Eco-DAS IX Symposium

Full Citation: Morris, J. Jeffrey and Laura R. Hmelo, 2014. Organizing principles for marine microbial consortia. p. 1-15. In P.F. Kemp [ed.], Eco-DAS IX Symposium Proceedings. ASLO. [doi: 10.4319/ecodas.2014.978-0-9845591-3-8.1]

ABSTRACT: Microbiologists commonly speak of microbial communities, but the degree to which assemblies of microbes are governed by the rules of classical community ecology is unclear. Specifically, microbes are much more easily dispersed, and have much faster growth rates, than macroscopic organisms, potentially changing the relative importance of various forces in community assembly. In the well-mixed, liquid environment of the pelagic ocean, these differences are likely to be most pronounced (and most easily studied). Here we develop a framework for understanding community assembly in marine microbial populations. We begin by constructing a simple neutral model that predicts what consortia should look like if they are randomly assembled. From there, we consider what rates determine whether consortia will persist long enough to form a “climax” community. With these possibilities representing “extremes,” we explore possible intermediate successional stages driven by lottery competition for space and/or local co-evolution toward cooperative exclusion of other species. We further discuss what empirically measurable traits we would expect to exist under these four different scenarios and suggest experiments to distinguish between these possibilities.

Full Citation: Brum, Jennifer R., J. Jeffrey Morris, Moira Décima, and Michael R. Stukel. 2014. Mortality in the oceans: Causes and consequences p. 16-48. In P.F. Kemp [ed.], Eco-DAS IX Symposium Proceedings. ASLO. [doi: 10.4319/ecodas.2014.978-0-9845591-3-8.16]

ABSTRACT: Microorganisms dominate the oceans and exert considerable control over fluxes of nutrients, organic matter, and energy. This control is intimately related to the life cycles of these organisms, and whereas we know much about their modes and rates of reproduction, comparably little is known about how they die. The method of death for a microorganism is a primary factor controlling the fate of the nutrients and organic matter in the cell, e.g., whether they are incorporated into higher trophic levels, sink out of the water column, or are recycled within the microbial loop. This review addresses the different sources of mortality for marine microbes including grazing, viral lysis, programmed cell death, and necrosis. We describe each mode of death, the methods used to quantify them, what is known of their relative importance in the ocean, and how these vectors of mortality differentially affect the flow of organic matter in the open ocean. We then conclude with an assessment of how these forms of mortality are incorporated into current numerical ecosystem models and suggest future avenues of research to increase our understanding of the effects of death processes in oceanic food webs.

Full Citation: Stukel, Michael R., K. A. S. Mislan, Moira Décima, and Laura Hmelo. 2014. Detritus in the pelagic ocean. p. 49-76. In P.F. Kemp [ed.], Eco-DAS IX Symposium Proceedings. ASLO. [doi: 10.4319/ecodas.2014.978-0-9845591-3-8.49]

ABSTRACT: Detritus is a ubiquitous and diverse component of the pelagic ecosystem. It comprises a wide class of particles created by such diverse processes as cell death, egestion, and aggregation. Detrital particles span several orders of magnitude in size and have distinctly different chemical and physical properties. As a consequence, the propensity of detrital particles to serve as substrates for bacteria or grazers, passive particles drifting through the ocean, or conduits for rapid flux into the deep ocean is highly variable. In this chapter, we review the diverse nature of detrital particles and corresponding production and loss terms in the pelagic ocean, as well as current attempts to include detritus in ecological and biogeochemical models. Our goal is to bridge the gap between field experiments and modeling studies by highlighting properties of detritus that vary predictably between classes and can be both measured in the field and incorporated into the next generation of pelagic ecosystem models.

Full Citation: Small, Gaston, Helen Baulch, Heather Bechtold, Kimberly Holzer, Silvia Newell, and Raquel Vaquer-Sunyer. 2014. Headwaters to estuaries: Complex responses to cultural eutrophication at the watershed scale. p 106-118. In P.F. Kemp [ed.], Eco-DAS IX Symposium Proceedings. ASLO. [doi: 10.4319/ecodas.2014.978-0-9845591-3-8.106]

ABSTRACT: Aquatic scientists have long been concerned with understanding causes of eutrophication, and yet, even after decades of research, contradictory views remain concerning the need to control nitrogen inputs. At the heart of the current debate is the question of how well our understanding of ecosystem responses to nutrient loading can be applied at different scales and across systems. Here, we take a watershed-scale view of eutrophication. We review how aquatic ecosystems respond differently to nutrient inputs and discuss how processes such as nitrogen fixation, denitrification, and sorption/release of phosphorus can alter the relationship between nutrient loading in a watershed and downstream eutrophication. We recommend a context-specific approach to eutrophication management that considers ecosystem responses to nutrient loading throughout the watershed as well as controllability of various nutrient inputs. By beginning to develop a theory of eutrophication at the watershed scale, it is our hope that aquatic scientists can present a unified voice to managers.

Full Citation: Jelena H. Pantel, Daniel E. Pendleton, Annika Walters, and Lauren A. Rogers. 2014. Linking environmental variability to population and community dynamics. p 119-131. In P.F. Kemp [ed.], Eco-DAS IX Symposium Proceedings. ASLO. [doi: 10.4319/ecodas.2014.978-0-9845591-3-8.119]

ABSTRACT: Linking population and community responses to environmental variability lies at the heart of ecology, yet methodological approaches vary and existence of broad patterns spanning taxonomic groups remains unclear. We review the characteristics of environmental and biological variability. Classic approaches to link environmental variability to population and community variability are discussed as are the importance of biotic factors such as life history and community interactions. In addition to classic approaches, newer techniques such as information theory and artificial neural networks are reviewed. The establishment and expansion of observing networks will provide new long-term ecological time-series data, and with it, opportunities to incorporate environmental variability into research. This review can help guide future research in the field of ecological and environmental variability.