Benthic marine landscapes (BALANCE)
Short description
Summary This marine benthic landscape map of the Baltic Sea includes 60 broad scale habitat types which are defined according to different combinations of bottom substrate, photic zone and salinty level. Description This dataset was produced by the EU funded Balance project and maps the ecologically relevant benthic landscapes (broad-scale benthic habitats) of the Baltic Sea, identified on salinity, sediments and photic depth (as light touching the seabed). This marine benthic landscape map of the Baltic Sea includes 60 broad scale habitat types which are defined according to different combinations of bottom substrate, photic zone and salinty level. Each habitat is described with a three digit grid code, where the first digit refers to bottom substrate, the second digit refers to photic zone and the third refers to salinity. Description of grid code digits: Bottom substrate: 1= bedrock, 2 = hard bottom, 3 = sand, 4 = hard clay, 5 = mud Photic zone: 1 = photic, 2 = aphotic Salinity: 1 = 0-5 psu, 2 = 5 - 7.5 psu, 3 = 7.5 -11 psu, 4 = 11 - 18 psu, 5 = 18-30 psu, 6 = <30 psu The approach to marine landscape mapping within the Baltic Sea is based on the use of available physical, chemical and hydrographic data to prepare ecologically meaningful maps for areas with little or no biological information. It is basically a broad-scale map-ping/modelling approach based on presenting geophysical and hydrographical data in thematic GIS layers from which “marine landscapes” can be derived. In order to limit the number of possible landscapes the thematic layers are typically presented in a lim-ited number of categories reflecting shifts in major ecological entities (e.g. distinguish between habitats assumed to be within or below the photic zone). The approach aims to recognise the ecological linkage between major assemblages of species and the physical environment in which they reside. It can be applied to charac-terising broad-scale benthic complexity using parameters such as surface sediment, temperature, water motion, photic depth and slope and for semi-enclosed areas, like the Baltic Sea, salinity and oxygen content.Due to the limited resolution of the dataset, it should be only used for broadscale purposes. The dataset also requires verifications. (The quality of data collated differs from high to low-resolution data. Some of the modelled datasets has 7km resolution while others have ~600m resolution. All datasets were re-gridded to a 200 × 200m grid. This process ensures data continuity but it does not increase the out-put map resolution.)
Point of contact
HELCOM Secretariat
data@helcom.fi
Spatial extent
['2.80654', '41.807265', '50.978554', '68.340172']
Type
dataset
Metadata information
Identifier
Keywords
Bio-geographical regions ; Habitats and biotopes ; GEMET - INSPIRE themes, version 1.0 ;

ocean ; benthic ecosystem ; habitat ; mapping ; GEMET ;

MADS ; biota ;

MADS ; broad-scale benthic habitats ;

MADS ; marine benthic landscapes ;

MADS ; habitat modeling and mapping ;

Baltic Sea ; Continents, countries, sea regions of the world. ;

Resource provider(s)
HELCOM Secretariat
data@helcom.fi

Lineage
As the first step the necessary environmental parameters and data sets were selected for the identification of marine landscapes in the Baltic Sea. The next step was to harmonise and standardise the selected individual data sets and present them in unified formats. To produce the broad-scale benthic marine landscape map from a number of different sources efficiently raster map algebra in a GIS was used. The primary environmental parameters included for the developing the benthic marine landscapes were sediment, the photic – non-photic zone (where 1% of available light reaches the seabed) and salinity as they are important for determining broad-scale dis-tribution of species in a regional Baltic Sea context. National seabed sediment classification categories were harmonized in order to produce one classification scheme, which had to be as simple as possible, but still take into account biological importance. The resulting classification scheme consisting of five sediment classes are applied in the mapping and modelling of the Baltic Sea marine landscapes. These are: I. Bedrock. II. Hard bottom complex, includes patchy hard surfaces and coarse sand (some-times also clay) to boulders. III. Sand including fine to coarse sand (with gravel exposures). IV. Hard clay sometimes/often/possibly exposed or covered with a thin layer of sand/gravel. V. Mud including gyttja-clay to gyttja-silt. Available light at the seabed was included and divided into two categories, the photic and non-photic zones. The Baltic Sea is characterised by some fairly stable salinity gradients ranging from > 30psu in the northern Kattegat to almost fresh water in the Bothnian Bay. As the salt concentration influences marine life in a number of different ways, salinity was split into 6 categories reflecting the distribution of structuring species. The approach used by the BALANCE project is fully applicable for an ecologically relevant characterisation of the Baltic Sea, however, end users might find it necessary to validate and further refine and improve the maps. Such validations and refinements are necessary in order to fully exploit the potential application of the maps and for linking them to the implementation of national and international legislation. For more information, see the Balance technical summary report no. 2 Baltic Sea marine landscapes and habitats: Mapping and modelling (http://balance-eu.org/xpdf/balance-technical-summary-report-no-2-4.pdf).