Trophic interactions, foodweb dynamics and ontogeny in juvenile Pacific salmon in lakes and coastal marine ecosystems

湖泊和沿海海洋生态系统中太平洋鲑鱼幼体的营养相互作用、食物网动态和个体发育

• 批准号: RGPIN-2014-05713
• 负责人: Mazumder, Asit
• 金额: $ 1.97万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611800
• 关键词: Trophic; interactions; foodweb; dynamics; ontogeny

Pacific salmon, regarded as sentinel species with significant economic, social and cultural benefits. Specifically, there are major gaps in understanding resource partitioning, trophic interactions and foodweb dynamics of juvenile Pacific salmon in freshwater and marine ecosystems. From my past research on sockeye systems in Alaska, we found that the growth and survival of sockeye fry in freshwater lakes are affected by both density dependent and density independent factors, as do the size and age distribution of smolts migrating to ocean. However, significant further research is needed to understand and quantify the processes and mechanisms leading to variable size- and age-structure of sockeye fry and smolts for specific lake systems. However, achieving these is further complicated by the shifting climate regimes (precipitation and temperature) in coastal region. Further complications are be due to introduced species like perch and bass to several of the sockeye lakes in BC, which as juveniles may have significant niche overlaps with sockeye fry as well as stickleback, while as adults they become predators of sockeye fry and stickleback. It would be fundamentally importance to determine how these variable scenarios and the associated processes influence the size- and age-distribution of sockeye fry, their food and feeding habits, niche shifts and their trophic interactions with cohabiting fish and invertebrate predators, and how these affect their growth and survival, out-migrating size and ages of smolt, and their performance during early marine growth. Similarly, the sizes of the juveniles of other Pacific salmon species (e.g., coho and Chinook) at ocean entry also vary greatly between years and among stocks, which may have significant implications for their performance during their early growth in the coastal marine ecosystems. As the juvenile salmon enter the ocean, they share common feeding grounds and niches among themselves and with other forage fish species, my research interest will also be to understand the ontogenetic niche shifts within species, niche overlaps among species, and their implications for ocean growth and survival. In line with my long-term research goals of looking at the patterns of nutrient-foodweb dynamics of aquatic systems, and their links with trophic interactions and growth of juvenile salmon, energy and contaminant transfer along aquatic foodweb, planktonic biodiversity and water quality, I will continue along the same theme during the next 5 years. I propose the following research objectives: 1) test how the variable density of sockeye fry modifies the structure and size-based efficiency of lower trophic levels, growth of sockeye fry and size and age structure of out-migrating smolts; 2) model spatial (littoral versus pelagic) patterns of resource utilization by sockeye fry and niche overlaps or lack there of with cohabiting planktivores under contrasting predator-prey scenarios; 3) test how the introduced predatory fish species shift ontogeny of sockeye fry and associated demography of out-migrating smolts; 4) characterize and model the foodwebs of juvenile sockeye and two other Pacific salmon species (coho and chinook) as a function of size at ocean entry and during early marine growth; and 5) model spatial (onshore vs. offshore) and temporal (inter-annual) variation in trophic position, resource allocation and ontogenetic niche shifts in juvenile Pacific salmon as a function of size. About 6-8 graduate students and 10-12 undergraduate students will be trained through proposed research projects that will generate fundamentally important and new knowledge towards understanding of the processes linked with highly variable performances of juvenile Pacific salmon.

太平洋鲑鱼，被视为具有重大经济、社会和文化效益的哨兵物种。具体而言，在了解淡水和海洋生态系统中太平洋鲑鱼幼鱼的资源分配、营养相互作用和食物网动态方面存在重大差距。根据我过去对阿拉斯加红鲑系统的研究，我们发现淡水湖中红鲑鱼苗的生长和生存受到密度依赖和密度无关因素的影响，迁移到海洋的小鲑鱼的大小和年龄分布也是如此。然而，需要进一步开展大量研究来了解和量化导致特定湖泊系统的红鱼鱼苗和小鲑鱼体型和年龄结构可变的过程和机制。然而，沿海地区气候状况（降水和温度）的变化使实现这些目标变得更加复杂。进一步的复杂性是由于引入了鲈鱼和鲈鱼等物种到不列颠哥伦比亚省的几个红鱼湖，幼鱼可能与红鱼鱼苗和刺鱼有显着的生态位重叠，而成年后它们成为红鱼鱼苗和刺鱼的捕食者。确定这些可变情景和相关过程如何影响红鱼鱼苗的大小和年龄分布、它们的食物和摄食习惯、生态位变化及其与同居鱼类和无脊椎动物捕食者的营养相互作用，以及这些如何影响，是至关重要的。它们的生长和生存、小鲑鱼迁出的大小和年龄，以及它们在早期海洋生长过程中的表现。同样，其他太平洋鲑鱼品种（例如银鲑鱼和奇努克鲑鱼）的幼鱼在进入海洋时的大小在年份和种群之间也有很大差异，这可能对其在沿海海洋生态系统中早期生长期间的表现产生重大影响。当幼年鲑鱼进入海洋时，它们之间以及与其他饲料鱼类共享共同的觅食地和生态位，我的研究兴趣还将是了解物种内的个体发育生态位变化、物种之间的生态位重叠及其对海洋生长的影响和生存。 根据我的长期研究目标，即研究水生系统的营养食物网动态模式，及其与营养相互作用和幼鲑生长、沿水生食物网的能量和污染物转移、浮游生物多样性和水质的联系，我未来 5 年将继续遵循同一主题。我提出以下研究目标：1）测试红鱼鱼苗的可变密度如何改变较低营养级的结构和基于尺寸的效率、红鱼鱼苗的生长以及外迁小鲑鱼的尺寸和年龄结构； 2）在对比捕食者-被捕食者情景下，模拟红鱼鱼苗资源利用的空间（沿海与中上层）模式以及与同居浮游动物的生态位重叠或缺乏； 3) 测试引入的掠食性鱼类如何改变红鲑鱼苗的个体发育以及外迁小鲑鱼的相关人口统计； 4) 将红鲑幼鱼和其他两种太平洋鲑鱼（银鲑鱼和奇努克鲑鱼）的食物网描述为入海时和早期海洋生长期间大小的函数，并对其进行建模； 5) 模拟幼年太平洋鲑鱼的营养位置、资源分配和个体发育生态位变化的空间（陆上与近海）和时间（年际）变化作为大小的函数。大约 6-8 名研究生和 10-12 名本科生将通过拟议的研究项目接受培训，这些项目将产生非常重要的新知识，有助于理解与幼年太平洋鲑鱼的高度可变性能相关的过程。