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- Albertsson, Jan, 1959-, et al.
(författare)
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Impact of a borrowing deposit-feeder, Monoporeia affinis, on viable zooplankton resting eggs in the northern Baltic Sea
- 2000
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Ingår i: Marine Biology. - Umea Univ, Dept Ecol & Environm Sci, S-90187 Umea, Sweden. : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 136:4, s. 611-619
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effect of different densities of the burrowing deposit-feeding amphipod Monoporeia affinis on the potential for recruitment of zooplankton from benthic resting eggs. Hatching of resting eggs was induced in the laboratory on sliced and resuspended 1-cm depth-sections of sediment cores, collected at six stations ill an archipelago area of the Gulf of Bothnia, Baltic Sea. The uppermost 5 cm of the sediment was studied. The most common species that hatched was Eurytemor affinis (Copepoda). Individuals from another copepod genus, Acartia, hatched in significant numbers only in the cores from two stations with low amphipod abundance. Cores from stations with high amphipod densities showed a deeper distribution of emerging E. affinis nauplii compared with stations with few amphipods: the oxidised sediment layer was also deeper at high M. affinis densities than at low. Total (0 to 5 cm strata pooled) number of hatched E. affinis nauplii was independent of amphipod density. This indicates that the effect of M. affinis on E. affinis eggs involves deeper burial due to bioturbation, rather than predation. Decreased benthic recruitment of zooplankton at localities with high M. affinis density is suggested, since more deeply positioned eggs are less likely to hatch. When hatching was induced in intact, non-sliced cores from one station, the number of E. affinis nauplii that hatched was on average 43% of the number that hatched in the upper centimetre of the sliced cores from the same station. This fraction (43%), if applied to the other stations, implied a potential for benthic recruitment of up to 80000 ind m(-2) for E. affinis. Due to its high abundance, M. affinis is likely to greatly reduce benthic recruitment of zooplankton in this system.
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| 2. |
- Albertsson, Jan, 1959-, et al.
(författare)
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Deposit-feeding amphipods (Monoporeia affinis) reduce the recruitment of copepod nauplii from benthic resting eggs in the northern Baltic Sea
- 2001
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Ingår i: Marine Biology. - Umea Univ, Dept Ecol & Environm Sci, S-90187 Umea, Sweden. Umea Univ, Umea Marine Sci Ctr, S-90187 Umea, Sweden. : Springer Science and Business Media LLC. - 0025-3162 .- 1432-1793. ; 138:4, s. 793-801
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally investigated the effect of different densities of the burrowing, deposit-feeding amphipod Monoporeia affinis on the recruitment of zooplankton from benthic resting eggs. Intact sediment cores with in situ density and species composition of zooplankton resting eggs and benthic fauna were collected in the northern Bothnian Sea, part of the Baltic Sea. We removed as many M, affinis as possible from the cores and then added different numbers of ill. affinis to the cores to generate a range of densities. The cores were exposed to different densities of M. affinis for either 3 or 40 days, after which the hatched zooplankton was registered. One subset of the cores were initially incubated under low temperature (2-3 degreesC, to prevent hatching) for 37 days (the resting phase), to allow for effects of M. affinis on unhatched resting eggs. These cores were then incubated under higher temperature (13 degreesC) for 3 days (the hatching phase), to induce hatching and allow for effects on hatching or hatched specimens. In a second subset of cores with the same time and temperature schedule, the M. affinis density was experimentally reduced at the start of the hatching phase, to evaluate the effect of M. affinis during the hatching phase. To a third subset of cores, we immediately initiated the hatching phase, without an experimental resting phase, to evaluate the effects induced during the resting phase. The most common zooplankton species that hatched was Eurytemora affinis (Copepoda), followed by Bosmina longispina maritima (Cladocera). In all cores that were subjected to a resting phase, the numbers of hatched E. affinis were log-linearly negatively related to density of M. affinis. An increase of M. affinis density from 1,000 to 5,000 individuals m(-2), normal field densities, reduced the hatching by 60-70%. The negative impact was mainly exerted during the hatching phase, suggesting predation on, burial of or physical injury of hatching nauplii or eggs in a late development stage as likely mechanisms. Also, the number of B. longispina maritima that hatched was reduced by M. affinis during the hatching phase, but no clear relation to density of M. affinis could be identified. The results show that M. affinis can reduce recruitment to zooplankton from benthic resting eggs. Such impact by the benthos on resting stages of zooplankton is therefore a potentially significant link between the benthic and pelagic systems.
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