Chemical and Biological Oceanographic Conditions on the Scotian Shelf and in the Eastern Gulf of Maine during 2023

Description

Casault, B., Johnson, C.L., Devred, E., and Beazley, L. 2025. Chemical and Biological Oceanographic Conditions on the Scotian Shelf and in the Eastern Gulf of Maine during 2023. Can. Tech. Rep. Fish. Aquat. Sci. 3658: vi + 57 p. https://doi.org/10.60825/4d69-8120 Nutrient and plankton metrics are assessed in the context of physical conditions observed in the Maritimes region in 2023. Sub-surface (50-150 m) nitrate inventories were spatially variable across the region in 2023 but indicated a gradual return toward near-normal levels, except in the Bay of Fundy (i.e., at Prince-5) where a record-low value was observed in 2023. Bottom nitrate concentrations during summer were predominantly below normal across the region in 2023. In situ chlorophyll-a inventories were on average higher than normal in the region in 2023. Surface chlorophyll-a concentrations measured by satellite remote sensing reached record-high values in some sub-regions in 2023. The spring phytoplankton bloom timing was later than normal with a mainly lower-than-normal intensity in 2023. The fall bloom was generally earlier than normal with a higher-than-normal intensity. Diatoms abundance at Halifax-2 indicates increasing levels over the last three years. The abundance of Calanus finmarchicus was on average slightly above normal in the region in 2023, contrasting with the low abundances observed since 2011. Pseudocalanus spp. abundance was on average above normal in the region while zooplankton biomass and the abundance of Arctic Calanus species remained mainly near or below normal levels in 2023.

Resources

Name Format Description Link
Figure 11 : Chlorophyll a inventory at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_11.zip
Figure 13 : Phytoplankton abundance and community composition at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_13.zip
Figure 18 : Zooplankton (> 200 µm) abundance and community composition at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_18.zip
Figure 19 : Annual anomaly scorecards for zooplankton abundance and biomass CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_19.zip
Figure 20 : Copepod abundance and composition at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_20.zip
Figure 22 : Calanus finmarchicus abundance and developmental stage distribution at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_22.zip
Figure 23 : Zooplankton biomass at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_23.zip
Figure 24 : Calanus finmarchicus abundance during the ecosystem trawl surveys CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_24.zip
Figure 25 : Mesozooplankton dry biomass during the ecosystem trawl surveys CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_25.zip
Figure 26 : Calanus finmarchicus abundance during the seasonal surveys on the core sections CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_26.zip
Figure 27 : Mesozooplankton dry biomass during the seasonal surveys on the core sections CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_27.zip
Figure 28 : Annual anomaly scorecard for non-copepod groups abundance on the Scotian Shelf sections CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_28.zip
Figure 29 : Annual anomaly scorecards for copepod indicator species grouped abundance CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_29.zip
Figure 6: Nitrate inventories at the Maritimes high-frequency sampling stations CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_6.zip
Figure 7: Annual anomaly scorecards for surface (0–50 m) and deep (50–150 m) nitrate, silicate, and phosphate inventories CSV https://api-proxy.edh-cde.dfo-mpo.gc.ca/catalogue/records/2bd03ad9-e955-4087-a1ff-f108f09e39d7/attachments/Figure_7.zip
Canadian Technical Report of Fisheries and Aquatic Sciences 3658 PDF https://publications.gc.ca/collections/collection_2025/mpo-dfo/Fs97-6-3658-eng.pdf

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