ABSTRACT: The trophic ecology of mixotrophic, zooxanthellate jellyfishes potentially spans a wide spectrum between autotrophy and heterotrophy. However, their degree of trophic plasticity along this spectrum is not well known. To better characterize their trophic ecology, we sampled the zooxanthellate medusa Mastigias papua in contrasting environments and sizes in Palau (Micronesia). We characterized their trophic ecology using isotopic (bulk δ¹³C and δ¹⁵N), elemental (C:N ratios), and fatty acid compositions. The different trophic indicators were correlated or anti-correlated as expected (Pearson’s correlation coefficient, r_P > 0.5 or < -0.5 in 91.1% of cases, p < 0.05), indicating good agreement. The sampled M. papua were ordered in a trophic spectrum between autotrophy and heterotrophy (supported by decreasing δ¹³C, C:N, proportion of neutral lipid fatty acids (NLFA:TLFA), n-3:n-6 and increasing δ¹⁵N, eicosapentaenoic acid to docosahexaenoic acid ratio (EPA:DHA)). This trophic spectrum was mostly driven by sampling location with little influence of medusa size. Moreover, previous observations have shown that in a given location, the trophic ecology of M. papua can change over time. Thus, the positions on the trophic spectrum of the populations sampled here are not fixed, suggesting high trophic plasticity in M. papua. The heterotrophic end of the trophic spectrum was occupied by non-symbiotic M. papua, whereas the literature indicates that the autotrophic end of the spectrum corresponds to dominant autotrophy, where more than 100% of the carbon requirement is obtained by photosynthesis. Such high trophic plasticity has critical implications for the trophic ecology and blooming ability of zooxanthellate jellyfishes.

中文翻译：

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混合营养型玛斯提亚虫（Mastigias papua-Symbiodiniaceae holobiont）的高营养可塑性：对人畜共患的水母生态的影响

摘要：混合营养型，人畜共患的水母的营养生态可能跨越自养和异养之间。然而，它们沿该光谱的营养可塑性程度尚不为人所知。为了更好地描述其营养生态，我们在帕劳（密克罗尼西亚）的不同环境和大小下，对人兽共患病美杜鹃玛斯提亚虫（Mastigias papua）取样。我们其特征在于利用同位素其营养生态学（散装δ ¹³ C和δ ¹⁵ N），元素（C：N比），和脂肪酸的组合物。不同的营养指标按预期相关或反相关（Pearson相关系数，在91.1％的情况下，r _P > 0.5或<-0.5，p <0.05），表明有很好的一致性。采样的巴氏甲烷八叠球菌在自养和异养（负载之间的营养谱被命令通过降低δ ¹³ C，C：N，的中性脂质的脂肪酸比例（NLFA：TLFA）中，n-3：n-6和δ增加¹⁵ N，二十碳五烯酸，以二十二碳六烯酸比率（EPA：DHA））。这种营养谱主要是由采样位置驱动的，而对水母大小的影响很小。此外，以前的观察表明，在给定的位置，巴氏甲烷八叠球的营养生态会随时间变化。因此，这里采样的种群在营养谱上的位置不是固定的，这表明巴氏甲烷八叠球的营养可塑性很高。营养谱的异养端被非共生的M. papua占据，而文献表明光谱的自养末端对应于显性自养，其中通过光合作用获得了超过100％的碳需求。如此高的营养可塑性对虫黄藻水母的营养生态和开花能力具有至关重要的意义。