The Silent Adaptation: How Marine Fungi Are Evolving to Survive Climate Change
Deep beneath the ocean's surface, a silent, unseen revolution is underway. As climate change reshapes our marine environments, scientists are discovering that fungi—nature's master adapters—are undergoing remarkable evolutionary shifts to survive and thrive in the new normal of our warming world.
"We address the ecology and evolution of marine fungi and the effects of climate change on them to explain the adaptation mechanism,"
Researchers note, highlighting how these organisms are responding to environmental shifts 1 .The Hidden World of Marine Fungi
For centuries, fungi were largely overlooked in marine science, perceived as minor players compared to bacteria and algae. Today, cutting-edge genetic technologies are revealing that marine fungi represent a vast, untapped biological frontier, with less than 10% of species identified globally 6 . These hidden organisms are not merely passive inhabitants of the seas—they are active ecosystem engineers, capable of remarkable transformations that may hold keys to addressing some of our most pressing environmental challenges.
The Unseen Regulators of Ocean Health
Marine fungi represent a diverse biological kingdom distinct from plants and animals, inhabiting environments from sunlit surface waters to the deep-sea floor 1 6 . They perform critical ecological functions that sustain marine life: breaking down organic matter, recycling nutrients, and facilitating energy flow through ecosystems 1 .
Perhaps their most crucial role lies in carbon cycling—the process that determines how carbon moves through marine environments and ultimately affects atmospheric CO₂ levels. Recent research has revealed that fungi account for a disproportionate share of extracellular carbohydrate-active enzyme expression in oxygen minimum zones, with glycoside hydrolase family 7 (GH7) emerging as the dominant enzyme for particle degradation .
Diversity of Marine Fungi and Their Ecological Roles
| Habitat | Fungal Types | Key Ecological Functions |
|---|---|---|
| Coastal Waters | Filamentous higher fungi, yeasts | Decomposition of mangrove wood, nutrient recycling 1 |
| Open Ocean | Yeasts, planktonic fungi | Organic matter degradation, parasitism, symbiosis 9 |
| Deep Sea | Yeasts, novel phylotypes | Sediment nutrient cycling, humic aggregate formation 1 |
| Extreme Environments | Novel species from hydrothermal vents | Adaptation to high pressure, temperature, salinity 1 |
Nutrient Cycling
Marine fungi play a crucial role in breaking down organic matter and recycling nutrients through marine ecosystems, supporting the entire food web 1 .
Carbon Sequestration
Through specialized enzymes like GH7, marine fungi contribute significantly to carbon cycling in oxygen minimum zones, affecting global climate regulation .
Climate Change: The Great Selector
The Mediterranean Sea, a biodiversity hotspot home to more than 17,000 marine species, provides a sobering case study of the pressures marine ecosystems face. This region is experiencing climate change at an accelerated pace, with seawater temperature increases more than double global averages and acidification rates approximately 1.5 times higher than the global ocean 2 .
Temperature Increase
More than double global averages in the Mediterranean Sea 2 .
Acidification Rate
Approximately 1.5 times higher than the global ocean 2 .
These rapid environmental changes function as a powerful selective force, agitating interactions between organisms and their environment and forcing them to adapt, migrate, get replaced by others, or face extinction 1 . Research indicates that coastal ecosystems face particularly severe threats, with risk levels expected to become "very high" once global warming exceeds 0.8°C above the 1976-2005 period 2 .
Marine Fungi Adaptation Mechanisms
Metabolic Flexibility
Many marine fungi demonstrate remarkable ability to shift their metabolic processes to utilize different nutrient sources as availability changes 7 .
Genetic Innovation
Through horizontal gene transfer and rapid evolution, marine fungi can acquire new genetic traits that improve fitness in changing conditions 6 .
Symbiotic Relationships
Some species form new partnerships with other marine organisms, creating collaborative survival strategies in stressful environments 9 .
Case Study: Unveiling Fungal Secrets in the Oxygen-Depleted Ocean
A groundbreaking 2025 study published in Microbiome Journal investigated previously unexplored fungal diversity in the Eastern Tropical North Pacific Ocean (ETNP), home to the world's largest oxygen minimum zone . This research provides unprecedented insights into how fungi are adapting to some of the most challenging marine environments.
Methodology: A Multi-Technique Approach
Sample Collection
Seawater was collected from three stations within the ETNP, representing peripheral, offshore, and coastal oxygen minimum zones. Samples were taken at various depths to capture changes across oxygen gradients .
Advanced Filtration
Researchers used an air-operated diaphragm pump to rapidly filter large volumes (30 liters) of seawater through fine-pore membranes, capturing even the scarcest fungal cells .
Genetic Analysis
The team extracted both DNA and RNA from the same filters, allowing them to identify not only which fungi were present (via DNA) but also which genes were actively being expressed (via RNA) .
Multi-Platform Sequencing
Cutting-edge Illumina and Nanopore sequencing technologies were employed to achieve comprehensive genetic coverage, enabling the identification of novel fungal lineages .
