In palaeontological and archaeozoological studies dealing with tilapia remains, identifications are usually limited to the level of the tribe Tilapiini (now called Haplotilapiini). In the present study, dry skeletons of Oreochromis niloticus (Linnaeus, 1758), Oreochromis aureus (Steindachner, 1864), Sarotherodon galilaeus (Linnaeus, 1758) and Coptodon zillii (Gervais, 1848) were analysed with the aim of defining morphological characters on a series of isolated skeletal elements. Eighteen different skeletal elements that have good chances of being well preserved (and of being recognised as tilapia) were analysed, i.e. premaxilla, dentary, maxilla, articular, lacrimal, palatine, quadrate, hyomandibula, operculum, preoperculum, posttemporal, cleithrum, supracleithrum, urohyal, vomer, and the first three precaudal vertebrae. Diagnostic criteria are described and illustrated with figures. It appears from the comparative analysis, and also from blind tests carried out afterwards, that identification is possible except for the articular and the third vertebra. More accurate identification of fossil and subfossil finds of Haplotilapiini should allow a better documentation of the zoogeographical history of these taxa in the future.
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RBINS Staff Publications 2017
To predict the response of the European flat oyster (Ostrea edulis) and Pacific cupped oyster (Crassostrea gigas/Magallana gigas) populations to environmental changes, it is key to understand their life history traits. The Dynamic Energy Budget (DEB) theory is a mechanistic framework that enables the quantification of the bioenergetics of development, growth and reproduction from fertilization to death across different life stages. This study estimates the DEB parameters for the European flat oyster, based on a comprehensive dataset, while DEB parameters for the Pacific cupped oyster were extracted from the literature. The DEB parameters for both species were validated using growth rates from laboratory experiments at several constant temperatures and food levels as well as with collected aquaculture data from the Limfjorden, Denmark, and the German Bight. DEB parameters and the Arrhenius temperature parameters were compared to get insight in the life history traits of both species. It is expected that increasing water temperatures due to climate change will be beneficial for both species. Lower assimilation rates and high energy allocation to soma explain O. edulis’ slow growth and low reproductive output. Crassostrea gigas’ high assimilation rate, low investment in soma and extremely low reserve mobility explains the species’ fast growth, high tolerance to starvation and high reproductive output. Hence, the reproductive strategies of both species are considerably different. Flat oysters are especially susceptible to unfavourable environmental conditions during the brooding period, while Pacific oysters’ large investment in reproduction make it well adapted to highly diverse environments. Based on the life history traits, aquaculture and restoration of O. edulis should be executed in environments with suitable and stable conditions.
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RBINS Staff Publications 2022
