Page 224 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 5 3.1.6 3.1.6 Saprobic indices Saprobity is the effect of decaying organic nutrients,

analogous to eutrophy which is the effect of inorganic
nutrients. The saprobic index relates directly to measures of
The saprobic index is the principal metric used to determine
putrescible organic matter, in particular biochemical oxygen
river invertebrate status in central Europe. It is used in the
demand (BOD), and saprobic values for individual species
UK as a component of the SmartRivers biometric analysis
(Section 3.1.24) because it is based on species-level data.
are determined by their relation to this measurement (Table
(76)
5.1). The monograph by Sládeček (1973)
explains how this
It is a measure of sensitivity to organic enrichment
(saprobity) and is often used in combination with other
metrics to determine status, in the same way that WHPT
derivation of biotic indices relating to other chemicals and
ASPT is used with WHPT NTaxa in the UK. can be done, and the same guidance can be applied to the
pressures.
The saprobic index is the earliest biotic index of water
pollution, first devised by Zelinka and Marvan in 1908–1909,
Saprobic indices and its basic principles are followed by almost all subsequent
biotic indices of organic pollution. The index has undergone
Saprobic indices are used mainly in central Europe as many revisions since then, and there are now many regional
an index of organic enrichment and are used in many variations. The index has been extended to cover not only
countries as a basis for WFD river invertebrate status natural waters, but treated water for domestic and other
classification. There are many versions of saprobic uses, through to conditions found in waste (Table 5.1 and
indices but they are generally based on species-level Figure 5.3). Saprobic indices exist for all types of biological
analyses. quality elements, from protists to fish, birds and mammals,
but they are most often applied to macroinvertebrates.

Table 5.1
Degrees of saprobity: red text indicates extended scale beyond that found in surface waters and used for waste waters;
green text indicates extended scale into water treated for supply (drinking water).

Index Value BOD5

Xenosaprobity 0 0

Oligosaprobity 1 <1

β-mesosaprobity 2 <5

α-mesosaprobity 3 <13
Polysaprobity 4 >20

Isosaprobity 5 Ciliates

Metasaprobity 6 Flagellates

Hypersaprobity 7 Bacteria

Ultrasaprobity 8 Abiotic

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