GLOBAL: First findings of unique ocean expedition
The Hespérides arrived after a month-long voyage from Cape Town. The scientists on board are part of a US$23 million (EUR17 million) worldwide ocean research project - the Malaspina Circumnavigation Expedition. It involves more than 400 scientists from 10 countries, including researchers from the Oceans Institute at the University of Western Australia (UWA) and the Commonwealth Scientific and Industrial Research Organisation, CSIRO.
Some 4,000 ocean samples were collected in the Indian Ocean from as deep as 4,000 metres as part of an investigation recording greenhouse gas concentrations in the water, levels of persistent organic pollutants, high zooplankton levels, and the release of buoys to validate salinity measurements from space as part of a satellite mission by the European Space Agency.
The nitrogen supply from the atmosphere plays an important role in regulating climate because it helps plankton grow and capture carbon dioxide from the atmosphere.
"Nitrogen is a key nutrient for phytoplankton to grow, perform photosynthesis and capture atmospheric carbon dioxide," said Professor Carlos M Duarte, Coordinator of the Malaspina expedition. He is a research scientist with the Spanish National Research Council, which is leading the expedition, and also the newly appointed Director of UWA's Oceans Institute.
"The microorganisms that make up the phytoplankton community, remove more CO2 from the atmosphere than land plants do and therefore play a critical role in climate regulation," he said.
The Hespérides is the first of two ships to take part in the Malaspina expedition and it set out from Cádiz last November. Duarte said the expedition would not only circumnavigate the globe but also "breathe new life into Spanish oceanography by combining efforts and generating a new culture of cooperation".
The Hespérides was followed in January by the Sarmiento de Gamboa and the two ships will spend a total of nine months at sea, covering some 33,000 nautical miles or nearly 60,000 kilometres. Most of this distance will be sailed by the Hespérides, which will dock in Río de Janeiro, Cape Town, Fremantle, Sidney, Auckland, Honolulu, Panamá and Cartagena de Indias, ending next July in Cartagena in Spain.
The Sarmiento de Gamboa sailed from Spain in January to cross the Atlantic from Las Palmas de Gran Canaria to Santo Domingo. During their stopovers in port, the two ships will run a series of lectures and other events to raise awareness about the effects of global change, highlight the importance of marine research and describe the Malaspina expedition.
More than 250 researchers from 19 Spanish institutions are taking part in the project while another 150 include students and researchers at 16 associated foreign institutions, among them NASA, the European Space Agency and the universities of California, Río de Janeiro, Washington and Vienna.
Research teams on the two vessels will perform tests at 350 points and collect more than 70,000 samples of air, water and plankton from the surface down to depths of 5,000 metres.
One novel aspect of the project is the launch of 19 Argo buoys to measure the ocean's temperature and salinity, in 10-day cycles, from the surface down to a depth of 2,000 metres, many of them in zones that have never been monitored.
A further 20 buoys were launched from the Hespérides and were designed specifically for the project to measure salinity at a depth of 50 centimetres and send the data via the SMOS satellite. This will enable the first satellite map of marine salinity to be charted in the collaboration between the Malaspina project and the European Space Agency.
The researchers on board Hespérides found high concentrations of silicate in water samples collected in the Indian Ocean, from the surface down to 4,000 metres.
"We have found silicate concentrations three times higher than those in the Atlantic Ocean," said researcher Dr Jordi Dachs, who was the Chief Scientist for the Cape Town-Perth section of the voyage, the fourth leg of the circumnavigation.
"This is significant because silica is an essential element for diatoms to grow, and these diatoms, which contain symbionts able to fix atmospheric nitrogen, play a particularly important role in carbon cycling in the ocean," Dachs said.
The Malaspina scientists also discovered numerous Rhizosolenia diatoms in the water column extending from the surface down to 100 metres. This genus tends to be associated with a nitrogen-fixing cyanobacteria to produce organic matter with which to build their cells.
"The fact that the concentration of silicate in the Indian Ocean exceeds that of other nutrients such as nitrate and phosphate favours diatom associations with nitrogen fixing bacteria," Dachs said.
During the voyage from Cape Town to Fremantle, the Malaspina scientists investigated the Indian Ocean ecosystem with nets, sampling bottles and other instruments at 24 sampling stations. The 4,000 samples collected are being studied to examine the concentration of greenhouse gases in the water and the isotopic composition of atmospheric water vapour, thereby helping to resolve water cycling in the atmosphere over the Indian Ocean.
The scientists also conducted a detailed study of persistent organic pollutants and their cycling in the Indian Ocean - a study that has never been conducted before.
A small portion of the samples collected on the voyage will be stored in the Malaspina Collection, a time capsule that will remain locked for 30 years. The specimens will be investigated by future scientists, possibly using research tools not yet available and posing new research questions.
The Hespérides was in Fremantle until 17 March and then continued its circumnavigation, sampling in the Southern Ocean, sailing on to Sydney and then Auckland. As part of this leg, scientists are undertaking research in conjunction with the CSIRO and the UWA Oceans Institute, including towing a plankton recorder to provide a continuous inventory of the abundance and diversity of plankton organisms in Australian waters.
"The ocean south of Australia is a particularly interesting region where three oceans - the Indian, Pacific and Southern - converge," said Professor Susana Agustí, Chief Scientist on the Perth-Sydney leg of the voyage and a research professor with Oceans Institute. "Exploring the biodiversity of these waters will surely reveal surprises."
The unique global expedition was named by the Spanish organisers after Alejandro Malaspina, a frigate captain in the Spanish navy who died 200 years ago last year. In July 1789, Malaspina led two frigates on the first Spanish circumnavigation expedition and, during the five-year voyage, researchers collected data, charted territories, recorded fauna and explored the sea.
Although Malaspina was promoted on his return, he was later accused of conspiracy, imprisoned and then exiled. This resulted in his expeditions being forgotten until late last century. According to the Spanish organisers, the current project aims to restore Malaspina's pioneering expedition to the prominence it deserves.
* For more science reports, see this week's Science Scene section.