A: Introduction

The health of the Salish Sea ecosystem is directly influenced by both human activities and natural events (Ruckelshaus and McClure 2007). The mechanisms through which these actions lead to ecosystem changes are complex. Yet, the identification of threats and their myriad impacts is necessary to strategically and effectively manage their causes and their impacts on the Salish Sea (strategies discussed in Chapter 4 of the Puget Sound Science Update). In this Chapter, we identify threats to the Salish Sea ecosystem and provide empirical evidence for the causal linkages between high priority threats and their associated ecosystem impacts. Although we do not comprehensively or systematically attempt to identify and propose indicators that will allow us to track change in the health of the Salish Sea (see Chapter 1), we do identify potential indicators from the literature which together with the information we reviewed can serve as a basis for selecting indicators of the health of Puget Sound.

The goals of this Chapter are to:

  1. Identify terrestrial, freshwater and marine derived threats to the Salish Sea ecosystem including the freshwater and terrestrial environments.
  2. Review threat ranking schemes and identify the threats with highest impact.
  3. Use a conceptual model to examine the causal relationships between threats and their impacts on the environment (Driver-Pressure-State-Impact-Response (DPSIR) framework). We emphasize what is known about the geographic scope, severity, irreversibility, imminence, and uncertainty of high impact threats and identify associated knowledge gaps.
  4. Identify ecosystem models that have been developed for the Puget Sound region that identify and rank ecosystem threats or that help us identify indicators of ecosystem health.

1. Methods

We conducted a literature review to synthesize information on threat ranking schemes, threats described as having the greatest ecological impact on the Salish Sea ecosystem, the impacts of individual threats, and models to use as tools to evaluate the impacts of human activities. We report on peer-reviewed scientific literature but also include relevant technical memos and government reports when appropriate. We do not include original analyses. Therefore, our Chapter serves to synthetically report on what is already known in the scientific literature and identify knowledge gaps.

We recognize that human activities that threaten ecosystems may also contribute positively to human health and wellbeing. For example, shoreline hardening has negative physical and biological impacts such as contributing to the loss of beaches and spawning habitat for fish but also has positive impacts on human wellbeing by preventing erosion and loss of property at local scales (see shorelines in this Chapter). In this first edition of the Chapter on threats, we focus on the negative ecological and physical impacts of human activities. In future editions of this Chapter, we anticipate both a review and evaluation of the threats relative to human systems (economies, human health and wellbeing, cultural resources, etc.) as well as ecological systems. More specifically, future editions should include evaluations of the linkages between threats, human systems and ecological systems, highlighting not simply how enhancement of one system is costly to the other, but how the two systems benefit from each other. Future integration of the two systems and is necessary as a foundation for analyzing tradeoffs associated with various conservation actions.

Next Step: Impacts of threats to human health and wellbeing – positive or negative - were not addressed in this chapter and should be included in future editions.

 

2. Causal relationships between threats and their impacts to the environment

To help us better understand the high impact threats and their effects on the ecosystem, we use a conceptual framework designed to examine the relationship between human activities and the environment, namely “Driver-Pressure-State-Impact-Response” (DPSIR) (e.g., Langmead et al. 2009, Carr et al. 2007, Elliot 2002). Drivers are factors that result in pressures that, in turn, cause changes in the ecosystem. Drivers are both natural (e.g., natural climate variability, earthquakes, tsunamis) and anthropogenic (e.g., residential and urban development, human-caused climate change). In principle, human drivers can be changed via responses such as regulation, restoration, and education and natural environmental drivers cannot be controlled but must be accounted for when assessing interactions among drivers and pressures or the effectiveness of management responses. Pressures are factors that cause changes in a state or condition and are caused by specific drivers. For example, the driver “residential, urban and industrial development” can cause the ecological pressures of pollution and vegetation loss. State variables describe the condition (including physical, chemical, and biotic factors) of the ecosystem such as the presence of 6 parts per million of a given contaminant in Commencement Bay. Impacts comprise measures of the effect of change in these state variables such as loss of biodiversity, declines in productivity and yield, etc. Responses are the actions (regulatory, management or educational activities) that are taken in reduce the pressures and impacts caused by various drivers in order to achieve a desired state (e.g., cleaner water).

