Changes of shell microstructural characteristics of Cerastoderma edule (Bivalvia) — A novel proxy for water temperature
Milano, S.; Schöne, B.R.; Witbaard, R. (2017). Changes of shell microstructural characteristics of Cerastoderma edule (Bivalvia) — A novel proxy for water temperature. Palaeogeogr. Palaeoclimatol. Palaeoecol. 465: 395-406. dx.doi.org/10.1016/j.palaeo.2015.09.051
In: Palaeogeography, Palaeoclimatology, Palaeoecology. Elsevier: Amsterdam; Tokyo; Oxford; New York. ISSN 0031-0182; e-ISSN 1872-616X, more
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| Author keywords |
Microstructure; Bivalve shell; Prism size; Prism elongation; Temperature proxy; Scanning electron microscopy |
| Authors | | Top |
- Milano, S.
- Schöne, B.R.
- Witbaard, R., more
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| Abstract |
Shells of bivalves potentially provide an excellent archive for high-resolution paleoclimate studies. However,quantification of environmental variables, specifically water temperature remains a very challenging task.Here, we explore the possibility to infer water temperature from changes of microstructural characteristics ofshells of the common cockle, Cerastoderma edule. The size and elongation of individual microstructural units,i.e., prisms, in the outer shell layer of seven three to five year-old, specimens collected alive from the intertidalzone of the North Sea near Texel, The Netherlands, and Schillig, Germany,were measured by means of automaticimage processing. Growth patterns (circatidal, ciralunidian and fortnightly increments and lines), shell oxygenisotope values and mark-and-recovery experiments were used to place the shell record in a precise temporalcontext. Irrespective of the locality and ontogenetic age, size and elongation of the prisms increased nonlinearlywith water temperature. Small (0.12 ± 0.05 µm2) and round prisms (elongation: 2.42 ± 0.31) wereformed at temperatures of ca. 10 °C (late April), whereas larger (0.33 ± 0.11 µm2) and more elongated prisms(3.26±0.28) occurred during hot summer (ca. 22 °C).No clear-cut or consistent correlation existed between microstructuralcharacteristics and growth rate aswell as a variety of other environmental variables such as salinity,chlorophyll a and turbidity. Based on these findings, a model was constructed fromthree shells at Texel that enablesreconstruction ofwater temperaturewith a precision of 1.7±1.0 °C fromprismsize and elongation: SST=9.02 + 17.25 Ps + 1.10 Pe. This model was successfully tested at four shells from Schillig. The new temperatureproxy can be of particular interest for paleoclimate studies in nearshore settings when non-recrystallizedC. edule shells are available. Future studies are required to verify our findings and check if other species withthe same and different microstructures show similar relationships with water temperature. |
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