Short-term impact of blue mussel dredging (Mytilus edulis L.) on a benthic community

• Published in: Hydrobiologia Vol. 465; no. 1-3; pp. 115 - 127
• Main Authors: DOLMER, P, KRISTENSEN, T, CHRISTIANSEN, M. L, PETERSEN, M. F, KRISTENSEN, P. S, HOFFMANN, E
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Dordrecht Springer 01.12.2001; Springer Nature B.V
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Community structure; Crangon crangon; Denmark; Dredging; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fundamental and applied biological sciences. Psychology; Marine; Mollusks; Mytilus edulis; Ocean floor; Polychaeta; Sediments; Species composition; Denmark; Europe; North Sea; ANE, Denmark; Community structure; Brackish water environment; Crangon crangon; Growth; Mytilus edulis; Dredging; Perturbation; Coastal zone; Macrura; Fishing gear; Crustacea; Fishery; Bivalvia; Arthropoda; Benthos; Decapoda; Invertebrata; Mollusca; Non target organism; Population density; Species richness; Anthropogenic factor
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1023/A:1014549026157

The short-term effect of mussel dredging in a brackish Danish sound was studied. A commercial dredging track was identified and an analysis of the species composition inside the track and at an adjacent control area showed that dredging changed the community structure by reducing the density of polychaetes. In order to investigate the extent and the duration of the dredging impact experimental dredging was conducted. The experimental dredging removed 50% of the mussels in two dredged areas. Immediately after dredging, a significantly lower number of species was measured inside the mussel beds in dredged areas compared to control and boundary areas. This effect lasted for at least 40 days. The analysis of the species composition showed that the dredged area had a significantly lower density, particularly of polychaetes compared to the boundary area. An increased number of species was recorded outside the mussel beds just after dredging, but this effect lasted for less than 7 days. After dredging, brown shrimps, Crangon crangon invaded the dredged areas. This species is an important predator of smaller invertebrates, and it is suspected that it was feeding on small vulnerable polychaetes exposed at the sediment surface after dredging. The dredging process was observed to form 2-5-cm deep furrows in the seabed, but the sediment texture and the organic content of the sediment was not affected. The biomass accumulation of individual blue mussels was significantly lower in the dredged area compared to the boundary area. This indicates that the disturbance of the mussel bed structure reduced growth and that the lowering of intraspecific food competition caused by a reduced density of mussels did not increase the accumulation of biomass in the mussels which remained in the dredged area.