High abundance of the jellyfish Aurelia aurita excludes the invasive ctenophore Mnemiopsis leidyi to establish in a shallow cove (Kertinge Nor, Denmark)
Riisgård, H.U.; Barth-Jensen, C.; Madsen, C. (2010). High abundance of the jellyfish Aurelia aurita excludes the invasive ctenophore Mnemiopsis leidyi to establish in a shallow cove (Kertinge Nor, Denmark). Aquat. Invasions 5(4): 347-356. https://dx.doi.org/10.3391/ai.2010.5.4.03
In: Aquatic Invasions. Regional Euro-Asian Biological Invasions Centre (REABIC): Helsinki. ISSN 1798-6540; e-ISSN 1818-5487, more
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| Keywords |
Aquatic communities > Plankton > Zooplankton
Interspecific relationships > Competition
Aurelia aurita (Linnaeus, 1758) [WoRMS]; Aurelia coerulea von Lendenfeld, 1884 [WoRMS]; Mnemiopsis leidyi A. Agassiz, 1865 [WoRMS]
Marine/Coastal |
| Author keywords |
gelatinous plankton, predation impact, specific growth rate, half-life of zooplankton |
| Authors | | Top |
- Riisgård, H.U.
- Barth-Jensen, C.
- Madsen, C.
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| Abstract |
The population dynamics of the invasive ctenophore Mnemiopsis leidyi, which showed mass occurrence in Kerteminde Fjord (Denmark) for the first time in 2007, and the indigenous common jellyfish, Aurelia aurita, was followed in the fjord system Kerteminde Fjord/Kertinge Nor during late 2008 and 2009. The population density of A. aurita was always highest in Kertinge Nor while the density of M. leidyi was always highest in Kerteminde Fjord, indicating recruitment of the ctenophore from the adjacent sea (Great Belt). In the shallow cove of Kertinge Nor, the first A. aurita ephyrae appeared in March, by the end of May the medusae had obtained their maximum umbrella diameter of only 30 mm due to food limitation, and the estimated half-life of zooplankton was very low, <1 day from May to September 2009. The high predation impact explains why the holopelagic ctenophore, which presumably survives the winter in the adjacent open sea, is likely to be outcompeted in Kertinge Nor where the polyp stage of A. aurita every spring ensures a very large population of very small medusae. The population density of jellyfish, in Kertinge Nor, during the summer period is dependent on the extend of flush-out due to density-driven water exchange. A survey of data obtained every year in August since 1991 indicates that the unusually high population density (36 ± 34 ind. m-3) and the small umbrella diameter (56 ± 5 mm) of A. aurita have remained unchanged during the last 20 years, and further, that a relatively high population density of jellyfish in certain years is correlated with a relatively small mean umbrella diameter. |
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