A DPSIR approach allows us to organize and present a wide range of issues that shape our understanding of the problem: the contribution of human activities to the problem, the extent and magnitude of the problem and the harm it causes in the ecosystem, and the range of possible strategies we might employ to mitigate it. These three ideas are reflected in three Chapters, collectively, of the Puget Sound Science Update. Using DPSIR terminology, the present Chapter (3, Impacts of Natural Events and Human Activities on the Ecosystem) discusses the Threats, or Drivers and Pressures in the system (and associated states and impacts); Chapter 2, Biophysical status of Puget Sound reviews the status of and trends in current condition of the ecosystem (State and Impacts); Chapter 4, Effectiveness of Strategies to Protect and Restore the System addresses the human Response to the problem.

We use the DPSIR framework because it: (1) identifies likely causal linkages between human activities and changes in ecosystem states; (2) simplifies the complex relationship between human activities and changes in the environment; (3) is a tool for communicating complex relationships and potential solutions between policy makers, scientists and the general public; (4) provides a framework for identifying indicators and what they indicate (e.g. indicators of pressures and states); (5) allows for a better understanding of the likely effects of response actions on the desired state; and (6) is widely used in the peer–reviewed literature. This framework has been used to identify indicators (Mangi 2007), to identify issues associated with pollinator loss (Kuldna et al. 2009), to address wind power management (Elliot 2002), to model choices associated with ecosystem recovery (Langmead et al. 2009), to create a conceptual framework for marine protected areas (Ojeda-Martinez et al. 2009), and for socio-ecological modeling (Langmead et al. 2009). The DPSIR framework can be modified to examine the effects of various drivers on human health and wellbeing.

Method used: To help us better understand the high impact threats and their effects on the ecosystem, we use a conceptual framework designed to examine the relationship between human activities and the environment, namely “Driver-Pressure-State-Impact-Response.”

 

In the following text, we treat most of the identified high impact threats as “drivers” or “pressures” and examine their impact on ecosystem states.

3. Results

Threat Ranking and identification of high impact threats

Our literature review revealed qualitative approaches for identifying and ranking the relative impacts of threats to the Salish Sea ecosystem. Of the six sources that identified threats to this ecosystem, all of them were governmental efforts, and one of ranked threats using an expert based approach (Table 1):

  • “Identification, Definition and Rating of Threats to the Recovery of Puget Sound,” (Neuman et al. 2009). This technical memo describes an expert review process using the Miradi Open Standards for the Practice of Conservation to identify threats to this ecosystem and rank threats as “low”, “medium”, “high”, and “very high”.
  • Puget Sound Partnership Action Agenda (2008, see Appendix, Threats and Drivers Summary in the Appendix). A categorized list of threats impacting Puget Sound that was developed as part of a DPSIR Demonstration Project in support of PSP’s Action Agenda.
  • Washington Department of Ecology list of significant threats to Puget Sound (WA DoE 2010): This list of threats emphasizes the agency’s focus on air and water contaminants.
  • U.S. Environmental Protection Agency Region 10 indicators for Puget Sound/Georgia Basin (US EPA 2010): Not a list of threats per se, but rather a list of broad-level indicators that are proposed or currently being monitored. Some of these indicators reflect one or more threats.
  • Washington Biodiversity Council (WBC 2007): Identification of threats associated with the loss of biodiversity but also relevant to ecosystem processes in general.
  • Significant threats to nearshore habitats in Cherry Point, WA (Hayes and Landis 2004): list of threats and impacts identified through an environmental assessment conducted in 2001 using a Regional Risk Assessment model to characterize high versus moderate risk threats. Comprising a small sub-region within the Puget Sound/Georgia Basin system, the Cherry Point assessment provides a useful illustration of how the specific scale of assessment can affect the level of risk posed by a particular threat.

