title: On the myths of indicator species: issues and further consideration in the use of static concepts for ecological applications.
abstract: The use of static indicator species, in which species are expected to have a similar sensitivity or tolerance to either natural or human-induced stressors, does not account for possible shifts in tolerance along natural environmental gradients and between biogeographic regions. Their indicative value may therefore be considered at least questionable. In this paper we demonstrate how species responses (i.e. abundance) to changes in sediment grain size and organic matter (OM) alter along a salinity gradient and conclude with a plea for prudency when interpreting static indicator-based quality indices. Six model species (three polychaetes, one amphipod and two bivalves) from the North Sea, Baltic Sea and the Mediterranean Sea region were selected. Our study demonstrated that there were no generic relationships between environment and biota and half of the studied species showed different responses in different seas. Consequently, the following points have to be carefully considered when applying static indicator-based quality indices: (1) species tolerances and preferences may change along environmental gradients and between different biogeographic regions, (2) as environment modifies species autecology, there is a need to adjust indicator species lists along major environmental gradients and (3) there is a risk of including sibling or cryptic species in calculating the index value of a species.
authors.affiliation: Leibniz Institute for Baltic Sea Research, Warnemünde, Rostock, Germany.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Zettler
authors.forename: C Edward
authors.initials: CE
authors.lastname: Proffitt
authors.forename: Alexander
authors.initials: A
authors.lastname: Darr
authors.forename: Steven
authors.initials: S
authors.lastname: Degraer
authors.forename: Lisa
authors.initials: L
authors.lastname: Devriese
authors.forename: Clare
authors.initials: C
authors.lastname: Greathead
authors.forename: Jonne
authors.initials: J
authors.lastname: Kotta
authors.forename: Paolo
authors.initials: P
authors.lastname: Magni
authors.forename: Georg
authors.initials: G
authors.lastname: Martin
authors.forename: Henning
authors.initials: H
authors.lastname: Reiss
authors.forename: Jeroen
authors.initials: J
authors.lastname: Speybroeck
authors.forename: Davide
authors.initials: D
authors.lastname: Tagliapietra
authors.forename: Gert
authors.initials: G
authors.lastname: Van Hoey
authors.forename: Tom
authors.initials: T
authors.lastname: Ysebaert
mesh_terms: D033304:Amphipoda; D000818:Animals; D044822:Biodiversity; D004463:Ecology / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D054712:Salinity; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical