Today’s post comes from Samantha Stephens, a science and conservation photojournalist who spent last summer residing at the Algonquin Wildlife Research Station.
The thrill of discovery is a feeling that everyone has experienced. Finding a new favorite hiking spot or adding a “life” to your bird-watching list are some examples familiar to nature lovers.
For a naturalist, the most exciting discovery comes from observing how known species interact in ways that have not been documented before.
That’s what happened to Patrick Moldowan, a University of Toronto doctoral student who is leading a long-term study of spotted salamanders in Algonquin Provincial Park.
Patrick spends his summers living at the Algonquin Wildlife Research Station, documenting various aspects of salamander populations.
And that’s what led him to participate in the discovery that carnivorous plants eat baby salamanders.
Did you say “carnivorous plants”!?
Normally, plants obtain nutrients from the soil.
However, swamps are nutrient-poor environments, so carnivorous plants that grow in this habitat have developed a strategy to supplement their diet. They have become carnivores, which means they eat animal meat.
These plants have specialized bell-shaped leaves that form “pitchers” capable of collecting rainwater, into which they excrete digestive juices. These liquid-filled jars attract invertebrate insects, such as flies, moths, and wasps.
The insects become trapped in the jar and are subsequently decomposed by a combination of digestive juices and microorganisms that live in rainwater.
But these plants eat more than insects.
In 2017 and 2018, college students and instructors working on ecology projects as part of a field biology course were surveying carnivorous plants with the intent of documenting invertebrate prey.
Amanda Semenuk inspecting the plants. Photo: Samantha Stephens
To their surprise, they found more than just insects.
Trapped and swimming inside the jar was a baby spotted salamander!
These observations intrigued Patrick and the field course instructor, Dr. Alex Smith, and led them to further investigate the phenomenon. Later surveys found salamanders trapped in 1 in 5 plants.
These observations were published in a paper that was published last spring (2019) and the remarkable discovery has since received international attention.
The essential role of salamanders is expanded
Salamanders spend most of their lives underground or under covered objects on the forest floor, such as rocks and logs, so they are rarely seen by hikers.
Spotted salamander (Ambystoma maculatum) migration in Algonquin Provincial Park. Photo: Patrick Moldowan
But don’t confuse this hidden presence with the fact that they are rare; In fact, the abundance of salamanders in the forest ecosystem may exceed that of other animal groups, such as birds and mammals.
And they have a very important role to play.
In the spring, cold rains bring adult salamanders out of their underground wintering sites and provide them with perfect conditions to make the trip to ponds, ponds, or spring lakes, where they mate and lay masses of gelatinous eggs. Once this task is completed, they will travel from these bodies of water back to the forest.
Spotted salamanders in the adult (left) and juvenile (right) life stages. When young, individuals can weigh as little as 0.3 g and measure as little as 3 cm in length. At this size, juveniles are small enough to fall prey to carnivorous plants. Photo: Samantha Stephens
Over the course of the summer, the egg masses they have left behind will hatch into aquatic tadpole-like larvae and then, in the fall, they will transform again, this time into juvenile terrestrial salamanders. These “metamorphs” can weigh as little as 0.3 g and measure just 3 cm in length.
These tiny young salamanders must travel from these aquatic hatching areas to find shelter underground during the winter. It is at this stage that salamanders may have to traverse a swamp mat, where carnivorous plants lurk.
What does this mean?
Salamanders have long been recognized as important nutrient cyclers in forest ecosystems.
As they move between terrestrial and aquatic sites, they redistribute nutrients between the two types of habitat. They devour invertebrates, many of which are involved in decomposition. In this way, salamander populations have profound effects on the rate of forest soil decomposition.
With the discovery that salamanders are consumed by carnivorous plants, they may be a great source of nutrients for these plant populations.
In 2018, juvenile salamanders were found on 1 in 5 plants surveyed at the study site. In some cases, more than one salamander was observed at a time in a jar. The record number of salamanders found in a single jar so far is four. Photo: Patrick Moldowan
For a carnivorous plant that is used to capturing small insect prey, a salamander is a comparatively large feast!
But more questions need to be answered before researchers can say for sure how salamanders contribute to plant diets.
Just the beginning of the story.
One of the most inspiring things about science is that with every new discovery, more questions arise!
The story of carnivorous plants eating salamanders is still developing.
Last summer, Patrick and Amanda Semenuk, a Guelph university researcher working in Dr. Alex Smith’s lab, were knee-deep in swamps, surrounded by a swarm of mosquitoes, conducting field work to delve into the details of this story.
Amanda Semenuk conducted surveys this summer (2019) to gather more information about the emergence of this predator-prey phenomenon. Rainwater found on the leaves of the pitcher plant often became quite cloudy as the invertebrates and salamanders decomposed, so a turkey baster was sometimes used to better observe the contents of a pitcher. . Photo: Samantha Stephens
Again, they collected data on how often salamanders are caught, this time including more plants, not only at the original discovery site but also within other carnivorous plant populations in the park.
Will salamanders end up in the pitchers by “accident”?
Some pitchers are flush with the surface of the swamp, so juvenile salamanders may end up trapped in them simply because they took an unfortunate step.
However, in other cases the salamanders would have had to climb up to 10 cm up the side of a jar to end up inside. Are salamanders attracted to insect prey in pitchers for their own food? Or perhaps they intend to use the pitcher as a refuge from predators?
To answer these questions, Patrick and Amanda began by looking at the morphological characteristics and location of casters that have successfully caught salamanders.
Patrick collects a sample of Pitcher Plant material to be used for nitrogen analysis. This analysis will help answer whether plants are able to utilize nitrogen, a nutrient necessary for plant growth and reproduction, that the decomposing salamanders release into the pitcher. Photo: Samantha Stephens
Interestingly, only spotted salamanders have been found on plants. Researchers have not yet found any cases of plants trapping the very similar blue-spotted salamanders. Spotted juveniles outnumber blue-spotted juveniles by approximately 30 to 1 at the study site, so perhaps the lack of this observation is due to their low abundance and the study’s search effort.
But the possibility remains that there is another explanation for why only the spotted salamander has been observed on pitchers so far.
More to learn
These are just some of the questions raised by this discovery, and we can expect many interesting findings as research continues.
This discovery shows that even in a place that has hosted researchers for 75 years, there is still much about natural history that we have not yet discovered.
All the more reason to get out and explore!
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