Page 236 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 5 3.1.15 – 3.1.16 3.1.15 SPEAR (species at risk) indices overview

SPEAR (SPEcies At Risk) indices are based on various life-cycle and physiological traits of the constituent taxa to which
species are defined either as being at risk or not at risk. The biotic index for a sample is expressed as the proportion (as a
percentage) of taxa or individuals (depending on the pressure) of species at risk. SPEAR indices therefore address directly
the ratio of disturbance-sensitive taxa to insensitive taxa demanded by WFD normative definitions (WFD, Annex V).

SPEAR – Species at risk indices

This group of Species at Risk indices are based on various life-cycle
and physiological traits of the constituent taxa. They have been
developed to assess different types of pressures. They can be
regarded as an alternative to the saprobic approach.

SPEAR is an alternative to the saprobic approach to developing and
calculating biotic indices. Different SPEAR indices have been developed to
assess different types of pressures:

SPEAR habitat – Species at risk from habitat
SPEAR herbicides – Species at risk from herbicides, based on diatoms
SPEAR mesocosm – Species at risk from pesticides in mesocosm studies
SPEAR metals – Species at risk from dissolved metals
SPEAR pesticides – Species at risk from pesticides
SPEAR salinity – Species at risk from salinity (Australia)
SPEAR refuge – Species characteristic of refuge areas

Apart from SPEAR herbicides (Wood et al. 2019) (100) which is based on diatoms,
SPEAR indices have been developed for invertebrates.

The next section, about SPEAR pesticides, provides an overview of principles of
the SPEAR method.

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