Integrating DNA barcoding of fish eggs into ichthyoplankton monitoring programs


Lewis, Leah A., David E. Richardson, Evgeny V. Zakharov, and Robert Hanner
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The data collected through ichthyoplankton monitoring surveys provide valuable insight into the spawning dynamics of multiple species. Fish eggs, more than larvae, offer a more precise evaluation of species-specific spawning characteristics; however, egg collections are greatly underused because of the limitations associated with morphology- based identifications. In recent years, a new means of molecular identification, termed DNA barcoding, has made species identification readily available across a broad range of taxa. We used DNA barcoding to identify ethanol-preserved fish eggs collected during 2002–2012 along the northeastern U.S. continental shelf. A subsampling protocol was used to select 1603 unidentified eggs for analysis. DNA sequences were successfully obtained from 1495 (93.26%) of these eggs, representing 50 species—many of which have either never before been identified to the species-level as eggs or have been identified previously only to a higher taxonomic level or during specific developmental egg stages. In comparison with past attempts at morphological identification, our molecular identifications comprise a broader diversity of eggs and provide a technique with high success rates of unambiguous identifications that is not sensitive to egg stage. Overall, this work shows that DNA barcoding of fish eggs is sufficiently advanced to be incorporated into long-term, regional-scale ichthyoplankton monitoring programs.