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Eco-DAS VIII Symposium Proceedings

The Ecological Dissertations in the Aquatic Sciences (Eco-DAS) symposia bring together 35-40 recent PhD recipients for one week in alternate years. Eco-DAS X was held in 2008. Eco-DAS is sponsored by the Center for Microbial Oceanography: Research and Education (C-MORE), the University of Hawai`i School of Ocean and Earth Science and Technology (SOEST) and its Department of Oceanography, and the Association for the Sciences of Limnology and Oceanography (ASLO). The Proceedings of Eco-DAS X includes nine chapters published in open access.

Editor: Paul F Kemp
Funding provided by U.S. National Science Foundation award OCE08-12838 to Paul F. Kemp

Table of Contents

For the entire book, a suggested citation is as follows. P.F. Kemp [ed.] 2010. Eco-DAS VIII Symposium Proceedings. Waco, TX:American Society of Limnology and Oceanography. doi:10.4319/ecodas.2010.978-0-9845591-1-4. For an individual chapter, a suggested citation is provided in the accompanying abstract.

Julie E. Keister, D. Lani Pascual, Jessica L. Clasen, Kristine N. Hopfensperger, Noreen Kelly, Joel K. Llopiz, Serena M. Moseman, and Laura E. Petes 
Climate and anthropogenic change in aquatic environments: a cross ecosystem perspective
Chapter 1, p. 1-16
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Full Citation: Julie E. Keister, D. Lani Pascual, Jessica L. Clasen, Kristine N. Hopfensperger, Noreen Kelly, Joel K. Llopiz, Serena M. Moseman, and Laura E. Petes. 2010. Climate and anthropogenic change in aquatic environments: a cross ecosystem perspective, p. 1-16. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.1]

ABSTRACT: In an effort to foster collaboration among researchers across diverse ecosystems, a group of early career scientists whose interests span the aquatic sciences, convened at the University of Hawai`i to participate in the 2008 Eco-DAS symposium. During a break out session of the symposium in which participants were charged with discussing how to best approach mitigation of climate and anthropogenic threats to aquatic ecosystems, participants concluded that effective mitigation will depend upon prioritizing threats across ecosystems. These priorities were documented using a thought experiment in which participants defined their ecosystem of expertise, and then ranked the highest-priority threats to them. Results revealed that marine (open ocean, deep sea, coastal oceans, and rocky intertidal) researchers ranked climate-related impacts (i.e., temperature and ocean acidification) as the highest priority threats whereas estuarine, marsh, wetland, stream, and lake/reservoir researchers ranked the direct anthropogenic impacts of land-use change and nutrient inputs (eutrophication) highest. With such a diverse group, it became apparent that working across ecosystems is limited by issues ranging from a lack of large-scale, long-term monitoring to provide baseline data, to broader questions of how changes in one ecosystem cascade across interconnected ecosystems. Here we summarize the discussions, offer insight into the rankings for specific ecosystems, and propose ideas of how past, current, and future research can be used to support a cross-ecosystem perspective on climate and anthropogenic change.

Chris L. Dupont, Dreux Chappell, Ramiro Logares, and Maria Vila-Costa
A hitchhiker's guide to the new molecular toolbox for ecologists
Chapter 2, p. 17-29
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Full Citation: Chris L. Dupont, Dreux Chappell, Ramiro Logares, and Maria Vila-Costa. 2010. A hitchhiker's guide to the new molecular toolbox for ecologists, p. 17-29. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.17]

ABSTRACT: Thirty years ago, marine microbes were described by crude morphology and the ability to grow on different carbon sources. Our understanding of their ecological role in aquatic environments was murky at best. Since then, the development of new molecular methods facilitated by DNA sequencing resulted in a revolution in the field of microbial molecular ecology and evolution. Plummeting sequencing costs and the resulting massive flux of data introduced novel challenges to marine microbiologists, in particular, and the infrastructure of science in general. In a cycle of positive feedbacks, a wide array of novel molecular and bioinformatic tools have been developed, addressing these challenges and allowing microbiologists to investigate subjects that previously stymied the field. Additionally, these advances fostered new connections between previously disparate disciplines. Here we provide a summary of the challenges of the new molecular toolkit, a history of the molecular revolution in microbial ecology, and a glimpse into the future. Finally, for the interested hitchhikers, we present a theoretical approach to integrating the new molecular toolkit into any ecological research program.