We also include two threat identification and ranking processes that resulted from a similar restoration effort in the Chesapeake Bay and for the California Current ecosystem:

  • Chesapeake Bay Program’s lists of pressures (CBP 2010): despite the differences between the Puget Sound and Chesapeake Bay (in terms of climate, structure, etc.), they appear to share many of the same threats. As with EPA’s list above, Chesapeake Bay Program’s list includes a collection of indicators for monitoring the status and impacts of important threats.
  • Human impacts to the California Current marine coastal ecosystems (Halpern et al. 2009). This study maps the cumulative human impacts to California Current marine ecosystems. This system has direct physical and biotic linkages to the Salish Sea and this analysis included the Salish Sea. This assessment reflects differences in relative impacts of various threats as a function of scale (as well as important biophysical differences between marine coastal and inland estuarine systems).

Identifying the most important threats: Is one threat more important than the other in Puget Sound? Threats in Puget Sound were ranked as low, medium and high based on expert opinion in various venues (Table 1). Our review of the literature suggests that threat identification and ranking approaches used in the Puget Sound region largely lack peer-review and are not necessarily comprehensive, indicating the need for a more quantitative and systematic approach that addresses uncertainty surrounding the relative magnitude of threats. We propose approaches to get to the answer in our introduction and model sections.

 

Table 1. Comparison of Threat Identification and Ranking Lists for Puget Sound/Georgia Basin and Comparable Ecosystems1. Although there is considerable overlap in the threats identified in each scheme presented, each presents a unique threat list. X’s indicate threats that were identified as significant but were not ranked according to their relative importance.

 

PSSU Threats

PSP Open Standards Rating

Washington Department of Ecology

EPA Region 10

Washington Biodiversity Council

Cherry Pt., WA

CA Current Coastal Assessment

Chesapeake Bay Program

Residential, Commercial, & Industrial Development

Very High

X

X

X

High

 

X

Climate Change

Very High

 

 

X

 

 

X

Non-native & Invasive Species

High

 

X

X

Medium

Medium

X

Point & Non-point Water Pollution

High

X

X

X

Medium

Medium

X

Shoreline Modification

High

X

 

X

Medium

Medium

 

Species Harvesting

High

 

X

X

 

 

X

Transportation

High

 

 

X

 

 

X

Air Pollution & Atmospheric Deposition

Medium

 

X

 

 

High

X

Forest Practices

Medium

 

X

X

 

 

X

Oil & Hazardous Spills

Medium

X

X

X

Medium

Medium

X

Recreational Activities

Medium

 

 

X

High

Medium

 

Water Demands, Withdrawals & Diversions

Medium

 

 

X

 

 

X

Agriculture Practices

Low

 

 

X

High

 

 

Aquaculture Practices

Low

 

X

 

 

Medium

X

Derelict Gear & Vessels

Low

 

 

 

 

Medium

 

Dredging Activities

Low

 

 

 

 

 

 

Physical Disturbance/Disruption of Species

Low

 

 

 

High

Medium

 

Military Exercises

Low

 

 

 

 

 

 

Mines

Low

 

 

 

 

 

 

There is fairly high consistency among ranking schemes in the threats identified for Puget Sound and for similar ecosystems (Table 1). Because only one assessment effort ranks threats Sound-wide (Neuman et al. 2009), we use this scheme to help us focus our efforts on the threats thought to have the greatest impact on the health of Puget Sound. Specifically, we only review the “very high” and “high” threats identified in Neuman et al. (2009). We did not have time to address one of the “High” ranked threats, unsustainable harvest, and recommend that future editions of this Chapter describe this threat (Table 2). To better fit into our DPSIR approach, we characterize the threats slightly differently from Neuman et al. (2009). For example, “Physical disturbance/disruption to species” which is a “Low” rank threat under Neuman et al. (2009) is partially covered as a “State” under our more comprehensive driver, “Residential, Commercial and Industrial Development”. The use of DPSIR and resulting change in threat categories resulted in partial reviews of some lower ranking threats. For the threats reviewed, our work is incomplete and we welcome input from experts to help make this product more comprehensive. To help with this process, we highlight obvious gaps in our assessment with placeholders in the text.

Table 2. Threats and their ranks from Neuman et al. (2009) reviewed in this Chapter.

Threats from Open Standards Neuman et al (2009)

Open Standards ranking

Where we include threats from the Open Standard process in this chapter

Climate Change

Very High

Climate Change

Residential, Commercial, Port & Shipyard Development

Very High

Residential, Commercial and Industrial Development

Surface Water Loading and Runoff from the Built Environment

High

Residential, Commercial and Industrial Development

Roads,Transportation and Utility Infrastructure

High

Residential, Commercial and Industrial Development

Shoreline Armoring

High

Shoreline Modification

Dams, Levees and Tidegates

High

Shoreline Modification

Invasive Species (marine, freshwater and terrestrial)

High

Invasive and Non-native Species

Point & Non-point Water Pollution

High

Pollution – focus on impacts to biota

Unsustainable Species Harvest

High

Not covered – high priority for next update

Air Pollution & Atmospheric Deposition

Medium

Pollution - incomplete

Forest practices

Medium

Not covered

Oil & Hazardous Spills

Medium

Pollution - incomplete

Recreational activities

Medium

Not covered

Water Demand, Withdrawals and Diversions

Medium

Residential, Commercial and Industrial Development – incomplete

Agriculture practices

Low

Not covered

Aquaculture practices

Low

Not covered

Derelict Gear & Vessels

Low

Not covered

Dredging activities

Low

Not covered

Physical disturbance/disruption to species

Low

Residential, Commercial and Industrial Development – just terrestrial

Military Exercises

Low

Not covered

Mines

Low

Not covered

Of the high impact threats identified by the Puget Sound Partnership, we addressed: Climate Change, Residential, Commercial and Industrial Development, Shoreline Modification, Invasive and Non-native Species, Pollution, with a focus on impacts to organisms

 

High impact threats not addressed in this chapter: Unsustainable species harvest

 

 

We did not review all threats identified by the Open Standards process (Table 1).

 

4. Information Needs

Identifying the most significant threats and the most important management strategies is extremely complex, especially if threats interact and their effects are multiplicative in nature. For example, threats to marine ecosystems often include simultaneously terrestrial, freshwater and marine based effects (Halpern et al. 2007). The current approaches to threat identification and ranking described above largely lacks peer-review. Our review of the literature suggests the need for a more comprehensive, quantitative and systematic assessment that addresses uncertainty surrounding the relative magnitude of threats. There are many approaches to both identifying and ranking threats in the published literature (e.g., Iannuzzi et al. 2009, Newsome et al. 2009, Selkoe et al. 2008, Halpern et al. 2007, Given and Norton 1993). Our review revealed the following considerations when conducting such a threat assessment:

