In February 2026, during an environmental monitoring in the Bullines Lagoon of the Nahuel Huapi National Park, researchers detected for the first time the presence of the freshwater jellyfish Craspedacusta sowerbii, an invasive species originating from Asia.
The discovery, made within the framework of studies on the huillín, constitutes an unprecedented record within the protected area and poses new challenges for the management of aquatic ecosystems.
Scientific Analysis
The park called upon the Landscape Scale Aquatic Systems Ecology Group (GESAP), belonging to INIBIOMA (CONICET–National University of Comahue), to assess the situation.
Researchers María del Carmen Diéguez and Mariana Reissig conducted studies in Bullines Lagoon to determine the degree of establishment of the species and its possible ecological effects.
The jellyfish has a dimorphic life cycle:
- Polyp phase: microscopic, attached to the bottom, capable of withstanding adverse conditions.
- Medusa phase: visible in the water column during brief periods when the temperature exceeds 17 °C.
Dispersion Risks
The species can easily spread through the unintentional transport of microscopic polyps attached to aquatic plants, fish, birds, boats, or fishing equipment.
Therefore, the park emphasized the need to implement biosecurity measures to prevent its dispersion in the Limay River basin.
Main Recommendations
- Avoid transferring water, plants, and animals between aquatic environments.
- Completely drain boats and floating devices outside lakes and lagoons.
- Disinfect boots, nets, boats, and motors with hot water, saline solutions, or bleach.
- Allow boats and equipment to dry before moving them between bodies of water.
Characteristics of Craspedacusta sowerbii
- Morphology: transparent or whitish bell-shaped body, 20–25 mm in diameter, with up to 400 tentacles equipped with stinging cells.
- Habitat: calm waters such as lakes, lagoons, and reservoirs, especially when the temperature exceeds 17–19 °C.
- Ecological Impact: feeds on zooplankton and can alter local food webs if it reaches densities above 30 individuals per m³.
- Danger to humans: minimal, as its stinging cells do not penetrate the skin; although isolated cases of irritation have been reported.
Importance of Monitoring
The record reinforces the need to maintain systematic monitoring programs and preventive management. Protected Natural Areas function as early warnings against climate change and invasive species, allowing for the adaptation of conservation strategies.
In case of observing jellyfish in lakes or lagoons of the park, it is requested to immediately notify 105 or contact the conservation area.
The detection of this freshwater jellyfish in Nahuel Huapi is a reminder of the fragility of aquatic ecosystems and the importance of prevention. Although it does not pose a direct risk to people, its potential ecological impact requires constant vigilance and citizen cooperation to protect Patagonian biodiversity.
