Effects of turbidity on survival of larval ayu and red sea bream exposed to predation by jack mackerel and moon jellyfish |
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Authors: | Ryosuke Ohata Reiji Masuda Masahiro Ueno Yuichi Fukunishi Yoh Yamashita |
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Institution: | (1) Maizuru Fisheries Research Station, Field Science Education and Research Center, Kyoto University, Nagahama, Maizuru Kyoto, 625-0086, Japan |
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Abstract: | We conducted laboratory experiments to examine the effects of turbidity on the survival of red sea bream Pagrus major and ayu Plecoglossus altivelis altivelis larvae when exposed to either visual (jack mackerel juveniles) or tactile (moon jellyfish) predators. The experiments were
conducted in 30-l tanks with three different levels of turbidity obtained by dissolving 0, 50, or 300 ppm kaolin. Predators
were introduced to the experimental tanks followed by larvae of either red sea bream (mean ± standard deviation 6.1 ± 0.3
to 11.4 ± 2.1 mm standard length) or ayu (6.6 ± 0.3 and 24.4 ± 1.8 mm). When exposed to jack mackerel, the mean survival rate
of larvae was significantly higher in 300 ppm treatments compared with the other turbidity levels. When exposed to moon jellyfish,
however, there was a less marked difference in the survival rates among different turbidity treatments. Survival rates of
ayu larvae exposed to moon jellyfish were generally lower than those of red sea bream. Our study indicates that anthropogenic
increases of turbidity may increase the relative impact of jellyfish predation on fish larvae. |
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