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Technical Documentation, State of the Ecosystem Report

64 Calanus Stage

Description: Calanus abundance by life stage

Found in: State of the Ecosystem - Gulf of Maine & Georges Bank (2021), State of the Ecosystem - Mid-Atlantic (2021)

Indicator category: Database pull with analysis

Contributor(s): Ryan Morse

Data steward: Ryan Morse

Point of contact: Ryan Morse

Public availability statement: Please contact Harvey Walsh () for raw data.

64.1 Methods

64.1.1 Data sources

Zooplankton data are from the National Oceanographic and Atmospheric Administration Marine Resources Monitoring, Assessment and Prediction (MARMAP) program and Ecosystem Monitoring (EcoMon) cruises detailed extensively in Kane (2007), Kane (2011), and Morse et al. (2017).

64.1.2 Data analysis

This index tracks the overall abundance of mature adult Calanus finmarchicus copepods and immature copepodite stage-5 (c5) Calanus finmarchicus copepods on the US Northeast Shelf ecosystem. The life cycle of C. finmarchicus relies on an overwintering phase (diapuse) where immature c5 copepodites build a lipid reserve prior to entering diapuse and remain at depth until favorable conditions for growth emerge. Because of this lipid reserve, diapausing c5 copepodites are a primary food source for many organisms, including the North Atlantic right whale.

Data are processed similarly to Morse et al. (2017), except that cruises were partitioned into three seasons based on the median day of the year (DOY) for a given cruise. Cruises with median DOY between 0 and 120 were classified as spring cruises (i.e. their bimontly median dates correspond to 1 or 3). Cruises with a median DOY between 121 and 243 were classified as summer (bimonthly means of 5 or 7). Cruises with a median DOY between 244 and 366 were classified as fall (bimonthly mean cruise date of 9 or 11). Samples were assigned to EPUs based on their location, and transformed from raw counts to units of number per 100 m^-3 following MARMAP protocols. Samples were then aggregated to EPU by year using log transformed abundance. Cruises with less than 10 sampling days per cruise were removed due to incomplete surveys. Samples were limited to Calanus finmarchicus adults and copepodite stage-5 (c5) for inclusion as an indicator.

Code used to analyze calanus stage data can be found at this link.

64.1.3 Data processing

The Calanus Stage indicator was formatted for inclusion in the ecodata R package using the R script found here.

catalog link

References

Kane, Joseph. 2007. “Zooplankton abundance trends on Georges Bank, 1977-2004.” ICES Journal of Marine Science 64 (5): 909–19. https://doi.org/10.1093/icesjms/fsm066.
———. 2011. “Multiyear variability of phytoplankton abundance in the Gulf of Maine.” ICES Journal of Marine Science 68 (9): 1833–41. https://doi.org/10.1093/icesjms/fsr122.
Morse, R. E., K. D. Friedland, D. Tommasi, C. Stock, and J. Nye. 2017. “Distinct zooplankton regime shift patterns across ecoregions of the U.S. Northeast continental shelf Large Marine Ecosystem.” Journal of Marine Systems 165: 77–91. https://doi.org/10.1016/j.jmarsys.2016.09.011.