Key Findings: Revolutionizing Our Understanding
Evolutionary Distinctness
Oceanic fungi form distinct evolutionary clades that diverge from their terrestrial counterparts, challenging earlier models of multiple marine-terrestrial transitions .
Outsized Functional Role
Despite comprising a very low percentage of the total DNA and RNA pool, fungi accounted for a disproportionate share of extracellular carbohydrate-active enzyme expression .
Specialized Enzymatic Toolkit
The glycoside hydrolase family 7 (GH7) emerged as the dominant enzyme, suggesting a specialized fungal role in particle degradation, potentially acting on cellulose and chitosan .
Cross-Kingdom Collaboration
A strong correlation was found between fungal GH7 gene expression and bacterial chitin deacetylase, indicating potential synergy between bacteria and fungi in breaking down chitin .
Fungal Gene Expression Across Oxygen Gradients in the ETNP
| Gene Category | Function | Expression Pattern | Implications |
|---|---|---|---|
| GH7 Enzymes | Cellulose degradation | Highest in oxygen-deficient zones | Specialized role in carbon cycling under low oxygen |
| Denitrification Genes | Nitrate reduction to nitrous oxide | Activated in anoxic conditions | Contribution to greenhouse gas production |
| Chitinase Genes | Chitin breakdown | Correlated with bacterial activity | Cross-kingdom collaboration in nutrient cycling |
The correlation between dissimilatory nitrogen cycling processes and fungal hydrolytic activities provides new evidence for fungi as key players linking carbon remineralization and nitrogen cycling in oxygen minimum zones . This challenges traditional models of marine biogeochemistry that have largely overlooked fungal contributions.
The Scientist's Toolkit: Technologies Revealing Hidden Fungal Worlds
Marine mycologists—scientists who study marine fungi—rely on an array of sophisticated tools to uncover the secrets of these elusive organisms. The table below highlights essential reagents and technologies driving discoveries in this field:
| Tool/Technology | Function | Research Application |
|---|---|---|
| Next-Generation Sequencing (NGS) | High-throughput genetic analysis | Revealing novel fungal lineages and evolutionary relationships 1 |
| Whole Genome Sequencing | Comprehensive genetic blueprint mapping | Characterizing adaptation mechanisms in novel strains 7 |
| Metatranscriptomics | Analysis of actively expressed genes | Understanding real-time fungal responses to environmental changes |
| Specialized Culture Media | Isolating and growing marine fungi | Building fungal collections for biotechnological exploration 5 9 |
| Bioprospecting Assays | Screening for bioactive compounds | Identifying antimicrobial, antioxidant, and industrial applications 5 7 |
From Lab to Biotech: The Applied Potential of Adapted Fungi
The unique adaptations of marine fungi have sparked excitement in biotechnology circles. At the Marine Biological Association in the United Kingdom, scientists have established a comprehensive Marine Fungi Culture Collection containing over 500 fungal strains from seawater, sediments, and seaweeds 5 . This repository represents a treasure trove of biological innovation with diverse applications:
Medical Frontiers
Marine fungi produce an arsenal of antimicrobial compounds as defense mechanisms. A novel strain of Fusarium proliferatum isolated from Calabrian coastal waters produces 9‐O‐methylbostrycoidin and 9‐O‐methylfusarubin, which demonstrate significant activity against pathogenic bacteria like Staphylococcus aureus and Listeria monocytogenes 7 . With antimicrobial resistance rising, these fungal compounds offer promising avenues for new drug development.
Sustainable Food Production
Researchers are exploring marine fungi as alternative protein sources by fermenting seaweed to create nutritious mycoprotein 5 . This approach could help address food security challenges while utilizing marine biomass waste from the growing seaweed industry, projected to be worth up to €9.3 billion by 2030 5 .
Environmental Solutions
The remarkable enzymatic capabilities of marine fungi make them ideal candidates for bioremediation applications. Their catalase, laccase, and peroxidase enzymes can break down environmental contaminants, including toxic compounds and microplastics 7 .
Conclusion: The Rising Tide of Fungal Research
Once overlooked, marine fungi are now recognized as critical components of marine ecosystems with enormous potential to help us understand and address climate change impacts. Their remarkable adaptability, coupled with their diverse biotechnological applications, positions them as unexpected allies in our rapidly changing world.
As research continues to unveil the hidden lives of these oceanic organisms, one thing becomes increasingly clear: the future of marine conservation, biotechnology, and climate resilience may well be fungal. The silent adaptation occurring beneath the waves represents not just a scientific curiosity, but a potential reservoir of solutions for some of humanity's greatest challenges.
The rising tide of marine fungal research is only beginning to reveal what these remarkable organisms can teach us about survival, adaptation, and innovation in a changing world 3 . As we continue to explore this frontier, we may find that some of our most powerful tools for addressing climate change have been hiding in plain sight—or more accurately, beneath the waves—all along.