Blaine D. Griffen, Daniel Spooner, Amanda C. Spivak, Andrew M. Kramer, Alyson E. Santoro, Noreen E. Kelly 
Moving species redundancy toward a more predictive framework
Chapter 3, p. 30-46
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Full Citation: Blaine D. Griffen, Daniel Spooner, Amanda C. Spivak, Andrew M. Kramer, Alyson E. Santoro, Noreen E. Kelly. 2010. Moving species redundancy toward a more predictive framework, p. 30-46. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.30]

ABSTRACT: Human activities are driving rapid changes in species diversity in a wide range of habitats globally. These changes in species diversity raise questions about the ability of altered systems to continue to offer valuable ecosystem services. Maintenance of ecosystem services under changing biodiversity depends largely on the ability of persisting species to fill the functional gaps left by species in decline, and thus on the ecological or functional redundancy of species. Previous work suggests that the concept of species redundancy holds little applied value because, among other reasons, this concept is highly context dependent. Our goal in this chapter is to demonstrate a conceptual framework in which the prevalence and importance of redundancy is examined across example environmental and biological gradients to determine conditions or situations in which redundancy should play a significant role. By exploring general conditions that should elevate the importance or prevalence of redundancy, we hope to demonstrate that this concept can be used predictively, despite its context-dependent nature.

Jessica L. Clasen, Joel K. Llopiz, Carrie E. H. Kissman, Daniel Marshalonis, and D. Lani Pascual 
The vulnerability of ecosystem trophic dynamics to anthropogenically induced environmental change: A comparative approach
Chapter 4, p. 47-66
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Full Citation: Jessica L. Clasen, Joel K. Llopiz, Carrie E. H. Kissman, Daniel Marshalonis, and D. Lani Pascual. 2010. The vulnerability of ecosystem trophic dynamics to anthropogenically induced environmental change: A comparative approach, p. 47-66. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.47]

ABSTRACT: We employed a comparative approach to review the vulnerability of the trophic interactions within aquatic systems to global threats associated with anthropogenic activities. The goal of this chapter was to identify and characterize mechanisms by which human-mediated environmental threats may modulate trophic dynamics across aquatic ecosystems. Trophic dynamics include some of the most obvious and pervasive factors influencing ecosystems and were used as a metric because of their importance and commonality across all aquatic environments. Our use of trophic dynamics proved to be insightful, illustrating that the flow of energy through aquatic food webs will be (or already has been) altered by invasive species, land use change, nutrient loading, exposure to ultraviolet radiation, overharvesting, acidification, and increasing global temperatures. The response of trophic dynamics to these threats was often similar across oceans, estuaries, lakes, and rivers. This similarity proved to be interesting given the differences in both the level of concern expressed by scientists and the predicted variability in environment- specific responses. As the trophic interactions of an ecosystem are at the root of its function and structure, examining trophic dynamics could be an informative method for evaluating the response of aquatic environments to global threats. If future analyses validate the use of trophic dynamics as a metric, it is our hope that trophic dynamics can be used by scientists and politicians to mitigate the effects of human actions.

Laurel Larsen, Serena Moseman, Alyson E. Santoro, Kristine Hopfensperger, and Amy Burgin 
A complex-systems approach to predicting effects of sea level rise and nitrogen loading on nitrogen cycling in coastal wetland ecosystems
Chapter 5, p. 67-92
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Full Citation: Laurel Larsen, Serena Moseman, Alyson E. Santoro, Kristine Hopfensperger, and Amy Burgin. 2010. A complex-systems approach to predicting effects of sea level rise and nitrogen loading on nitrogen cycling in coastal wetland ecosystems, p. 67-92. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.67]

