The Phenom - A Valuable and Cost-Effective Instrument for Imaging and Classification of Diatoms - Application Note by Phenom-World

Topics Covered

Introduction
Diatoms as Water Quality Indicators
Long Term Perspective
Acknowledgement

Introduction

Diatoms provide information on both the biological integrity of the ecosystem and those factors likely to be causing any observed changes. Researchers are rapidly developing new techniques for using diatoms to provide even more quantitative and accurate inferences of ecosystem condition, and diatoms are being included in a growing number of local and regional-scale monitoring programs. FEI Company's Phenom(TM), a new type of microscope, proves to be a valuable and cost-effective instrument for imaging and classification of diatoms at the Dutch Water Treatment & Control Laboratories.

Diatoms have cell walls which are perforated and ornamented with many holes

Diatoms as Water Quality Indicators

Diatoms are single-cell algae which can be identified from the shape of their skeleton. Diatoms are divided into two groups based on overall symmetry of the cell walls; radially symmetrical forms are informally called "centric" diatoms while bilaterally symmetrical forms are referred to as "pennate" diatoms. One remarkable aspect of these organisms is that they have cell walls made of glass (silicon dioxide). The glass cell walls are perforated and ornamented with many holes, which are usually arranged in definite patterns. The nature of these perforations as well as their orientation and densities help in the identification of diatom species.

They live in all our lakes and rivers and are of interest to aquatic system managers as indicators of water quality - acidity, salinity, organic pollution load and pollutant types. There are more than 7000 species living in fresh and brackish water, population mix and species diversity reflecting environmental conditions. They supplement chemical analysis, covering too short a time span, with additional and sometimes more reliable information. Their continually changing classification must be mastered since more than 400 new taxons are described each year.

Detail of the cell wall of a diatom

Long Term Perspective

Although diatoms are widely distributed as a group, most species occur only in habitats with specific physical, chemical, and biological characteristics. Ecologists have long made practical use of this habitat specificity by collecting and analyzing individual species and community data to determine the quality or condition of aquatic habitats. Both long-term monitoring of specific lake and stream habitats and analysis of diatom remains (that become part of the sedimentary record of lakes) allow scientists to obtain a unique long-term historical perspective on these ecosystems. This perspective is especially valuable in assessing the long-term effects of human activities on aquatic and terrestrial ecosystems.

Diatoms in their natural aquatic habitat

Acknowledgement

This application note has been created with the help from Mr. B. Pex, Waterboard Roer & Overmaas, The Netherlands.

A complete set of references is available be referring to the source document.

Source: "Diatoms tell the truth about our environment" Application Note by Phenom-World

For more information on this source please visit Phenom-World