Salamanders die from a fungal disease. How did they get it?

‘Uh! Right through my glove! Roen Post, an applied biology student at Aeres MBO in Almere, pulls his bleeding finger out of the trap. It is attacked by a yellow-edged aquatic beetle larva. “They can bite furiously.”

The grub is just an bycatch today. The animal in question has already ended up in a bucket of water from the trap: a small adult specimen of the Great Knott’s smoot. It is not yet fully grown, and its length is already ten centimeters from head to tail. Its back is black, and when it is really mature, a majestic emblem will appear on it. “It’s like a little dragon,” says Annemariki Spitzen, an ecologist at Ravon – the Dutch organization for research on reptiles, amphibians and fish.

Since 2020, Spitzen, with teammate Jesper Berndsen and Post, has been searching for salamanders in swimming pools around Zutphen. In the spring and summer they follow the animals every two weeks. Today Brandsen is sick, and he helps 12-year-old son Spitzen empty the snares for a day. “We weigh it, measure it, take skin samples with a cotton swab, photograph it, and then it can go back into the water,” he says. His mother points out the belly of the crested knut she weighs: yellow with large black dots. “The dot pattern allows us to identify individual animals.” Salamanders are willingly examined. Every now and then one opens their mouth to reveal a row of tiny teeth. Spitzen: “Measuring and weighing only take a few minutes.”

Monitoring is important because salamanders in the Netherlands and elsewhere in Europe have been threatened for about ten years by a deadly fungal disease. Batrachochytrium salamandrivoransIn short, basal affects the skin through ulcers so that you die. Salamanders breathe through the skin, among other things; So it is vital. Bsal was discovered in 2013 in the Netherlands, says Spitzen, in a rare fiery salamander. “He really became Bassal’s victim,” Post says. In the Netherlands, three such groups occurred in Limburg. “Of those three, only 0.1 percent is left.” Another went completely, the third small group is very little data.

The researchers now want to know how sensitive the Bsal is to two other species: the lower newt and the crested newt.

Red belly and black dots

“Crowned newts are rare in the Netherlands,” says Spitzen. “We’ve discovered that in the pool we’re in right now, 80 percent of Crested Newtons are infected with the fungus.” By comparison: only 6 percent of baby newts — a common species about ten centimeters long, with a red belly and black spots — were found to be infected.

However, there is a bright spot: Oddly enough, a portion of it appears to heal on its own. Spitzen: “It appears that some individuals who were suddenly sick in the past no longer have the fungus when measured later. Very strange, because infected animals are always doomed to fail in the laboratory.” It remains to be seen if there is a real cure, or whether the fungus is temporarily hiding inside the salamander’s body. “More research is needed for that. So swab, swab, swab.”

Cleanse, and we move on to the next pool. Scales, ruler: After the measurements, everything is disinfected with alcohol and VirkonS disinfectant. Post: “Sometimes you have up to eighty salamanders in one counting site. Then the mountain of disposable green gloves grows fast.”

Cleaning rubber shoes

Spitzen sprays cleaning agent onto our rubber boots with a high pressure sprayer. “Otherwise, you can take the mushroom with you to the next location.” That’s the weird thing, she says as we walk down a grassy path to the pool. “All of our sampling sites are completely isolated, on private land. So not many passersby. How do mushrooms end up in such a pond?”

They scanned the environment with E-dna. With this technique, you can detect the fungus’ DNA in water by taking a sample of the water. For example, we discovered that mushrooms occur in more places in the region, but the distribution appears to be random at the moment. Now we’d like to see if we can see if there is a pattern and what explains that pattern.” She points to the tall reed plumes and water lilies in front of us. In theory, swimmers could carry it with them, for example, but people don’t seem to swim in it often. So perhaps the spread occurs in a different way, for example by waterfowl. But it is more likely a human being. Through mud on shoes, by moving aquatic animals and plants.” She adds that mushrooms can also live on plants. “So it is never a good idea to give aquatic plants from your pond to neighbours, or give them some of your salamanders as a gift. You do Basal a favor.”

Read an interview with biologist Anneke Ter Schure: “Electronic DNA tells which organisms lived in a particular area, even if they left it long ago”

Meanwhile, Teun discovers a strange gelatinous dot in one of the traps. A kind of jelly candy. It turned out to be garlic frog larvae: an extremely rare species that lives in this area. Could it be that amphibian lovers come here from far and wide, cleaning all the water and thus spreading the fungus? “Who knows,” Spitzen says. “But that’s all speculation: the real cause is still not clear yet.”

The point is rolled back, as well as the larvae of the crested newt. Post photographed them extensively prior to their release. “How many beautiful animals live under water,” he sighs with relief. The bite on his finger has already been forgotten and forgiven.

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