2006/06/29 第073回 - Dr. David Dettman

第73回汽水域懇談会

7月24日(月曜日)夕方より第73回汽水域懇談会を行います。皆様お誘い合わせの上、ご参加下さいますようお願い申し上げます。

 

『High resolution life history records from biomineralized tissue: a tool for conservation paleobiology』

Dr. David Dettman University of Arizona

アリゾナ州立大学研究員のデットマン博士は地球化学や古環境学、古生態学がご専門です。今回は、それらで用いる手法を応用した絶滅危惧種の生態研究についてお話いただきます。皆様のご来聴をお待ちしております。

日時:平成18年7月24日(月曜日)午後5時より1時間程度
場所:島根大学汽水域研究センター2階演習室(201)


Abstract:
Studying the conservation biology of rare, remote, or endangered animals presents significant challenges because these animals cannot easily be observed, captured, or killed. In addition, there is often a lack of baseline data on the environment in which these animals thrived prior to human modification. Using the remains of dead animals or specimens from museums or archaeological sites can provide information on the habitat and climate in which the animals lived. This talk discusses "conservation paleobiology" - the application of paleontological and geochemical techniques to the study of endangered species.
Hard tissues like mollusk shells and fish otoliths contain geochemical records of the environment in which the animals lived. Using life history reconstructed from the hard-parts of two endangered fish, Totoaba macdonaldi and Cynoscion othonopterus. We can see that they relied in the lower salinity estuary zone at the mouth of the Colorado River early in their life. After the damming of the river this brackish zone disappeared and growth rates in these fish declined significantly. The nearly extinct Mulinia coloradoensis, an endemic bivalve in the northern Gulf of California, has also been affected by the change in the Colorado River delta from a low salinity area to a hypersaline environment. Stable isotope geochemistry is used here to document the pre-dam salinity regime in the delta region. Taphanomic analysis also shows that the decline of M. coloradoensis had a major impact on Colorado River delta predators (snails and crabs).