5 Zooplankton Indices
Last updated July 23, 2026
Description: Model-based abundance and annual center of gravity indices for zooplankton groups sampled by NEFSC surveys
Contributor(s): Abigail Tyrell, Sarah Gaichas, Harvey Walsh
Affiliations: NEFSC
Indicator Family:
Indicator Category:
Synthesis Theme:
5.1 Introduction to Indicator
Zooplankton are primary consumers in marine ecosystems that transfer energy from phytoplankton to fish, marine mammals, and birds. The Northeast Fisheries Science Center has conducted zooplankton surveys since the 1970s. Spatially explicit indices of abundance for several zooplankton groups were estimated using spatio-temporal modeling (VAST, [12]; [13]).
The zooplankton groups in the model include:
Copepods
Calanus finmarchicus, = Single species group, used to represent large copepods in the small-large index)
Large copepods ALL: Calanus finmarchicus, Metridia lucens, Calanus minor, Eucalanus spp., Calanus spp.
Small copepods ALL: Centropages typicus, Pseudocalanus spp., T_emora longicornis_, Centropages hamatus, Paracalanus parvus, Acartia spp., Clausocalanus arcuicornis, Acartia longiremis, Clausocalanus furcatus, Temora stylifera, Temora spp., Tortanus discaudatus, Paracalanus spp.
Small copeopods SOE (used to represent small copepods in the small-large index): Centropages typicus, Pseudocalanus spp., Temora longicornis, Centropages hamatus
Euphausiids (krill) modeled as family level group; not differentiated to species in data
Zooplankton volume a metric of total zooplankton; all groups combined displacement volume in the collection net
5.2 Key Results and Visualizations
Abundance Large and small copepod groups are mainly fluctuating without trend in both spring and fall across the EPUs. Large copepod biomass has a short-term decline in the spring in both the GOM and GB. Small copepods have a long-term decline in the MAB in fall, and a long-term increase in the GOM in the spring. Euphausiid show increasing trends over time in all regions during fall. Zooplankton volume is fluctuating without long term trends over time.
Center of Gravity Small copepods in fall are trending northeast similar to forage fish and aggregated survey species. Small copepods in spring are trending north. There is a short-term westward trend for Calanus finmarchicus in the spring. There has been no other significant change for Calanus finmarchicus, large copepods, euphausiids, or zooplankton volume center of gravity over time.
Mid-Atlantic, Calfin, index
New England, Calfin, index
Mid-Atlantic, Euph, index
New England, Euph, index
Mid-Atlantic, Smallcopesoe, index
New England, Smallcopesoe, index
Mid-Atlantic, Lgcopeall, index
New England, Lgcopeall, index
Mid-Atlantic, Zoopvol, index
New England, Zoopvol, index
Mid-Atlantic, Smallcopeall, index
New England, Smallcopeall, index
Mid-Atlantic, Calfin, cog
New England, Calfin, cog
Mid-Atlantic, Euph, cog
New England, Euph, cog
Mid-Atlantic, Smallcopesoe, cog
New England, Smallcopesoe, cog
Mid-Atlantic, Lgcopeall, cog
New England, Lgcopeall, cog
Mid-Atlantic, Zoopvol, cog
New England, Zoopvol, cog
Mid-Atlantic, Smallcopeall, cog
New England, Smallcopeall, cog
5.3 Implications
Fluctuations in zooplankton community composition can affect both the consumption of phytoplankton vs the export of energy to the benthos, as well as the availability of prey for zooplankton feeding forage fish, marine mammals, and seabirds.
The relative dominance of large and small copepods in Northeast US ecosystems has been liked to changes in fish productivity [14].
Distribution shifts for zooplankton may result in mismatches with zooplankton feeding fish, marine mammal, and seabirds.
5.4 Indicator statistics
Spatial scale: by EPU and full shelf
Temporal scale: Spring (January-June), Fall (July-December)
Variable definitions
5.5 Get the data
Point of contact: EDAB, edab.data@noaa.gov
ecodata dataset: ecodata::zooplankton_index
Tech Doc link: https://noaa-edab.github.io/tech-doc/zooplankton_index.html
5.5.2 Accessibility Constraints
Request from Harvey Walsh, harvey.walsh@noaa.gov