  • Importance of identifying clear objectives that define the 1) geographic scope, 2) ecosystem(s), ecological communities, and species of interest (what is threatened), and the 3) temporal scope.
  • A systematic and comprehensive assessment of threats (e.g., Halpern et al. 2007).
  • Expert opinion is often used in the absence of models for identifying and ranking threats. The literature suggests the following considerations when using this approach:
    • Quantitatively assess vulnerability and mathematically embrace uncertainty in our knowledge about the threats and their associated impacts when developing threat ranks (e.g., Cooke and Goossens 2004). Consistency between the top threats volunteered by experts and the top threats revealed using vulnerability scores from these same experts can be low (Halpern 2007, Teck et al. 2010, Payne et al. 1992; Lichtenstein and Slovic 2006) and suggests the importance of a more quantitative approach. There are many approaches for addressing uncertainty (e.g., Teck 2010, Iannuzzi et al., 2009, Halpern et al. 2007, Garthwaite et al. 2005, Cooke and Goossens 2004, Morgan 2003, Cleaves 1994) and we suspect that a Bayesian belief network approach (e.g., Garthwaite et al. 2005) could also be applied if threats and their consequences can be expressed as probabilities and as discrete values.
    • Recommend developing criteria when selecting experts to make sure that the appropriate representation and level of knowledge is included (e.g., level of education, type of research experience, management experience, type of organization, etc.)
    • Address sources of bias: (1) self interest or personal values of those included as experts (see Cleaves 1994); (2) institutional, educational and sex biases (see Halpern 2007 for an analytical approach for addressing this issue)
    • Integrate published material and expert opinion (e.g., information on magnitude, extent and uncertainty associated with threats; Iannuzzi et al., 2009).
    • Integrate expert based threat ranking with quantitative information (e.g.,Teck et al. 2010 Iannuzzi et al., 2009) to provide a systematic foundation for ecosystem-based management
  • There are modeling approaches that help both identify and rank threats and are discussed in the Modeling section and the concluding paragraphs of this Chapter of the Update.

Next Step: Work is needed to more comprehensively evaluate the impact of single threats as well as the interactions among them. We included placeholders to guide future editions of this section.

 

 

Key information gap: Quantitative and analytical approaches to ranking threats in Puget Sound

 

 

 

References

 

Carr, E. R., P. M. Wingard, S. C. Yorty, M. C. Thompson, N. K. Jensen, and J. Roberson. 2007. Applying DPSIR to sustainable development. International Journal of Sustainable Development and World Ecology 14:543-555.

CBP. 2010. Bay Pressures, http://www.chesapeakebay.net/. Chesapeake Bay Program, Annapolis, MD.

Cleaves, D. A. 1994. Assessing uncertainty in expert judgments about natural resources. Report No. GTR SO-110, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station.

Cooke, R. M. and L. H. J. Goossens. 2004. Expert judgement elicitation for risk assessments of critical infrastructures. Journal of Risk Research 7:643-656.

Elliott, M. 2002. The role of the DPSIR approach and conceptual models in marine environmental management: an example for offshore wind power. Marine Pollution Bulletin 44:III-VII.

Garthwaite, P. H., J. B. Kadane, and A. O'Hagan. 2005. Statistical methods for eliciting probability distributions. Journal of the American Statistical Association 100:680-700.

Given, D.R., and D.A. Norton. 1993. A multivariate approach to assessing threat and for priority setting in threatened species conservation. Biological Conservation 64:57-66.

Halpern, B. S., C. V. Kappel, K. A. Selkoe, F. Micheli, C. M. Ebert, C. Kontgis, C. M. Crain, R. G. Martone, C. Shearer, and S. J. Teck. 2009. Mapping cumulative human impacts to California Current marine ecosystems. Conservation Letters 2:138-148.

Halpern, B. S., K. A. Selkoe, F. Micheli, and C. V. Kappel. 2007. Evaluating and ranking the vulnerability of global marine ecosystems to anthropogenic threats. Conservation Biology 21:1301-1315.

Hayes, E. H. and W. G. Landis. 2004. Regional ecological risk assessment of a near shore marine environment: Cherry Point, WA. Human and Ecological Risk Assessment 10:299-325.

Iannuzzi, T. J., J. L. Durda, D. V. Preziosi, D. F. Ludwig, R. G. Stahl, Jr., A. A. DeSantis, and R. A. Hoke. 2009. Development of a preliminary relative risk model for evaluating regional ecological conditions in the Delaware River Estuary, USA. Integrated Environmental Assessment and Management 6:164-179.

Kuldna, P., K. Peterson, H. Poltimae, and J. Luig. 2009. An application of DPSIR framework to identify issues of pollinator loss. Ecological Economics 69:32-42.

