Zwei Islandmuscheln auf grauem Hintergrund. Man erkennt deutlich Ringe an der Valve. Unter den Muscheln befindet sich ein Beschriftung mit Eigenschaften

© Bangor University

Eine unscheinbare aber langlebige Muschelart, die Islandmuschel, konnte Wissenschaftlern Aufschluss geben über die Populationsentwicklung und die Bestände der Heringe während der letzten 450 Jahre. Möglich ist dies durch chemische Untersuchungen der Muschelschalen, welche eine Art Jahresringe bilden. Wie lassen sich aus der Beschaffenheit dieser Ringe Rückschlüsse auf das Klima oder gar die Veränderung von Fischpopulationen ziehen? Forschungsergebnisse dieser Art sind beispielhaft für die Komplexität unserer Ökosysteme. Sie zeigen wie eng der Lebensraum Ozean und die Arten, die er beheimatet, und das Klima zusammenhängen.

Hakaimagazine, 26.06. 2019, Autorin: Rachel Fritts

Scientists have reconstructed a detailed account of North Sea herring stocks that stretches back more than 450 years. This is the first time researchers have modeled recruitment—a measure of the number of eggs that survive to become young fish—for herring living before the 20th century. This lengthy record of herring health stems from measurements taken from a wholly unlikely source: the ocean quahog.

Ocean quahogs, palm-sized clams that live in the North Atlantic, might seem like unorthodox record keepers. But the shellfish have two very useful traits: they live for an exceedingly long time—the oldest on record was 507 when it died in 2006—and their shells have visible growth increments, much like tree rings, with a new band forming each year.
Juan Estrella-Martínez, a paleoceanography doctoral student at Bangor University in Wales, led the research. He and his colleagues used quahog shells collected from Scotland’s Fladen Ground in the North Sea to produce a data series showing how the ratios of oxygen and carbon isotopes in the shells and in the water changed from 1551 to 2005.

The isotope ratios reflect shifts in environmental conditions, such as water temperature. Providing a year-by-year account stretching centuries, the quahog shell data offers a way to better understand long-term climate patterns, such as the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation, which cause changes including large-scale variations in rainfall, hurricane activity, and fish populations.

Estrella-Martínez wanted a useful application for his new centuries-long record, and decided to see if his carbon isotope data could be used to help understand long-term variability in important fisheries.
“I started looking at the herring fishery because it had the most historic data available,” he says. “Without historical records, the most we could have done was speculate.”
[…]

Den kompletten Artikel findet ihr im Hakai Magazine.

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