Mushrooms as Bioindicators: A Natural Solution to Environmental Monitoring

In the complicated interplay that makes up Earth’s ecosystems, even the smallest shifts can have major consequences for our planet’s well-being. As a result, we must have a means of detecting and alerting us to these changes, given the delicate balance at play. Fungi are like a canary in a coal mine, acting as bioindicators for environmental changes.

Because fungi have such an intimate connection with their surroundings, they have the unique ability to reflect the state of their local ecosystem. Changes in moisture levels, soil composition, and air quality trigger reactions in mushrooms as their biological functions are intricately intertwined with the rhythms of nature. Scientists carefully observe these reactions to gain insights into the health of our environment, making fungi an invaluable ally in our endeavors to monitor and comprehend ecological harmony.

What are bioindicators?

Bioindicators can be defined as living organisms or biological processes that are used to indicate the health of an ecosystem or the presence of pollutants. They act as organic sensors that reflect the condition of the environment. They are carefully chosen by scientists based on their susceptibility to changes, such as shifts in climate or exposure to contaminants. These changes can be measured and used to evaluate environmental quality and identify human interference’s impact on nature.  

Bioindicators serve as nature’s way of informing us about the condition of our environment. \ They can reveal how different environmental changes play out, showing us what’s positively and negatively impacted.

These natural indicators do more than just gauge our environment’s health; they also clue us in on the biological processes that happen within it, like how plants react to different amounts of lighting or how fish numbers shift when the water gets polluted. A dependable bioindicator has many determining factors. It should be extensively studied,  widely present in regions connected to natural circumstances, capable of detecting changes at an early stage, and easy to monitor. 

There is a wide array of organisms that fit the criteria of a bioindicator. For instance, amphibians like frogs and salamanders have sensitive, permeable skin and a life cycle that spans aquatic and terrestrial environments. As a result, they are susceptible to changes in both habitats. Whether their numbers are thriving or declining in an environment can be one of the first indicators of ecological stress and contamination.

Birds are another excellent example of bioindicators. Since birds can occupy a wide array of habitats, they can help indicate the health of various ecosystems. Shifts in migratory patterns, population numbers, and breeding rates can mean changes in environmental conditions. These conditions may include habitat modifications, food source availability, and the presence of pollutants in their habitats.

Lichen, a symbiotic relationship between fungi and algae, are effective bioindicators of air quality because they must obtain all their nutrients from the air around them. If their surroundings have high air pollutants, their growth and survival can be negatively impacted. They can also help detect radioactive elements, acid rain, and heavy metals since they can accumulate these substances over time. The various species found and their health and abundance can point to healthier air quality in a specified area. 

Like these other organisms, fungi play a vital role in indicating the health of their ecosystem. Mushrooms are the fruiting body of an entirely larger fungal organism hidden beneath the soil or inside trees. This hidden network, known as mycelium, interacts with plant roots and other soil organisms, making fungi an essential component in the cycling of nutrients and energy flow within ecosystems. Fungi respond to differences in their environment, and the presence or absence of certain mushrooms can indicate changes not only in the health of the soil but also in the interconnected organisms in their vicinity.

Mushrooms as bioindicators

The concept of using living organisms as indicators of environmental health has been around since the 1900s. However, it wasn’t until around the mid-20th century that scientists began using fungi as a means to monitor ecosystem health. Industrial activities began to boom after World War II, and our world started to see a dramatic increase in pollution.

Therefore, the need for more accurate environmental monitoring heightened. Mushrooms became an important tool for these means since they are found widely and can be easily collected and examined. Researchers have found that many types of fungi have the ability to absorb and store heavy metals and pollutants, making them valuable tools for assessing environmental contamination. This capability gained attention after the Chernobyl disaster in 1986 when scientists extensively researched fungi due to their ability to absorb and indicate the presence of radioactive substances in their environment.

Mushrooms like Cortinarius caperatus and some species within the Boletus genus were found to be highly effective in absorbing a radioactive compound called cesium-137 from the soil. These findings have provided insights into how contaminants disperse and accumulate in ecosystems, improving our understanding of environmental protection strategies. This discovery has impacted scientists to develop effective strategies to address the consequences of nuclear accidents in the future (1). 

Fungi have several biological processes and ecological roles that make them efficient bioindicators. One major factor is their ability to bioaccumulate substances. The mycelium network beneath the mushroom has a relatively large surface area concerning its volume, which allows it to efficiently absorb any available substances around it.

