Algae in nutrient-poor environments are more susceptible to climate change

The increased temperature and acidity of sea waters can cause changes in the structured communities of algae in coastal habitats.

By Elton Alisson

Agência FAPESP – Recent studies indicate that marine organisms that live in nutrient-poor environments will be more susceptible to the impacts of global climate change on the oceans than will those in nutrient-rich environments.

 

Organisms in nutrient-poor environments are more vulnerable because, given the reduced availability of nitrogen and phosphorus (among other nutrients) in the places where they reside, they are likely to be less  resistant to the effects of climate change than their counterparts in areas with greater availability of these “foods.” As a result, these organisms are likely to be more vulnerable to the 4-degree Celsius increase in seawater temperatures and the 0.6 pH unit reduction projected for this century.

 

A series of experiments with algae conducted by researchers, including six Brazilians, on five continents corroborates these observations. The group found that algae living in nutrient-poor environments are more susceptible to changes in temperature, pH and ultraviolet radiation caused by climate change than are algae in places where more nutrients are available.

 

As a result, the increases in the temperature and acidity of seawater could cause changes in the community structure of algal habitats, reducing the primary productivity (of organisms that conduct photosynthesis). Consequently, the contribution that oceans make to mitigating the effects of climate change will be reduced because algae are among the principal participants in carbon dioxide sequestration.

 

“Some of the studies have pointed to this hypothesis, which we have now corroborated through a series of experiments conducted under different conditions,” commented Fanly Fungyi Chow Ho, a researcher at the Édison José de Paula Marine Algae Laboratory (within the Botany Department at Universidade de São Paulo’s Biosciences Institute) and one of the participants in the study, in an interview with Agência FAPESP.

 

The research group conducted the experiments during the 9th International Workshop of the Group for Aquatic Primary Productivity (GAP). The workshop was held in Malaga, Spain at the end of September and was organized by the University of Malaga and the Spanish Oceanography Institute in partnership with the International Society of Limnology. The idea behind the workshop differs from the concept behind other conventional scientific events.

 

Instead of conference, panel and round table presentations, actual studies were conducted during the scientific meeting. These studies, including experiments in the field and in tanks and laboratories, were planned a year in advance with the objective of achieving a better understanding of the impacts of global climate change on certain species of macro- and microalgae.

 

Approximately 100 researchers and graduate and postgraduate students participated in the event. They were split into four workgroups to conduct the experiments. Two groups conducted experiments in tanks and in the coastal waters of Malaga to analyze the chemical and physiological responses of particular species to environmental stress conditions.

 

The other two groups – one of which was coordinated by Chow Ho – conducted experiments in which algal samples were collected from aquaria containing different concentrations of nutrients and with different water temperature, acidity and UV radiation conditions to simulate the conditions that can occur in an environment affected by climate change.

 

At the same time, the scientists studied a series of parameters specifying the physiological responses of the algae to these environmental variations. These parameters included growth, the capacity for photosynthesis and the production of biochemical compounds of biotechnological interest, such as antioxidants and pigments.

 

The preliminary results of the analyses indicate that the changes in acidity, temperature and nutrient availability changed the capacity of the algae for photosynthesis, growth and biochemical compound production. However, reducing the availability of the nutrients in the water was also found to be potentially useful for improving the physiological and biochemical characteristics of certain microalgae of interest for biotechnological applications.

 

Laboratory experiments with Chlorella microalgae conducted by researchers during the event revealed that growth of algae – which yield a nutritional supplement favored for its high antioxidant properties and are widely viewed as a source of raw material for the development of biofuels and bioremediation of waste water – is only moderately affected by alterations caused by climate change. Furthermore, algae are capable of accumulating more lipids that have food and energy applications if subjected to nutrient-poor conditions.

 

“The reduction in the quantity of nutrients in water can be beneficial for increasing production of the biomass of these microalgae,” evaluates Chow Ho, who has already had multiple projects funded by FAPESP and is currently participating in a study on the integrative physiology of macroalgae under stressful conditions.

 

Unprecedented results

 

Several of the findings of the collaborative studies conducted by the group of international researchers were presented and discussed at the event. Additional results are in the analysis stage and should be published in 2013 in a special volume of Aquatic Biology that will include approximately 15 articles.

 

“The landmark results will require more time to be generated because they need more in-depth analysis in the laboratory than we were able to do during the 10-day event,” explained Chow Ho.

 

In all, the researchers collected approximately 9,000 samples of algae and 10,000 individual data points during the event. These research findings will be subjected to chemical, genomic and transcriptomic analyses in laboratories in Ireland, the United States, France and Spain throughout 2013. The group of Brazilian researchers will participate in the statistical analysis and tabulation of the results.

 

In addition to Chow Ho, other Brazilian participants in the experiments were the researchers Cristina Nassar and Rodrigo Mariath of Universidade Federal do Rio de Janeiro (UFRJ), José Bonomi Barufi of Universidade Federal de Santa Catarina (UFSC), Margareth Copertino of Universidade Federal do Rio Grande (FURG), and Moacir Aluísio Torres of Universidade Estadual de Santa Catarina (UESC). Barufi and Torres completed their master’s degrees with FAPESP fellowships.