Oceanographic conditions in the Atlantic zone in 2022

Abstract

Monthly and seasonal average sea surface temperatures were normal to above normal in ice-free areas, with a single monthly exception in the Estuary. Many regional monthly and seasonal records were set. The spatially weighted zonal average was at a record high. The Labrador Current transport was above normal along the Newfoundland and Labrador Shelf break. The transport along the Scotian Shelf break was near normal and has not been above normal since 2011. Winter average sea ice conditions were below normal in the Gulf of St. Lawrence and near normal on the Newfoundland and Labrador Shelf as well as in the Northern Labrador Sea. The winter surface cooling in the central Labrador Sea was the highest since 2015, while the resulting convection depth of 1 600 m was near normal. The cold intermediate layer (CIL) was anomalously warm and of limited extent in the Gulf of St. Lawrence; its August-September volume was second lowest of the time series. However, no CIL metrics can be reported for the rest of the Zone. Bottom temperatures were substantially above normal across the zone, including record highs in the deep waters of the northern Gulf of St. Lawrence, off southern Newfoundland and on the Scotian Shelf. The zonal average index for CIL-influenced bottom temperatures was third highest of the time series and the zonal average index for warmer, below-CIL deep waters was at a record high. At the high-frequency sampling sites, seasonal average 0-50 m and bottom temperatures were all above normal, including a series record in bottom temperature at Rimouski station. Stratification was at a record high at Station 27, offshore of St. John’s. Deep nitrate inventories were above normal off Newfoundland, in the central Gulf of St. Lawrence and Cabot Strait, below normal in the northern Gulf of St. Lawrence and Shediac Valley, and slightly above normal or normal in the southern Gulf of St. Lawrence and on the Scotian Shelf, except for the Bay of Fundy. Surface chlorophyll inventories were highly variable throughout the Atlantic Zone. Above normal inventories occurred on the Newfoundland Shelf, most of the Gulf of St. Lawrence including Cabot Strait, and on the central and western Scotian Shelf. Below normal inventories occurred in the Grand Banks and Flemish Cap, Shediac Valley and the Bay of Fundy. The onset of the spring phytoplankton bloom was normal to late throughout most of the Atlantic Zone, with exceptions in the northern Gulf of St. Lawrence and central and western Scotian Shelf where the time series earliest timing of the spring bloom were observed. The magnitude of the bloom was generally below normal across the zone, but reached record highs on Hamilton Bank, St. Pierre Bank and central Scotian Shelf. The duration of the bloom was mainly shorter than normal, with exceptions of longer than normal values in northern Gulf of St. Lawrence and western Scotian Shelf. The Eastern Scotian Shelf exhibited its latest onset, lowest magnitude and shortest duration on record. Copepod abundance was generally above normal on the Newfoundland Shelf, northwest Gulf, Shediac Valley and Bay of Fundy, and normal or below normal in the rest of the Atlantic Zone. The abundance of non-copepods was close to normal on most of the Newfoundland Shelf, the eastern Scotian Shelf and Bay of Fundy, and above normal off Labrador, the southern Grand Banks and throughout most of the Gulf of St. Lawrence. The abundance of Calanus finmarchicus was below normal on the Scotian Shelf with a record low on the Halifax Line, generally normal in the rest of the Atlantic Zone, and above normal at Station 27. Pseudocalanus spp. abundance was mainly above normal on the Newfoundland Shelf, northwestern Gulf of St. Lawrence, Shediac Valley and Bay of Fundy, below normal in the eastern and central Gulf of St. Lawrence, and mainly normal on the Scotian Shelf. Zooplankton biomass was mostly near normal on the Newfoundland Shelf, above normal in the southern Gulf of St. Lawrence and in the Bay of Fundy, and below normal across the rest of the Gulf of St. Lawrence and most of the Scotian Shelf, reaching a record low in the northwest Gulf of St. Lawrence and Louisbourg section. Dissolved oxygen concentration generally declined in the deep waters of the Gulf of St. Lawrence and was at a record low in the Estuary. The bottom waters at some stations on the Grand Banks, in the Avalon channel and near Cape Breton were undersaturated with respect to Aragonite in the fall. The bottom waters of the St. Lawrence Estuary also reached new record low pH (more acidic conditions). The Central Labrador Sea exhibited record high Pseudocalanus spp. abundance and record low abundance of amphipods.