Andrew Gorton's picture

frog spawn distribution

Looking at a pond near me, I noticed that there was a lot of frog spawn.

It all seemed confined to the Northwest corner of the pond, around the edges, and not anwhere else in the pond.

It looked as though the water was deeper there than anywhere else, so could this account for it, or are there other factors, such as temperature, that affects frog spawn distribution?

Andrew

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Masked Marvel's picture

I believe they normally go

I believe they normally go for the warmest part of the pond as this will speed up the development of the eggs. This should be the sunniest and shallowest part of the pond which would typically be along the southern bank. However, if there are tall trees along the southern side, the northern edge will get more sun and therefore be warmer.

Thistle's picture

Freezing?

I would have thought that the edges are where the water freezes first. I understand that the spawn if fairly immune from frost damage but I'd have thought that avoiding freezing conditions would still help to speed development.

Ian

Alurophile's picture

Common Frog spawning sites

Choice of spawning site is dictated primarily by water depth. Rana temporaria (the Common Frog) lays spawn clumps which do not float. It is fundamentally a creature of flooded fields. If supporting plants aren't available, the spawn will sink & most probably die. The edges of water bodies are often shallow as well as vegetated, hence the abundance of frogspawn in such places.
There is also the testosterone factor, which excites other frogs, which often spawn en masse. Whilst is is not good for frogspawn to freeze, the dehydration of the jelly gives a leathery surface layer which tends to insulate the embryos underneath.