ABSTRACT: To effectively manage coastal ecosystems, we need an improved understanding of how tidal marsh ecosystem services will respond to sea-level rise and increased nitrogen (N) loading to coastal areas. Here we review existing literature to better understand how these interacting perturbations will likely impact N removal by tidal marshes. We propose that the key factors controlling long-term changes in N removal are plant-community changes, soil accretion rates, surface-subsurface flow paths, marsh geomorphology, microbial communities, and substrates for microbial reactions. Feedbacks affecting relative elevations and sediment accretion rates will serve as dominant controls on future N removal throughout the marsh. Given marsh persistence, we hypothesize that the processes dominating N removal will vary laterally across the marsh and longitudinally along the estuarine gradient. In salt marsh interiors, where nitrate reduction rates are often limited by delivery of nitrate to bacterial communities, reductions in groundwater discharge due to sea level rise may trigger a net reduction in N removal. In freshwater marshes, we expect a decrease in N removal efficiency due to increased sulfide concentrations. Sulfide encroachment will increase the relative importance of dissimilatory nitrate reduction to ammonium and lead to greater bacterial nitrogen immobilization, ultimately resulting in an ecosystem that retains more N and is less effective at permanent N removal from the watershed. In contrast, we predict that sealevel–driven expansion of the tidal creek network and the degree of surface-subsurface exchange flux through tidal creek banks will result in greater N-removal efficiency from these locations.

Jennifer G. Howeth, Alison M. Derry, and Adam M. Reitzel 
Metacommunity biology as an eco-evolutionary framework for understanding exotic invasion in aquatic ecosystems
Chapter 6, p. 93-109
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Full Citation: Jennifer G. Howeth, Alison M. Derry, and Adam M. Reitzel. 2010. Metacommunity biology as an eco-evolutionary framework for understanding exotic invasion in aquatic ecosystems, p. 93-109. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.93]

ABSTRACT: One of the greatest threats to the biotic integrity of native aquatic communities over contemporary time scales is the invasion and rapid geographic spread of exotic species. Whereas dispersal rates of exotic species are documented to affect invasion success, few studies acknowledge the role of dispersal in both exotic and native species in mediating exotic establishment and the evolutionary response of native communities. In this chapter, we suggest that the metacommunity concept may serve as an informative, spatially explicit framework in which to describe dispersal-mediated trajectories of exotic invasion and the associated evolutionary response of native species. We outline ways in which metacommunity biology may enhance our understanding of the spatio-temporal invasion sequence, including exotic establishment, geographic spread, and interactions with native species. The integrative framework is subsequently applied to case studies of eco-evolutionary interactions between exotic and native species within invaded aquatic metacommunities, where dispersal-mediated evolutionary responses in both exotic and native species appear to be important. Finally, we propose a molecular toolkit that may facilitate understanding the evolutionary processes underlying different stages of the spatio-temporal invasion sequence. We suggest that the advances gained from adopting the metacommunity concept may inform conservation strategies by serving to identify native aquatic communities that will resist exotic invasion or evolve in response to the non-native species.

Dana E. Hunt, Eva Ortega-Retuerta, Craig E. Nelson 
Connections between bacteria and organic matter in aquatic ecosystems: Linking microscale ecology to global carbon cycling
Chapter 7, p. 110-128
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Full Citation: Dana E. Hunt, Eva Ortega-Retuerta, Craig E. Nelson. 2010. Connections between bacteria and organic matter in aquatic ecosystems: Linking microscale ecology to global carbon cycling, p. 110-128. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.110]

ABSTRACT: The primary aim of this chapter is to synthesize research relevant to the microscale interactions between bacteria and organic matter in freshwater and marine pelagic environments. Heterotrophic bacterioplankton provide an important ecosystem service by remineralizing dissolved and particulate organic material in aquatic ecosystems. However, both heterotrophs and organic matter are generally treated as "black boxes" in models of pelagic ecosystem metabolism owing to our poor understanding of their diversity and spatial/ temporal dynamics. Such models necessarily mask a complex set of interactions because of the difficulty in observing and quantifying this "microscale" ecology. Bacteria exhibit tremendous phylogenetic and metabolic diversity, and we now understand that organic matter comprises a heterogeneous matrix of particles, gels, polymeric matrices, colloids, and dissolved macromolecules. The physicochemical organic matter continuum is dynamic and patchy; which translates to a complex array of ecological microenvironments for bacterioplankton. The phylogenetic and functional diversity of bacteria is thus intertwined with the chemical and physical complexity of their organic matter resources. Characterizing bacterial-organic matter interactions at the appropriate temporal and spatial scales will fundamentally enhance our knowledge of pelagic ecosystems.

