Rivers phytoplankton, macrophytes

It is possible that more than one metric contributes to die poor status. In lakes it is common for quality elements of phytoplankton, macrophytes and fish to fall short of the quality criteria. In rivers, macrofauna and fish are likely to have inadequate scores. In both situations the steering factors form a complex. In the example of lakes, this is known as a eutrophication complex. In rivers it is caused by canalisation and normalisation. And, third, the complex causing an inadequate score for macrofauna and fish in the metric for transitional waters is called coastal defences. 

Soley S (2010) Interaction between macrophytes and phytoplankton compartments for the uptake and decomposition of phosphorus compounds, the case of the Ebro river (NE Spain). Master thesis. University of Girona, Spain... 

Overall, these results suggest a general pattern of carbon flow in lakes on the central Amazon floodplain. Nutritious plant materials, primarily derived from C-3 plants (phytoplankton, periphyton, C-3 macrophyte leaves, tree fruits, and seeds) are selectively consumed by aquatic herbivores and detritivores and dominate the organic carbon flow to higher trophic levels. Some C-3 plant materials and the bulk of C-4 plants decompose and release their organic carbon, predominantly in the dissolved form, to the water column. The labile component of this DOC, dominated by C-4 plant carbon, is rapidly consumed by heterotrophic bacterial communities and released as either CO2 or CH4 to the atmosphere. The more refractory DOC component has a much slower turnover rate and tends to persist in the system where it is eventually exported to the main river channel. 

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