Aquatic Plants: Emergent and Submerged Growth
Most aquatic plants available at fish stores can be classified into two types: emergent and submerged. These terms are defined by how we plant these plants in the aquarium.
In nature, what we consider aquatic plants may not necessarily spend 100% of their life submerged below the water surface. While some do, it's more common for our favorite aquatic plants to grow in shallow areas along coastlines, lakes, rivers, streams, and shallow pools, exposed to natural sunlight, collecting nutrients through their roots and substrate. Many of these locations will experience seasonal flooding, forcing plants to be completely submerged in water for short periods. However, most of the year, they are only seen rooted underwater.
This is common in low floodplain areas, where plants can survive submerged for months. While underwater undoubtedly has its benefits, this environment exposes plants to many pollutants present in natural waterways. We must acknowledge that things are inherently different from the closed environment of an aquarium. Continuously altering water levels is impractical for us, so we must choose our plant species based on the layout and style of the aquarium we are planning.
The main distinction between these two categories is easily explained. Emergent plants grow above the water surface, while submerged plants grow within the water column below the surface. There is typically also a difference in price between the two. Creating conditions suitable for planting submerged aquatic plants is an expensive process. Planting emergent aquatic plants is more cost-effective and quicker!
Firstly, let's clarify a common misconception. "Plants growing above the water surface are not as adaptable to aquariums as those growing underwater."
Usually, when emergent aquatic plants from emergency cultivation are placed underwater. Unlike submerged vegetation, emergent aquatic plants' original leaves (produced in terrestrial conditions) will melt away. Many aquarists quickly assume the erosion of leaves indicates failure of their new plants, without understanding the adaptation of plants to the new environment at this stage.
However, it's worth waiting for this to happen. Patience is the secret weapon of aquascapers.
This process takes time, and we should always expect some leaves to melt away. As long as we provide nutrition and the aquatic plants root in the substrate, new leaves will emerge. Newly emerged underwater leaves often contrast with the original leaves in shape and color. Interestingly, when plants accustomed to growing on dry land above water are submerged, new leaves tend to form rounder than before. Fresh leaves are entirely normal and part of the adaptation process.
Adaptation takes various forms depending on the type of aquatic plant:
- Stem plants (stem plants like Rotala, Ludwigia, Limnophila, Myriophyllum) adapt well to underwater conditions.
- Hygrophila and Alternanthera plants have a longer adaptation time than the aforementioned plants. In habitats with insufficient light, they lose leaves close to the substrate.
- In most cases, Cryptocoryne plants (suitable for both emergent and submerged growth) lose leaves (also known as "crypt melt"). It helps to cut off the diseased leaves, leaving only the rhizome, which will assist in the next few days when new plants begin to grow, fully adapting to the aquarium's conditions.
- Echinodorus plants can adapt to aquarium habitats quickly depending on the species (colorful artificial hybrid strains are more difficult to adapt). In most cases, the adaptation process starts from the surface of the leaf, and eventually, the entire leaf dies. In the following days, new plants emerge from the rhizome, adapting to the aquarium's conditions.
- Microsorum and Anubias plants - adapt to aquariums without any problems. This is because their native habitats are the banks of rivers, streams, and wetlands.
The above information relates to aquariums suitable for each type of plant. Adequate lighting power (minimum 0.4W/l for small aquariums), soft to hard water, and pH 6.5-8, fertile soil, and CO2. Providing CO2 when adding new emerging plants will significantly benefit their recovery time. We must consider that all plants initially grown under emergency conditions have access to an unlimited amount of atmospheric CO2. It only makes sense to provide something extra CO2 to compensate for this new habitat.
- Floating plants from local fish stores are hardier than those grown underwater. They grow under natural light, promoting rapid metabolism and appropriate levels of enzymes and plant hormones, not limited by nutrients in the water. This environment establishes vibrant, resilient plants capable of successfully introducing into the aquarium environment.
- Plants growing above the water surface have sturdier stems, which is beneficial when transporting plants from suppliers to stores and from stores to your aquarium.
- They store a considerable amount of nutrients, which will come in handy during the transition to underwater habitats.
- They are free from waterborne diseases and parasites. No longer will unwanted pests like snails hitchhike into your aquarium.
- They are free from hard-to-remove algae spores and cyanobacteria. Ultimately, no algae plants leave algae balls in your court. If you provide proper care, you shouldn't see unwanted algae in your aquarium.
Common errors and issues with plant adaptation that prevent plants from successfully acclimating to aquarium habitats:
- Impatience: Remove old leaves as they die off. Always allow time for new aquatic leaves to form.
- Lack of nutrients: Placing new aquatic plants in sterile substrates such as ordinary gravel is insufficient to sustain new growth during the transition period.
- Poor filtration: Insufficient filtration leads to the accumulation of unwanted substances and algae formation.
- Insufficient lighting: Plants need light. Strong, consistent lighting periods are essential for photosynthesis, crucial for the growth of all plants. Research the requirements of your plants and use timers to provide relevant light length and intensity (light cycle).
- Lack of CO2: Plants need carbon dioxide. While fish produce a small amount in your aquarium, it's often not enough for most aquatic plants. Providing CO2 will benefit significantly during the transition period.
- Irregular water changes: Lack of regular water changes damages the aquarium, but when adding new plants, weekly water changes are necessary to maintain optimal conditions.
- Incorrect water parameters: Just like fish, they require specific conditions. pH, temperature, and hardness are elements we should aim for to provide all the tools needed for robust plant growth.
Summary Maintaining an aquarium with submerged and emergent growth is possible. Modern aquascapers can benefit from obtaining high-quality substrates, nutrients, lighting, and CO2 injection. Therefore, with a little foresight, you can appreciate the beautiful displays of all different types of plants.
Some species even flower once matured, which is very satisfying. Why not try creating a shallow pool-style aquascape that combines submerged and emergent growth. This design integrates both categories, creating a very natural display.