3. Habitat Evaluation

This version of the Puget Sound Science Update provides an initial evaluation of habitat indicators, but is not intended to be comprehensive. Highlights include evaluation of marine and interface habitats (area and condition), as well as evaluation of a number of indicators of freshwater and terrestrial habitats condition. Many measures of habitat condition, especially those relating to water quality, were addressed under the PSP Water Quality goal.

• The inclusion of more candidate indicators for habitat area and pattern/structure (of all domains)
• Evaluation of habitat area and pattern/structure indicators for freshwater and terrestrial habitats
• Evaluation of freshwater habitats condition indicators
• Defining or identifying ‘priority habitats’ for priority habitats condition indicator (which appears under marine, freshwater, and terrestrial domains)

Commonly used data sources to evaluate habitat indicators included: Washington Departments of Ecology, Fish and Wildlife, and Natural Resources, and the Washington Biodiversity Council.

Habitat area and pattern/structure are key measures of the overall health of a system, especially when they represent priority habitats. Insight into the status and trends of priority habitats area or pattern/structure can be used to infer changes in the status and trends of biota as well as abiotic processes. For example, changes in habitat area or pattern/structure can influence the amount of water runoff or coastal flooding, as well as regional species persistence. Thus insight into the status and trends of habitat area and pattern/structure can be useful for interpreting changes in ecosystem structure, function and processes.

Habitat area reflects the areal extent of a habitat as well as its shape, and can influence local population persistence and size for a single species (Fahrig and Merriam 1994). While habitat area is important for maintaining biota, pattern/structure measures (e.g., the number of patches of each habitat, fractal dimension, and connectivity) also plays a significant role. The number of patches of each habitat (i.e., patch richness) may be correlated with species richness, thus monitoring patch number may be used to interpret trends in species biodiversity. Fractal dimension provides a measure of habitat complexity; natural areas tend to be more complex compared with human-altered areas, leading to changes in species richness (Krummel et al. 1987, Senft et al. 1987). Connectivity between habitat patches affects the ability of an organism to cross between patches, and can be important for regional population abundance and survival (Fahrig and Merriam 1994). WDNR monitoring programs, among others, provide an abundant source of information on habitat area in Puget Sound.

Whereas the preceding attribute is concerned with measures of habitat area and pattern, it is also important to assess habitat quality or condition. Habitat condition reflects the basic needs of a species (e.g., food, water, cover) and is a critical component to predict species distributions (Environmental Protection Agency 2002) and population abundance and survival (Fahrig and Merriam 1994). For example, important variables for fish habitat would include water quality parameters (e.g., DO levels, temperature) as well as the presence and abundance of non-native invasive species or nuisance species that compete for resources. Thus, habitat condition refers to abiotic (i.e., physical and chemical properties) and biotic properties (e.g., invasive or nuisance species, dominant species), as well as dynamic structural characteristics.

Abiotic properties (e.g., water and benthic quality parameters) are the most widely available indicators for habitat condition in Puget Sound. However, according to the PSSU framework, they fall under the Water Quality goal and will therefore be discussed in that section. Biotic properties, such as the status and trends of harmful algal blooms or the presence of nuisance species, are a key measure of habitat health and can be used to interpret changes in native species abundance, distribution, and survival. Dynamic structural characteristics cause changes in physical habitat complexity and morphology, and are included in habitat condition because they maintain (or eliminate) the diversity of natural habitats. Data collection led by WDNR, WDFW, and the Washington Biodiversity Council provides important information on habitat condition in Puget Sound.

There were sixty habitat indicators identified by O’Neill et al. (2008) and of these, we have evaluated thirty-seven. The majority of those evaluated are indicators of area and condition for marine and interface habitats. A small subset of indicators has been evaluated for Freshwater and Terrestrial Habitats, and future versions of this document should focus on completing these evaluations. The current status of indicator evaluations for each habitat focal component is summarized below.

