The water column component provides a classification of water column physico-chemical properties, layers and structural forms, termed hydroforms. The water column component is described by both non-hierarchical and hierarchical descriptors. Only the hydroform classes are truly hierarchical. The water column component follows the CMECS descriptors with some additions to provide compatibility with the JNCC-EUNIS water column descriptors.

Classification of the water column features within CBiCS follows the following principles:

1. Water column components link with biotic component classes in ecologically meaningful ways (e.g. energy levels for defining different infralittoral rock biotopes);
2. Hydroform classes are hierarchically nested according to the type and scale of the hydroform structure; and
3. Classes are relevant to describing biotopes by using both physico-chemical properties and environmental processes that are known to drive biological assemblage distributions.

Physico-Chemical Parameters

The water column component includes the parameters:

• Hydroform.
• Water column layer, such as surface layer, upper water column, pycnocline, and lower water column. See image below for working definitions following CMECS.
• Depth band.
• Wave and tidal energy level.
• Tidal streams.
• Temperature regime.
• Salinity regime.
• Light climate (in development)
• Other biogeochemical features (where known).

Although biogeochemical features of the water column are important influences that describe both benthic and water column biotopes, there is substantial work to be done in standardising these descriptors.

For example, neither CMECS nor JNCC / EUNIS directly classify the light climate, which has particular relevance to biotopes on infralittoral and circalittoral rock. The light climate is influenced by several factors, including local resuspension of sediments, terrestrial  inputs of turbid water, plankton blooms and shading by shoreline topography and structures. Work is presently being done to define a set of biologically relevant light climate classes for CBiCS.

Hydroforms

The hydroform classes are arranged in a hierarchical structure with respect to spatial and temporal scales of formation, as per CMECS. There is considerable work required to further develop and standardise the classification of hydroforms. This development will occur with further information on the linkages between biotope occurrances and associated hydroforms.

Water Column Hierarchy Explorer

The water column component hierarchy can be explored by clicking here.

Key CBiCS Distinctions

The CBiCS water column component combines descriptors from both the CMECS and JNCC/EUNIS schema, adding a placeholder for light climate classes. The hierarchy for hydroforms is presently drawn from CMECS.

Definitions

CBiCS will update and maintain and update a dictionary of standard terminology used in each component.