Bill
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- Jun 2, 2009
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- Lancaster, PA
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In late March I found a pool that had wood frog and spotted salamander eggs. Rafts of r. sylvatica eggs were already established, and I think I had just missed the a. maculatum breeding: the bottom was festooned with spermatophore and there were several dozen fresh egg masses. This is a fairly small pool, about 10 feet across, max 18" depth. It is quite remote, very difficult and ugly to access, and I like to think I'm the only one who pays any attention to it. Since the first visit, I've been returning weekly to monitor the populations. For the first month my dip net was bringing up larvae at a pretty consistent (approx) ratio of 1 a. maculatum to 10 r. sylvatica. For the last 6 weeks I have brought up zero a. maculatum. Today, zero again. Plenty of sylvatica. I really want this population of a. maculatum to flourish.
Several possibilities I have thought of:
*The a. maculatum have morphed. But a parallel group of 6 from that brood in a replica pool at my house has not yet morphed, and I think mine have better conditions for development.
*The a. maculatum larvae are better at eluding capture, maybe as older larvae they are inhabiting a different strata of the pool and my net is missing them.
*I have read that some populations in the northeast are dying out because of acid precipitation. In that case, older adults from the 70's or 80's may keep returning to the pool for their annual mating convention, but no pups are returning to the woods. If there is a threshold PH for a. maculatum larvae development of which someone can inform me, I will check that out.
*One dip several weeks ago brought up a very fat red spotted eastern newt. Predation? I was very tempted to do a dissection but didn't.
Any thoughts would be appreciated.
Several possibilities I have thought of:
*The a. maculatum have morphed. But a parallel group of 6 from that brood in a replica pool at my house has not yet morphed, and I think mine have better conditions for development.
*The a. maculatum larvae are better at eluding capture, maybe as older larvae they are inhabiting a different strata of the pool and my net is missing them.
*I have read that some populations in the northeast are dying out because of acid precipitation. In that case, older adults from the 70's or 80's may keep returning to the pool for their annual mating convention, but no pups are returning to the woods. If there is a threshold PH for a. maculatum larvae development of which someone can inform me, I will check that out.
*One dip several weeks ago brought up a very fat red spotted eastern newt. Predation? I was very tempted to do a dissection but didn't.
Any thoughts would be appreciated.