This is a picture of a former riffle.  The stream is subject to water withdrawal for a public water supply, which caused the river to dry up into this series of isolated pools.  Some of our most unusual and rare macroinvertebrates live only in riffle areas because these areas provide oxygenation to the water and the constant flow brings food (organic material) within reach.  Isolated pools limit the movement and migration of aquatic species.

 

 

 

 

 

 

 

 

 

 

 

 

Low flows or pooled conditions cause nutrients and toxic pollutants to become concentrated in a smaller area.  In this picture, the concentration of nutrients in the water has caused an algal bloom.  When these algae die, they will fall to the bottom and decay.  This decaying process consumes oxygen and can create anoxic conditions in the river.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

An extreme example of low flow problems!

Isolated pools don’t provide sufficient habitat for most aquatic organisms.  There is no cover or habitat structure and movement is restricted.  Predator-prey relationships are completely altered and some species may be eliminated form these pools.  Under these conditions, it is crucial that individuals of each species are able to survive further downstream to repopulate upstream areas once adequate stream flow returns.
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Text Box: Study Idea . . .     vBacteria •Indicator organism ~ the Coliform Group sTotal coliform sFecal coliform sEscherichia coli (E.coli) v Enterococcus, (Fecal streptococcus) vCryptosporidium, Guiardia, Swimmers itch…   A direct link to public health concerns and, with sophisticated testing, may pinpoint source. Wet vs dry weather results usually dramatically different. $$  

Text Box: Ipswich River, Ipswich Recreation  

Text Box: Study Idea . . . Introduced Substances Toxins   •  Solvents, cleaners, paints…   Pesticides, Petroleum based substances     Metals  Man-made compounds  Sewage ü   Often both a threat to public and ecosystem health. Can be expensive and difficult to test. There may be some information available as a permit requirement.  

Text Box: Introduced Substances  

Text Box: Study Idea . . . Nutrients   Nitrogen   Phosphorus   An overabundance can lead to eutrophication and long term degradation of aesthetics and ecosystem health. If combined with flow  information, loadings can be calculated.  $$-$$$  

Text Box: Nutrients & Aesthetics  

Text Box: Habitat Alewife Brook Essex