Area and Pattern/Structure. Three indicators of marine habitat area were identified (Table 16). Of these, two (eelgrass status and trends and kelp status and trends) were evaluated and performed adequately against the criteria. Both indicators were theoretically-sound, but do not respond predictably to management actions or pressures. In particular, it is difficult to determine causes of variation in habitat area (e.g., natural vs. anthropogenic impacts). Ongoing monitoring programs led by WDNR and the Pacific Northwest National Laboratory, among others, provided extensive information for these indicator evaluations.

Table 16. Summary of Marine Habitats – Area and Pattern/Structure indicator evaluations. The numerical value that appears under each of the considerations represents the number of evaluation criteria supported by peer-reviewed literature. For example, Eelgrass status & trends has peer-reviewed literature supporting 2 out of 5 Primary Considerations criteria. Details can be found in the accompanying spreadsheets.

Habitat Condition. There were seventeen indicators of marine habitat condition identified (Table 17). The majority of those listed refer to biotic properties (e.g., non-native invasive aquatic species); considerably fewer relate to abiotic properties. Two indicators (upwelling zones and marine water quality parameters) were evaluated under Marine Water Quality; three indicators (non-native invasive marine species threat, number of marine native nuisance species, and priority habitats condition) have yet to be evaluated. Several indicators performed poorly against all criteria because we were unable to determine what they were an indicator of. These included the number of salmon net pens, number of oyster culture sites, and number of clam culture sites, and may better serve as ‘pressure’ indicators.

Table 17. Summary of Marine Habitats – Condition indicator evaluations. The numerical value that appears under each of the considerations represents the number of evaluation criteria supported by peer-reviewed literature. For example, Non-native invasive aquatic marine species has peer-reviewed literature supporting 2 out of 5 Primary Considerations criteria. Details can be found in the accompanying spreadsheets.

A subset of related indicators performed well against all criteria and included the number of marine species at risk that are threatened/endangered/candidate, number of marine species listed under Federal ESA, number of marine species of concern on State list, number of marine species of greatest conservation need, and number of marine species of conservation concern. These indicators were originally evaluated under Marine Species (population condition), but were moved to Marine Habitats because the absolute number of species on any of these lists is a better reflection of habitat or environmental condition. All were theoretically-sound, but because each indicator is a compilation of species, it is difficult to conclude whether they respond predictably to management actions. These indicators appear to convey redundant information. Information on these indicators was principally obtained through WDFW and the Washington Biodiversity Council.

Two indicators, aggregation/deposition zones and harmful algal blooms status and trends, performed well against primary and data considerations. The remaining indicators (intertidal biotic community status and trends and non-native invasive aquatic marine species) received poor evaluations. Monitoring efforts by WDFW, WDOH, WDNR, among others, provided important data sources for these evaluations.

Area and Pattern/Structure. O’Neill et al. (2008) identified three indicators for freshwater habitat area (Table 18). These indicators (freshwater physical habitat, floodplain connectivity, and instream habitat) have yet to be evaluated. As well as evaluating these indicators, it may be useful to develop additional candidate indicators for this section.

Table 18. Summary of Freshwater Habitats – Area and Pattern/Structure indicator evaluations.

Habitat Condition. Eighteen indicators of freshwater habitat condition were identified, half of which have not been evaluated (Table 19). Several indicators including max temperature, sediment loadings rate, stream and lake water quality parameters, and spawning habitat water quality, are evaluated under Water Quality though they do pertain to habitat condition.

Table 19. Summary of Freshwater Habitats – Condition indicator evaluations. The numerical value that appears under each of the considerations represents the number of evaluation criteria supported by peer-reviewed literature. For example, Number of freshwater species of conservation concern has peer-reviewed literature supporting 3 out of 5 Primary Considerations criteria. Details can be found in the accompanying spreadsheets.

Evaluated indicators for freshwater habitat condition represent a group of related indicators that performed well against all criteria. These included the number of freshwater species listed under Federal ESA, number of freshwater species of concern on State list, number of freshwater species of greatest conservation need, and number of freshwater species of conservation concern. These indicators were originally evaluated under Freshwater Species (population condition), but were moved to Freshwater Habitats because the absolute number of species on any of these lists better reflects habitat or environmental condition. All were theoretically-sound, but because each indicator is a compilation of species, it is difficult to conclude whether they respond predictably to management actions. These indicators appear to convey redundant information. Information on these indicators was principally obtained through WDFW and the Washington Biodiversity Council.

