"What Is That Disgusting Lump in the Water?"... Bizarre Organism Found in Bukhan River

Pectinatella magnifica colonies found in Paroho Lake, Gangwon Province
Ministry of Environment: "No ecotoxicity or harmful effects"

A colony of magnificent bryozoans has been found in Lake Paroho in the upper reaches of the Bukhan River in Gangwon Province.

On October 17, colonies of magnificent bryozoans were easy to spot in shallow water around Heart Island, a tourist attraction in Lake Paroho in Dosong-ri, Gandong-myeon, Hwacheon County, Gangwon Province. The colonies were especially abundant along the filled-in section connecting the shore to the island, where water tends to stagnate because its flow is obstructed.

At first glance, magnificent bryozoans can be mistaken for giant salamander egg masses. Both salamander egg masses and magnificent bryozoans look like jelly underwater.

A colony of magnificent bryozoans found in Lake Paroho in Hwacheon, Gangwon Province. Yonhap News

However, salamander egg masses are reproductive structures containing multiple black or brown eggs inside transparent or translucent, jelly-like egg sacs. By contrast, the tiny brown dots densely covering the surface of a magnificent bryozoan colony are individual bryozoans, each a small animal.

They also differ in shape. Salamander egg masses consist of egg sacs or two rows of egg clusters, while magnificent bryozoans are irregular in shape and larger. They also appear at different times: salamander egg masses are seen mainly in spring, during the breeding season, while magnificent bryozoans appear in warmer seasons. This non-native species emits a strong foul odor and typically lives attached to rocks and aquatic plants in lakes with sluggish currents.

Inland fishermen said, "That disgusting thing appears in even greater numbers when it's particularly dry or hot," adding, "When that happens, catches drop, which is a real headache." Large colonies of magnificent bryozoans have not been reported in the Lake Paroho area of Hwacheon before.

One of the best-known cases of magnificent bryozoans being found in Korea occurred in 2014, when large colonies of the species were confirmed in the basins of the four major rivers, including the Nakdong and Geum rivers. At the time, the Ministry of Environment announced, based on research by specialized institutions such as the National Institute of Environmental Research, that magnificent bryozoans posed no ecological toxicity or harm. It explained that although they thrive in areas with slow-moving water, their presence alone does not prove that the water is polluted.

Environmental groups, however, argued that the appearance of magnificent bryozoans was "evidence that large amounts of their food, such as algal blooms and aquatic microorganisms, are present" and "a sign of deteriorating water quality."

This content was produced with the assistance of AI translation services.