A bibliometric study on diatom DNA meta-barcording for water quality monitoring: a global perspective

Aquatic biota have been used for decades in water quality assessment since they reflect the changing physicochemical conditions of waterbodies. Among the aquatic organisms used in biological assessment are diatoms. Initially, morphological studies of diatoms were preferred in monitoring but today the new technique of diatom DNA meta-barcoding is gaining preference. This study aimed at (1) summarising the thematic study areas on diatom DNA meta-barcoding for water quality monitoring, (2) identification of past and future trends of research on diatom DNA meta-barcoding for water quality monitoring, and (3) determination of regional and institutional trends in studies involving diatom DNA meta-barcoding for water quality monitoring. We obtained data from the Web of Science (WoS) using research queries like "Diatoms DNA meta-barcoding for water quality monitoring", "Diatoms DNA meta-barcoding for water quality biomonitoring", and "Diatoms DNA sequencing for water quality monitoring". We identified 127 articles that had published on diatoms DNA meta-barcoding in water quality monitoring between the years 2003 and 2022. Our study revealed that the developed nations, led by France, followed by Germany and USA, dominated the research areas involving the use of diatoms DNA meta-barcoding in water quality monitoring. Additionally, our present study showed that DNA meta-barcoding was related to biodiversity assessment, rbcL, species identification and taxonomy, a finding which is in line with previous studies conducted recently that have revealed that DNA-based approaches, for example the use of rbcL genes, are more effective in the determination of diatom community structures compared to morphological methods. Although DNA meta-barcoding is rapidly gaining popularity in water biomonitoring, there are biases when explaining the differences between morphological and molecular based diatom indices, among them the incompleteness of the reference library such as R-syst::diatom database. To address this disparity, there is need to use environmental sequences from high-throughput sequencing (HTS) runs which can subsequently be related to morphological observations, followed by integration of the same into the reference libraries after setting up several guidelines and quality criteria. Consequently, the findings of this study present insights that will contribute globally to the development of water quality monitoring frameworks using diatoms.