Sparks

How is climate change affecting oceans?

 By Anna Volpicelli

Coralline algae and bryozoans (small invertebrates) could reveal important information about the effects climate change is having on our oceans

This is the core of Chiara Lombardi‘s study, a researcher at the National Agency for New Technology, Energy, Sustainable Economic Development – ENEA Biodiversity and Ecosystem Services Laboratory at the Santa Teresa Research Center in La Spezia, Italy. The marine ecologist has spent years analyzing and investigating the climatic effects on organisms that have a calcium bicarbonate skeleton—like that of a hard-boiled egg—including coralline algae and bryozoans.
The research, called “Ice-ClimaLizersAntarctic Biomineralizers as Proxies of Climate change was launched at the end of 2018 and saw the construction of a laboratory placed at 25.5 meters depth in the waters of the Ross Sea in Antarctica. The project is coordinated by ENEA in collaboration with two CNR institutes (Bologna Marine and Genoa Sea Engineering), Sopot Institute of Oceanology (Poland), University of Portsmouth and Natural History Museum of London (United Kingdom) and University of Burgundy (France). Funded by the National Program for Research in Antarctica (PNRA), it is the first Italian climate project focused on the role of Antarctic biomineralizers as indicators of climate change, in particular of ocean acidification.
“These organisms are important because they are bioindicators that are able to record the environmental conditions in which they live”, explains Lombardi. “They are also bioconstructors because they promote biodiversity“.

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A colony of the modern marine bryozoan Flustra foliacea (Hans Hillewaert, Flickr)

A protected area

According to Lombardi, both Antarctica and the Arctic are environments in which climate change is extremely accelerated. She explains: “The climate of the Antarctic is changing rapidly, and the southern ocean is expected to be vulnerable to changes induced by human activities, and in particular to the effects of acidification. The South Pole is very important because the ocean current flow is responsible for the worldwide circulation of the nutrients, the organisms and the biodiversity. It is essential to know the responses of these organisms to protect them and safeguard the biodiversity associated with them, especially in an area like the Ross Sea”. In 2017, the whole zone became a protected area.

The study of the species

The mission relies on the Mario Zucchelli Station, the famous Italian scientific base in Antarctica, which has been in operation since 1985. During last year’s 34th expedition, Lombardi and a team of experts sampled 6-7 different bryozoan species and 1 species of algae (for a total of 40 algae, 30 shells and 60 bryozoans) at temperatures of -1.8 degrees. During the dives, the researchers collected the organism on the Tethys Bay inlet with the support of the Navy’s divers and of a submarine remote-controlled ROV for exploring deep environments (up to 120 m). The species collected, partially by human hands and partially by the robot, were placed in 12 cages—six for coralline algae and six for the bryozoans—and equipped with light and temperature sensors. Here, the organisms were marked with non-toxic substances and then positioned on the bottom of Tethys Bay, inside an aluminum structure.

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The twelve cages (ENEA)

“Marking them was necessary because it allows us to determine the growth and development of these organisms from the beginning of the experiment”, explains Lombardi. In addition, a probe placed in the cage records the main environmental data, including PH, temperature, oxygen, light intensity, salinity. “During the winter, the bryozoans interrupt their growth by forming on their skeleton a sort of scar, similar to the rings of the trees. From the count of the scars, it is possible to trace their age“, says Lombardi. “Moreover, through complex physiological processes, these organisms can form a calcium carbonate skeleton, which contains information on its external environmental conditions. The algae have a resistant structure and yet it is extremely vulnerable to climate change“.

The Italian case

Before starting this adventure in the South Pole, the marine ecologist and her research team carried out experiments in Italy. The project, called “Will Corallines Algae Reef Mitigate Climate Change Effects on Associated Fauna”, was funded by the Royal Society (International Exchange Grant RS-CNR). It involved the construction of 60 artificial “mimic” algae that were transplanted to the seabed of La Spezia’s Santa Teresa Bay. After six months (June 2017 to December 2018), the “mimic” algae, made of non-toxic silicones resin, were brought to the lab and analyzed to see if they could be used as tools for restoring natural ecosystems compressed by climate change.

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The "mimic" algae of the Santa Teresa Bay (ENEA)

Waiting for the answers

If the Italian experiment is based on artificial algae, the research in Antarctica, instead, relies only on real organisms. “What I’m trying to do with this work is to highlight the role of bryozoans in their important functions”, explains Lombardi. “They are organisms that, like algae, can help implement a series of climate change mitigation strategies. Algae, like trees, can produce oxygen through the chlorophyll photosynthesis process”. Lombardi continues to emphasize the importance of protecting them. “It is essential because, one day it may be possible to replant these organism in other areas, like seaports. This would create a sort of green lung within these areas that are heavily exploited. The same is true for the bryozoans; they cannot do any photosynthesis, but their skeletons are very fundamental for the information they provide”. Answers to all these questions will start to emerge by late November 2019, when Lombardi and her team will return to Ross Sea for the 35th expedition of the PNRA to remove the cages and a multi-parameter probe. “It will take time to get all the information we need, so we expect to be able to start to analyze the data in 2020. We hope to have a few answers by the end of the next year”. With the 35th expedition, it will be possible to compare the data of the organisms with the environmental data recorded by the probe to validate the function of coralline algae and bryozoans as indicators of climate change, as well as to understand their potential for adaptation to the conditions of the oceans of the future.

Cover image by: Erwan AMICE, Wikimedia

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about the author
Anna Volpicelli