The Microbiology of Streams and Rivers
by
Eugene P. Macri Jr.

The microbiology of streams and rivers is some of the most complex undertaking in the biological sciences.  Why?  Because most bacteria and algae from rivers and streams do not cultivate well on agar or artificial substrates.  I worked for over two years cultivating and identifying bacteria and algae during my undergraduate studies.  It's difficult work and I had the advantage of my advisor who was an expert standing over my shoulder helping me learn the craft.

A new approach which is used in conjunction with normal cultivation methods is VIT-Gene Probe Technology. It uses the biological gene signature of bacterial genes in database to compare dye marked genes under LED and Fluorescent Microscope technology.

Most streams and rivers have a microfloral periodicity.  This means that the microflora (algae, bacteria etc.) have a seasonal progression.  This progression is different for different types of streams and rivers and is influenced by day length, water level and velocity, substrate types and inputs into the system. These include both algae in the water column and those on substrates. This periodicity includes the microscopic forms of algae as well as the macroforms as shown below.

Algae work well in environmental assessments however, they are not used as much as they as once were do to the lack of Phycologists at major academic institutions and the difficulty in identification and length of study needed for accurate results. The periodicity of algae sometimes seen as blooms in the water column are often the trigger for growth periods of macroinvertebrate communities. Because algae are the starting point for most aquatic food chains they serve the fundamental role in biogeochemical cycling. Algae are classified differently than most plants and are often included in the Kingdom Protista.  However, many aquatic scientists use general classifications for observing algae such as greens, blue greens and diatoms. These are the terms you may see in scientific papers.

Many algae populations will serve as pollution indicators in stream and river studies. The change in population, density, and species composition reflect the physical, biological and chemical inputs and characteristics of streams and rivers. Proper analysis with comparative data over specific time periods can give one of the best representations of the true health of a stream or river.  This is especially true if used in conjunction with proper  macroinvertebrate studies.

The fact that we don't study the microbiology of streams and rivers like we should is one of the reasons why we seldom know what's going on in many of our waters.