In this article we'll review how the Pulsar 4400 ultrasound significantly reduced Harmful Algae Blooms (HAB's) in an Ecuadorian Shrimp Farm.

Harmful algae blooms (HABs) are one of the biggest ongoing challenges in modern shrimp farming. When cyanobacteria and nuisance algae take over production ponds, they can reduce dissolved oxygen, create toxins, stress shrimp, and even impact product quality and flavor.

A 2024 case study conducted at a large commercial shrimp farm in Ecuador explored whether ultrasonic algae control technology could help shift pond ecology away from harmful cyanobacteria and toward a healthier, more balanced phytoplankton community. The results were significant.

According to the report, the use of dual Pulsar 4400 ultrasonic units led to a 91% reduction in cyanobacteria over 14 weeks, while increasing beneficial diatoms and green algae populations.

Read the full report here.

Ecuador’s Massive Shrimp Industry Faces Algae Challenges

Ecuador is currently the world’s leading shrimp producer, with approximately 233,000 hectares dedicated to shrimp cultivation.

The study was conducted at Naturisa S.A., a major aquaculture company with roughly 5,400 hectares suitable for aquatic production. The company supplies SONGA S.A., one of Ecuador’s largest shrimp exporters.

Like many shrimp farms, maintaining stable dissolved oxygen levels and controlling harmful algae blooms are ongoing operational concerns.

The report noted that harmful algae blooms in shrimp ponds can:

• Block light needed by beneficial microalgae

• Reduce dissolved oxygen levels

• Produce toxins harmful to shrimp

• Cause off-flavor issues in harvested shrimp

The study specifically identified problematic cyanobacteria including:

• Oscillatoria

• Raphidiopsis

• Microcystis

• Spirulina

• Merismopedia

• Anabaenopsis

The report also noted that peroxide and sulfate-based algae control programs were already being used at substantial cost:

• Approximately $150,000 annually for peroxide treatments

• Approximately $31,000 annually for sulfate treatments

Why Dissolved Oxygen Matters in Shrimp Ponds

Dissolved oxygen (DO) is one of the most critical water quality parameters in shrimp production systems.

The report emphasized that shrimp farms ideally maintain DO levels above 5 mg/L.

Unfortunately, dense microalgae blooms often create unstable oxygen swings:

• Photosynthesis raises oxygen during daylight hours

• Respiration consumes oxygen at night

• Large bloom die-offs can rapidly strip oxygen from the water

To compensate, shrimp farms commonly rely on:

• Paddlewheel aerators

• Water circulation systems

• Pumping between ponds and water sources

Even with aeration, persistent cyanobacteria blooms remain difficult to manage.

The Pulsar 4400 Ultrasound Trial

The study installed a dual Pulsar 4400 ultrasonic algae control system in pond #256 at the Naturisa facility.

Key details of the trial included:

• Pond depth: approximately 1.5 meters

• Weekly phytoplankton sampling for 14 weeks

• Monitoring of algae abundance and species composition

• Shrimp stocking after six weeks

• Histological analysis of shrimp tissues to evaluate potential impacts from ultrasound exposure

Initial water samples showed the pond was heavily dominated by cyanobacteria:

• 82% cyanobacteria

• 18% diatoms

The dominant nuisance species were identified as Oscillatoria and Raphidiopsis.

Results: 91% Cyanobacteria Reduction

By week 14, the results showed a dramatic shift in the pond ecosystem.

The study reported:

• 91% reduction in cyanobacteria

• 58% increase in diatoms

• 67% increase in green algae

Even more importantly, cyanobacteria levels dropped below the maximum thresholds established by the Cargill Health Department by the third week of the trial.

The report also documented:

• Lower total microalgae abundance overall

• Increased species richness

• Increased phytoplankton diversity

• A noticeable ecological shift toward more desirable algae communities

The Shannon-Weaver diversity index increased from 1.60 at day zero to 2.08 by week 14, indicating a more balanced and stable phytoplankton ecosystem.

A Shift Toward Beneficial Algae

One of the most interesting findings from the study was not simply algae reduction, but a shift in algae dominance.

During the ultrasound exposure period:

• Green algae became dominant during weeks 5–7

• Diatoms dominated during weeks 11–13

• Cyanobacteria steadily declined throughout the study

This is important because many shrimp systems actually benefit from certain types of microalgae.

Diatoms and green algae can:

• Improve water stability

• Support healthier food webs

• Provide natural supplemental nutrition

• Reduce the dominance of toxin-producing cyanobacteria

Rather than sterilizing the pond, the ultrasound appeared to encourage a healthier phytoplankton balance.

Did Ultrasound Harm the Shrimp?

A major concern with ultrasonic algae control is whether the technology negatively impacts aquatic organisms.

In this study, the researchers specifically evaluated shrimp tissues including:

• Gonads

• Stomach tissue

• Hepatopancreas

• Gills

The report concluded that ultrasound exposure:

• Did not affect shrimp survival

• Did not impair growth

• Did not damage tissue structure or morphology

The pond achieved:

• 82% shrimp survival

• Average growth of 2.24 grams during the monitored period

Histological images included in the report showed normal tissue structure throughout the study period.

What This Means for Aquaculture and Pond Management

This case study suggests that ultrasonic algae control may offer an alternative or supplemental strategy for managing HABs in aquaculture systems.

Instead of relying entirely on repeated chemical treatments, ultrasound may help:

• Suppress cyanobacteria dominance

• Improve ecological balance

• Reduce HAB-related oxygen crashes

• Encourage beneficial algae populations

• Potentially reduce long-term chemical costs

That said, ultrasound is not a magic bullet.

Success likely depends on several factors including:

• Nutrient loading

• Pond depth

• Water movement

• Organic accumulation

• Overall system management

Still, the results from this Ecuador shrimp farm demonstrate that under the right conditions, ultrasonic technology may significantly improve harmful algae management in commercial aquaculture systems.

Final Thoughts

The 2024 Naturisa shrimp farm study adds to growing interest in non-chemical approaches to HAB management.

In this trial, the Pulsar 4400 system helped reduce cyanobacteria by 91% while improving phytoplankton diversity and maintaining healthy shrimp growth and survival.

For pond managers, aquaculture operators, and water quality professionals, the study highlights an important concept:

Sometimes the goal is not eliminating all algae — it is shifting the ecosystem toward a healthier biological balance.

Source Report: “Pulsar 4400 case study for algae control in shrimp farms,” Dr. Viviana Almanza, March 15, 2024.