Trophic Interactions of Ambush Predator Dinoflagellates in Estuarine Microbial Food Webs

伯克霍尔德9403920各式各样的异养甲藻包括自由生活的河口物种，它们表现出对藻类、原生动物或鱼类猎物的“伏击捕食者”行为。这种行为模式很普遍；到目前为止，地中海、墨西哥湾和西大西洋都报告了这种行为模式。在过去的两年里，埋伏捕食性恐鞭毛虫的一个新属，Pfiester(nov.Gen.)已被发现，已知物种具有至少15个阶段的复杂生活史。这些阶段包括持久的变形虫异养生物和短暂的“幻影状”鞭毛虫，它们常见于富营养化的大西洋中部和墨西哥湾沿岸河口，很可能广泛分布于暖温带和亚热带水域。这些阶段在水柱和沉积物中的普遍存在和丰富，它们对细菌、藻类和微型动物猎物的贪婪捕食，以及它们对鱼类的杀伤力，表明伏击捕食者甲藻在河口食物网的结构和功能中发挥着重要作用。本项目旨在通过实验研究鱼腥藻Pfiester ia piscimorte(nov.将军。Et sp.)作为一种典型的有毒埋伏捕食者，确定这些生物--以它们的多种形式--在河口食物网中的作用。本项目将：(1)研究双鞭毛虫和变形虫对被捕食者刺激性分泌物的腐生营养作用；(2)研究Pfiester(nov.Gen.)以及(3)确定双鞭毛虫和变形虫阶段对典型微生物捕食者的影响。从这项研究中获得的见解将改变关于甲藻在富营养化暖温带河口食物网的结构和功能中所起作用的一般范式。

BURKHOLDER 9403920 The diverse heterotrophic dinoflagellates include free- living estuarine species that demonstrate "ambush predator" behavior toward algal, protozoan, or fish prey. This behavioral pattern is widespread; thus far, it has been reported from the Mediterranean Sea, the Gulf of Mexico, and the western Atlantic. Within the past two years, a new genus of ambush predator dinoflagellate, Pfiesteria (nov. gen.) has been discovered, with known species having a complex life cycle that includes at least 15 stages. Among these stages are persistent amoeboid heterotrophs and ephemeral "phantom-like" flagellates that are common in eutrophic mid-Atlantic and Gulf Coast estuaries, and likely are widespread throughout warm temperate and subtropical waters. The ubiquitous occurrence and abundance of these stages in the water column and sediments, their voracious phagotrophy on bacterial, algal, and microfaunal prey, and their lethality to fish point to a major role of ambush predator dinoflagellates in the structure and function of estuarine food webs. This project is to experimentally examine the nutritional ecology and trophic interactions of abundant stages of Pfiesteria piscimorte (nov. gen. et sp.) as a representative toxic ambush predator, toward determining the role of these organisms -- in their many forms -- within estuarine food webs. This project will: (1) examine saprotrophic nutrition of the biflagellate and amoeboid forms on stimulatory secretions of finfish prey; (2) characterize phagotrophic interactions between Pfiesteria (nov. gen.) and bacterial, algal and microfaunal prey; and (3) determine the influence of the biflagellate and amoeboid stages on representative microbial predators. The insights gained from this research will alter general paradigms about the role of dinoflagellates in the structure and function of food webs n eutrophic warm temperate estuaries.