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Current Conditions of the Northeast U.S. Shelf Ecosystem: Fall 2022 Update

A summary of temperature, salinity, chlorophyll and other conditions on the Northeast U.S. Continental Shelf during the first half of 2022.

New England/Mid-Atlantic

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Introduction 

“Current Conditions” is a biannual report on ecosystem and fisheries data for the Northeast U.S. continental shelf ecosystem. The report includes selected indicators of the physical and biological environment focusing on changes in the first half year and reflect data collected in seasonal scientific surveys. You may use this link to access archived reports.

Summary 

  • During the first half of 2022, sea surface temperatures in the Northeast U.S. Shelf Ecosystem continued to be well above average. A shift in thermal conditions began around 2010 with a step change of near 1°C higher temperatures in most subregions of the ecosystem. 
  • The spring thermal transition on Georges Bank was the earliest in the time series in 2022, indicating a transition date to spring conditions of May 14, which represents a shift of 3 to 4 weeks earlier. 
  • Spring phytoplankton blooms did not form in either the Gulf of Maine or Georges Bank ecoregions in 2022; however, there was evidence of winter blooms in some areas. Chlorophyll concentrations were generally below average throughout the ecosystem.
  • Fish and macroinvertebrate distributions have shifted to deeper depths and more to the northeast along the coast. 

Temperature

Daily Sea Surface Temperature for the First Half of the Year

Daily sea surface temperatures were at or above average conditions during the first half of 2022. The Georges Bank and Gulf of Maine ecoregions had the largest departures from average conditions. Spring temperatures were approximately 2°C above the long-term average. In the Mid-Atlantic, temperatures fluctuated around the mean for the second half of the spring. In all areas except for the Mid-Atlantic Bight, temperatures moderated well above the mean by mid-year. 

Four line graphs showing the daily sea surface temperatures for all years between 1982 and 2021 for the first six months of the year. Top Row: Georges Bank and Gulf of Maine. Bottom Row: Middle Atlantic Bight and Scotian Shelf.
The 2022 (red) daily sea surface temperature compared to temperatures from 1982 through 2021 (transparent blue). The dotted lines represent the plus/minus one standard deviation from the 1982–2021 time series mean (black line). Credit: NOAA Fisheries

Sea Surface Temperature Trends for the First Half of the Year

Average sea surface temperatures for the first half of 2022 continued at high levels in all ecoregions. In Georges Bank, thermal conditions were the second warmest since the record-high temperatures observed in 2012. Spring temperatures in all areas appear to have experienced a change in level around the year 2010, increasing the mean temperature by 1°C. 

Four line graphs showing sea surface temperature for the first six months of the year from 1982 to 2022. Top Row: Georges Bank and Gulf of Maine. Bottom Row: Middle Atlantic Bight and Scotian Shelf.
Mean sea surface temperature for the first six months of the year. The red lines show the linear trend, the titles indicate the trend’s significance, and the blue lines represent change points. Credit: NOAA Fisheries

The distributions of sea surface temperature by ecoregions were generally above normal. However, monthly sea surface temperature imagery shows that temperatures were below normal in the Mid-Atlantic during May. The strongest temperature anomalies were observed in Georges Bank area along its southern flank.

ix maps of the Northeast U.S. continental shelf showing 2022 monthly sea surface temperature differences from the long-term 1982-2020 baseline shown as color difference. Top row: January, February, and March. Bottom row: April, May, and June. Darker cool colors dominate the Mid Atlantic Bight in the May map. Vibrant hot color dominates the southern edge of Georges Bank in May and June.
Monthly mean sea surface temperature anomalies showing the difference between the monthly 2022 average and the long-term 1982-2020 temperature baseline. Credit: NOAA Fisheries

Trends in Variability of Sea Surface Temperature for the First Half of the Year

Sea surface temperature variability (the standard deviation within each ecoregion) for the first half of 2022 increased in the more northern Northeast Shelf ecoregions. The increase in variability appears to be significant in the Gulf of Maine and Scotian Shelf but not significant in the other areas. There were no clear-cut patterns in any change points in variability between areas.

Four line graphs showing sea surface temperature standard deviation for the first half of 2022. Top row: Georges Bank and Gulf of Maine. Bottom row: Middle Atlantic Bight and Scotian shelf.
Variability of sea surface temperature for the first six months of each year. The red lines show the linear trend, the titles indicate the trend’s significance, and the blue lines represent change points. Credit: NOAA Fisheries

Long-term Trends of Sea Surface Temperature for the First Year

We derived the long-term temperature time series from the Extended Reconstructed Sea Surface Temperature dataset. It provides a low-resolution depiction of sea surface temperature on the Northeast Shelf since the 1850s. The data is based on historical shipboard measures and augmented with other data in recent years. The temperature for the first half of 2022 was above average and was among the highest values in the data time series.

Line graph showing the mean sea surface temperature for the first six months of the year from 1850 to 2022 for the Northeast Shelf. Range is 6 to more than 10 degrees Celsius. The linear trend line rises gradually by year, from left to right. The change point line also rises left to right. The dots vary, but their values also rise gradually from left to right.
The long-term (1854–2022) mean sea surface temperature for the first six months of each year. The dots are the annual mean temperature values, the red line shows the linear trend, the blue lines represent change points, and the titles indicate the trend’s significance. Credit: NOAA Fisheries

Spring Thermal Transition Day

Phenology is the seasonal timing of plant and animal production cycles. Many marine organisms time their reproductive cycles to make best use of seasonal phytoplankton blooms, such as the spring and fall blooms. In turn, temperature plays a role in the development of blooms. The initiation date of the spring transition temperature, which varies by region, is likely related to different forcing factors. The spring thermal transition date was relatively constant from 1982 to approximately 2010 for the Northeast Shelf ecoregions. A change point appeared in the northern areas around 2010, when the transition date advanced by approximately two weeks. In recent years, the trend toward earlier spring transition dates appears significant in northern segments of the ecosystem—the Gulf of Maine and Scotian Shelf ecoregions, noting that the 2022 spring transition in the Georges Bank was the earliest in the time series.

Four line graphs showing fall temperature transition date from 1982 to 2022. Top row: Georges Bank and Gulf of Maine. Bottom row: Middle Atlantic Bight and Scotian Shelf. The values decline by year, sloping downward from left to right.
The spring temperature transition date. The red lines show the linear trend, the titles indicate the trend’s significance, and the blue lines represent change points. Credit: NOAA Fisheries

Chlorophyll Concentration

Weekly Chlorophyll for the First Half of the Year

Phytoplankton blooms, measured as chlorophyll concentration, are a major component of the food web. They are a primary food source for zooplankton and filter feeders such as shellfish. Chlorophyll concentration was generally below average during the first half of 2022. In areas that typically have a spring bloom, such as Georges Bank and the Gulf of Maine, chlorophyll concentration varied below the long-term average through the bloom period. The chlorophyll concentration for the Middle Atlantic Bight and Scotian Shelf also tended to be below the long term mean.

Four line graphs showing the 8-day mean chlorophyll concentration from 1998 to 2022 for the first six months of the year.Top row: Georges Bank and Gulf of Maine. Bottom row: Middle Atlantic Bight and Scotian shelf. The line representing chlorophyll concentration by year is generally below the line representing the average by year.
The 8-day mean chlorophyll concentration (2022 in red and 1998–2021 in transparent blue). The dotted lines represent the plus/minus one standard deviation from the 1998–2021 time series mean (black line). Credit: NOAA Fisheries

Chlorophyll Concentration Trends for the First Half of the Year

Average chlorophyll concentrations during the first half of the year appears to have decreased in recent years in all subareas of the ecosystem to a low point in 2019. With the exception of the Scotian Shelf, the declining trends were significant. In the Gulf of Maine and Scotian Shelf, chlorophyll concentrations appear to be increasing in recent years. It is noteworthy that we have identified a change point in chlorophyll concentration in all areas within the last decade or so.

Four line graphs showing mean chlorophyll concentration for the first six months of the year from 1998 to 2022. Top row: Georges Bank and Gulf of Maine. Bottom row: Middle Atlantic Bight and Scotian shelf. The lines representing average chlorophyll concentrations during the first half of the year slope downward by year, from left to right. The line representing yearly values show increases in the Gulf of Maine and on the Scotian Shelf since 2019.
Mean chlorophyll concentration for the first six months of each year. The red lines show the linear trend, the titles indicate the trend’s significance, and the blue lines represent change points. Credit: NOAA Fisheries

Fish Distribution from Spring Survey Data

  • The distribution of Northeast Shelf ecosystem species have changed over recent decades. Individual species have shifted distribution for numerous of reasons, and these shifts can be characterized in a number of different ways. Three metrics have been used to characterize species distribution on the Northeast Shelf:The position in the ecosystem along an axis oriented from the southwest to the northeast referred to as the along shelf distance. Along- shelf distances range from 0 to 1360 km, which relates to positions along the axis from the origin in southwest to northeast.  
  • The depth of occurrence, which ranges from 0 to -260 m The distance from the coastline, from 0 to 110 km

These indices are based on 48 of the most abundant taxa. Along-shelf distance has increased over time, reflecting a shift in species distribution to the Northeast; the 2022 distance was the second highest in the time series. Depth of occurrence has also increased over time, reflecting a greater use of deeper habitats. There is no significant trend in distance to the coastline. The map position of the center of gravity for these species was at its second most extreme northeastern position in 2022, east of Nantucket Island, in contrast to the first point in the time series 1968, which was well to the south and west. 

Three line graphs showing the distribution parameters for the spring time period from 1998 to 2022 and a map with dots. Top Row: Along shelf distance and depth. Bottom Row: Distance to the coast and center of gravity map showing the movement to the northeast.
Mean distribution parameter for the spring time period. The red lines show the linear trend, the titles indicate the trend’s significance, and the blue lines represent change points. Map shows the center of gravity for all species, with the first and last years of the time series marked in red. Credit: NOAA Fisheries

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Last updated by Northeast Fisheries Science Center on 11/08/2024

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