Collaborative Research: Trophic Structure and Interactions of the Pelagic Nekton Associated with the Mid-Atlantic Ridge

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Once considered pristine and undisturbed, the deep-sea environment is becoming progressively impacted by anthropogenic activities. The impact of removing top predators by deep-sea fishing activities cannot be assessed given our present state of knowledge. A recent study found that oceanic top predator diversity has declined between 10% and 50% in all oceans in the past 50 years, and that the protection of regional "hotspots" may be critical in thwarting what may be an ecological disaster. An understanding of trophic interactions is an essential requirement for ocean management policy. This study will provide novel information on the trophic interactions and ecological regulatory forces that shape oceanic communities. The international collaborations developed for this project, as well as the shiptime and equipment contributions of the MAR-ECO program, from which the opportunity and the ecological framework for this investigation is derived, represent a huge cost savings and added value. Understanding the structure of food webs and the flow of organic matter in deep-pelagic ecosystems requires an integrated approach in which several key community elements are addressed in a quantitative manner. A recent, large-scale exploration of the deep waters over the northern Mid-Atlantic Ridge (MAR) has resulted in one of the largest (if not the largest) multitrophic level, deep-pelagic (200 - 3000 m) sample collections ever obtained, presenting an unprecedented opportunity to understand deep-sea food webs. Utilizing this collection, a comprehensive background dataset, and an international partnership with some of the world's foremost experts on deep-sea taxonomy, ecology, and hydroacoustics, this project will comprise a coordinated investigation utilizing quantitative microscopical trophic analysis, molecular prey-DNA analysis, and stable isotope analysis to understand the trophic structure and interactions of the pelagic nekton (actively swimming fauna) associated with the MAR. This investigation will provide an initial characterization of a major but poorly known trophic interaction in the deep ocean interior - the utilization of gelatinous energy sources by biomass-dominant groups of deep-pelagic fishes. In addition to its intellectual contributions, the work described in this proposal will contribute significantly to education and the development of human resources in science at the K-12, undergraduate and graduate levels, strengthening American position in ocean science and furthering international collaborations. Interest in deep-sea science will be stimulated through hands-on, interactive tutorials in which students will simulate an ongoing scientific study, and compare their findings to those of the model study. This tutorial, developed as a unit on "Deep-Sea Food Webs," will be delivered via the Ridge 2000 SEAS (Student Experiments At Sea) educational website. The project will also provide financial support and participation in field and lab research for several graduate students. The students will share authorship on publications, reports, and will gain experience through presentation at national meetings.