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 Paläontologie und Historische Geologie
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Bivalve shells as environmental archives

Beate Bader, Priska Schäfer, Nils Andersen, Helena Fortunato, Parissa Strey

Comparison of isotope signals in shells of tropical bivalves and gastropods are used to test contradicting hypotheses concerning cardinal factors controlling stable isotope signals. How do changes in temperature/salinity and food supply affect growth rates of molluscs? Are different interannual (El Niño), annual (wet/dry season), and lunar (tides) parameters ducemented in the shells? Do these cycles correspond to growth growth increments?

Alive and dead shells of the venerid bivalve Megapitaria aurantiaca have been collected in Pacific waters along the coast of Panama (Gulf of Panama, Gulf of Chiriqui) during two cruises with RV „Urraca“ (Smithsonian Tropical Research Institute STRI, Panama City) for stable isotope analysis and sclerochronology. A few shells from archaeological sites in Panama (supposed age 4-5 ka) and a fossil specimen (isotope stage 6) supplement our material. Oxygen isotope signals documented in shells from the Gulf of Panama and Gulf of Chiriqui depict differences in temperature and growth rates.