2003 ASLO Aquatic Sciences Meeting

Sub-theme 3: Spatial Patterns in Aquatic Systems

Plenary presentation by Jim Elser, Department of Biology, Arizona State University

Sub-theme 3 Organizers: Craig Carlson (carlson@lifesci.ucsb.edu) and Carla Koretsky (carla.koretsky@wmich.edu)

Complex spatial patterns in aquatic systems occur at local, regional and global scales. These patterns result from dynamic interplays between biotic and abiotic forcing factors at small (sediment-water interface, connections between littoral and pelagic processes) to very large, global processes, such as ENSO events. Sessions in this sub-theme may include: watershed and regional oceanic responses to climate or anthropogenic forcing, emergent properties of aquatic ecosystems, biocomplexity, application of a regional landscape perspective to lake districts, or comparative studies of coastal ocean responses to perturbations.

SS3.01 Emergent Properties of Complex Aquatic Ecosystems: A Macroecological Perspective
Organizer: Andrea Belgrano (belgrano@unm.edu)

A macroecological view of the ecosystem offers the possibility to integrate information at large spatial and temporal scales over a variety of complex ecological systems. Macroecology can be regarded as a new research area aiming to develop new models, which can explain the emergent structure and dynamics of complex ecological systems in terms of basic physical and biological principle. Macroecological perspectives and emergent properties of aquatic systems have received relatively little attention in aquatic ecology. This special symposia session will discuss the importance of considering macroecological and complexity theory to untangle patterns that underlie the relationships between species abundance and other biotic and abiotic factors linking community ecology to ecosystems structure and function in aquatic systems.

SS3.02 Terrigenous Subsidies in Freshwater and Marine Systems
Organizers: Bopi Biddanda (biddandb@gvsu.edu) and Jim Cotner (cotne002@tc.umn.edu)

Nearly one and a half centuries ago, Henry David Thoreau made the profound observation that natural water bodies are the “Earth’s Eyes” that reflect the impressions from the surrounding landscape. Since then, considerable advances have taken place in our understanding of land-water linkages. This session will serve as a forum to examine the emerging topic of the role of terrigenous matter in influencing nutrient cycles and food webs in receiving aquatic ecosystems. We invite original research and ideas in the following areas for oral and poster presentations: origin, composition and transformation of terrigenous matter in natural waters, role of terrigenous subsidies in carbon and nutrient balance within aquatic ecosystems, contribution of terrestrial inputs (including those transported via atmosphere) to the productivity of water bodies, effect of terrigenous pollutants in aquatic ecosystems, land use and resulting consequences within natural waters, and the role of terrigenous inputs to aquatic ecosystems in the context of the global carbon cycle. Today, we live on a rapidly changing planet, with much of the recent change derived in some way from human influence that are superimposed on natural transformations. Can we use our natural water bodies as “Earth’s Eyes” to “see” natural processes and our impact on the Earth? This forum will seek to assess how far we have come in our understanding of land-water linkages and Thoreau’s remarkable insights about how the Earth’s land and water are linked together as one.

SS3.03 Landscape Ecology and Environmental Grain from a Microbial Perspective
Organizers: Paul Kemp (paul.kemp@stonybrook.edu) and Josephine Aller

A key point of classical ecology studies has long been that the impact of spatial structure can only be recognized when sampling is carefully designed to reflect the dominant spatial structure of the sampled community. Carl Troll (1939) coined the term “landscape ecology” to describe the interaction of geography and ecological studies on scales large enough to include spatial heterogeneity, or “environmental grain.” McGarigal (2002) summarizes the concept as follows: “From an organism-centered perspective, the size of a landscape varies depending on what constitutes a mosaic of habitat or resource patches meaningful to that particular organism. From an organism-centered perspective, the smallest scale at which an organism perceives and responds to patch structure is its ‘grain’.” What, then, is a meaningful environmental grain size to an aquatic microbe? Over what spatial scale should the environmental landscape of a microbe be studied? What new insights can we gain by appropriately recognizing the graininess of the microbial environment, as perceived by the microbes themselves? The devices used to sample aquatic microbes are enormous in comparison to the immediate environment of a microbial cell. What does this mean to our assessments of microbial diversity? How structurally complex are microbial communities in reality? Does the composition of a 16S rDNA library really imply the possibility of their interaction, when the microbial community is sampled without recognizing the microbes’ own perceptions of environmental grain?

SS3.04 The Biogeochemistry of Hg from Watershed to the Global Scale: A Tribute to the Contributions of WF Fitzgerald
Organizers: W. Berry Lyons (lyons.142@osu.edu) and Rob Mason

The biogeochemical flux, dynamics and fate of mercury(Hg) into the landscape is a global problem. In order to understand the biogeochemistry of Hg, one must first be able to measure the concentration of this trace metal at very low background levels. The seminal work of WF Fitzgerald help lead to the first actual measurements of Hg in aquatic systems. This session will address our current understanding of Hg biogeochemistry on numerous scales, from watershed to global. Fitzgerald has been a leader in this field for over 25 years.

SS3.05 Significance of Small-scale Benthic Processes for Large Ecosystems
Organizers: Douglas C. Miller (dmiller@udel.edu) and Kevin R. Carman (zocarm@lsu.edu)

While most research is necessarily done at small scales in the laboratory and field, important natural and human impacts often occur on much larger scales. How do we extrapolate from the small to the large? The aim of this special session is to highlight research done at small scales that has direct relevance to processes at the ecosystem level, ranging from lakes, rivers and watersheds to estuarine, coastal and deep-sea regions. Research areas of interest include (but are not limited to) benthic ecology, benthic-pelagic coupling, productivity and geochemistry at the sediment-water interface, nutrient cycling, habitat quality and use, and direct human impacts on benthic systems. We seek presentations from the full range of freshwater, estuarine and marine ecosystems.

SS3.06 Landscape Context of Ultraviolet Radiation Effects on Aquatic Ecosystems
Organizers: Wendy Palen (wpalen@u.washington.edu) and Sandra Cooke (sac6@lehigh.edu)

We propose a symposium that aims to focus on the broad ecological context of ultraviolet radiation (UVR) in aquatic ecosystems. Over the past decade a wealth of research has established UVR as a key structuring mechanism for aquatic systems. A critical mass of individual studies now provide the opportunity to evaluate the generality of the diverse effects of UVR across a range of spatial scales. This synthesis is required to understand the importance of UVR at the landscape scale. Our intention is to emphasize how linkages between UVR and other environmental factors contribute to the structure and function of aquatic ecosystems.

SS3.07 Does Microbial Diversity Matter in Ecosystem Function?
Organizer: Bess Ward (bbw@princeton.edu)

Although complexity exists at all levels in natural systems, the level of microbes and their interaction with the environment at organismal and molecular scales is one of great current interest. The emergent properties of aquatic systems, such as maintenance of consistent elemental stoichiometries, reasonably balanced nutrient budgets, and stable predictable community structure, must arise somehow from the chaos of nearly infinite microbial diversity and metabolic function. Papers in this session will address the complexity of aquatic ecosystems in both spatial and temporal terms as appropriate. We expect to focus on linking biogeochemical cycles to larger scale physical processes on one scale and to molecular diversity and function at the other end of the scale. Are patterns in rate processes across ecosystem scales (e.g., estuary - coastal ocean - open sea) linked to community structure and diversity at the level of microbes, genetics and biochemistry?

SS3.08 Organic Matter in Aquatic Systems: Sources, Characterization, Distribution, and Quantification
Organizers: Juanita Urban-Rich (juanita.urban-rich@umb.edu), Bob Chen and Diane McKnight

This special session will focus on either discrete biotic or abiotic sources of dissolved organic matter (DOM). Multiple dissolved organic matter sources have been suggested (e.g. salt marshes, mangrove swamps, photochemical processes, hydrothermal vents, marine snow, ice algae, zooplankton, catchments, sewage, rainfall, soil leaching) in aquatic systems that can lead to small-scale variability in DOM distribution and composition. Both biotic and abiotic processes can result in the production of DOM with their own unique chemical, optical, and biological properties. Knowledge about the temporal and spatial distribution of production rates, fluxes, composition and reactivity of these DOM sources are critical to our understanding of the functioning of freshwater and marine systems. Anthropogenic stresses such as land use changes, eutrophication, or resource management practices can potentially change the DOM concentration, distribution, and composition within the surrounding water. Since DOM is vital for microbial processes and influences the distribution and lability of anthropogenic pollutants, knowledge about the sources of DOM is critical for future management of our aquatic systems.

SS3.09 Cross-system Comparison of Sources, Composition, and Reactivity of DON
Organizers: Margie Mulholland (mmulholl@odu.edu) and Deborah Bronk (bronk@vims.edu)

During the last decade information on the dissolved organic nitrogen (DON) pool from a variety of aquatic systems has increased substantially. However, investigators still generally study DON as a component of either the C or N cycles. The recognition that organic compounds are a significant source of nutrients to autotrophs and that mixotrophy appears to be a more widespread phenomenon than previously thought highlights the central roles that DON plays in linking the C and N pools and as an important interface between autotrophic and heterotrophic processes. Utilization of the DON pool has also recently been shown to be an important contributor to eutrophication and may be a key factor in defining community structure and the increase of harmful algal blooms, many of which are mixotrophs. The goal of this session is to promote interactions between investigators working in a range of ecosystems on different facets of DON cycling including: chemical characterization, biotic and abiotic regenerative processes, and novel utilization mechanisms.

SS3.10 Emergent Properties and Biocomplexity of Tropical Ecosystems
Organizer: Ilka C. Feller (feller@serc.si.edu)

Mangrove swamps dominate the world’s tropical and subtropical coasts, paralleling the geographical distribution of coral reefs. In these coastal wetlands, dynamic interactions of biological, geochemical, geological, and physical processes result in complex spatial patterns at local, regional, and global scales. Ecological processes are influenced by inputs from the land, sea, and sky, which result in extreme fluctuations of flooding, salinity, temperature, light, and nutrient availability. Physiological and structural adaptations as well as extreme ecological plasticity characterize the organisms that inhabit this variable environment. Because mangroves are generally considered to be oligotrophic ecosystems, anthropogenic over-nutrient enrichment has the potential to alter these and other coastal systems. Human-caused nutrient pollution (i.e., cultural eutrophication) of the coastal zone is widely recognized as one of the major threats to marine environments worldwide. System-specific attributes lead to large differences among estuarine-coastal systems in their sensitivity and susceptibility to eutrophication. The complex suite of direct and indirect responses in coastal systems to nutrient over-enrichment potentially include changes in water chemistry, distribution and biomass of plants, sediment biogeochemistry, nutrient cycling, nutrient ratios, phytoplankton communities, habitat quality for metazoans, reproduction, growth, and survival of benthic invertebrates, and ecosystem functions.

SS3.11 Ecology and Management of the Riparian Habitat of Lakes
Organizers: Mark Scheuerell (scheuerl@u.washington.edu) and Daniel Schindler (deschind@washington.edu)

Limnologists have generally neglected the riparian habitat in models of lakes as integrated ecosystems. A growing body of literature demonstrates the importance of the terrestrial-aquatic interface for both aquatic and terrestrial organisms associated with lakes. Furthermore, anthropogenic activities are increasingly altering the riparian habitats of lakes and subsequently affecting in-lake processes. This session seeks papers that integrate processes occurring at the aquatic-terrestrial interface with in-lake processes.

SS3.12 Trophic Focusing and Subsidy in Aquatic Ecosystems
Organizers: Amatzia Genin (amatzia@vms.huji.ac.il) and Mark Benfield (mbenfie@lsu.edu)

The average concentration of resources is insufficient for growth and survival of a variety of marine species, ranging from planktonic larvae to top predators. Therefore, their survival depends on encountering patches of aggregated prey. This session will focus on the transport and accumulation of trophic resources in oceans and lakes. Examples include the aggregation of zooplankton along fronts and over abrupt topographies, gathering of predators around artificial structures, flow patterns that concentrate resources and cross-habitat redistribution of carbon and nutrients by migrating animals. We invite observational, experimental and theoretical papers that describe such patterns and address the underlying mechanisms and implications.

SS3.13 Advances in Understanding Estuarine Ecosystems From Real-Time Remote Monitoring Data
Organizers: Howard Glasgow (howard_glasgow@ncsu.edu) and Robert Magnien (rmagnien@dnr.state.md.us)

Within the past decade, real-time remote monitoring systems (RTRM) have enabled intensive assessment of the physical, chemical and biological dynamics of estuaries at local and regional scales, including changes from watershed land use. This session will focus on the power of high-frequency, continuous data from RTRM in providing new insights about linkages between land use, anthropogenic forcing, and estuarine response, as well as strengthened understanding about physical, chemical and biological properties of estuaries. Presentations will integrate available and experimental technologies to examine time-relevant relationships between watershed nutrient inputs, mixing patterns and rates, and biological responses such as harmful algal blooms, hypoxia, and fish kills.

SS3.14 Novel Approaches to Modeling Food Web and Ecosystem Biogeochemistry
Organizer: Joe Vallino (jvallino@mbl.edu)

Classic approaches to modeling ecosystem biogeochemistry, such as PZN-type compartment models, appear inadequate to capturing the behavior and dynamics observed in marine ecosystems, especially when systems encompass steep resource gradients, as occurs in coastal zones and at water-sediment interfaces. In order to have prognostic models that operate robustly in environments with steep gradients, novel modeling approaches that employ more abstract representations of real systems must be developed, and tied into available measurements; although, new measurements may also require development. There is also a need to determine the trade off between the levels of model detail and predictive capability, because it is likely that the predictive capability of models with a large number of processes and states will degrade rapidly over time. What we hope to accomplish in this session is the examination of novel modeling approaches that may lead to better prognostic capabilities.

SS3.15 Coupling Seagrass Dynamics to Water Column and Sediment Geochemistry
Organizers: Peter Eldridge (pete.eldridge@epa.gov) and James Kaldy (kaldy.jim@epa.gov)

We propose that a special session on seagrass, water column and sediment geochemical interactions would be well received within the ASLO community. There are a wide variety of specific research topics from boreal, temperate and tropical regions that would fit into this session. For example, recent work has focused on the sources of organic carbon to estuarine systems looking at the relative contributions from various components. Additionally, there have been recent advances in the models (and empirical work) used to examine the interaction between seagrass production and sediment biogeochemical processes. Other potential topics include contributions of seagrass to DOM pools and the influence of CDOC and TSS on the underwater light environment (including inherent optical properties).

SS3.16 Microscale Biogeochemical Processes in Aquatic Systems
Organizers: Martial Taillefert (mtaillef@eas.gatech.edu) and Pieter Visscher (visscher@uconnvm.uconn.edu)

In many aquatic environments (e.g., sediments, microbial mats), biogeochemical processes occur on very small spatial scales because microorganisms form small niches where geochemical conditions may be totally different from their surroundings. In these environments, nano- to microscale measurements in multidimensions are needed to characterize and quantify these changes. This session will focus on biogeochemical processes affecting the distribution of pH, oxygen, redox sensitive chemical species, and trace elements in freshwater and marine microenvironments. Topics may include, but are not limited to, the development and application of new and existing microsensors, microscale in situ measurements in aquatic environments, as well as laboratory studies at the nano- or microscale to identify fundamental biogeochemical mechanisms occurring in aquatic systems.

SS3.17 Spatial Patterns in Marine Fluxes: Global Perspectives from the JGOFS Program
Organizer: Adrian Burd (adrian@plankton.marsci.uga.edu)

Spatial patterns in material flux arise spatial heterogeneity of the physical and biological mechanisms that produce and transform the material being transported. Large scale patterns result from, for example, changes in primary productivity and changes in remineralization rates. Interfaces and chemical gradients can result in small scale patterns. This session will concentrate on results from both JGOFS process studies and modeling programs which concentrate on spatial patterns (regional, global, vertical and horizontal) in flux, the mechanisms responsible for them, and their implications.

SS3.18 Biogeochemistry of the Tropical and Subtropical North Atlantic
Organizers: Craig A. Carlson (carlson@lifesci.ucsb.edu) and Dennis Hansell (dhansell@rsmas.miami.edu)

The tropical and subtropical North Atlantic is and has been a host to numerous expeditionary programs as well as several time-series programs in the waters off Bermuda and Puerto Rico that have investigated ocean biogeochemical and atmospheric processes. This region of the North Atlantic spans spatial gradients of dust input, nitrogen fixation, water column stratification, organic matter accumulation and remineralization, and gradients of ecosystem structure and production. The focus of the session will be to bring together presentations of an interdisciplinary nature in order to gain further insight into the large-scale biogeochemistry of the region.

SS3.20 Landscape and Land-use Influences on Methylmercury Contamination of Aquatic Resources
Organizers: James Wiener (wiener.jame@uwlax.edu) and David Krabbenhoft (dpkrabbe@usgs.gov)

Mounting evidence indicates that the long-range atmospheric transport and deposition of anthropogenic mercury has surficially contaminated the Earth's landscapes on a global scale. The presence of mercury on the landscape can devalue the goods and services produced by aquatic ecosystems and may retard recovery from mercury pollution as anthropogenic emissions are gradually reduced. Methylmercury, produced by the microbial methylation of inorganic mercury, can bioaccumulate and biomagnify to problematic concentrations, causing widespread contamination of aquatic resources and posing risks to humans and wildlife atop aquatic food webs. Recent and ongoing studies show that methylmercury produced on natural and altered landscapes can contribute substantially to the contamination of aquatic food webs. Papers in this session will examine the influence of watershed processes, landscape factors, and land use on methylmercury contamination of aquatic resources. Current approaches for reducing human exposure to methylmercury involve further reduction of mercury emissions and issuance of advice concerning consumption of fish and other aquatic biota. A third, albeit largely untested approach - management of contaminated landscapes to decrease the net production of methylmercury - may merit consideration as a potential means of reducing methylmercury contamination and exposure.

SS3.21 Research Experiences of Undergraduates in Ocean Sciences
Organizers: Russell L. Cuhel (rcuhel@uwm.edu) and Carmen Aguilar (aguilar@uwm.edu)

Increasingly complex, large-scale studies of aquatic ecosystems require broadly-trained yet disciplinarily-expert scientists for the 21st Century. A variety of laboratory research opportunities, from grant-supported undergraduate assistants to programmatic offerings such as the NSF-OCE Research Experience for Undergraduates (REU) Sites offer a valuable introduction to research activities and lifestyles. Distributed among a wide variety of aquatic research institutions, REU Sites in particular provide diverse project and informational experiences. This session specifically offers undergraduates an opportunity to present their research findings in a collegial but lower-stress poster session amid the showcase of full-spectrum aquatic science presentations. Engaged in one of the premier aquatic science meetings of the year, networking and personal interaction facilitate recruitment of top candidates into the career path progression.


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