For Antarctic Clams Age Matters
April 19, 2013

For Antarctic Clams, Age Is Important For Climate Change Adaptability

April Flowers for - Your Universe Online

According to a new study from the British Antarctic Survey (BAS), the University of Kiel, and the Alfred Wegener Institute, age matters for Antarctic clams when it comes to adapting to the effects of climate change. The study, published in the journal Global Change Biology, provides new insights into the likely impact that predicted environmental change could have on the future of ocean biodiversity.

The Antarctic clam (laturnula elliptica) is a long-lived and abundant species that lives in cold, oxygen-rich waters around the South Pole. Their reaction to environmental change, according to the study, differs markedly depending on the age of the animal.

When young clams — average three years old — sense warmer temperatures or reduced oxygen levels, they try to move to a better area in the sea-bed sediments. However, older clams — average 18 years — are more sedentary and tend to stay put. These findings have implications for future clam populations because older clams are the ones that reproduce, and scientists predict that future oceans will be slightly warmer and contain less oxygen, a condition known as hypoxia.

“Antarctic clams play a vital role in the ocean ecosystem. They draw down carbon into sea-bed sediments and circulate ocean nutrients. We know that they are extremely sensitive to their environment. Our study suggests that the numbers of clams that will survive a changing climate will reduce," said Melody Clark of BAS.

“The Polar Regions are the Earth´s early warning system and Antarctica is a great natural laboratory to study future global change. These small and rather uncharismatic animals can tell us a lot about age and survival in a changing world — they are one of the ℠engines of the ocean´.”

Eva Phillipp of the University of Kiel comments, “The study shows that it is important to investigate different ages of a population to understand population wide changes and responses. In respect to Antarctic clams it has been indicated in previous studies that older individuals may suffer more severely in a changing environment and the new study corroborates this assumption. Only the investigation of population-wide effects makes it possible to draw conclusions for coastal ecosystems.”

Clams lose muscle mass as they age much like humans. This makes them more sedentary and leads to a tendency to "sit out" changing environments until conditions revert back to normal.

“Our study shows that the physiological flexibility of young clams diminishes as they get older. However, the species has evolved in such a way that the fittest animals, that can tolerate life in an extreme environment, survive to reproduce into old age. Climatic change, affecting primarily the older clams, may interfere with this evolutionary strategy, with unpredictable consequences for ecosystems all around Antarctica," said Doris Abele of the Alfred Wegener Institute in Germany.