It's raining again! 10.5mm so far. We probably won't get much more but it will be good for the crops and frogs. They are still quiet - and I have been amazed at how little water the pond has been losing to evaporation over the last month, despite the warm (20C days) weather we've had.

Last night, I discovered that the comment-email function on this blog wasn't working, and read through some comments that I'd missed. An interesting comment was by Michael Angel on End of Season, where I'd been thinking about whether my spraying glyphosate might have affected the frogs in the dam. Michael reckoned the surfactant in the glyphosate could be a bigger problem than the glyphosate itself. I've had a brief look around and found this online thesis by RM Mann:

Toxicological Impact of Agricultural Surfactants on Australian Frogs

Much of it has been published elsewhere, including the reference I'd used on glyphosate toxicity in the earlier post. It may be a useful link for people who don't have access to the journal articles.

Looking at it very briefly, surfactants seem to affect tadpoles at 1.1 mg/L and higher, depending on type. I'd estimated 250mg surfactant (50ml Glyphosate 450 containing 10% surfactant, 5% landing on water in the dam) added to 150L or more of water, so there could have been a mild effect. What interests me more though, is how the surfactants in our shampoo, washing detergent and soap might have affected the frogs. They were living and breeding in our greywater, after some treatment in a septic tank and a bit of 'biofiltration' in the dam. But that's a calculation for another day!