Large-Scale Proliferation of Red Tide Organism "Noctiluca scintillans" Confirmed Near Sihwa Lake

A large-scale proliferation of the red tide organism "Noctiluca scintillans" has been confirmed in Sihwa Lake in Gyeonggi Province.

The Gyeonggi Province Institute of Marine and Fisheries Resources announced on April 15, 2026, that it had investigated the orange-colored bands observed in the waters near the Ansan Sihwa Narae Rest Area on April 14 and confirmed that the organism was the non-toxic red tide species Noctiluca scintillans.

The investigation found that approximately 200,000 individuals of Noctiluca scintillans were distributed per liter in the area. Noctiluca scintillans is known to have no direct impact on human health or the safety of seafood. The species tends to gather in locations where conditions such as an increase in food sources, water current movement, and stagnation of seawater overlap.

The Institute explained that while the population was distributed at low density along the coastal region during winter, environmental changes in spring led to their concentration inside harbors, causing the seawater to appear orange or reddish-brown.

Large-scale breeding of jellyfish is occurring near the beach close to Ansan Sihwa Narae Rest Area. Provided by Gyeonggi Province

The Institute conducts regular surveys twice a month through its "Gyeonggi Sea Environmental Survey" program and has continuously monitored the occurrence trends of Noctiluca scintillans. A similar case was observed in April last year at Gungpyeong Port in Hwaseong, and this year, the Institute predicted the possibility of occurrence between March and April, providing advance notice to fishers and relevant agencies.

So far, no damage directly caused by Noctiluca scintillans itself has been identified, but the Institute plans to continue monitoring, as there is a possibility of temporary changes in water quality, such as a drop in oxygen levels, during the mass die-off phase following a large-scale bloom.

Kim Seonggon, Director of the Gyeonggi Province Institute of Marine and Fisheries Resources, said, "Noctiluca scintillans is a non-toxic organism, so there is no need for excessive concern. However, since it can become densely concentrated in certain areas, we will continue to closely monitor changes in the marine environment. We will also meticulously observe changes in the coastal ecosystem through regular marine environmental surveys and respond swiftly to any abnormal occurrences by utilizing social media and other means."

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