A Diet of Snow: Energetics and Nutrition of Leptocephalus Larvae

雪的饮食：薄头鱼幼虫的能量和营养

• 批准号: 9712572
• 负责人: Joseph Torres
• 金额: $ 30万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2000-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9712572&HistoricalAwards=false
• 关键词: Diet; Snow; Energetics; Nutrition; Leptocephalus

Leptocephali are the unusually large, transparent larvae of five orders of bony fishes. They are found at warm temperate and tropical latitudes throughout the world ocean and during peak periods of reproduction form an important component of the blue water micronekton/macrozooplankton community. However, their importance is not one of numbers and biomass, it is in the fact that they are (polar oceans excepted) a globally distributed group of unique trophic specialists. For the 230 years between their discovery and 1993, a phase I leptocephalus was never observed with food in its gut. However, recent histological evidence suggests that phase I leptocephali may ingest larvacean houses and zooplankton fecal pellets. Further evidence suggests that particulate organic material (POM) and dissolved organic matter (DOM) provide an important source of nutrition. Both particulate and dissolved organic material comprise the major carbon reservoir in the world ocean, yet their significance to pelagic metazoan life remains a cipher. To describe the leptocephalus trophic niche, larvacean houses and the larvae will be examined and the proteoglycan structure of both will be determined; gut morphology will be examined (including gut contents, if present) in four different species. Sites of nutrient uptake will be determined via radiolabelled amino acids and autoradiography. Daily metabolic demands will be quantified by determining diel consumption rates of individual larvae. Growth of the larvae will be determined by microincremental analysis of otoliths and compared to growth indices determined by RNA DNA analysis. Proximate and elemental composition will provide values for the calories and carbon stored in the living populations and their daily production. The leptocephalus larval form may be the only example of a vertebrate that obtains its nutrition from DOM and POM. If this is the case, leptocephali would comprise a unique trophic link in the pelagic food web. Our research will answer the riddle of how leptocephali acquire and utilize energy and describe the leptocephalus larva's position in the trophic hierarchy of the pelagial.

细头鱼是五个硬骨鱼目中非常大的透明幼体。它们分布在世界海洋的暖温带和热带地区，在繁殖高峰期是蓝水微型浮游动物/大型浮游动物群落的重要组成部分。然而，它们的重要性不在于数量和生物量，而在于它们是（极地海洋除外）一个全球分布的独特营养专家群体。从他们被发现到1993年的230年里，从未观察到一种第一阶段的细头龙肠道中有食物。然而，最近的组织学证据表明，第一阶段leptocephali可能会摄取幼虫的房子和浮游动物粪便颗粒。进一步的证据表明，颗粒有机物（POM）和溶解有机物（DOM）提供了重要的营养来源。 微粒和溶解有机物质构成了世界海洋中的主要碳库，但它们对远洋后生动物生命的重要性仍然是一个谜。 为了描述leptocephalus营养生态位，将检查幼虫的房屋和幼虫，并确定两者的蛋白多糖结构;将在四个不同的物种中检查肠道形态（包括肠道内容物，如果存在）。将通过放射性标记氨基酸和放射自显影术确定营养摄取部位。通过测定个体幼虫的日消耗率来定量每日代谢需求。幼虫的生长将通过耳石的微增量分析来确定，并与通过RNA DNA分析确定的生长指数进行比较。近似成分和元素成分将提供生物种群及其日常生产中储存的卡路里和碳的值。 leptocephalus幼虫形式可能是唯一的例子，脊椎动物，获得其营养的DOM和POM。如果是这种情况，细头鱼将构成远洋食物网中的一个独特的营养环节。我们的研究将回答细头蚴如何获得和利用能量的谜团，并描述细头蚴幼体在浮游生物营养层次中的地位。