Original scientific paper

Interannual size changes of adult Aurelia sp.5 medusae stage in the Marine Protected Area of Mljet Island South Adriatic

Tjaša KOGOVŠEK ; Marine Biology Station, National Institute of Biology, Piran, Slovenia
Juan Carlos MOLINERO ; Helmholtz Centre for Ocean Research Kiel (GEOMAR), Marine Ecology/Food Webs, Kiel, Germany
Davor LUČIĆ ; Institute for Marine and Coastal Research, University of Dubrovnik, Croatia
Ivona ONOFRI ; Institute for Marine and Coastal Research, University of Dubrovnik, Croatia
Barbara GANGAI ; Institute for Marine and Coastal Research, University of Dubrovnik, Croatia
Marijana MILOSLAVIĆ ; Institute for Marine and Coastal Research, University of Dubrovnik, Croatia
Delphine BONNET ; Laboratoire ECOSYM, UMR 5119, Université Montpellier 2, CC093, 34095 Montpellier Cedex 05, France
Alenka MALEJ ; Marine Biology Station, National Institute of Biology, Piran, Slovenia

Abstract

Aurelia aurita s.l. is the most widespread scyphozoan jellyfish that recurrently appear “en mass” and forms large aggregations mainly in coastal waters, embayments and estuaries. Beside anthropogenic factors controlling jellyfish populations climate change may play an important role. The aim of this study was to assess whether climate-related factors in absence of other anthropogenically induced stressor influence medusae size. We investigated seasonal and interannual changes in the size of Aurelia in a “jelly lake” in the National Park of Mljet Island (Croatia) where minimal human impact on the environment makes the Veliko Jezero a natural mesocosm for understanding the impact of climate change on the Aurelia population. The observed changes suggest Aurelia medusa population response to changing environment, in particular to enhanced temperature, by reduced body sizes. Comparison of Aurelia population dynamics from different regions in the Mediterranean Sea revealed the unique feature of the Veliko Jezero population. Despite the similarity of the environmental windows of medusae occurrences in the Veliko Jezero and regions in the Mediterranean Sea, medusae in the Veliko Jezero are present all year round. It seems that the lake bathymetry enables medusae to vertically migrate to deeper and cooler water layer, avoiding the limiting temperatures developed in the upper layer during the summer. These conditions may prolong the Aurelia medusae life span and together with continuous strobilation support the stability of the Aurelia medusae population all year round.

Keywords

moon jellyfish; marine lake; climate-related factor; vertical migration; Mediterranean Sea

Hrčak ID:

94425

URI

https://hrcak.srce.hr/94425

Publication date:

1.12.2012.

Article data in other languages: croatian

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