Researchers from Chile have been investigating a “red tide” Heterosigma akashiwo algal bloom in early April 2024, — possibly caused by a changing climate.
“Red tide” blooms, are a natural phenomenon caused by an exponential increase of microalgae, giving the ocean a reddish, green or brown tinge but they can also harm people, animals, or the local ecology: in 1972, three fisherman were the first recorded deaths in Chilean Patagonia attributed to the toxins.
Andrea Corredor-Acosta, a researcher at the the Center for High Latitude Marine Ecosystem Dynamics Research (IDEAL) at the Universidad Austral de Chile, says her research focuses on using satellite and field data to monitor changes in the annual growth cycles of micro-algae off the coast of Chilean Patagonia and the West Antarctic Peninsula.
“Since this type of environmental forcing has been changing as a function of global climate variability, changes in the productive activity of these micro-algae are also expected,” she says, “In this climate change scenario, certain phytoplankton species become more sensitive to oceanographic/climate variability in different areas of Patagonia, promoting in many cases potentially harmful algal blooms (HABs).”
In order to understand the causes of this latest event in Hornopiren in Chile’s Patagonia region, an expedition led by Dr. Jorge Mardones, a researcher at the Center for Marine Research of the University of Chile focused on analyzing that bloom from different disciplines: ecology, oceanography, toxicology, dissecting fish, meteorology and aerial overflights.
Mardones explained that the aquaculture industry, academia and institutions linked to the state, in charge of monitoring and environmental environmental assessment related to HABs, have been waiting for months with uncertainty as to where and when such an event would occur.
“We are learning step by step how to interpret the biological, oceanic and biological, oceanic and climatic signals that warn us of a higher probability of an HAB occurrence in Patagonia,” he says.
From The Andes To Cold Seas
Corredor-Acosta was born and raised in Bogota, Colombia, but also had the chance to swim off Colombia’s Caribbean coast, with one of her uncles, a marine biologist.
“So much richness of marine life and colors was always shocking to me,” she says, adding that during her undergraduate studies in physics at the Universidad Distrital Francisco José de Caldas, in Bogota, she realized she wanted to focus on the characterization of ocean circulation under different climatic regimes using satellite images in the Colombian Pacific.
“My experience in the development of this work was spectacular, there was a world to learn, work and investigate,” Corredor-Acosta says, adding that she would go on to obtain a Master’s degree in Exact Sciences and a PhD in Oceanography at the University of Concepción, Chile.
For her postdoctoral studies, Corredor-Acosta arrived at IDEAL in Chile.
“During these years of specialization, my research focus has been mainly oriented to investigate the coupling of phytoplankton life cycles with the oceanographic conditions of the environment, and this in turn with climate variability off the Colombian Pacific and Chilean coast,” she says.
Corredor-Acosta explains that the seas and coastlines of Patagonia are a highly diverse system, which has become increasingly vulnerable to changes in climate and human impact.
“An analysis of how these interactions have changed in recent decades will allow us to project how this region, and others of similar characteristics in other parts of the planet, will potentially change in the near future,” she says.
Documenting Blooms in Patagonia
Another researcher working on algal blooms in Patagonia is José Luis Iriarte, an oceanographer working at Universidad Austral de Chile and Principal investigator at the IDEAL in Punta Arenas, Chile.
Corredor-Acosta’s postdoc supervisor, he was the scientific leader of 24 Chilean and foreign scientists on board the Chilean Navy scientific vessel Cabo de Hornos in 2023, with a documentary crew also capturing the expedition on film.
The team aimed to detect new toxins in the southern marine system, as well as to learn about the environmental factors that may explain the distribution of the toxic blooms.
Iriarte says that several marine toxin-producing species have been observed along the coasts of Patagonia including new ones that affect fishes, as well as those that cause paralysis and food poisoning in humans (known as red tide poisoning)
“It is a scientific challenge the understanding of how toxic species along the coast could be associated with unknown environmental climatic-hydrologic and oceanographic features coupled with a changing ocean scenario,” he says.
