While they are an important part of aquatic ecosystems, much scientific and commercial interest has been placed in these organisms for their promising resources in various industries. At Merkel.co.il, correct measurement of algae is valued, whether it be academic or industrial, for research and monitoring purposes. It is in this article that we take a look at some of the best methods available to date that at least provide quantitative measurements in respect of algae concentration and health, which are informative to the researcher and practitioner in the field.
Thus, the measurement of algae is important on many aspects-from the assessment of water quality in natural ecosystems to optimization in biofuel production. This quantification capability about algal biomass and monitoring health provides superior management of water resources, efficient cultivation of algae, and an advanced understanding of ecological processes.
Major Methods of Measurement of Algae Concentration
Measurement of Chlorophyll-a
The exact quantification of algae concentration is done by measuring the amount of chlorophyll-a present in a sample. Chlorophyll-a is a photosynthetic pigment acting as the primary bioactive compound in algae and is considered an excellent proxy for algae biomass. That gives quite accurate results but is usually very costly and cumbersome and requires special equipment in most laboratories.
Turbidity Measurements
Turbidity denotes a water cloudy state from suspended particles, and the same method can also be used to provide quick and cheap estimates of algae concentration. A turbidity meter can be used to make measurements in NTU. This is very relevant for routine monitoring or field purposes.
The following procedures are considered in the estimation of the algae concentration by using turbidity.
1. Take a turbidity reading of the algae sample that you have prepared, using a turbidity meter.
2. The NTU readings are transformed into cell concentration by an appropriate species-specific standard equation.
3. In this case, to calculate the turbidity reading of 391 NTU for Tetraselmis suecica would be as follows:
Y = 5370.9X + 4E+06
Where X is the turbidity in NTU and Y is the resultant cell concentration, 2.10 × 10^6 cells/ml.
Different equations that change from species to species may be involved in the conversion of turbidity to cell concentration.
Spectrophotometry
Another quick way of measuring the concentration of algae includes a spectrophotometric reading of the absorbance or optical density. This will measure the amount of light absorbed at particular wavelengths, usually within the range of 680 nm to 750 nm, where the chlorophyll absorbs light, on the sample algae.
Packed Cell Volume (PCV)
Adaptation of the hematocrit method-in which a known volume of algae suspension is centrifuged in specially designed tubes-provides a direct measure of the algal biomass as the volume of the cell pellet. Easy to carry out, this method can be less accurate for certain species, especially those of irregular shapes.
Direct Cell Counting
Conventional methods of cell count involve using a hemocytometer under the microscope, which gives good results to accurately count the number of cells. However, these are really cumbersome tasks and might not be feasible to use for high-throughput applications or even for continuous monitoring purposes.
Advanced Techniques of Measurement and Monitoring of Algae
Fluorescence Measurements
Fluorescence-based methods have evolved into powerful tools that can be used not only for quantification of algae biomass but also for evaluation of the algal health. In fact, these techniques are non-invasive, fast, and can provide data on algal populations in near real time.
- In vivo Chlorophyll Fluorescence: In vivo chlorophyll fluorescence is a measure of the fluorescence emitted by the chlorophyll molecules of living algae cells. It is proportional to biomass concentration and can thus be used as estimation of biomass concentration. Without preparation of the sample, this method has fast measurement. For continuous monitoring in bioreactors or in natural water bodies, it can be very suitable.
- PAM Fluorometry: PAM fluorometry does more than estimate biomass. It informs on photosynthetic efficiency and hence overall health of algal populations. One can measure parameters such as Fv/Fm (variable fluorescence / maximum fluorescence) by which stress in algal communities can be detected prior to changes in biomass or pigmentation can be visible.
Consider the following when using PAM fluorometry:
Appropriate developmental device: PAM-2500 of research-grade or portable AquaPen AP100 for field application
Pre-treatment: The dark adaptation of the samples to be compared should be the same.
Sometimes, apparent cell density shows different results because the density of the cells can interfere with one another, so the protocol needs to be calibrated for various concentration ranges.
How to Measure Algae Properly-Things to Consider
Some of the most important factors to be taken into consideration in the measurement of algae include accurate and reliable measures such as the fact that:
1. Consistent sampling needs to be conducted. One should develop and follow some standard procedures related to sample collection and preparation.
2. In choosing any measurement methodology, the specific attributes of your algae need to be considered.
3. If by turbidity determine with a turbidity meter meeting the ISO 7027 and using wavelengths above 800 nm. These meters offer significantly less interference due to the algal pigments.
4. For long-term measurements, periodic calibration of the instruments is an essential element of a program that ensures the accuracy of the measurements.
5. Whenever possible, employ multiple measurement approaches to cross-validate each other and obtain an integrated view of algal assemblages.
Conclusion
While knowledge concerning algae and their applications is continuously evolving, so is the increasing need for precise measurement methodologies. Simple turbidity measurements to the latest fluorescence-based methods are some of the tools available to researchers and practitioners for the quantification and monitoring of algal populations.
Coupled with best practices in the areas of sampling and measurement, the combination of such techniques can provide a range of information on growth, health, and productivity. This will continue to be a necessity as we look towards exploiting the potential for algae, ranging from environmental management through to renewable energy production.
Merkel.co.il will continue at the leading edge of research and measurement methodologies of algae. Availing of the high-tech measurement methods puts Merkel .co.il in a better position to understand and exploit these amazing organisms in advancing science, industry, and the environment.