Mycelium seeks out water and nutrients, but any pollutants present can be absorbed as well. Since many contaminants are water soluble, they are readily absorbed along with any water the mycelium takes in. Fungi have been found to break down a wide range of organic compounds, sometimes turning pollutants into less harmful substances, but in the process, the contaminants are taken up in the fungal tissues. As a result, fungi can accumulate higher levels of pollutants in the environment around them. This provides scientists with evidence that pollutants exist within the ecosystem’s soil.

Additionally, many forms of fungi are capable of establishing relationships with certain tree species. These fungi, known as ectomycorrhizal fungi, collaborate with their plant partners to promote their health and growth. This type of fungi assists in expanding the root systems of associated trees. In return, they receive nourishing carbohydrates produced by the plant during photosynthesis. This connection means that any changes in the environment that affect the tree will also affect the fungi, and visevera, helping indicate environmental quality. 

Ectomycorrhizal fungi also have a high tolerance to heavy metals compared to many other types of fungi. Research has found that ectomycorrhizal fungi can survive in soils with high levels of lead, cadmium, and mercury. Some of these fungi are able to change the pH of their soil surroundings to reduce how soluble heavy metals are, therefore limiting their uptake. Others bind heavy metals and carbon into their cell walls and store them away, which could be used as a means of bioremediation (2). 

Another reason that mushrooms are frequently used as bioindicators is due to how sensitive they are to any changes that occur around them. Factors such as pH levels, temperature, moisture, and the presence of toxic substances can greatly alter their growth patterns and abundance. Such sensitivity means that a noticeable shift in mushroom populations, whether it’s a decline in fruiting or a change in species composition, can serve as an early indicator of environmental stress. This responsiveness helps provide researchers with early warnings that can prompt timely interventions.

Fungi have also been found to be effective bioindicators in aquatic communities. One study on river ecosystems looked into how fungi react to changes in certain factors like organic matter, total nitrogen, water temperature, and pH. The results found that certain fungi have sensitivity to these changes and can be studied to provide potential improvements to water quality and restoration. This method could be used in marine environments and other aquatic ecosystems as well with further research (3).

Overall, fungi, especially ectomycorrhizal types, play a major role in indicating environmental conditions. Their unique ability to withstand and even mitigate heavy metal pollution in soils, along with their sensitivity to changes in various factors, makes them incredibly valuable for monitoring.

This level of sensitivity aids in identifying the early signs of environmental stress, helping indicate potential problems with forest and plant health, radiation levels, soil contamination, water quality, air quality, and even the broader impacts of climate change (4).

Advantages over other testing methods

Utilizing mushrooms as bioindicators has several advantages over traditional methods of environmental monitoring, such as soil and sediment sampling, water sampling, vegetative sampling, and chemical testing. These benefits are not only advantageous from an ecological standpoint but also have practical and economic implications.

Minimal wildlife disturbance

Since mushrooms grow above the surface of the soil, scientists can learn about several environmental conditions without conducting any disruptive or invasive tests that may harm the ecosystem. Soil and sediment sampling is one of the main approaches used to assess the health of an ecosystem; however, this technique involves digging, drilling, or extracting samples from the ground.

These actions can potentially disrupt the soil’s structure and affect the microhabitats and organisms residing within it. Additionally, there is a risk of unintentionally introducing contaminants or pathogens into the ground during this process. Sensitive and protected environments like forests, wetlands, and protected ecosystems are especially vulnerable to invasive testing methods, which makes mushroom sampling a more gentle means of monitoring the health of these delicate habitats.

Mushroom sampling is a far less intrusive method in comparison since collecting mushrooms from the surface avoids any significant disruption to the soil and its inhabitants.

Ease of sampling and cost-effectiveness

Another advantage of mushroom bioindication is the ease of sampling, especially when compared to other methods. Collecting mushrooms for analysis is a simple process that does not require any particular equipment or training.

Other forms of sampling often require specialized tools for a more accurate collection and analysis. The costs that come with testing and materials can add up quickly, especially in large-scale or long-term projects. In contrast, collecting mushrooms for testing does not require the same level of technical skills. This opens up environmental monitoring to a broader audience, as ordinary citizens and amateur mycologists can participate in data collection. 

For instance, the iNaturalist app allows people from across the globe to contribute to biodiversity science by documenting their mushroom sightings. The application allows users to upload images of fungi and other organisms for identification suggestions through algorithms and community input.

Scientists utilize user contributions to help track species distribution and monitor biodiversity changes, which helps advance conservation efforts. This approach goes beyond data gathering; it serves as an educational tool, deepening public understanding of local biodiversity and the intricacies of environmental well-being.

