PHYtoBenthic Index for Baltic inner COastal waters is a classification system for macrophytes (defined as angiosperms and macroalgae).
Its concept has been developed by University Rostock, working group Aquatic Ecology between 2003–2005 and has been tested in the field, revised and supplemented by MariLim GmbH between 2004–2008. An evaluation of the assessment system with the data sets collected so far has been made in 2013/2014 resulting in a restructure of assessment parameters and the final assessment, requiring a renaming of the assessment system into PHYBIBCO. In the years 2016 and 2017 the monitoring already was performed according to the improved methods.
The classification scheme is valid for inner coastal waters (national water type B1 and B2) (see BALCOSIS). With regard to the spatial extent, soft bottoms are dominant in the inner coastal waters and thus PHYBIBCO uses the characteristic vegetation elements for soft bottom for the assessment: submersed higher plants (spermatophytes/angiosperms) an stonewort (charophytes). Unattached, specific forms of Fucus and Furcellaria, morphologically adapted to the soft bottom habitat, are regarded at least in specific water types. PHYBIBCO consists of two separate parameters reflecting the different impacts of eutrophication on vegetation:
- ecological significance/species composition and
- depth limit of rooted plants (higher plants and/or charophytes).
Additionally a correction factor has been developed for the metric ecological significance to highlight bays having only remnant vegetation. If the dominance of emergent, rooted plants exceeds the dominance of submersed, rooted plants (angiosperms and charophytes), the assessment of ecological significance is downgraded even if the species composition alone is still comparable sufficient.
By this the normative definitions “occurrence of sensitive species”, “abundance”, “diversity” and “species composition” of the WFD have been covered for soft bottom vegetation in the sublitoral. For each parameter a 5-step classification system has been developed. This allows evaluating, if certain vegetation elements or metrics may react different towards anthropogenic stressors.
How the assessment system PHYBIBCO is to be used is described on the website surface waters assessment.