Ocean architects at risk from combined impact of acidification and ocean warming

A research team from the Institut de Ciênces del Mar (ICM-CSIC) published a study in Communications biology Showing how the acidification and warming of the ocean – two of the main consequences of global climate change – can simultaneously affect the structure, mineral composition and bryozo microbiome, crucial colonial invertebrates to form marine habitats. The results indicate potentially serious ecological consequences in an accelerated climate change scenario.

The study characterizes for the first time the microbiome of Myriapora Truncata, a housing format species known as “false coral” and widely distributed throughout the Mediterranean. He also analyzes the response of this Bryozoa species and another encrust under future environmental conditions. False corals form three -dimensional structures which offer shelter to many species, just like other bryozoans which can even form reef -type systems – although corals generally receive more attention as manufacturers of primary marine habitats.

“Although it is a different phylum, very diverse and abundant on a global scale, these small architects of the sea are often ignored in studies on responses to environmental changes,” explains Blanca Figuerola, ICM-CSIC researcher and the main study of the study. She points out that this work opens a new window to better understand how bryozoaries can react to the rapid ocean changes.

The researcher notes that “the Bryozoa play a very important ecological role”, although little is known before their response to the combined effects of acidification and warming of oceans. She adds that “their microbiome had been practically unexplored”.

A natural laboratory to predict future scenarios

To conduct the study, the team used a “natural laboratory”: on the island of Ischia (Italy), the volcanic bubbles of the seabed, which allow the simulation of the conditions of acidification of the ocean projected for the end of the century.

“This area offers a unique opportunity to study how marine species react to acidification in natural conditions,” explains Núria Teixidó, researcher of the Stazione Zoologica Anton Dohrn and last author of the article.

Using this approach, the researchers compared morphology, skeletal mineralogy and the colonial microbiome of two species of exposed bryozoaans and not exposed to these conditions. The results show that the species has a certain acclimatization capacity, modifying their skeletal mineralogy to become more resistant and maintain a relatively stable microbiome composition.

“However, we have observed a loss of functional microbial diversity, with a drop in genres potentially involved in key processes such as nutrition, defense or resistance to environmental stress,” said Figuerrola.

These microbial changes can have significant long -term consequences, because the microbiome plays a fundamental role in the health and resilience of the Bryozoans. “Even if the colonies seem healthy, changes in the microbiome could serve as early bioindicators of environmental stress,” adds Javier Del Campo, researcher at the Institute of Evolutionary Biology (IBE, CSIC-UPF).

Warming amplifies the impacts

During a five -year surveillance period, the study also examined the effects of increasing temperatures – another key factor in climate change.

“The models used indicate that the combination of these two stress factors intensifies the observed effects, considerably reducing the coverage of the encrusting bryozoa and increasing mortality. Although the species has a certain morphological plasticity, it is not enough to compensate for the combined impact of acidification and warming,” explains Pol Capdevila, researcher at the University of Barcelona.

To achieve these conclusions, the team used advanced techniques such as modeling and microTomography calculated to obtain, for the first time, 3D images of the internal skeleton structure of these species. These images are precious for both research and for scientific communication and environmental education. The team is currently preparing a scientific animation for the general and educational public, in collaboration with the team of Cooked Illustrations, a visual narrative studio.

Implications for marine conservation

The results have important implications for the management and conservation of Mediterranean marine ecosystems, in particular in the context of climate change. Habitat formative species such as bryozoans are not only vulnerable, but their disappearance could trigger cascade effects on many other species that count on them for shelter or food.

The characterization of the microbiome and the preliminary identification of potentially beneficial microorganisms open up new research paths to improve the resilience of Holobionts (host and its associated microbiome) through nature-based approaches.

This research line, initiated as part of the Medcalres National Plan project, is now continuing with the Holochange consolidation project and the national Medacidwarm plan, which aims to deepen the understanding of the Bryozoaan-Microbiome interactions to anticipate and reduce the impacts of climate change.

“The complexity of the problem requires integrated analyzes,” concludes Figuerola. “This study shows how interdisciplinary approaches can help us anticipate future scenarios and more effectively protect marine ecosystems.”