Weisz Jeremy B, Massaro Andrew J, Ramsby Blake D, Hill Malcolm S
Department of Biology, University of Richmond, 28 Westhampton Way, Richmond, VA 23173, USA.
Biol Bull. 2010 Dec;219(3):189-97. doi: 10.1086/BBLv219n3p189.
Sponges belonging to the genus Cliona are common inhabitants of many coral reefs, and as bioeroders, they play an important role in the carbonate cycle of the reef. Several Cliona species maintain intracellular populations of dinoflagellate zooxanthellae (i.e., Symbiodinium spp.), which also form symbioses with a variety of other invertebrates and protists (e.g., corals, molluscs, foraminifera). Unlike the case of coral symbioses, however, almost nothing is known of the metabolic interaction between sponges and their zooxanthella symbionts. To assess this interaction, we performed a tracer experiment to follow C and N in the system, performed a reciprocal transplant experiment, and measured the stable carbon isotope ratio of Cliona spp. with and without zooxanthellae to study the influence of environment on the interaction. We found strong evidence of a transfer of C from zooxanthellae to their sponge hosts but no evidence of a transfer of N from sponge to zooxanthellae. We also saw significant influences of the environment on the metabolism of the sponges. Finally, we observed significant differences in carbon metabolism of sponge species with and without symbionts. These data strongly support hypotheses of metabolic integration between zooxanthellae and their sponge host and extend our understanding of basic aspects of benthic-pelagic coupling in shallow-water marine environments.
属于凿船贝属的海绵是许多珊瑚礁的常见栖息生物，作为生物侵蚀者，它们在珊瑚礁的碳酸盐循环中发挥着重要作用。几种凿船贝物种维持着虫黄藻（即共生藻属物种）的细胞内种群，虫黄藻也与多种其他无脊椎动物和原生生物（如珊瑚、软体动物、有孔虫）形成共生关系。然而，与珊瑚共生的情况不同，关于海绵与其虫黄藻共生体之间的代谢相互作用几乎一无所知。为了评估这种相互作用，我们进行了一项示踪实验来追踪系统中的碳和氮，进行了一项相互移植实验，并测量了有和没有虫黄藻的凿船贝属物种的稳定碳同位素比率，以研究环境对这种相互作用的影响。我们发现了有力证据，证明碳从虫黄藻转移到其海绵宿主，但没有证据表明氮从海绵转移到虫黄藻。我们还看到环境对海绵代谢有显著影响。最后，我们观察到有共生体和没有共生体的海绵物种在碳代谢方面存在显著差异。这些数据有力地支持了虫黄藻与其海绵宿主之间代谢整合的假设，并扩展了我们对浅水海洋环境中底栖 - 浮游耦合基本方面的理解。
