Influence of water hyacinth (Eichhornia crassipes) on concentration and
distribution of Escherichia coli in water surrounding an informal
floating community in Iquitos, Peru
Abstract
Floating communities exist throughout the world. Many live on water with
a high pathogen load due to difficulties associated with sewage
management. In Claverito, an informal floating community in Iquitos,
Peru, we conducted a controlled experiment to test the ability of water
hyacinth (Eichhornia crassipes) to remove Escherichia coli from water.
When river E. coli concentrations were at or below ~1500
CFU 100 mL-1, water hyacinth reduced shallow concentrations (8-cm depth)
down to levels deemed safe by U.S. EPA for recreational use. Above this
threshold, plants were able to reduce E. coli levels within shallow
water, but not down to “safe” levels. At deeper depths
(>25 cm), there was evidence that plants increased E. coli
concentrations. Water hyacinth removed E. coli from shallow water by
providing a surface (i.e., submerged roots) onto which pathogens sorbed
and by protecting organisms that consume E. coli. Unfortunately, because
of root association, the total E. coli load within the water column was
greater with water hyacinth present, and results hinted that the plants’
protective environment also harbored parasites. The use of water
hyacinth to keep surface water around floating communities low in E.
coli could be beneficial as this is the water layer with which people
most likely interact. Aquatic vegetation naturally proliferates in and
around Claverito. While this study was based on curating aquatic plants
in order to achieve a water-quality outcome, it nonetheless supports
concrete actions for Claverito residents under non-curated conditions,
which are outlined at the end of the manuscript.