Effects of temperature and light intensity on asexual reproduction of the scyphozoan, Aurelia aurita (L.) in Taiwan

Abstract

Jellyfish blooms cause problems worldwide, and they may increase with global warming, water pollution, and over fishing. Benthic polyps (scyphistomae) asexually produce buds and small jellyfish (ephyrae), and this process may determine the population size of the large, swimming scyphomedusae. Environmental factors that affect the asexual reproduction rates include food, temperature, salinity, and light. In this study, polyps of Aurelia aurita (L.), which inhabit Tapong Bay, southwest Taiwan, were tested in nine combinations of temperature (20, 25, 30°C) and light intensity (372, 56, and 0 lux) in a 12 h light-12 h dark photoperiod. Production of new buds decreased with warmer temperature and stronger light intensity. Warm temperature accelerated strobilation and increased the daily production of ephyrae. The proportion of ephyrae of total asexual reproduction (new buds ? ephyrae) increased dramatically in warmer temperature and more light. Survival was reduced in the highest temperature. Strobilation did not occur in the lowest temperature in darkness. All measures of total asexual reproduction indicated that mid-to high temperatures would lead to faster production of more jellyfish. Continuous high temperatures might result in high polyp mortality. Light affected asexual reproduction less than did temperature, only significantly accelerating the strobilation rate. Because the interactive effects of light and temperature were significant for the time period polyps survived and the potential production of jellyfish polyp -1 , combined light and temperature effects probably are important for strobilation in situ.

Temperature effects on asexual reproduction of the scyphozoan Aurelia aurita s.l.: differences between exotic (Baltic and Red seas) and native (Mediterranean Sea) populations

“…3). Although it is known that a temperature change can trigger strobilation (Purcell et al 1999;Lucas 2001;Liu et al 2009), surprisingly, Mediterranean Sea scyphistomae did not strobilate when the temperature changed from 14 to 21 or 28°C, unlike Baltic and Red Sea scyphistomae. The cold water population (Baltic Sea) showed better reproductive adaptation to higher temperatures than did the warm water population (Red Sea).…”

“…Strobilation equalled the proportion of scyphistomae in each treatment that had strobilated after mid-December. Potential production was calculated as in Liu et al (2009) [(number of buds+1)9number of ephyrae produced Á days of experiment À1 ] and was expressed as the total number of ephyrae per day.…”

Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela

“…In many senses, the polyps can be considered immortal (Galliot and Schmid 2002), being able to encyst for prolonged periods of time (as can planulae) under adverse conditions (Arai 2009) and to regrow from fragments if damaged (Arai 1997). Under certain circumstances, they can also proliferate, for example by budding (Willcox et al 2007, Liu et al 2009, Han and Uye 2010.…”

Have jellyfish in the Irish Sea benefited from climate change and overfishing?

“…Sea temperature is presumably linked to jellyfish reproduction (through the sexual medusa stages, settlement of larvae and/or the asexual development of the benthic polyp) and this would explain the lagged correlations between medusa abundance and SST ( Figure S3a). However, the varied processes that impact on jellyfish reproduction are complex, and the direct effects of temperature can be positive (increased strobilation rates and hence the production of young medusoids) and negative (increased mortality of the benthic polyp, Liu et al, 2009). In addition, cold temperature stress will trigger strobilation (e.g.…”