Archive for July, 2011

Global warming may mean big changes to marine ecosystems

July 20, 2011

As the Earth’s climate continues to warm, what kind of effects will we see in the ocean and the world in general? Seeking the answer to that broad question is one of the reasons scientists from the Skidaway Institute of Oceanography are working with an international team of scientists on an experiment in Bergen, Norway.

“There is really no doubt that our planet is changing,” said Skidaway Institute scientist Marc Frischer. “Levels of carbon dioxide are increasing, and we are seeing changes in climate. There is very little controversy about that anymore.”

According to Frischer, scientists need to investigate what those changes will mean to life in the ocean — from the tiniest bacteria up to fish and larger organisms.

“Those are the kinds of questions that are important to us humans, because we are dependent on the life in the oceans for our existence here on Earth,” added fellow Skidaway Institute scientist Jens Nejstgaard.

Frischer, Nejstgaard, Skidaway Institute research coordinator Stella Berger, and graduate student Zachary Tait are part of a team of 37 scientists who have come together from 13 countries to join their individual expertise in an effort to solve some of these very complicated questions.

Skidaway Institute mesocosm research team (l-r) Zac Tait, Jens Nejstgaard, Marc Frischer and Stella Berger

“What’s happening with climate warming is not only are we increasing temperature, we are also increasing the carbon dioxide (CO2)which has the effect of acidifying the ocean – just like a can of cola,” said Frischer. “In this experiment we are studying not just temperature or acidity individually, but their combined synergistic effects”.

What makes it so complicated to study is that there are many different organisms interacting with each other, and at the same time reacting differently to the climate change.

“So instead of just picking out a few organisms to look at in the laboratory, we have to investigate large representative pieces of the ecosystems to tell what effect the climate changes will have on the environment,” said Nejstgaard.

The experiment was conducted at a mesocosm facility of the University of Bergen. There, the scientists could enclose two and a half cubic meters of natural seawater in each of 14 tanks, recreating an ecosystem with all the biological and chemical components that exist in the natural water column. They are called mesocosms because they represent intermediate systems that are bigger than a laboratory test tube but smaller than the ocean. The researchers changed the temperature and CO2concentrations in the mesocosms, and then observed how the various parts of the ecosystem reacted.

The Bergen mesocosm facility

“Mesocosms provide the opportunity to conduct controlled experiments that are impossible to do either directly in the ocean or in the laboratory,” said Nejstgaard.

The team also added a third factor to the experiment. Gelatinous organisms are an important part of the oceanic ecosystem, but typically they are fragile and do not survive the process of pumping seawater into the mesocosm tanks. In order to more closely mimic the natural marine environment, the researchers added tiny gelatinous organisms called appendicularians as representative “jellyfish” to the tanks after they were filled.

The Bergen mesocosm facility is the longest continuously operating mesocosm facility in the world. It has run for 33 years and Nejstgaard has led international experiments there for the two last decades.

Since 2009, Nejstgaard has directed the first European coordination of mesocosm facilities, MESOAQUA (, together with Berger as a scientific coordinator. Although Nejstgaard relinquished his position in Bergen in order to join the faculty of the Skidaway Institute of Oceanography in January 2011, Berger maintains a part time position in the MESOAQUA program. Frischer and other Skidaway Institute scientists have been collaborating with the Bergen facility for more than a decade. This was their fifth experiment there.

The funding for this experiment was complicated. Both American and European scientists applied for research grants. The Europeans got their funding; the Americans did not. The funding came from the Norwegian Research Council, the Nordic Council of Ministers (NordForsk) and MESOAQUA. Luckily two of the three European grants provided some travel support for non-Europeans, making it possible for the Skidaway team to participate.

Although the team was international, the original design for the project came from a small group including Frischer, Nejstgaard and Norwegian colleagues. Their primary focus was on the effect ongoing changes would have on oceanic bacteria. Very preliminary results look good for bacteria, but not so much for the rest of the marine ecosystem.

“Our preliminary data suggests that rising acidity increases bacterial activity, which has some profound implications on how the ocean is going to change,” Frischer said. “If conditions favor the growth of more bacteria, they will benefit at the expense of other types of microscopic marine life, particularly marine algae like phytoplankton.”

Phytoplankton are a major part of the bottom of the food web. Their productivity has a direct effect on the food supply for microscopic animals (zooplankton) and all larger marine animals. On the other hand, energy that goes into the bacteria is believed to just cycle among very small organisms that are hard for the larger organisms to eat. If that is so, the global warming spell even more problems for the ocean’s already troubled fisheries.

“When you start looking at how all the little pieces are connected, those insights we gain will help us understand how our planet will change and what that will mean,” Frischer concluded. “That is what we are trying to learn and it is important to every aspect of our society.”

Since it is important to investigate the effect of environmental changes on different natural communities, the Skidaway Institute team hopes to be able to obtain funding to continue experiments in Bergen, and elsewhere, including in our own backyard.

“We hope to develop a world-class mesocosm research center at the Skidaway Institute of Oceanography where we believe the potential exists for the Institute to become a leading facility for the region,” said Nejstgaard. “Such a center would contribute to future studies of the many environmental challenges that face our region.”