Although accurate identification of species requires some expertise and further testing for bioaccumulated compounds, the cost of analyzing mushrooms for pollutants is usually less resource-intensive than the detailed chemical analyses required for soil or water samples. 

Integrated environmental assessment

Because mushrooms absorb and accumulate substances from their environment, they can help reflect the environmental conditions over a span of time. As a result, mushrooms provide a more comprehensive understanding of the ecosystem’s health.

Traditional methods usually only offer a snapshot based on the moment of sampling, while mushrooms can absorb and retain substances throughout their growth cycle, allowing them to effectively capture the history of conditions (5). Over time, this integration plays a role in comprehending long-term environmental patterns and shifts.

Moreover, mushrooms are not confined to one location or habitat; they can be found scattered across ecosystems. Their wide distribution makes them natural observers capable of conducting health assessments in ecological landscapes. Plus, mushroom’s ability to bioaccumulate substances means that they can detect even the slightest traces of contamination that might otherwise go undetected by other methods.

Global integration and future research

As environmental challenges continue to escalate, fungi remain a key tool in ecological research and monitoring. Though using fungi bioindicators is still a relatively new approach to ecosystem management, further analysis can allow scientists to have a deeper understanding of its environmental dynamics to push conservation efforts and climate change research further. 

Because fungi are so sensitive to small changes, they can offer clues into how climate variations can impact terrestrial and aquatic ecosystems. With this knowledge, scientists can devise strategies to mitigate the effects of climate change and determine the best ways to protect Earth’s ecosystems.

A global integration of fungi bioindication methods could lead to innovative solutions that would benefit multiple regions and ecosystems. This integration would require international collaboration and joint efforts in research, but by gathering resources together, the scientific community can accelerate the development of new solutions to environmental issues. A unified framework around mushroom bioindication would help standardize methodologies and simplify the process further. 

These efforts can further improve through community-based initiatives like mycological societies, citizen scientists, and amateur mycologists documenting their findings to provide more information to researchers. The more information made available, the more likely scientists will find ways to streamline more reliable methods for mushroom bioindication for ecosystem preservation. However, this would require more than just collaborative efforts. 

Unfortunately, a significant amount of fungi are under threat because of habitat loss and climate change. The extinction or even slight decline of these species could spell negative consequences for their native ecosystems. Conserving fungal diversity is necessary to maintain ecosystem integrity and continue to contribute to future ecological research and biotechnical applications. 

Fungi protect the environment through their ability to detect contaminants and through their ability to store them, and disrupt carbon cycling. Ensuring the preservation of species and their habitats is integral to maintaining ecological equilibrium and fostering a more sustainable future. Preserving fungi and continuing vital research will require a combined effort from researchers, policymakers, and citizens alike to ensure a healthier planet for future generations.

References

1. Ab Rhaman, Siti Maryam Salamah, Laila Naher, and Shafiquzzaman Siddiquee. 2021. “Mushroom Quality Related with Various Substrates’ Bioaccumulation and Translocation of Heavy Metals.” Journal of Fungi 8 (1): 42. https://doi.org/10.3390/jof8010042.
2. Bai, Yaohui, Qiaojuan Wang, Kailingli Liao, Zhiyu Jian, Chen Zhao, and Jiuhui Qu. 2018. “Fungal Community as a Bioindicator to Reflect Anthropogenic Activities in a River Ecosystem.” Frontiers in Microbiology 9 (December). https://doi.org/10.3389/fmicb.2018.03152.
3. Ediriweera, Aseni Navoda, Samantha Chandranath Karunarathna, Pinnaduwage Neelamanie Yapa, Douglas Allen Schaefer, Arani Koshathaki Ranasinghe, Nakarin Suwannarach, and Jianchu Xu. 2022. “Ectomycorrhizal Mushrooms as a Natural Bio-Indicator for Assessment of Heavy Metal Pollution.” Agronomy 12 (5): 1041. https://doi.org/10.3390/agronomy12051041.
4. Kauserud, Håvard, Leif Christian Stige, Jon Olav Vik, Rune H. Økland, Klaus Høiland, and Nils Chr Stenseth. 2008. “Mushroom Fruiting and Climate Change.” Proceedings of the National Academy of Sciences 105 (10): 3811–14. https://doi.org/10.1073/pnas.0709037105.
5. Marović, Gordana, Zdenko Franić, Jasminka Sencar, Tomislav Bituh, and Ozren Vugrinec. 2008. “Mosses and Some Mushroom Species as Bioindicators of Radiocaesium Contamination and Risk Assessment.” Collegium Antropologicum 32 Suppl 2 (October): 109–14. https://pubmed.ncbi.nlm.nih.gov/19138015/.