Initiation and Maintenance of Population Maxima of the Ctenophore Mnemiopsis leidyi in Northern Coastal Waters

北岸水域莱氏沼虾种群最大值的形成和维持近十年来，在位于该物种地理分布北部边界的河口纳拉甘西特湾，莱氏沼虾种群的峰值浓度出现了实质性的增加。在海湾水温较早变暖的年份里，脉动的季节时间也从夏末转移到了初春。这种临时引入的重大生态后果潜在地是巨大的。在该地区鱼类产卵的高峰期，锰现在很丰富。2000年春季和夏季，浮游动物资源严重枯竭。该物种的季节性和丰度的类似变化可能也发生在东北部的其他河口。尽管大型鞭毛虫具有明显的生态重要性，但理解导致种群快速增长的条件的量化基础是有限的。虽然温度和食物供应最终肯定是控制该物种生长和繁殖的主要变量，但关于越冬种群的繁殖或有利于幼虫在春季生长的条件的信息很少。在这项研究中，研究人员将在整个年度周期内对线虫进行田间和实验室研究，以确定温度、食物供应和食物质量对繁殖率和幼虫生长的影响。微型浮游动物的作用，在以前的两项实验室研究中只涉及到这一点，将在实地和实验室两个部分得到充分讨论。纳拉甘西特湾最近观察到在冬季维持着出人意料的大量种群的地区，以及种群脉冲被推迟到春季的地区，将进行比较。将收集和检查水文数据，以了解物理因素对人口增长的直接和间接影响，包括热分层在人口脉冲启动中的作用。鉴于季节性或地理入侵对生态系统造成破坏的证据，以及在其地理范围的北部边缘对该物种进行的研究数量有限，这项研究的理由是令人信服的。在本研究中收集的关于温度和食物对莱氏沼虾幼虫和成虫影响的详细定量信息将极大地促进我们对该物种启动和维持种群脉冲所需因素的理解。

Initiation and Maintenance of Population Maxima of the Ctenophore Mnemiopsis leidyi in Northern Coastal WatersSubstantial increases in peak concentrations of the ctenophore Mnemiopsis leidyi have occurred in the last decade in Narragansett Bay, an estuary at the northern boundary of the geographic distribution of this species. The seasonal timing of Mnemiopsis pulses has also shifted from late summer to early spring during years with earlier warming of bay water temperatures. Significant ecological consequences of this temporal introduction are potentially great. Mnemiopsis is now abundant during the peak period of fish spawning in the region. Severely depleted stocks of zooplankton have been observed in spring and summer of 2000. Similar changes in seasonality and abundance of the species are likely to be occurring in other estuaries in the northeast. Despite the clear ecological importance of large pulses of ctenophores, the quantitative basis for understanding conditions giving rise to rapid population increases is limited. While temperature and food supply must ultimately be dominant variables controlling growth and reproduction of this species, there is little information about reproduction of over-wintering populations or conditionswhich favor growth of larvae in spring. In this study the investigators will conduct field and laboratory studies of Mnemiopsis over the full annual cycle to determine effects of temperature, food supply and food quality on reproductive rates and larval growth. The role of microzooplankton, addressed in only two previous laboratory studies will be fully addressed in both field and laboratory components. Areas of Narragansett Bay which have recently been observed to sustain unexpectedly large population of Mnemiopsis in winter, as well as areas in which populations pulses are delayed until spring will be compared. Hydrographic data will be collected and examined for both direct and indirect effects of physical factors on population growth, including the role of thermal stratification in population pulse initiation. Given the evidence for disruptive effects on ecosystems of seasonal or geographic invasions of Mnemiopis leidyi and the limited number of studies of this species at the northern edge of its geographic range, justification for this study is compelling. Quantitative information on the influence of temperature and food on both larval and adult M. leidyi at the level of detail collected in this study will significantly advance our understanding of factors required for initiation and maintenance of population pulses of this species.