The Microbiology of Streams and
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 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
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
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.
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.