Active movement to coarse grained sediments by globally endangered freshwater pearl mussels (Margaritifera margaritifera)

• Published in: Hydrobiologia Vol. 850; no. 4; pp. 985 - 999
• Main Authors: Eissenhauer, Felix, Grunicke, Felix, Wagner, Annekatrin, Linke, Daniel, Kneis, David, Weitere, Markus, Berendonk, Thomas U.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-02-2023; Springer; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Ecological distribution; Ecology; Emigration; Fresh water; Freshwater; Freshwater & Marine Ecology; Gravel; Habitats; Inland water environment; Life Sciences; Margaritifera margaritifera; Marking and tracking techniques; Microenvironments; Microhabitat; Microhabitats; Mollusks; Movement; Mussels; Primary Research Paper; Sediment; Sediment composition; Sediments; Sediments (Geology); Transponders; Zoology; Horizontal locomotion; PIT-tag; Fine sediment; Behavior; Microhabitat requirements
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-023-05138-1

The freshwater pearl mussel
Margaritifera margaritifera
is an endangered bivalve which is usually regarded as sedentary, although individual movement has been observed both vertically and horizontally. Little is known about the causes and rates of mussel movement. The objective of this study was to test the effect of microhabitat characteristics on the horizontal movement distance and rates of freshwater pearl mussels. A total of 120 mussels (length range 40–59 mm) were marked individually with passive integrated transponder tags, placed in stream microhabitats differing in their sediment composition and monitored biweekly over a period of 10 weeks. Mussels situated in sand-dominated habitats had a significantly higher mean movement rate (3.2 ± 4.2 cm/day, mean ± SD) than mussels situated in gravel-dominated (1.9 ± 2.7 cm/day) or stone-dominated habitats (1.8 ± 3.2 cm/day). The direction of the movements appeared random; however, an emigration from sandy habitats was observed, probably to avoid dislodgment from these hydraulically unstable habitats. This study demonstrates that freshwater pearl mussels can actively emigrate from unsuitable microhabitats. Once suitable streams with respect to physical, chemical, and biological quality were identified, it is therefore only necessary to identify suitable mesohabitats (area of 10–30 m
2
) when reintroducing or relocating mussels.