Mapping Gaps in Current Knowledge on the Biology and Ecology of Five Mediterranean Non-Indigenous Fishes: Are International Bibliometric Databases Adequate?

The Mediterranean Sea represents a hotspot of non-indigenous fish species introductions. Here, we provide a comprehensive bibliographic synthesis on five Lessepsian fish invaders—Fistularia commersonii, Lagocephalus sceleratus, Pterois miles, Siganus luridus, and S. rivulatus—verifying whether international bibliographic databases (IBDs) and online biodiversity information facilities (BIFs) provide adequate information on their occurrence, biology, ecology, and potential or extant commercial use. To this end, we extended to non-indexed bibliographic (NIB) sources available on Google Scholar and compared the results on spatial expansion dynamics and bibliographic trends. We demonstrate that the information provided on occurrence records exclusively by IBD and BIF sources underestimated the total expansion area of invaders by up to 14.8% and determined artifactual temporal voids. Remarkable knowledge gaps were identified in the literature on the reproductive biology and commercial use of all the species, independent of the literature sources, while a relatively larger breadth of information was available on their morphometrics and trophic ecology. Noticeably, NIB sources provided more complete bio-ecological information, particularly for L. sceleratus. In addition, the majority of the studies on commercial uses were published in NIB sources, to the point that for some species, IBD sources provided negligible or null information on the topic. This study indicates that disregarding non-indexed literature sources might exacerbate knowledge voids exclusively related to linguistic barriers or geographic biases, weakening the scientific support necessary for identifying appropriate strategies of control and mitigation of bioinvasions in the Mediterranean Sea.