View in Vital Signs- Thriving Species and Food Web
- Zooplankton
- Indicator
- Annual average zooplankton biomass
- Vital Sign Indicator
- Each Unit (number)
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No targets are currently set for this indicator.
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BethElLee Herrmann
- Contributing Partners
- Last Updated
- 10/15/2024 22:47:46
This indicator measures the annual average zooplankton biomass (mg C/m3) integrated annually across multiple locations in Northern Washington and Puget Sound marine ecosystems and captures the variability in zooplankton biomass among years.
Annual Average Zooplankton Biomass (mg C/m3) in 2014-2023 for five taxa groups integrated across multiple locations in two regions, Northern Washington (NWA – yellow line) and Puget Sound (PS – purple line).
Annual Average Zooplankton Biomass was selected to indicate variability in zooplankton biomass among years to relate to environmental changes (e.g., heatwaves), and corrects for biases due to inconsistent sampling among stations and years.
- The annual average biomass for all zooplankton was higher in Puget Sound (PS) than in Northern Washington (NWA) during warmer years (2014-2017), yet similar or lower in the following cooler, more average years (2018-2021), with regional values diverging once again in the past couple of years. This pattern was clearly reflected in the juvenile salmon and forage fish prey field of small crustaceans (copepods, amphipods, krill, shrimp, and crabs).
- Total (all zooplankton) biomass displayed a zig-zag pattern in PS, alternating higher and lower biomass every other year for the first 7 years, a pattern somewhat consistent in small crustaceans and crab larvae.
- NWA crustacean biomass values were primarily driven by large to medium-sized ocean associated copepod species in the years following the marine heatwave, whereas Puget Sound (PS) biomass was driven by small Puget Sound resident species of copepods.
- Gelatinous zooplankton biomass was highest in 2014 in both regions, with a fairly high value remaining in PS in 2015. Biomass in subsequent years was relatively low and steady.
- Crab larval biomass was greater in NWA than PS in all years except 2022-2023. High values were driven by porcellanid, pinnotherid, and cancrid larval crabs in Bellingham Bay.
- Monitoring Program
Puget Sound Zooplankton Monitoring Program
- Data Source
The Puget Sound Zooplankton Monitoring Program (started as the Salish Sea Marine Survival Project in 2014) provides an extensive, ongoing dataset documenting metrics of zooplankton from 15 stations in the southern Salish Sea throughout Northern Washington (NWA) and Puget Sound (PS) (Figure 1). The data included in these Indicators are compiled from 200-µm mesh vertical net tows, which are collected bi-weekly all year round, with lower frequency in the winter. The nets are towed through the full water column, from within 5 m from the bottom, or to a maximum of 200 m, to the surface. Samples are preserved in 5% formalin and are processed by expert taxonomists at the University of Washington, with certain taxa identified to species level. Data are then statistically analyzed to develop indicators of environmental variability.
Please see the Zooplankton Vital Sign Indicators Annual Report for more about analysis methods and the King County Zooplankton Monitoring Annual Report for more details about sample collection and processing methods.
- Critical Definitions
Taxa of interest
All Zooplankton (total zooplankton biomass) includes all taxa collected, except for Noctiluca (dinoflagellates), eggs, copepod nauplii, and any unidentifiable organisms, as these are extremely small and inconsistently caught in the nets or damaged beyond recognition.
Crustaceans compose the majority of zooplankton biomass in the Salish Sea. This broad taxonomic group consists of several major taxa (copepods, amphipods, krill, shrimp, crabs, etc.), and is separated into size classes (large crustaceans >2.5 mm and small crustaceans <2.5 mm) relevant to forage fish and juvenile salmon diets, including Chinook and coho salmon.
Gelatinous zooplankton consist of cnidarians (e.g., jellyfish and siphonophores) and ctenophores (e.g., comb jellies). These soft invertebrates may have indirect, yet important, linkages to water quality and ecosystem health, and are important prey for pink and chum salmon.
Crab larvae are of high interest in fisheries management, especially several cancrid species, including Dungeness crab (Metacarcinus magister).
Targets are not defined for these indicators. When evaluating trends in the indicators, it is important to note that high biomass of any group would indicate high prey availability for their predators. However, because there is a complex food web in the Salish Sea where sustained predation will decrease biomass, low biomass does not necessarily indicate that the system is in an unhealthier state than when biomass is high.
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Many factors, such as increased ocean-estuary exchange, higher nutrients, and higher temperatures may have affected zooplankton growth, reproduction, and timing during the marine heatwave in 2015-2016, with lingering effects through 2017. The PS residents, which complete their entire life cycles in PS, would be especially affected by these local environmental changes; many of these are smaller crustacean species.
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Populations of larger, oceanic copepod species (mainly seen in NWA) are primarily advected in from the ocean. Therefore, their changes reflect changes in species composition in the coastal populations and changes in the volumes and timing of advection into the Salish Sea, rather than local environmental changes.
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The Puget Sound Partnership believes in the transparency and accessibility of the data used to address puget sound indicators. These data are provided by contributing partners to the Partnership and are made publicly available through the Puget Sound Info site. These data are available on an "as is" basis and the Partnership is not responsible for any errors, omissions, or inaccuracies. Please acknowledge the monitoring program and data source when using these data and obtain permission from the Vital Sign Indicator Reporter to use these data in a publication.
- Annual Average Zooplankton Biomass in Northern Washington and Puget Sound
- Uploaded On
- 09/20/2024
- File Type
- CSV
- Description
- Annual Average Zooplankton Biomass (mg C/m^3) in 2014-2023 for five taxa groups integrated across multiple locations in two regions, Northern Washington and Puget Sound
- Reporting Instructions
No Subcategories for this Puget Sound Indicator.