Langmead, O., A. McQuatters-Gollop, L. D. Mee, J. Friedrich, A. J. Gilbert, M. T. Gomoiu, E. L. Jackson, S. Knudsen, G. Minicheva, and V. Todorova. 2009. Recovery or decline of the northwestern Black Sea: A societal choice revealed by socio-ecological modelling. Ecological Modelling 220:2927-2939.

Lichtenstein, S. and P. Slovic. 2006. The Construction of Preference. Cambridge University Press, Cambridge, UK.

Mangi, S. C., C. M. Roberts, and L. D. Rodwell. 2007. Reef fisheries management in Kenya: Preliminary approach using the driver-pressure-state-impacts-response (DPSIR) scheme of indicators. Ocean & Coastal Management 50:463-480.

Morgan, M. G. 2003. Characterizing and Dealing With Uncertainty: Insights from the Integrated Assessment of Climate Change. Integrated Assessment 4:46 - 55.

Neuman, M., D. St. John, and J. Knauer. 2009. Identification, Definition and Rating of Threats to the Recovery of Puget Sound. Puget Sound Partnership, Olympia, WA.

Newsome, R., N. Tran, G. M. Paoli, L. A. Jaykus, B. Tompkin, M. Miliotis, T. Ruthman, E. Hartnett, F. F. Busta, B. Petersen, F. Shank, J. McEntire, J. Hotchkiss, M. Wagner, and D. W. Schaffner. 2009. Development of a Risk-Ranking Framework to Evaluate Potential High-Threat Microorganisms, Toxins, and Chemicals in Food. Journal of Food Science 74:R39-R45.

Ojeda-Martinez, C., F. G. Casalduero, J. T. Bayle-Sempere, C. B. Cebrian, C. Valle, J. L. Sanchez-Lizaso, A. Forcada, P. Sanchez-Jerez, P. Martin-Sosa, J. M. Falcon, F. Salas, M. Graziano, R. Chemello, B. Stobart, P. Cartagena, A. Perez-Ruzafa, F. Vandeperre, E. Rochel, S. Planes, and A. Brito. 2009. A conceptual framework for the integral management of marine protected areas. Ocean & Coastal Management 52:89-101.

Payne, J., J. Bettman, and E. Johnson. 1992. Behavioral decision research: A constructive processing perspective. Annual Review of Psychology 43:87-132.

Ruckelshaus, M. H., M. M. McClure, and coordinators. 2007. Sound Science: Synthesizing Ecological and Socioeconomic Information about the Puget Sound Ecosystem. U.S. Dept. of Commerce, National Oceanic & Atmospheric Administration (NMFS), Northwest Fisheries Science Center; prepared in cooperation with the Sound Science collaborative team, Seattle, WA.

Selkoe, K. A., B. S. Halpern, and R. J. Toonen. 2008. Evaluating anthropogenic threats to the Northwestern Hawaiian Islands. Aquatic Conservation-Marine and Freshwater Ecosystems 18:1149-1165.

Teck, S. J., B. S. Halpern, C. V. Kappel, F. Micheli, K. A. Selkoe, C. M. Crain, R. Martone, C. Shearer, J. Arvai, B. Fischhoff, G. Murray, R. Neslo, and R. Cooke. 2010. Using expert judgment to estimate marine ecosystem vulnerability in the California Current. Ecological Applications 20:1402-1416.

US EPA. 2010. Puget Sound Georgia Basin Ecosystem, http://www.epa.gov/pugetsound/. Region 10, U.S. Environmental Protection Agency, Seattle, WA.

WBC. 2007. Washington’s Biodiversity: Status and Threats. Washington Biodiversity Council, Olympia, WA.

WA DoE. 2010. Overview: Threats – Saving Puget Sound, http://www.ecy.wa.gov/puget_sound/threats.html. Washington State Department of Ecology, Olympia, WA.