Blue mussels, Mytilus edulis, at the edge of the range: population structure, growth and biomass along a salinity gradient in the north-eastern Baltic Sea

The blue mussel, Mytilus edulis, is the most conspicuous animal species in the northern Baltic rocky sublittoral. In the studied area the species lives at the margin of its salinity tolerance. Although dwarfed by the low-salinity conditions, blue mussels in the northern Baltic are very abundant and...

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Bibliographic Details
Published in:Marine biology 2002-05, Vol.140 (5), p.991-999
Main Authors: WESTERBOM, M, KILPI, M, MUSTONEN, O
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal species
Animal, plant and microbial ecology
Animals
Aquatic life
Autoecology
Biological and medical sciences
Brackish
Fundamental and applied biological sciences. Psychology
Marine
Marine biology
Mollusks
Mytilus edulis
Population growth
Population structure
Protozoa. Invertebrata
Salinity tolerance
Somateria mollissima
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Summary:The blue mussel, Mytilus edulis, is the most conspicuous animal species in the northern Baltic rocky sublittoral. In the studied area the species lives at the margin of its salinity tolerance. Although dwarfed by the low-salinity conditions, blue mussels in the northern Baltic are very abundant and have a decisive role in the benthic and pelagic ecosystems. We studied abundance, size distribution, biomass and growth rate of blue mussels along a 270 km salinity gradient in the northern Baltic Sea. Samples (n=317, 1998-1999) from moderately exposed and exposed rocky shores at seven study areas were collected in the southern Archipelago Sea in the west and into the central Gulf of Finland in the east, where the species is becoming increasingly rare. The results show a marked decline in mean mussel size and biomass from the saline west to the less saline east. The growth rate also decreased with lower ambient salinity. However, abundance of small mussels was considerably higher in the central and eastern parts of the study area. Vertically, the highest biomass was recorded at intermediate depths (5 and 8 m), being lower at both shallower (3 m) and deeper bottoms (12 m). It is concluded that salinity is the foremost factor determining size structure and growth rate among populations within the area. The results suggest that predation further influences the population structure of blue mussels living at the edge of their range in the central Gulf of Finland ultimately set by their salinity tolerance.
ISSN:0025-3162
1432-1793
DOI:10.1007/s00227-001-0765-6