Warning! This post contains images which some readers may find distressing.
Alert: Mass Mortality of Frogs Recorded in Kildare Pond
On the 24th of February 2014, The Herpetological Society of Ireland (H.S.I) received a report of a mass die-off of common frogs at a location in Co. Kildare. Within 24 hours the H.S.I were able to send a team to the site (led by Senior Science Officer Rob Gandola), in order to take water samples and collect dead animals for testing.
The conditions encountered at the site were extremely concerning, with an estimated 250-300 dead or dying frogs found in an area approximately 300m2, with the majority of the frogs found within 3m of the breeding pond. The primary symptoms observed were dry and cracking skin. The torn/damaged skin seemed to be focused on the neck area on many of the specimens. A smaller number of specimens displayed symptoms such as patches of red discolouration on the skin and areas of focal necrosis (small patches of dead tissue). Several specimens displayed no external symptoms outside of death or weakness. The science team took skin swabs which have been dispatched for DNA analysis in an effort to identify a potential cause for this mass mortality event. Analysis of water samples returned results that are within the normal range for a healthy habitat.
Photos taken by the science team show frogs found dead within metres of the breeding pond. Photos courtesy of Collie Ennis
This incident is similar to one reported from Waterford last year. As with this incident, the H.S.I sent a team to investigate and collect samples for further analysis. The society’s primary concern was that this may be an outbreak of an infectious agent such as Ranavirus or the amphibian chytrid fungus. The results of the analysis of last year’s die-off, performed at the Zoological Society of London, suggested that neither the Chytrid fungus nor Ranavirus were present in the samples collected.
Frog found at the Waterford Site 2013. Photo courtesy of Lisa Fay Davin
The common frog (Rana temporaria) is a protected species and forms an important part of Ireland’s natural heritage. It is absolutely vital that any threats to this species be identified and dealt with as soon as they emerge, particularly in the light of the catastrophic collapse of amphibian populations worldwide. Science Officer Cat Hendry emphasises the importance of continued vigilance: “While recent sampling of both healthy amphibian populations and instances of mass die-offs has not detected the presence of Chytrid or Ranavirus, that does not necessarily mean that these threats are not present in Ireland, rather that they were just not present in the sample taken. This is why it is critical that surveys are continued and any suspicious die-off is sampled.” The early stages of an investigation such as this one will involve a process of elimination. It may be that a less ominous explanation such as opportunistic predation is to blame, though there is little evidence to support this viewpoint as yet. “Each time we get a negative detection result it is a good thing for Ireland’s amphibians, however there is clearly some underlying issue causing these die-offs, and the H.S.I is doing everything we can to get to the bottom of it”.
A close up of the frogs found in Kildare, highlighting the symptoms observed. Photo courtesy of Collie Ennis
The Herpetological Society Of Ireland encourages anyone who observes similar incidents to contact us immediately via our website www.thehsi.org so that we can perform an investigation. Take note of the date, the location and anything noteworthy in the general area. If you can take photos safely and without disturbing wildlife this would also be beneficial. As with any potentially infectious site we would encourage the public to use caution and disinfect footwear after encountering such an event to reduce the risk that they will inadvertently spread pathogens to another habitat
The H.S.I would like to take this opportunity to thank the vigilant member of the public who brought this to our attention.
This story was covered by Michelle Hennessy in The Journal.