Can i know about the different universal macrophyte indices that can be used for reserviors or slow/non flowing water? 

the trophic index of macrophytes (TIM), 

reference index (RI)

The index is a ratio of redundancy index R (Eqs. 1, 2, 3) and colonisation index Z (Eq. 4), where:

1

2

3

where ni is the proportion of the lake area inhabited by each plant community in the total area of the phytolittoral, N is the total area vegetated (100 %) and S is the total number of plant communities; and:

4

where N is the total phytolittoral area and Pisob2.5 is the potential phytolittoral area bounded by the 2.5 m isobath (lake area with a depth of less than 2.5 m). The values of IS can vary within wide limits; the higher the IS, the more altered and anthropogenic is the structure of the lake vegetation. IS allows the classification of a lake to the one of five classes of synanthropisation of aquatic vegetation, where an IS value in a range from 0.0 to 0.25 denotes near natural conditions and an IS > 1.0 indicates the most degraded ecosystems.?