Mytilus distribution
Short description
Distribution of blue mussel based on data submission by HELCOM contracting parties. Mainly pointwise occurrences of Mytilus spp. were submitted, originally gathered in national mapping and monitoring campaigns, or for scientific research. Point data from Poland was digitized based on Polish Marine Atlas. From Lithuania, a polygon delineating reefs was used to present Mytilus occurrence. For Germany, point data was complemented with a model describing Mytilus biomass in the German marine area (Darr et al. 2014), where predicted biomasses > 1g dw/ m2 were included as presence. From Estonian waters, a predictive model was used (200m resolution), that was converted to presence/absence using minimized difference threshold (MDT) criteria. All data (points, polygon and the raster presenting predicted presence of Mytilus) were generalized to 5km x 5km grid cells.
Point of contact
HELCOM Secretariat
data@helcom.fi
Spatial extent
['7.530495', '34.131647', '52.277123', '66.475422']
Type
dataset
Metadata information
Identifier
Keywords
Habitats and biotopes ; Species distribution ; GEMET - INSPIRE themes, version 1.0 ;

marine ecology ; GEMET ;

MADS ; HOLAS2 ; ecosystem component ;

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

Lineage
Data source: Denmark: Point data from national monitoring along transects (dive and video), data from 2005-2015. Data is available through Miljøportalen Estonia: Modelled distribution of Mytilus spp. based on observations from national monitoring (dive and drop video) during 2005-2014 Finland: Point data gathered during the national marine mapping programme VELMU (2004-2015) and inventories from Åland Islands Germany: Point data originally collated for monitoring and research purposes (video, photos, dive, wading, snorkeling), data from 2010-2015, complemented by a Mytilus model published in: Darr, A., Gogina, M., Zettler, M., 2014. Detecting hot-spots of bivalve biomass in the south-western Baltic Sea. Journal of Marine Systems 134:69-80. Latvia: Point data of from national monitoring (dive and drop video) campaigns during 2006-2013. Lithuania: A delineation of reefs was used as a proxy for Mytilus occurrence Poland: Point data digitized based on Polish Marine Atlas http://www.iopan.gda.pl/hm/atlas/Atlas_all.pdf . Russia: No GIS data reported. Mytilus occurs in the Kaliningrad region, although not presented on the map. Sweden: Point data from national monitoring and mapping surveys (1995 -2015) extracted from SMHI SHARK database. The dataset was approved by all HELCOM Contracting Parties in the HOLAS II Ecosystem component data review process during first quarter of 2017 after corrections from Germany, Poland and Sweden. 2018 updates: Updated data from Sweden and Finland were included. The grid of the raster was changed to match with other benthic habitat layers used in HOLAS II. Data quality: Mapping is not exhaustive and sampling density varies between the countries. No reported data from the Russian coastal waters. Attribute information: Raster value representing presence (1) or absence (0) of Mytilus. Spatial resolution: 1 km x 1 km grid (originally 5 x 5 km).