Newman RA (1992) Adaptive plasticity in amphibian metamorphosis. (1983) Prey size preference of predators: differential vulnerability of larval anurans. This confluence of natural and anthropogenic factors makes my task more challenging, but armed with a broader ecosystem perspective that includes those underwater creepy-crawlies (and some multivariate statistics!) I hope to better understand tadpole responses to urbanization.īrodie ED, Jr, and Formanowicz DR, Jr. Additionally, there are a multitude of urban factors – such as lawn fertilizers, road salts, reduced forest canopy cover, altered hydrology – which likely influence tadpole health, growth, and survival. Because these insects are everywhere and their natural predation pressure on tadpoles can be strong disentangling the “true” response of tadpoles to urbanization (as opposed to predation) may not be so easy. Predatory insects are ubiquitous: we have found them even in our most urban sites. Other experiments have demonstrated that exposure to predator cues can slow tadpole growth and result in smaller froglets emerging from pools. Experiments have shown that even when predators cannot come in contact with tadpoles, the presence of a caged predator or even just water with predator chemical cues results in tadpoles that forage less and grow larger tails. Tadpoles are so adapted to living with the dangers of insect predators that they can even “smell” them. In pools with relatively high densities of insect predators tadpoles grow larger, thicker tail fins to better “sprint” away from a predator in case of attack. Because many insect predators in vernal pools cue on prey movements, tadpoles move less in their presence to prevent attack. Wood frog tadpoles are well known to adapt their growth and behavior to cope with the predator pressures in a pool. The deeper I dug, the more cool things I found out about how predatory insects influence tadpoles. From the viewpoint of a tadpole perhaps these insects are the farmers and chefs of the vernal pool world. These nutrients can then be incorporated into the biofilms upon which tadpoles feed with their rasping-tadpole-mouths. As they breakdown plant matter these insects facilitate the release of detritus-bound energy and nutrients. Other insects, such as caddisfly larvae, are more like ecosystem engineers, shredding the leaves and twigs that fall in the pool. They may look like creepy-crawlies at first glance, but from the perspective of a tadpole these insects might be voracious predators. When a tadpole has been successfully captured, this arm-like mouthpart will hold the tadpole to the dragonfly larva’s mouth where it can “chew” on the tadpole.Īlthough vernal pools are known to be breeding areas for amphibians such as wood frogs and spotted salamanders, a multitude of insects also rely on these pools for life and help orchestrate the underwater food web. These bugs are definitely an important component of the vernal pool food web.Īeshnid dragonfly larvae have a mouthpart that can extend like an arm and grab a tadpole in a split second. After several first-hand observations of tadpoles missing chunks of their tails (or sometimes nearly the entire tail!) I realized it was time to learn a bit more about those ravenous predators. I am of course talking about the subject of this blog post – aquatic insects! When I started studying wood frog ( Lithobates sylvaticus) tadpoles I set out with the goal of trying to understand how various aspects of vernal pools influence tadpole health, growth, and survival in urbanizing landscapes. Oftentimes in the world of vernal pools, we focus on the charismatic, “cute” animals – turtles, frogs, and salamanders – but pay less attention to some of the lesser known, yet incredibly important animals. “Argh! Bugs are attacking me for no reason all the time!” – Zach B. “They’re not so bad…if you wear gloves.” – Carly E. Carly Eakin – PhD Researcher, University of Maine Department of Wildlife, Fisheries, and Conservation Biology
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