Laser impact on marine planktonic diatoms: an experimental study using a flow cytometry system

Area of Science:

• Marine biology
• Environmental science
• Laser technology

Background:

• Biofouling is a persistent issue in industrial water systems, impacting efficiency and infrastructure.
• Marine diatoms like Chaetoceros gracilis and Skeletonema costatum are key primary producers in coastal ecosystems.
• Laser irradiation is explored as a novel method for biofouling control.

Purpose of the Study:

• To assess the impact of pulsed Nd:YAG laser irradiation on marine diatom cell density and chlorophyll a concentrations.
• To evaluate the effectiveness of laser irradiation in mitigating biofouling by targeting planktonic diatoms.
• To determine the relationship between laser fluence, flow speed, and the resulting damage to diatoms.

Main Methods:

• Utilized a flow cytometry system to monitor changes in diatom populations.
• Exposed two marine diatom species (Chaetoceros gracilis, Skeletonema costatum) to varying laser fluences (0.025, 0.05, 0.1 J cm-2) and flow speeds (9, 18, 27 ml min-1).
• Quantified reductions in cell density and chlorophyll a (chl a) concentrations compared to non-irradiated controls.

Main Results:

• Significant reductions in cell density (p < 0.001) and chlorophyll a (p < 0.05) were observed in both diatom species upon laser irradiation.
• Maximum mortality rates reached approximately 83% for C. gracilis and 78% for S. costatum at 0.1 J cm-2 and 9 ml min-1.
• Chlorophyll a concentration decreased by up to 27%, indicating a reduction in primary productivity.

Conclusions:

• Pulsed laser irradiation effectively reduces marine diatom populations and chlorophyll a levels.
• Laser treatment of cooling water could mitigate biofouling on industrial structures by damaging planktonic flora.
• Potential negative impacts on primary productivity and the broader marine ecosystem warrant careful consideration.