Area and Pattern/Structure. O’Neill et al. (2008) identified three indicators of terrestrial habitat area: terrestrial land cover status and trends, transportation impacts, and forests and forestry (Table 20). None of these indicators have been evaluated. This section may benefit from the addition of new candidate indicators, as well as evaluating the indicators currently identified.

Table 20. Summary of Terrestrial Habitats – Area and Pattern/Structure indicator evaluations.

Habitat Condition. There were nine indicators of terrestrial habitat condition identified (Table 21). Three indicators, old growth forest change, road densities, and priority habitats condition, have yet to be evaluated. Two indicators, non-native invasive terrestrial species threat and number of terrestrial native nuisance species, performed well against primary considerations but not data considerations. The Washington Invasive Species Council is leading efforts to compile numbers and occurrence data for these two indicators.

Table 21. Summary of Terrestrial Habitats – Condition indicator evaluations. The numerical value that appears under each of the considerations represents the number of evaluation criteria supported by peer-reviewed literature. For example, Number of terrestrial species of conservation concern has peer-reviewed literature supporting 3 out of 5 Primary Considerations criteria. Details can be found in the accompanying spreadsheets.

A subset of related indicators performed well against all criteria and included the number of terrestrial species listed under Federal ESA, number of terrestrial species of concern on State list, number of terrestrial species of greatest conservation need, and number of terrestrial species of conservation concern. These indicators were originally evaluated under Terrestrial Species (population condition), but were moved to Terrestrial Habitats because the absolute number of species on any of these lists better reflects habitat or environmental condition. All were theoretically-sound, but because each indicator is a compilation of species, it is difficult to conclude whether they respond predictably to management actions. These indicators appear to convey redundant information. Information on these indicators was principally obtained through WDFW and the Washington Biodiversity Council.

Area and Pattern/Structure. There were four indicators identified for interface habitat area (Table 22). Wetland acreage status and trends has not been evaluated. Two indicators, saltmarsh status and trends and riparian habitat, performed well against all criteria. In particular, riparian habitat fulfilled all of the primary considerations as well as most of the data considerations. Of note, saltmarsh status and trends did not fulfill the theoretically-sound criteria because it is most often used as part of an integrative assessment of ecosystem health, rather than a stand-alone indicator. Shoreline geomorphology received a poor evaluation because, while it is theoretically-sound and relevant to management, data trends are largely missing, especially as they relate to changes from natural versus anthropogenic impacts. Monitoring efforts by WDNR and Simenstad et al. (2010) provided valuable data for these evaluations.

Table 22. Summary of Interface Habitats – Area and Pattern/Structure indicator evaluations. The numerical value that appears under each of the considerations represents the number of evaluation criteria supported by peer-reviewed literature. For example, Saltmarsh status and trends has peer-reviewed literature supporting 3 out of 5 Primary Considerations criteria. Details can be found in the accompanying spreadsheets.

Habitat Condition. Percent of shoreline armored, nearshore physical and biotic habitats, and wildlife status and trends in restored habitats were selected as indicators for interface habitat condition (Table 23). All were theoretically-sound and relevant to management. Percent of shoreline armored may be a good indicator, although explicit linkages between armoring and effects on biota is largely absent. Nearshore habitats met most of the data and other considerations, and may be useful as a leading indicator of how habitat-forming processes have been altered in the nearshore environment. Wildlife status in restored habitats appears to be costly and time intensive to measure. Principal data sources for these evaluations included monitoring efforts by WDNR, as well as Simenstad et al. (2010).

Table 23. Summary of Interface Habitats – Condition indicator evaluations. The numerical value that appears under each of the considerations represents the number of evaluation criteria supported by peer-reviewed literature. For example, Nearshore physical and biotic habitats has peer-reviewed literature supporting 2 out of 5 Primary Considerations criteria. Details can be found in the accompanying spreadsheets.