Invasive Alien Species in Croatia: Citizen Participation
The Problem of Invasive Alien Species
Plant and animal species can be relocated from their natural habitats to ecosystems where they do not belong in various ways, either through human activity—such as trade, transportation, or intentional introduction—or due to natural factors. If their spread, competition for resources, predation, or disease transmission negatively impacts native species, they are classified as invasive alien species (IAS).
Why Get Involved?
Biological invasions pose a serious threat to native biodiversity, potentially causing negative effects on human health and the economy. Removing invasive alien species is a complex and costly process, which is why preventing their spread is the most effective strategy. By reporting observations of IAS, you can contribute to their early detection and containment. Field data is crucial for developing management plans to mitigate their negative impact on the environment and society.
How to Identify and Report IAS?
If you encounter foreign or invasive species in nature, you can report them through the Ministry of Environmental Protection and Green Transition’s mobile application "Invasive Species in Croatia" or via the online reporting form. The online form can be used independently of the app, but the advantage of the app is that it automatically records and saves coordinates, date, and observer details directly from the field, ensuring faster and more accurate data collection. To assist with IAS identification, the Ministry has published a comprehensive Guide to Identifying and Managing IAS, primarily intended for personnel of relevant authorities. However, the guide is also useful for individuals without a biological background, as it provides practical assistance in recognizing 114 different plant and animal IAS species. The guide and other useful educational materials can be found here.
Additionally, the mobile app features a species catalog with photos, and if you are unsure of the species, you can submit an observation under "Free Entry."
IAS Removal in the LIFE for Mauremys Project
One of the project's objectives is to remove invasive fish, turtles, and plants from all locations where habitat restoration and improvement efforts are being carried out. Specifically, the project will target the removal of the invasive red-eared slider (Trachemys scripta), the mosquitofish (Gambusia sp.), and the aquatic plant paspalum (Paspalum paspaloides).
- Red-eared sliders are naturally distributed from the southeastern United States to the Gulf of Mexico. They have been introduced worldwide as pets and are now found in nearly all of Croatia’s freshwater habitats. They are larger, more aggressive, and reach sexual maturity earlier than native freshwater turtles, giving them a competitive advantage in shared habitats. Moreover, they can transmit parasites and pathogens. These turtles are removed based on citizen reports and/or by installing basking platforms that function as passive traps for invasive freshwater turtles.
- It has been documented that insectivorous foreign fish species, such as the mosquitofish—originally introduced from North America to control mosquito populations - reduce the diversity of aquatic invertebrates, which serve as a food source for freshwater turtles. The introduction of foreign fish species can also introduce diseases and parasites to native fauna or endangered turtles (e.g., pentastomids and ranaviruses). Experts from the Faculty of Agriculture will remove these fish from ponds inhabited by the Balkan Terrapin (Mauremys rivulata).
- The overgrowth of small freshwater bodies with excessive aquatic vegetation makes it difficult for Balkan Terrapins to move and can lead to the complete disappearance of their habitats. Paspalum will be removed using a shading method with non-toxic wool-based bio-felt.
Through joint efforts, we can protect our natural habitats and ensure a better future for endangered species like the Balkan Terrapin. Get involved and be part of the solution!
