Methods

Benthic communities classification

in the Inner Puck Bay

Urszula Janas, Halina Rzemykowska, Institute of Oceanography, University of Gdańsk

• Information on vegetation – present/absent

• Vegetation cover

• Dominant species

% vegetation cover

• Visually by scuba divers observations – Circle (20 m diameter) at studied stations - 50 stations (Maritime Institute)- 31 stations (University of Gdańsk)

• Video camera records during cruises- 15 stations (Sea Fisheries Institute, University of

Gdańsk)

• Additionally by image analyses (6 pictures per stations or films).

• % vegetation cover was estimated using

12-grade scale

Taxa composition and dominant species- macroflora

• Samples taken by divers – 52 stations DAK sampler (Maritime Institute)

Dominant speciesone or several species > 50 % of total biomass

• Films (21 stations, Sea Fisheries Institute) and pictures (18 stations, University of Gdańsk)

• Dominance determined by visual volume (BalMar 2005)

• Visual volume >50 % of total visual volume

• Visual volume – index obtained by multiplaying the percentage coverage by average height of the species (BalMar 2005).

For pictures following groups were used:• Zostera marina• Other vascular plants: Potamogeton spp. /

Zannichellia palustris / Ruppia maritima • Chara spp.• Soft bottom

– Covered by filamentous algae– Animals or their activity– Sand

Taxa composition and dominant speciesmacrofauna

• Grabs samples collected at 54 stations.

• Dominant species or group of species

• Species with biomass >50 % of total biomass

• Dominant species names the biotope.

• The biotope name may include several species names, when no single species forms required 50 % of visual volume/biomass. In such a case, the next most abundant species are added untill they all together make up 50 % (BalMar 2005).

Sampling stations

• Knowledge

• Publications

• Aerial photographs and satelite images