Biodiversity Patterns and DNA Barcode Gap Analysis of COI in Coastal Lagoons of Albania.

Aquatic biodiversity includes a variety of unique species, their habitats, and their interactions with each other. Albania has a large hydrographic network including rivers, lakes, wetlands and coastal marine areas, contributing to a high level of aquatic biodiversity. Currently, evaluating aquatic biodiversity relies on morphological species identification methods, but DNA-based taxonomic identification could improve the monitoring and assessment of aquatic ecosystems. This study aims to evaluate the coverage of COI DNA barcodes in the reference libraries for the known aquatic animal species present in the coastal lagoons of Albania. In this study, the six most studied coastal lagoons of Albania were selected. Species data were gathered from the scientific literature and publicly available sites and studies. The collected species lists were taxonomically standardised using global public taxonomic databases like WORMS. The standardised lists were used to analyse the barcode gap of COI based on two public DNA barcode libraries: Barcode of Life Data Systems (BOLD) and NCBI GenBank. The results show that the COI DNA barcode gap in the coastal lagoons of Albania ranges from 7% (Lagoon of Patok) to 33% (Karavasta Lagoon). Fishes and Amphibia represent the groups with the lowest barcode gap (8% each), while Annelida shows the highest (47%). In conclusion, the COI gene marker for DNA-based biodiversity assessments is reliable for the coastal lagoons of Albania.