Dissolved Organics
Dissolved organics, often referred to as dissolved organic matter (DOM), are organic compounds that exist in the water column in a dissolved form. Unlike visible food particles or debris, dissolved organics are microscopic and cannot usually be seen with the naked eye.
In both natural reefs and reef aquariums, dissolved organics are constantly being produced through biological activity. Fish waste, coral mucus, uneaten food, bacteria, plankton, algae, and decaying organic matter all contribute to the pool of dissolved organics present within the water.
Although often overlooked, dissolved organics are an important part of reef ecosystems and play a significant role in nutrient cycling and coral nutrition.
Why Are Dissolved Organics Important?
Dissolved organics help move nutrients throughout the reef ecosystem.
They contribute to:
- Nutrient cycling
- Coral nutrition
- Bacterial activity
- Microbial biodiversity
- Ecosystem stability
- Natural food webs
Many reef organisms have evolved to utilize dissolved organic compounds as part of their overall nutritional strategy.
In natural reefs, dissolved organics are continuously available and form part of the complex nutritional environment that supports reef life.
Can Corals Use Dissolved Organics?
Yes.
While corals are best known for capturing plankton and food particles, many species can also absorb certain dissolved organic compounds directly from the surrounding water.
This allows corals to obtain nutrients even when visible food particles are not present.
Dissolved organics may contribute to the availability of:
- Amino acids
- Organic carbon compounds
- Nitrogen-containing compounds
- Various micronutrients
This ability provides an additional pathway through which corals can acquire nutrition.
Where Do Dissolved Organics Come From?
Dissolved organics are produced by many processes within the reef aquarium.
Common sources include:
- Fish waste
- Coral mucus
- Coral feeding
- Plankton breakdown
- Bacterial activity
- Uneaten food
- Decaying organic matter
- Algae and microorganisms
As organisms grow, feed, and interact with their environment, dissolved organics are continuously released into the water.
Dissolved Organics and Marine Snow
Many dissolved organic compounds eventually become part of larger nutrient cycles within the reef.
As bacteria and microorganisms process dissolved organics, nutrients may contribute to the formation of:
- Marine snow
- Bacterial biomass
- Microbial food webs
- Suspended organic particles
This recycling process helps keep nutrients moving throughout the ecosystem.
In many ways, dissolved organics represent one of the earliest stages of nutrient recycling on a reef.
Dissolved Organics and Coral Nutrition
Coral nutrition extends beyond visible feeding.
While corals obtain proteins, fatty acids, and other nutrients from food particles, dissolved organics provide an additional nutritional pathway that can supplement feeding and photosynthesis.
This highlights an important concept in reef keeping:
Corals do not live solely on light and food particles. They exist within a complex nutrient-rich environment where dissolved compounds also contribute to overall nutrition.
Common Misconception: All Dissolved Organics Are Waste
One of the most common misconceptions is that dissolved organics are simply pollutants that should be removed immediately.
While excessive accumulation can contribute to water quality issues, dissolved organics also play important biological roles within reef ecosystems.
Many organisms depend on these compounds as part of natural nutrient cycles.
The goal is balance rather than complete elimination.
Dissolved Organics and Nutrient Balance
Like many reef nutrients, dissolved organics can be beneficial in appropriate amounts but problematic when excessive.
Healthy reef aquariums maintain a balance between:
- Nutrient production
- Nutrient consumption
- Nutrient export
This balance allows biological processes to function while preventing excessive nutrient accumulation.
The Bottom Line
Dissolved organics are microscopic organic compounds suspended in the water column that originate from feeding, waste, bacteria, corals, and other biological processes. While often invisible, they play an important role in nutrient cycling, microbial activity, and coral nutrition. Understanding dissolved organics helps reef keepers appreciate that reef ecosystems are fueled not only by visible food sources but also by a complex network of dissolved nutrients that support life throughout the aquarium.
