Have you ever slipped on a slimy rock while walking along a river? If so, you have encountered a biofilm, a complex community of microorganisms that forms on surfaces in aquatic environments.
Biofilms may look like simple blobs of goo, but they are actually living factories that perform vital functions for the ecosystem and human well-being.
River biofilms filter pollutants and toxins from water
CRIS BOURONCLE/AFP via Getty Images
One of the most important roles of river biofilms is to act as natural filters that remove pollutants and toxins from water.
Biofilms are composed of bacteria, algae, fungi, and other microorganisms that can degrade or transform various substances that enter the water from agricultural runoff, industrial waste, or urban sewage.
For example, some bacteria in biofilms can break down organic matter, such as pesticides, herbicides, or pharmaceuticals, into harmless compounds.
Other bacteria can convert nitrogenous compounds, such as ammonia or nitrate, into nitrogen gas, which is released into the atmosphere.
This process reduces the amount of nitrogen that can cause eutrophication, a condition where excess nutrients stimulate algal blooms that deplete oxygen and harm aquatic life.
Biofilms can also bind or immobilize heavy metals, such as lead, mercury, or arsenic, that are toxic to humans and animals.
Some biofilms can produce extracellular substances, such as polysaccharides or proteins, that act as glue to trap metal ions on their surfaces.
Other biofilms can change the chemical form of metals to make them less soluble or more precipitable in water.
By doing so, biofilms reduce the availability and mobility of metals in the water column and sediment.
River biofilms regulate nutrient cycles and support food webs
Biofilms are involved in the cycling of carbon, nitrogen, phosphorus, sulfur, and other elements that are essential for life. It can capture and store nutrients from the water or release them back into the water depending on the environmental conditions.
For instance, some algae in biofilms can photosynthesize and produce oxygen and organic carbon during the day, while some bacteria in biofilms can respire and consume oxygen and organic carbon during the night.
This creates a dynamic balance of oxygen and carbon dioxide levels in the water that affects the metabolism and growth of other organisms.
Biofilms also serve as a source of food and habitat for many aquatic animals, such as insects, crustaceans, fish, and birds. It provides a rich and diverse diet of organic matter and microorganisms that animals can graze on or scrape off from surfaces.
Biofilms also offer shelter and protection from predators or environmental stressors for animals that live within or among them.
Moreover, biofilms can influence the behavior and movement of animals by creating chemical cues or physical barriers that attract or repel them.
River biofilms prevent diseases and infections in humans and animals
A third major benefit of river biofilms is to prevent diseases and infections in humans and animals.
Biofilms can act as natural barriers that prevent the invasion or proliferation of pathogenic microorganisms that cause illnesses such as cholera, typhoid fever, dysentery, or salmonellosis.
It can compete with pathogens for nutrients or space on the surfaces or produce antimicrobial substances that inhibit their growth or kill them.
It can also modulate the immune system of humans and animals by stimulating or suppressing inflammatory responses or producing beneficial molecules that enhance health.
However, not all biofilms are beneficial. Some biofilms can also harbor or transmit pathogens that pose a risk to human and animal health.
For example, some biofilms can grow on medical devices, such as catheters, implants, or artificial valves, and cause infections or complications in patients.
Other biofilms can form on drinking water pipes or faucets and contaminate the water supply with harmful bacteria or toxins. Therefore, it is important to monitor and control the formation and composition of biofilms in these settings to ensure safety and quality.
River biofilms are more than just slime. They are complex and dynamic communities of microorganisms that perform important functions for the environment and human well-being.
River biofilms help to clean water by filtering pollutants and toxins from agricultural runoff, industrial waste, or urban sewage.
They also regulate nutrient cycles and support food webs by capturing and storing nutrients from the water or providing food and habitat for aquatic animals.
Moreover, they prevent diseases and infections by competing with or killing pathogens that cause illnesses in humans and animals.
River biofilms are essential for maintaining the health and balance of aquatic ecosystems and should be protected and appreciated.
