What about nutrient/energy cycles in these wetlands?
• Die-off years vs non-die-off years?
• Different invertebrate species assemblages?
Data to come:
PCR screening of 2,200+ tissue samples for ranavirus
Water and tissue contaminant analyses
Bio-markers of (chronic) stress – metabolomics, CORT
Other fitness correlates – triglycerides & glycogen
PCA and Regression analyses