BSC studies changes in species distribution in Pacific islands due to climate change

27 October 2023
The MOANA project, led by Ariadna Mecho, a researcher at the Barcelona Supercomputing Center, aims to study the impact of climate change on some marine species in this delicate and unknown area of the planet

The marine ecosystem of the Pacific Ocean's islands and seamounts is susceptible to human activity's impact.

Modifying environmental conditions, such as temperature increase or water acidification, can alter the environment in which some species live, affecting the conditions necessary for their survival and reproduction.

Currently, one of the planet's least studied areas is the Pacific Ocean's islands and seamounts, mainly due to their difficult access and remoteness from continental areas. However, it has been shown that the marine ecosystems inhabiting these islands and seamounts are particularly sensitive to anthropogenic effects, such as the impact of climate change. Changes in environmental conditions such as increased temperature, decreased availability of oxygen or acidification of seawater can modify the habitat of species, causing the conditions for survival and reproduction, especially for some groups such as corals, to be inadequate in the near future.

These circumstances will generate a problem not only at the ecological level and loss of biodiversity but will also have a negative economic and cultural impact on the people living on these islands. For example, the possible disappearance of corals, a source of tourism and habitat for many species of fish and crustaceans consumed on the islands, will have disastrous consequences for the islanders. Another example is the "pures", small shells widely used in Polynesian communities for ornamentation and local clothing. The disappearance or decline of their populations would entail the loss of an ancestral culture.

Researcher Ariadna Mecho from the Climate Variability and Change group of the Earth Sciences Department of the Barcelona Supercomputing Center-Centro Nacional de Supercomputación (BSC-CNS) leads the MOANA project, which seeks to study the movement of these marine species in some islands and seamounts in the Pacific (such as Rapa Nui/Easter Island, French Polynesia or the Pitcairn Islands). The study actively collaborates with the Center for Ecology and Sustainable Management of Oceanic Islands (Centro de Ecología y Manejo Sustentable de Islas Oceánicas, ESMOI; Chile), which has been working in the area since 2014 and with which the BSC researcher has been actively collaborating since 2016. The MOANA project, funded through a postdoctoral fellowship from the European Marie Skłodowska-Curie program [GA-Nº-101107435], will also make it possible to obtain maps on the current and future distribution of 10 species of ecological and socioeconomic importance for the islands.

Using models that calculate the probability of finding a suitable environment in a particular geographic area using algorithms that combine information on the known presence/absence of the species and the environmental conditions in the area (e.g., temperature, pH, or nitrate concentration), the range of species of interest over much larger areas can be derived. Some of the most commonly used algorithms are based on machine learning models, which can process complex and massive data sets (Big Data).

For environmental conditions, Earth System Models (ESM) data are used. ESMs simulate physical, chemical and biological processes and their interactions and are widely used to study past, present and future changes. In addition, trained algorithms for species distribution models can include information from climate change projections under different scenarios, thus being able to estimate future habitat and species distribution changes over time.

This will make it possible to create maps of refuge areas for species, delimit risk and vulnerability zones, and demarcate their potential as ecologically or biologically critical marine areas. Decision-makers can then use this information to apply protection tools at the marine level, such as the formation of Mobile Protected Areas with Mobile Boundaries, which will adapt their boundaries to changes in the distribution/migration of species.

Recently, the MOANA project was presented to the Rapa Nui community during the seminar "Avances y Proyecciones en las Investigaciones Oceánicas en Rapa Nui y las Dorsales de Salas & Gómez y Nazca" organised by ESMOI and held at the Katipare Center. During the event, which was attended by important regional personalities, the researchers shared relevant information about their work on crucial issues for the biodiversity of terrestrial and marine fauna and the impact of the environmental crisis in the region.

"The most important thing is to inform the local community of what we are coming to do on the island since they are the first interested parties, and local knowledge of the species that inhabit the island is essential for our studies," says BSC researcher Ariadna Mecho, who participated in the seminar to present and explain the project to the islanders. She adds: "The Rapa Nui community, like all Polynesian peoples, has always lived in close relationship with the ocean, so they are very interested in knowing what will happen to marine species in the future".

In this line, these advances allow a better understanding of changes in climate and their impacts on marine ecosystems, enabling society to make informed decisions and promote the conservation of these precious and unique regions in the world.