Competition between the introduced polychaeteMarenzelleriasp. and the native amphipodMonoporeia affinisin Baltic soft bottoms

The North American spionid polychaeteMarenzelleriacf.viridiswas reported from the Baltic Sea for the first time in 1985. The species has spread rapidly and now dominates many soft-bottom communities, where it dwells in burrows down to 30 cm deep in the sediment. In the Baltic Sea, below 10 m water d...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2003-12, Vol.264, p.49-55
Main Authors: Neideman, Rasmus, Wenngren, Johan, Ólafsson, Emil
Format: Article
Language:English
Subjects:
Acclimatization
Brackish water
Burrowing
Crabs
Ecological competition
Introduced species
Seas
Sediments
Swimming
Worms
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Summary:The North American spionid polychaeteMarenzelleriacf.viridiswas reported from the Baltic Sea for the first time in 1985. The species has spread rapidly and now dominates many soft-bottom communities, where it dwells in burrows down to 30 cm deep in the sediment. In the Baltic Sea, below 10 m water depth, the macrobenthic community is composed of only a handful of species, among which the amphipodMonoporeia affinisis a key member. This species is highly mobile; it swims actively at night but remains burrowed in the sediment during the day. Due to similarities in feeding mode and sympatric occurrence, the polychaete may compete with the amphipod for both food and space. One plausible outcome of interactions between the 2 species is that the amphipod, the more mobile species, would avoid areas where the more sessile polychaete is present in high numbers. In the laboratory, we tested the hypothesis that, if given the choice, the amphipod avoids burrowing in sediment with high polychaete abundances. The amphipod burrowed in significantly lower numbers in patches with high polychaete abundance compared to those with lower abundance. Also, plastic tubes mimicking polychaete body structure were not avoided by the amphipods, indicating that the physical tube structure of the polychaetes does not explain the amphipod’s choice of burrowing site. Furthermore, the amphipod did not increase or prolong swimming activities as a function of higher worm density, indicating that increased swimming activity over dense polychaete patches and subsequent migration away from them is not a likely explaination of why this amphipod burrow less frequently in patches of high polychaete abundance.
ISSN:0171-8630
1616-1599