leeches in pond

Hello Caudata friends,
This is my first post, so I hope it fits in with the theme of this site. I have friends with a pond in Vermont that is loaded with leeches. 20 years ago it was full of Eastern newts (red-spotted) with few leeches, but when I visited two years ago I was horrified to see a profusion of leeches. I could even see that some of the newts had deformed portions of their bodies. A little bit of research has shown me that these leeches are passing diseases newt-to-newt. Yesterday I found out that the friend had stocked the pond with trout, and in fact the leeches are decreasing in number. However, I have read that it is best to control leeches with smaller fish like bluegill and sunfish. Will the trout eventually begin eating the newts? Should they buy bluegill? Thanks for all your advice in advance -- I really want to do what I can to stabilize that pond's population.

Salamanders and newts tend to avoid bodies of water with fish. It's certainly possible that adding fish to the pond has ruined any chance of the salamanders or newts staying in the pond.

What sort of pond is this? If it connects to any other body of water or if it may flood and drain into other bodies of water than your friend shouldn't be stocking any fish. Bluegill and sunfish, also known as black basses (Centrarchidae,) can be a very environmentally destructive fish. They out compete most native fishes and are in general an ecological pest. Anglers tend to move them around to stock lakes and ponds they want to fish in. I would advise against stocking bluegill or any other type of sunfish.

I don't really know what you can do to stop the leeches. It may be that they are just having a boom right now and will fade naturally. Eastern newts do have some mechanisms for coping with leeches, generally by leaving the pond long enough for the leeches to die.

Trying to add non-native animals (sunfish are not native to the pond) always results in unforeseen consequences, usually bad ones.

Abrahm said:

Salamanders and newts tend to avoid bodies of water with fish. It's certainly possible that adding fish to the pond has ruined any chance of the salamanders or newts staying in the pond.

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But Abrahm, isn't it true that N.viridescens is able to live in bodies of water with fish because of the toxicity of each stage in their life cycle?

The first time I ever saw wild eastern newts was in a pond that was heavily stalked with bluegill.

Nathan050793 said:

But Abrahm, isn't it true that N.viridescens is able to live in bodies of water with fish because of the toxicity of each stage in their life cycle?

The first time I ever saw wild eastern newts was in a pond that was heavily stalked with bluegill.

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True. I believe I've heard accounts of trouts avoiding adult newts as prey, possibly in Petranka? I was under the impression that larval N. viridiscens are considerably less toxic than adults or the highly toxic efts. I am guessing that adding sunfish to the pond would be much worse considering how voracious they are and the description of it being a small body of water.

Of course, I am against adding exotic species to habitats for basically any reason. So there is my bias, out in the open.

I agree. Adding any fish descreases the chance that salamanders (and probably frogs) would use this pond for breeding any more. Thus, in the long run, it's a bad thing for amphibians, regardless of what effect it may have on the leeches.

Leeches do pass diseases among eastern newts, I've read that too. But are these even the kind of leeches that infest newts at all? Most leeches are free-living, not parasitic at all.

I remember reading somewhere in the books I've read lately that leeches are a serious problem for newts, probably it was Notos. And I know what the pond leech did to my little Pee Wee (Noto), ripped off his arms from which he never recoverd.

Thank you so much Abram, Dawn and Jennewt. I do believe that the leeches are having a destructive effect just based upon their overpopulation. It is a small pond, perhaps 60 ft across and is filled by a fast flowing steep stream. In turn, it exits into a small river across the street which reaches the Connecticut River about 20 miles downstream. Of course I was hoping for a clear answer, but I'm not surprised that this is complicated. I hadn't considered that the sunfish might eat the larval newts. Someone must have done some studies on this.:wacko: