Final Report: Thresholds And Multiple Stable States In Southern New England Shallow Water Estuarine Communties

EPA Grant Number: R832448
Title: Thresholds And Multiple Stable States In Southern New England Shallow Water Estuarine Communties
Investigators: Osman, Richard W. , Whitlatch, Robert B. , Zajac, Roman N.
Institution: Smithsonian Environmental Research Center
EPA Project Officer: Hiscock, Michael
Project Period: September 1, 2005 through August 31, 2007 (Extended to August 31, 2008)
Project Amount: $299,694
RFA: Exploratory Research: Understanding Ecological Thresholds In Aquatic Systems Through Retrospective Analysis (2004) RFA Text |  Recipients Lists
Research Category: Aquatic Ecosystems , Ecosystems , Water

Objective:

We used a number of different modeling approaches to investigate threshold dynamics in a representative set of shallow-water communities of the southern New England region. Our goal was to determine how the distribution of distinct, easily-recognized alternate communities can be used to develop and measure the success of management decisions on local to regional scales. The main system was the Long Island Sound (LIS) estuary and its complex system of multiple habitats, sub-estuaries and rivers with multiple land uses and environmental stresses, both natural and anthropogenic. This system has a diverse set of management concerns that span site-specific to habitat to regional in scale. We focused on the diverse set of benthic invertebrate communities that are integral to multiple habitats within LIS, have a diversity of species and life-histories, and exist in at least four known community states. Our modeling was directed at the transitions among these communities. The two main objectives were:

  1. To use existing data to first examine the potential global, regional, and local processes that cause switches among threshold states of the communities in LIS and under what conditions these states remain resilient and unchanged.
  2. To contrast and evaluate adaptive management strategies for this system in the face of climate change.

Summary/Accomplishments (Outputs/Outcomes):

In 2005 - 2006 we concentrated on Objective 1, the developing and testing the necessary models for examining the processes contributing to thresholds as well as causing shifts among alternate threshold states. We:

  • Conducted an initial mini-workshop in early 2006 for the principal investigators to develop overall approaches and responsibilities for modeling.
  • Made the addition of a post-doctoral fellow responsible for population and community modeling and model integration. An international search was conducted and Dr. Pablo Munguia joined the project in the summer of 2006.
  • Began the critical assembling, cataloguing, and standardization of all data critical to model development and testing. Because different types of models are being applied under the direction of different investigators it is essential that the same biological, ecological, geographic, and environmental data are being utilized in all modeling efforts.
  • Developed a set of defined threshold characteristics that can be used in evaluating models. It is critical to define a priori what model outputs will be interpreted as system resilience and threshold states as well as what changes will be interpreted as a breakdown in a threshold, the absence of threshold behavior, or the transition to a new threshold state. The degree of variability that can be accommodated as part of any stable state remained to be defined.
  • Held a two day project evaluation and planning workshop at SERC in August 2006. Principal investigators and postdoctoral fellows involved in the project participated. Goals and responsibilities for the next phase of the project were discussed and particular attention was given to integration of the different modeling efforts.
  • Began developing and testing simpler population and community models using Matlab. This research was the initial focus of Dr. Munguia.
  • Modified and expanded the spatially-explicit, hydrographic model developed by Dr. John Hamilton, a postdoctoral fellow with Dr. Whitlatch. This model has been expanded to examine a larger geographic area, to include a greater diversity of species life-history characteristics that encompass the key threshold species and communities, and to encompass defined threshold states.
  • Began development of project geographic information system (GIS), including the assembly and verification of base layers, e.g. land use, infrastructure, shoreline, coastal features, bathymetry. Environmental data critical for developing GIS based threshold models continued to be added.
  • Developed methods to integrate models and define overlapping scales for models. A key element to the integration of the qualitative, population, community, spatially-explicit hydrographic, and geographic models was the overlap among model types in the questions and issues they address as well as their having comparable output.
  • Began integrating new information on a new invader in the region, the colonial ascidian, Didemnum sp. The recent invasion of this species has the potential to change threshold states or, possibly add a new state to the system being modeled. Other projects conducted by several of the principal investigators addressed the ecology of this species and these data were integrated into the modeling efforts. Including this species was particularly important because of its potential effects on deeper water and open coast habitats not usually impacted by the other invasive species. Because the management issues may be quite different for this species its inclusion will both address these issues and test the broader applicability of the models.

In 2007 - 2008 we applied four separate modeling approaches to address both Objectives 1 and 2 and developed and tested the necessary models for examining the processes contributing to thresholds as well as causing shifts among alternate threshold states. We:

  • Conducted a third project evaluation and planning workshop in early 2007 to review progress and develop strategies for future modeling efforts and their integration.
  • Participated in and presented our results to date at the EPA Program Workshop in June, 2007.
  • Finished the critical assembling, cataloguing, and standardization of all data critical to model development and testing. These core biological, ecological, geographic, and environmental data are being applied to the various models under the direction of different investigators.
  • Developed a set of defined threshold characteristics that can be used in evaluating models. It was critical to define a priori what model outputs would be interpreted as system resilience and threshold states as well as what changes would be interpreted as a breakdown in a threshold, the absence of threshold behavior, or the transition to a new threshold state. The degree of variability that can be accommodated as part of any stable state also was defined.
  • Developed and applied qualitative loop models to analyze the stability of the four defined states within the system and analyze what changes would lead to instability.
  • Completed the development and application of population and community models using Matlab. This research was the focus of Dr. Munguia. He has concentrated on the role and level of environmental disturbance necessary to change the spatial-temporal distribution of the four community states within the system.
  • Continued the expansion of the spatially-explicit, hydrographic model developed by Dr. John Hamilton, a postdoctoral fellow with Dr. Whitlatch. This model has been expanded to examine a larger geographic area, to include a greater diversity of species life-history characteristics that encompass the key threshold species and communities, and to encompass defined threshold states. Model output has also been greatly expanded to allow a greater flexibility in questions addressed and increased statistical rigor. Model input has been expanded to increase applicability to management decisions.
  • Continue the development of a geographic information system (GIS) risk assessment model to analyze the risk to temperate coastal systems of invasive fouling species.
  • Continued the development of methods to integrate models and define overlapping scales for models. A key element in this integration was examining the same questions using the different modeling approaches and contrasting predictions.
  • Continued integrating new information on a new invader in the region, the colonial ascidian, Didemnum sp. The recent invasion of this species has the potential to change threshold states or, possibly add a new state to the system being modeled. Other projects being conducted by several of the principal investigators are addressing the ecology of this species and these data are being integrated into the modeling efforts. Management issues for this species may be quite different for this species because it can occur in high abundances in deeper water habitats outside marinas. Its spread may be linked to bottom trawling of these habitats and its ability to thrive and spread as colony fragments created by trawling activities.
  • Conducted a workshop in early 2008 to evaluate progress and plan final project modeling efforts. This workshop focused on project productivity including publications, presentations at national meetings, and outreach to the management community.
  • On 4 August 2008, we conducted a workshop held at the NOAA-NMFS Laboratory in Milford, CT in order to present results of this project and initiate discussions with coastal zone managers on matters related to pressing management questions and how our research may help to provide input and guidance to these issues. Representatives from the Connecticut Department of Environmental Protection, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service and National Marine Fisheries Service were in attendance.


Journal Articles on this Report : 8 Displayed | Download in RIS Format

Other project views: All 34 publications 8 publications in selected types All 8 journal articles
Type Citation Project Document Sources
Journal Article Altman S, Whitlatch RB. Effects of small-scale disturbance on invasion success in marine communities. Journal of Experimental Marine Biology and Ecology 2007;342(1):15-29. R832448 (2006)
R832448 (2007)
R832448 (Final)
R830877 (Final)
  • Full-text: Science Direct Full Text
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  • Abstract: Science Direct Abstract
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  • Other: Science Direct PDF
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  • Journal Article Bullard SG, Lambert G, Carman MR, Byrnes J, Whitlatch RB, Ruiz G, Miller RJ, Harris L, Valentine PC, Collie JS, Pederson J, McNaught DC, Cohen AN, Asch RG, Dijkstra J, Heinonen K. The colonial ascidian Didemnum sp. A:current distribution, basic biology and potential threat to marine communities of the northeast and west coasts of North America. Journal of Experimental Marine Biology and Ecology 2007;342(1):99-108. R832448 (2006)
    R832448 (2007)
    R832448 (Final)
    R830877 (Final)
  • Full-text: Science Direct
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  • Abstract: Science Direct Abstract
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  • Other: Science Direct PDF
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  • Journal Article Bullard SG, Whitlatch RB. In situ growth of the colonial ascidian Didemnum vexillum under different environmental conditions. Aquatic Invasions 2009;4(1):275-278. R832448 (Final)
  • Full-text: Aquatic Invasions PDF
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  • Abstract: Aquatic Invasions
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  • Journal Article McCarthy A, Osman RW, Whitlatch RB. Effects of temperature on growth rates of colonial ascidians: a comparison of Didemnum sp. to Botryllus schlosseri and Botrylloides violaceus. Journal of Experimental Marine Biology and Ecology 2007;342(1):172-174. R832448 (2006)
    R832448 (2007)
    R832448 (Final)
    R830877 (Final)
  • Full-text: Science Direct Full Text
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  • Abstract: Science Direct Abstract
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  • Other: Science Direct PDF
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  • Journal Article Mercer J, Whitlatch RB, Osman RW. Potential effects of the invasive colonial ascidian (Didemnum vexillum) on pebble-cobble bottom habitats in Long Island Sound, USA. Aquatic Invasions 2009;4(1):133-142. R832448 (Final)
  • Full-text: Aquatic Invasions PDF
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  • Abstract: Aquatic Invasions
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  • Journal Article Osman RW, Whitlatch RB. Variation in the ability of Didemnum sp. to invade established communities. Journal of Experimental Marine Biology and Ecology 2007;342(1):40-53. R832448 (2006)
    R832448 (2007)
    R832448 (Final)
    R830877 (2005)
    R830877 (Final)
  • Full-text: Science Direct Full Text
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  • Abstract: Science Direct Abstract
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  • Other: Science Direct PDF
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  • Journal Article Stefaniak L, Lambert G, Gittenberger A, Zhang H, Lin S, Whitlatch RB. Genetic conspecificity of the worldwide populations of Didemnum vexillum Kott, 2002. Aquatic Invasions 2009;4(1):29-44. R832448 (Final)
  • Full-text: Aquatic Invasions PDF
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  • Abstract: Aquatic Invasions
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  • Journal Article Whitlatch RB, Osman RW. Post-settlement predation on ascidian rercruits: predator responses to changing prey density. Aquatic Invasions 2009;4(1):121-131. R832448 (Final)
  • Full-text: Aquatic Invasions PDF
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  • Abstract: Aquatic Invasions
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  • Supplemental Keywords:

    Ecological thresholds, multiple stable states, global climate, marine, estuary, ecological effects, ecosystem indicators, ecology, modeling, Northeast, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, climate change, Air Pollution Effects, Aquatic Ecosystem, Environmental Monitoring, Ecology and Ecosystems, Ecological Risk Assessment, Atmosphere, anthropogenic stress, estuarine research, ecological thresholds, anthropogenic impact, ecosystem indicators, modeling ecosystem change, aquatic ecosystems, water quality, ecosystem stress, riverine ecosystems, trophic interactions, ecosystem response

    Relevant Websites:

    These web sites have or will have links to the current EPA supported research project and will be periodically updated to include recent findings.

    http://www.serc.si.edu/labs/benthic_ecology/index.jsp
    http://www.marinesciences.uconn.edu/teamb/Pages/Team%20Benthos.htm
    http://newton.newhaven.edu/rzajac/index.html

    Progress and Final Reports:

    Original Abstract
  • 2006 Progress Report
  • 2007 Progress Report