Harm and Control of Macroalgae

2026-06-05

I. Harm Caused by Macroalgae

1. Competition for Living Space and Entanglement with Sea Cucumbers:

When large algae proliferate extensively—particularly when they form thick algal mats or floating clumps—they can occupy the habitat of sea cucumbers.

Entanglement in seaweed impairs the normal movement, feeding, and respiration of sea cucumbers, leading to stunted growth, emaciation, and even death—particularly in smaller-sized individuals.

2. Deterioration of the bottom substrate environment:

After a large number of algae die, they decompose and decay at the bottom.

High oxygen consumption: The decomposition process severely depletes dissolved oxygen in the bottom layer, leading to hypoxia and black, malodorous sediments.

Generation of toxic substances: Anaerobic decomposition produces hydrogen sulfide, ammoniacal nitrogen, nitrite, and other toxic and harmful compounds, posing a serious threat to sea cucumber survival—particularly during the overwintering and ice‑melting periods.

Substrate acidification: The decomposition of organic matter can lower the substrate pH, which is detrimental to sea cucumber growth.

Harmful bacteria thrive: Decaying organic matter provides an ideal breeding ground for pathogenic microorganisms.

Impact on light penetration and water temperature: A large biomass of algae, whether floating or attached to the substrate, can block sunlight, thereby inhibiting the reproduction of benthic diatoms and other natural food sources for sea cucumbers.

Algal mat coverage disrupts the natural diurnal temperature fluctuations at the pond bottom, which is detrimental to the normal physiological processes of sea cucumbers, such as aestivation and overwintering.

Treatment of Macroalgae — Case Study Sharing

Location: Blue Economic Development Zone, Dongying City, Shandong Province

Date: May 20, 2025

Customer Situation: On May 20, Mr. Wang of the Blue Zone observed a significant proliferation of large benthic algae—primarily green filamentous algae—in his sea cucumber pond.

Pond area: approximately 65 mu; water depth: about 1.2 meters.

Treatment plan: On the first day, apply 24 packets of Zhongren’s “Algae & Moss Killer.” Starting on the third day, the algae will turn yellow and begin to wither; within about ten days, it will largely disappear. Subsequently, use a powerful bottom‑decomposition agent in combination with the enhanced bottom‑conditioning formula to restore the pond substrate and prevent the dead algae from further degrading the pond bottom.

Day 1: Upon arriving at the aquaculture pond, we observed a large abundance of green algae on the sea cucumber reefs and along the shoreline. Subsequently, the farmer applied 24 packets of “Algae & Moss Eliminator,” dissolving them in water and evenly dispersing the solution throughout the entire pond.

Day 4: Some algae have died, turning pale and shriveling.

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Day 10: Algae are almost entirely dead.

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Product advantages of Zhongren’s algae‑removal solution:

1. This product employs the latest biosynthetic technology, setting it apart from commonly used algaecides on the market—such as dichlobenil and prometon—which effectively control algae but may lead to resistance.

2. This product eliminates algae by inhibiting the Hill reaction in algal photosynthesis, thereby preventing the algae from carrying out photosynthesis and absorbing nutrients. It is safe for cultured species such as sea cucumbers, razor clams, fish, shrimp, and crabs, causing no irritation or adverse effects.

3. With a broad spectrum of application, it effectively controls and eliminates common harmful algae such as yellow‑tube algae, green‑tube algae, Enteromorpha, Cladophora, and sponge‑like algae, thereby inhibiting their growth and reproduction and keeping the pond bottom clean and clear.

Post‑algae‑control treatment:

On the first day, apply the high‑efficiency bottom‑conditioning agent (70 mu/25 kg) to promptly improve the pond bottom, vigorously decompose dead algae and decaying moss, and purify the water. On the third day, use the enhanced bottom‑conditioning product (70 mu/25 kg) to further treat the bottom, oxidize and eliminate odors, and enhance the aquatic environment, thereby preventing the release of toxic gases such as hydrogen sulfide during decomposition, which can degrade water quality and lead to poisoning and oxygen‑depletion‑related mortality among cultured aquatic species.