A Marine Institute researcher co-authored a scientific paper examining marine heat waves on the Newfoundland and Labrador (NL) Shelf during a four-month period in 2023.

The study found that low winds, high freshwater content and high stratification were contributing factors to high sea surface temperature anomalies.

Dr. Frédéric Cyr, a research scientist with the Marine Institute’s Centre for Fisheries Ecosystem Research, is one of the paper’s six co-authors. Dr. Nancy Soontiens, a scientist with Fisheries and Oceans Canada, is the lead author.

Titled An analysis of the 2023 summer and fall marine heat waves on the Newfoundland and Labrador Shelf, the study was published in the journal State of the Planet on September 30.

Increasing surface temperatures

Defined as a prolonged period of above average sea surface temperatures, marine heat waves form when heat is trapped in a thin layer at the surface, unable to spread out over a thicker layer.

For this study, data was collected from the entire NL Shelf as well as from four specific regions within the Shelf: Labrador Shelf, Northeast newfoundland Shelf, Grand Bank and Flemish Cap.

Analyzing sea surface temperatures from July to October, researchers found that a series of marine heat waves occurred in each region throughout the timeframe.

Their study found that marine heat wave occurrence coincided with periods of increased stratification. These higher levels of stratification can be attributed to climate change causing an abundance of freshwater from ice melt and runoff.

“With continued anthropogenic climate change, it is likely these marine heat waves will continue to be prevalent in regions of the North Atlantic Ocean, including the Newfoundland and Labrador Shelf,” said Dr. Cyr.

The marine heat waves formed when heat was trapped in a thin layer, unable to spread out over a thicker layer.

Findings from the paper encourage taking marine heat waves into consideration with exploring ecosystem impacts.

“As marine heat waves sit on the surface of the ocean, they will have the greatest impact on ecosystem elements that are more reliant on stable surface conditions” added Dr. Cyr.

“Increased understanding and monitoring of marine heat waves will be important for future studies to see the effects they have on ecosystems in different geographic regions and depths.”

Global report

The study was conducted as part of a larger, annual initiative called the Ocean State Report (OSR) that provides changes in the ocean over time, with particular focus on extreme events from 2023 and 2024.

Now in its ninth edition, the report is a collaboration between experts from around the world and published by Copernicus Marine Service. The co-authored paper is featured in chapter four of the OSR9.