Marine Food Chain in Peril

Ocean Acidification caused by increasing CO2 emissions  combined with global climate change and rising sea temperatures  is putting severe stress on many marine organisms.

Calcifying organisms such as sea urchins, oysters, corals, calcareous plankton and pteropods (also known as sea butterflies) are particularly vulnerable to ocean acidification, as it reduces the saturation states of calcium carbonate minerals in the ocean, making it harder for them to both produce and maintain their CaCO3 skeletons and shells.

A team from the Hofmann Lab at the University of California, Santa Barbara, are studying the impacts of ocean acidification in calcifying marine invertebrates such as the pteropod Limacina helicina antarctica (pictured). 

  Pteropod Limacina helicina antarctica. Photo taken by the Hofmann Group, using a Wild M37 stereomicroscope and Linkam PE120 stage  

 

Pteropod Limacina helicina antarctica. Photo taken by the Hofmann Group, using a Wild M37 stereomicroscope and Linkam PE120 stage  

The team are based at the McCurdo research station in Antarctica, where they captured these fantastic images. 

  Aurora in Antarctica, photo by Jim Janoso  

 

Aurora in Antarctica, photo by Jim Janoso  

With the help of Jim Janoso from Northern Focus Optical Inc. they were also able to take this great footage of a swimming juvenile Limacina helicina antarctica, using a Wild M37 stereomicroscope and a Linkam PE120 stage. 

The group hope to understand the molecular and physiological responses of Limacina helicina antarctica to these increases in temperature and acidity. Using data from durafet-based pH sensors that have been deployed in the area since 2010, the team can predict future sea conditions and investigate the effect of these on the metabolism, gene expressions and shell morphology. 

Although small, pteropods are extremely environmentally important. They are a source of food for a huge range of species (from krill to whales, and many economically valuable fish species). Dr Gretchen Hofmann, professor of Marine Biology at the USCB and principal investigator of the Hofmann group, said "It's possible by 2050 [pteropods] may not be able to make a shell anymore. If we lose these organisms, the impact on the food chain will be catastrophic". 

Hoffman explains that as the acidity of the sea increases the pteropod larvae have to "re-tune" their metabolisms in order to make a shell. These strenuous physiological changes however make Limacina helicina antarctica less able to cope with the rising sea temperatures, and result in an organism of decreased size. 

You can follow the group's research both on their Facebook page and their  website

  Stage set-up, with Linkam PE120 in vertical position 

 

Stage set-up, with Linkam PE120 in vertical position 

By Frances Coles