A research team from the Institut de Ciències del Mar (ICM-CSIC) has unveiled alarming findings in Communications Biology regarding the impact of ocean acidification and warming on bryozoans, crucial marine habitat architects. These environmental stressors, driven by global climate change, threaten to alter the structure, mineral composition, and microbiome of these colonial invertebrates, potentially leading to severe ecological consequences.
The study focuses on Myriapora truncata, commonly known as “false coral,” a species prevalent in the Mediterranean. This research marks the first comprehensive characterization of its microbiome, alongside an analysis of its response to future environmental conditions. Bryozoans, often overshadowed by corals, play a vital role in forming three-dimensional marine structures that offer shelter to numerous species.
The “False Coral” and Its Ecological Role
Despite their ecological significance, bryozoans have been largely overlooked in studies concerning environmental changes. Blanca Figuerola, the lead author and ICM-CSIC researcher, emphasizes the importance of understanding these organisms’ responses to oceanic shifts. “Bryozoans play a very important ecological role,” she explains, noting the previous lack of knowledge about their microbiomes and their reactions to acidification and warming.
Using the island of Ischia in Italy as a “natural laboratory,” the team simulated future ocean acidification conditions. Volcanic CO₂ bubbles from the seabed provided a unique opportunity to observe marine species’ responses to acidification naturally. Núria Teixidó, a researcher at the Stazione Zoologica Anton Dohrn, highlights the significance of this approach in understanding species adaptation.
Adaptation and Microbial Shifts
The study revealed that bryozoans exhibit some acclimation capacity, adjusting their skeletal mineralogy to resist acidification while maintaining a stable microbiome composition. However, Figuerola warns of a decline in functional microbial diversity, which could affect key processes like nutrition and environmental stress resistance.
“Even if colonies look externally healthy, changes in the microbiome could serve as early bioindicators of environmental stress,” explains Javier del Campo, a researcher at the Institute of Evolutionary Biology (IBE, CSIC-UPF).
These microbial changes may have significant long-term implications for bryozoan health and resilience, potentially affecting the broader marine ecosystem.
Warming’s Amplifying Effects
Over a five-year period, researchers also examined the effects of rising temperatures, another critical climate change factor. Pol Capdevila from the University of Barcelona notes that the combination of acidification and warming significantly reduces bryozoan coverage and increases mortality, despite some morphological plasticity.
Advanced techniques like modeling and computed microtomography allowed the team to create 3D images of bryozoan skeletons, offering valuable insights for research and educational purposes. Collaborating with Cooked Illustrations, the team plans to produce a science animation to engage the public and raise awareness.
Implications for Marine Conservation
The study’s findings have profound implications for the conservation of Mediterranean marine ecosystems. The potential disappearance of habitat-forming species like bryozoans could trigger cascading effects on dependent species. The research opens new avenues for enhancing bryozoan resilience through nature-based approaches, focusing on their microbiome.
Ongoing projects like HOLOCHANGE and MedAcidWarm aim to deepen the understanding of bryozoan–microbiome interactions to better anticipate and mitigate climate change impacts. Figuerola concludes, “The complexity of the issue demands integrated analyses. This study shows how interdisciplinary approaches can help us anticipate future scenarios and more effectively protect marine ecosystems.”
