International Research Fellowship Program: Vulnerability and Resilience of Sponge Populations and their Bacterial Symbionts to Climate Change and Anthropogenic Disturbances

0853089erwin2009年美国复苏和再投资法案（公法111-5）资助该奖项。国际研究奖学金项目使美国科学家和工程师能够在国外进行9至24个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Patrick M. Erwin博士与Xavier Turon博士在西班牙布拉内斯高级研究中心和西班牙研究委员会开展为期24个月的研究。海洋生物对人为压力源的短期脆弱性和长期恢复力将决定水生生态系统的未来，并将反过来对人类与海洋的相互作用产生重大影响。人类活动的负面后果几乎影响到所有海洋生物；然而，居住在沿海环境中的无根、滤食性无脊椎动物尤其容易受到影响，因为它们成年后不活动、集中暴露于水媒污染物以及靠近密集的人口。海绵是一种古老的滤食性生物，在各种海洋环境中茁壮成长，对海洋生态系统的健康运作至关重要。海绵-微生物关联代表了基础和原始多细胞动物群体与古代细菌谱系之间独特的共生关系，这些细菌似乎共同进化并忍受了广泛的环境条件。微生物共生体组成的变化是海绵全息生物内部关系中断的早期信号，伴随着有益细菌的丧失和感染微生物和寄生微生物的增殖。相关微生物群落对宿主海绵健康至关重要，为研究自然和人为应激源对宿主-共生稳定性的影响以及破坏细菌共生群落对宿主海绵健康的影响提供了理想的系统。评估个体生物和整个生态系统对日益严重的污染和气候变化的脆弱性和复原力涉及监测致命和亚致命水平的影响。在群落和物种水平上研究了致命污染的影响，记录了群落组成的变化并跟踪了生物指示物种。这些反应是最终的，只有在长时间接触后才能证明。相比之下，对污染和气候变化的亚致死反应是在细胞和分子水平上研究的，因为小剂量的污染物或温度变化可能会影响生物体的生理功能和行为，而不会杀死它们。因此，分子水平的变化发生在那些可以通过传统监测和生物分析检测到的变化之前，因此分子生物标志物可以被视为污染和应激亚致死效应的早期预警系统。目前的研究是一个多尺度的研究项目，旨在研究地中海海绵及其共生菌群对自然和人为压力源的生态（生长和生存）、生理（宿主-共生体相互作用）和细胞（基因表达）反应。该研究的野外部分包括监测未受干扰和实验遮蔽的海绵（Ircinia fasciculata和I. variabilis）超过1.5年，以评估hsp70胁迫蛋白基因表达、共生体光合活性和共生体多样性的季节性变化，并确定来自共生体的自养营养在宿主海绵生长和胁迫状态中的作用。该研究的实验室部分包括在受控的水族箱条件下，将相同的海绵物种暴露于重金属、杀虫剂和海水温度升高中，以评估污染物和气候变化对微生物共生体群落结构和宿主海绵细胞应激反应的潜在影响。面对全球气候变化导致的人口增长和前所未有的环境条件，解决生物对新干扰制度的脆弱性和复原力对于保护当前生态系统和预测未来人为对自然系统的影响至关重要。

0853089ErwinThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Patrick M. Erwin to work with Dr. Xavier Turon at the Centre of Advanced Studies of Blanes and at the Spanish Research Council in Blanes, Spain.The short-term vulnerability and long-term resilience of marine organisms to anthropogenic stressors will dictate the future of aquatic ecosystems and will, in turn, have a large impact on humankind's interactions with the sea. The negative consequences of human activities affect nearly all marine organisms; however, sessile, filter-feeding invertebrates inhabiting coastal environments are especially susceptible, due to adult immobility, concentrated exposure to waterborne pollutants and proximity to dense human populations. Sponges are ancient, filter-feeding organisms that thrive in a variety of marine environments and are essential to the healthy functioning of marine ecosystems. Sponge-microbial associations represent unique symbioses between a basal and primitive multi-cellular animal group and ancient bacterial lineages that appear to have co-evolved and endured a wide range of environmental conditions. Changes in the composition of microbial symbionts are an early signal of the disruption of the relationships within the sponge holobiont, with the loss of beneficial bacteria and proliferation of infectious and parasitic microbes. The critical importance of associated microbial communities to host sponge health offers an ideal system to study the impact of natural and anthropogenic stressors on host-symbiont stability and the consequences of disrupting bacterial symbiont communities on host sponge fitness.Assessing the vulnerability and resilience of individual organisms and entire ecosystems to increasing pollution and climate shifts involves monitoring the effects of both lethal and sub-lethal levels. The effects of lethal pollution are studied at the community and species level, documenting shifts in community composition and tracking bioindicator species. These responses are ultimate and are evidenced only after prolonged exposure. In contrast, sub-lethal responses to pollution and climate change are studied at the cellular and molecular level because small doses of pollutants or temperature changes may affect the physiological functions and behavior of organisms without killing them. Thus, changes at the molecular level occur before those that can be detected by classical monitoring and bioassays so that molecular biomarkers can be considered as early warning systems for sub-lethal effects of contamination and stress.The current study is a multi-scale research project examining the ecological (growth and survival), physiological (host-symbiont interactions) and cellular (gene expression) responses of Mediterranean sponges and their symbiotic microflora to natural and anthropogenic stressors. The field component of the study involves monitoring undisturbed and experimentally shaded sponges (Ircinia fasciculata and I. variabilis) over 1.5 years to assess seasonal variability in gene expression of the hsp70 stress protein, symbiont photosynthetic activity and symbiont diversity and to determine the role of autotrophic nutrition from symbionts in host sponge growth and stress status. The laboratory component of the study involves exposing the same sponge species to heavy metals, pesticides and increased seawater temperatures under controlled aquaria conditions to assess the potential effects of pollutants and climate change on the community structure of microbial symbionts and the cellular stress responses of host sponges. In the face of increasing human populations and unprecedented environmental conditions resulting from global climate change, addressing the vulnerability and resilience of organisms to new disturbance regimes is critical to the preservation of current ecosystems and the forecasting of future anthropogenic impacts on natural systems.