What happens to dragonfly larvae if their pond dries up??

[zail]

Today I visited Priddy Mineries and the bottom pool (Waldegrave pool) was almost dried up with just a couple of puddles left where there is usually a big, although shallow, pond. Some small fish were trapped in one of the puddles - some people with a net caught a few of them and took them to a nearby other pool that's deeper and already has the same type of fish in it. I saw a few dragonfly larvae - emporerer, downy emerald and a couple more types that I couldn't identify and some of them got transfered to the other pond along with the fish but what will happen to those left in the dried up pond? Can they survive without water or will they die? Should they be taken to the other pond? Should I have brought some to my home pond if they are likely to die or should I just accept that's what happens and leave them? Any advice welcome!

[zail]

Anyone know?

[Deb London]

I don't know (sorry) but I've been wondering the same thing! An incredible number of local ponds are now dry. I assume they are all dead.

(Serves them right for not laying in my pond yet - they would be assured of the equivalent of first class accommodation with room service and a mini bar with all that they can drink, topped up daily if necessary).

[zail]

Thatnks Deb London - I've e-mailed the BDS to ask too... keep thinking maybe I should have relocated some to my pond but it's a tiny pond and I'm not sure it has the eco system they would require (or indeed whether it would be legal or even advisable to do so!)

[RoyW]

I believe that I'm correct in saying that there is no evidence that dragonfly larva can survive if the pond that they are in dries up completely. It is perhaps possible that some species may be able to survive in the mud if a pond temporarily dries up for a short period (some larva have been found to be able to survive becoming frozen into ice for a short period of time, but dessication will lead to entirely different problems).
There are species that have lifecycles which are adapted to allow them to live in ponds that dry up over the summer, and elsewhere in the world there are species that can breed in very tempory ponds that last for only a month or two (+ a few that seem able to survive in damp leaf litter). The British species that are most often associated with habitats that dry up are the Emerald Damselflies and (to some extent) Darter dragonflies. These species are often seen laying there eggs into plants above dry ponds, or dropping them into dry areas around the edges of ponds. The eggs may not hatch until the following spring, and the larvae then grow quickly and emerge as adults during the summer as the ponds are drying up. These species may be poorly adapted to compete with other species (and fish) so are able to survive better where these are not able to survive.

As for whether to save the larva or not - that would be entirely a personal descision. Unless there was a very scarce species which breed at the pond, and at very few other sites, it is highly unlikely to have any lasting effect on the species concerned. It's just unfortunate for the individuals concerned. Dragonflies of most species have very good dispersal abilities, ponds naturally dry out but they are readily able to colonise new sites (unless they require very specific conditions).
It may become more of a problem if our climate becomes warmer, and the demand for water increases though. Many dragonflies in the warmer parts of Europe are threatened because of the amount of water that people are taking, which is leading to many water bodies becoming dry during the summer.

[zail]

Thanks RoyW for such a detailed response

[Ukwildlifeo]

Just to add to RoyW's excellent post, ponds drying out can be beneficial for some species, such as scarce emerald, which prefer ponds with no fish as the active larvae are easy pickings for them and the drying out also removes the other competing species. As Roy said they survive the dry period and overwinter as eggs and then the nymphs go from new hatched to adult in a matter of weeks!

[George Carlin]

Hi there, first time poster here.

I'm doing an article for the Mid-Somerset series based in Wells.

I'm currently writing an article about the Priddy Mineries and in particular the pools, as I to have noticed the steady decline to mere puddles, in recent months. From research I've discovered that the Somerset Wildlife trust used to have a mutual agreement with the Waldegrave Estate but in 2006 this agreement ceased, I've yet to discover why but will follow that up. Perhaps this might go someway to explaining why the area has become so overgrown with reeds. I assume that lack of wardens to maintain it and the recent hot summer, are main reasons why it has dried up so rapidly.

Though after a visit on Sunday, hoping that the recent heavy rainfall might have made a minor improvement, left me disapointed.

The following is an extract from my article, I was wondering if you could confirm that it is 20 species and that the Downy Emerald can be found there.

"The site has long since been retired from its lead working days and today is classed as a Site of Special Scientific Interest (SSSI). Home to many plant and animal species, including 20 species of dragonflies one of which, the Downy Emerald, can only be found at that site in the Mendips. Many species of water bug and almost all British amphibians are native to the pools, of which only the Natterjack Toad is absent."

Please feel free to correct me in the above if I have, understated or misspoken about the subject.

Any information that you could provide me to strengthen the article and our case for the preservation of the Mineries would be gratefully received. I found these forums whilst researching the Mineries and thought that I would let you know that the issue been recognised and will appear in the following weeks paper.

Thanks in advance.

Tom