Two different food chains and a composite food web were used to explore the resilience of food chains/webs to small perturbations and the implications of assuming that the most stable food chain/web would control export production in the ocean. A food chain based on small phytoplankton and the microbial loop was found to be most stable under various combinations of high temperature and/or low primary production. A relatively short food chain based on large phytoplankton was never the most resilient of the three possibilities considered in this study. A food web that combined the small phytoplankton and large phytoplankton based food chains was most stable under various combinations of low temperature and/or high primary production. The export ratio associated with the small phytoplankton based food chain was 5.5%. The export ratio of the food web could theoretically vary between 5.5% and 68.5%, depending on the fraction of primary production accounted for by the small and large phytoplankton. The export ratio of the most stable configuration of the food web never exceeded 30%. The export ratio of the food web was negatively correlated with both temperature and primary production rate, but the effect of primary production on the export ratio was much smaller than the effect of temperature. The predictions of the model are compared with field data from the Hawaiian Ocean Time-series (HOT) and the Southern Ocean.
Dr. Edward Laws received his Ph.D in Chemical Physics from Harvard University in 1972. He was an instructor in the oceanography department at Florida State University from 1971 to 1974. He joined the faculty of the oceanography department at the University of Hawaii in 1975, where he became a professor of oceanography in 1984. He moved to Louisiana State University (LSU) in 2005 and served as the dean of the School of the Coast & Environment until 2008. He is currently a professor in the Center for Microbial Oceanography: Research and Education, University of Hawaii. Dr. Laws has published more than 170 refereed papers in scientific journals and is the author of two books, Mathematical Methods for Oceanographers and Aquatic Pollution. Aquatic Pollution is now in its 4th edition and has been translated into both Japanese and Chinese. Dr. Laws served on the editorial board of Limnology & Oceanography from 1981 to 1984. He received the Best Paper Award from the Organic Geochemistry Division of the Geochemical Society in 1995 and the Tyge Christensen Prize for best algal paper in Phycologia in 2007. He received the Qingdao Award from the Qingdao Municipal Government in 2012 and 2015 and delivered the Nanqiang Lecture “The Earth’s Changing Climate: Natural Cycles and Human Effects” at Xiamen University on July 23, 2013.