Wissner, Nora (2015) Regeneration and healing capacity of the invasive ctenophore Mnemiopsis leidyi under different temperature scenarios. (Bachelor thesis), Carl von Ossietzky Universität, Oldenburg, Germany, 40 pp.

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Abstract

Mnemiopsis leidyi A. AGASSIZ, 1865, is a successful invasive species spreading fast throughout all major European Seas in the last decades. Like for many other marine bioinvaders, the introduction of Mnemiopsis brings potential ecological and economic consequences with it. Ballast water discharge was assumed to be the major transport vector of this species from its native distribution areas of the West Atlantic coasts. However very little is known about survival mechanisms during the journey. Besides high feeding and reproduction rates, M.leidyi has a broad physiological tolerance and is able to regenerate missing body parts very well. There have been studies investigating the temperature threshold of this species or the regeneration potential separately. In temperature experiments either survival or reproduction was observed. And in studies regarding regeneration the organism was surrounded only by favourable temperature conditions. The basic hypothesis of this study is that the healing and regeneration capacity of Mnemiopsis might be important life traits for recovering from mechanical stress in natural environments and during the assumed vector transport in ballast water tanks. We tested temperature changes (in three levels of low, medium and warm temperature) as this factor greatly influences healing and regeneration speed and capacity. The results indicate a clear temperature effect on the survival rate of the organisms. The development differed in the treatments over time with higher survival in the coldest treatment. In warmer conditions the rate of regeneration was faster but also linked to higher mortality, as all specimens were dead after about 15-16 days. The highest regeneration degrees were reached in the low temperature after 8 days. Also the presence of an apical organ seemed to favour regeneration. Overall, temperature and the level of injury seem to effect regeneration. To understand this complex regeneration process further research on the linkage between ecological conditions and metabolism is needed.

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