DNA barcoding has enabled researchers to identify two invasive fish species, Gambusia holbrooki and Atherina boyeri, for the first time inhabiting the Upper Euphrates River Basin in Türkiye, shedding light on the growing concerns over non-native species and their impacts on local habitats.
The geographic location of Türkiye plays a significant role in its rich freshwater fish biodiversity. Including both endemic and non-native species, this diverse aquatic community faces increasing challenges from invasive populations. Gambusia holbrooki, introduced to Lake Amik for mosquito control back in the 1920s, was the first non-native species to inhabit Türkiye’s waters. Meanwhile, Atherina boyeri has recently found its way to Türkiye's ecosystems, presenting considerable ecological concerns.
Conducted by researchers at Fırat University and Ankara University and published recently, this study successfully discerned the genetic makeup of the two invasive species utilizing advanced DNA barcoding techniques. By focusing on the mitochondrial cytochrome c oxidase subunit I (COI) gene, the researchers confirmed their initial presence through specimens collected from Keban Dam Lake and Karakaya Dam Lake.
“The identification of invasive fish species using DNA barcoding is an effective technique, as evidenced by the comparison of amplified COI sequences to the BLAST database,” the authors stated, affirming the reliability of the method.
The recent findings are troubling, as invasive species like Gambusia holbrooki and Atherina boyeri pose substantial threats to local ecosystems, altering biodiversity and potentially outcompeting native species for limited resources. The competence of G. holbrooki to thrive under varying environmental conditions makes it particularly difficult to manage. It can survive temperatures ranging from 1 to 40 degrees Celsius and various salinity levels, allowing it to spread effectively across diverse habitats.
“The presence of invasive species such as G. holbrooki and A. boyeri is particularly worrisome since they have the capacity to disturb native ecosystems and pose a threat to local species,” the researchers noted.
This study marks the first recorded instances of these invasive species within the Upper Euphrates River Basin, contributing significantly to the existing knowledge of Türkiye’s fish fauna. Previously, investigations did not report the presence of these species, with studies mainly focused on native and other extant species. The new findings indicate how rapidly these species are adapting and spreading to new environments.
Notably, the genetic uniformity of these invasive populations suggests a global lineage, indicating their origin from widespread introductions for pest management across various regions. “The genetic uniformity of the inhabitants suggests these populations belong to a genetic lineage distributed worldwide,” the research team highlighted.
Given the ecological ramifications involved, it is imperative to monitor the establishment of invasive species within vulnerable ecosystems actively. Future research should not only continue to explore new introductions but also manage the impact of these species on native biodiversity. The dynamics of Atherina boyeri's more recent expansion to inland waters necessitate urgent attention to understand their long-term effects adequately.
Through this research, the authors provide valuable baseline data for policymakers and conservationists aimed at managing and mitigating the consequences of invasive species, underpinning the need for combined ecological assessments alongside advanced genetic methodologies for future monitoring strategies. Their work reinforces the significance of utilizing DNA barcoding as part of comprehensive ecological approaches to control and investigate the spread of non-native species.
This study emphasizes the growing challenges posed by invasive fish species within Türkiye's freshwater ecosystems and the need for engaged management practices to protect native biodiversity from the threats they pose.