In 2012, Dr. Chih-Wei Chang and I authored a book “Otolith Atlas of Taiwan Fishes”, published by National Museum of Marine Biology and Aquarium (NMMBA), Pingtung. It represents a major accomplishment supported by the Taiwan e-Learning and Digital Archives Program (TELDAP) and has been a significant focus of my dedication over the first two years of my appointment at the NMMBA. It represents the first complete guidebook of the subject in the study area to be used by taxonomists, ecologists, fish biologists, archeologists, and paleontologists. This opportunity helped me establish a comprehensive view of fish systematics and taxonomy, which can be regarded also as a huge expansion on my master’s thesis, “Morphology of otolith of living and fossil fishes from Taiwan”.
During my PhD studies, my largest contribution to the concerned subject is connecting recent fish communities with fossil assemblages, based on otolith remains in the sea bottom sediments. As my work established such connections, our understanding of the ecological and biogeographical basis of Recent otolith assemblages in the sea bottoms will enhance our ability, not only to interpret ancient environments but also using historical data to predict patterns of fish distribution and abundance in the future.
Fossil otolith-based assemblages have been reported from many regions of the world and many taxonomic works on fossil otoliths are concluded with a discussion on paleobiogeography and paleoecology. The interpretation is highly influenced by the taxonomic composition of a given fossil assemblage. However, several biases such as post-mortem transportation of the otoliths may be involved and therefore fossil materials may not always directly reflect in situ habitats at a particular time in the past. The aim of the project is thus to understand how otolith assemblages in the sea bottom sediments can be related to the standing living fish communities, and in which measure this can be applied to the evaluation that provides a higher precision on the interpretation of fossil otolith associations.
For the first time, ecological statistics was conducted on otolith assemblages. I found that the distribution of sea bottom otoliths not only agrees well with that of living fish biogeography but also reflects the general outline of fish communities at different depths. I also demonstrated that taxonomic composition and the relative abundance in a given otolith assemblage are equally important to draw ecological conclusions. The differences in the proportion of benthic and pelagic taxa, which can also be observed in the fossil materials, is explained by two sets of ecological and trophic strategies. Finally, the reason that otolith thanatocoenoses are reflective of fish biocoenoses is interpreted as the majority of the specimens to be recently added and dominant taxa are still numerically significant.
The Tortonian fish otoliths of northern Italy represent one of the best known otolith-based teleost faunas in the Miocene of the Mediterranean Basin. The assemblage has been studied for more than a century. In this study, new materials revealed 109 taxa of which 88 are recognized at the species level. I also described four new fossil species: Coryphaenoides biobtusus sp. nov., “Merluccius” rattazzii sp. nov., Neobythites auriculatus sp. nov. and Lesueurigobius stironensis sp. nov.
The importance of this study is that it provides an up-to-date knowledge of all Tortonian nominal species and a comparison of related fossil records. The fauna is characterized by many modern forms at the generic level, in which more than 90% can be assigned to present day genera. At the species level, however, more than half of the represented taxa are extinct. The Tortonian fauna is further characterized by many species that are apparently confined to the upper Miocene, resulting in a unique combination of its taxonomic composition. Consequently, while placing this association in time and space, I have demonstrated that the current Mediterranean fish fauna was well-structured in the early Miocene, but it was not until the Pliocene, after the Messinian Crisis that the modern species largely appeared.
This project represents a review of a continuous work that spans for 30 years. The Lutetian otoliths (44.05-47.40 Ma) revealed the presence of at least 89 otolith-based taxa within which I described 20 new fossil species. The important findings of this study are that firstly it found many nominal upper and/or lower Eocene species, suggesting that the important faunal renewal in the Eocene of the Aquitaine Basin is more gradual than previously believed. Secondly, the difference in the taxonomic composition between the Lutetian assemblages of Aquitaine and those of the neighboring Anglo-Belgo-Parisian basin and at Osteroden (Germany) is mainly environmentally based.