Sophia E. Fox, Ylva S. Olsen, and Amanda C. Spivak 
Effects of bottom-up and top-down controls and climate change on estuarine macrophyte communities and the ecosystem services they provide
Chapter 8, p. 129-145
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Full Citation: Sophia E. Fox, Ylva S. Olsen, and Amanda C. Spivak. 2010. Effects of bottom-up and top-down controls and climate change on estuarine macrophyte communities and the ecosystem services they provide, p. 129-145. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.129]

ABSTRACT: Macrophytes provide important estuarine benthic habitats and support a significant portion of estuarine productivity. The composition and characteristics of these benthic communities are regulated bottom-up by resource availability and from the top-down by herbivory and predation. Human activities in coastal zones have dramatically altered the relative strengths of these controls by delivering nutrients to coastal waters and overexploiting fishery resources. Here, we review bottom-up and top-down controls and how these may interact to structure estuarine macrophyte communities and the ecosystem services they provide. We further discuss the impacts of climate change on macrophyte communities and highlight the interactions that are likely to occur with our current knowledge of bottom-up and top-down forcings. Future research on the interactive effects of bottom-up and top-down controls and climate change on estuarine ecosystem properties (e.g., diversity, community structure, biogeochemistry, etc.) and the services they provide (e.g., food production, nutrient filtration, etc.) will supply important information for the preservation and management of these critical coastal habitats.

Tamara Harms, Brian Reid, Daniel Sobota, and Amy Burgin 
Biogeochemical reaction and transport within hydrologic landscapes: crossing disciplinary and ecosystem boundaries
Chapter 9, p. 146-165
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Full Citation: Tamara Harms, Brian Reid, Daniel Sobota, and Amy Burgin. 2010. Biogeochemical reaction and transport within hydrologic landscapes: crossing disciplinary and ecosystem boundaries, p. 146-165. In P.F. Kemp [ed.], Eco-DAS VIII Symposium Proceedings. ASLO. [doi:10.4319/ecodas.2010.978-0-9845591-1-4.146]

ABSTRACT: Delivery of materials from catchments to coasts constitutes a significant flux within many global elemental cycles. However, large uncertainties bracket estimates of land-sea fluxes, due to limited understanding of interactions among material retention, transport, and transformation within hydrologic landscapes. Freshwater ecosystems facilitate biogeochemical reaction by bringing reactants together in complex physico-chemical environments. Further, they comprise the transport network by which materials move from catchments to coasts. Whereas there have been significant gains in understanding and quantifying hydrologic transport (HT) and biogeochemical reaction (BR) within specific types of freshwater ecosystems (e.g., nutrient spiraling in streams), disparate methodologies and approaches among ecosystems hinder synthesis efforts across the hydrologic landscape. Our goal is to increase the potential for synthesis of HT and BR across traditional ecosystem boundaries. We review the methods and metrics for quantifying HT and BR for the major ecosystems within hydrologic landscapes: lakes, rivers, wetlands, and groundwater. We then identify the research challenges that currently limit integration of HTBR across hydrologic landscapes and discuss the potential for a common set of metrics and approaches to represent HT and BR across multiple freshwater ecosystems. We advocate an approach that ties distribution functions of water residence time explicitly with retention efficiency of materials and nutrients. Such an approach reduces the impact of ecosystem-specific complexities that confound scaling exercises, avoids the assumption of steady-state, and provides a means for direct comparison of material dynamics across the hydrologic landscape.