Chinese scientists have developed a detection algorithm for special oceanic features that serve as biodiversity hotspots, offering a possible breakthrough to help fishermen and researchers find prime fishing grounds.
The team’s dataset and detection algorithm on global ocean fronts – boundaries at which two distinct bodies of water meet – could have broad applications in oceanography, ecology and fisheries research.
The high-resolution dataset validated with on-site measurements could become a powerful tool for better understanding and managing the ocean, including examining the impact of climate change.
“This study provides the first publicly available global ocean front dataset covering the past 42 years,” the team said in a paper published in the peer-reviewed journal Earth System Science Data in June.
“Our open-access dataset and detection algorithm can provide a valuable tool for studies on ocean dynamics, marine ecology, biogeochemistry, ocean management, climate change and as a training dataset for artificial intelligence in both regional and global oceans.”
Ocean fronts are the meeting points or lines between two bodies of water with different properties, such as temperature, density or salinity. The fronts create areas where the exchange of energy and nutrients is stronger than elsewhere in the ocean.
This leads to an abundance of nutrients in fronts, attracting all kinds of marine organisms, including fish.
“Oceanographic features like fronts cannot be directly observed and are implicitly present in both observed and simulated marine environmental data,” the team said.
“This gap in interdisciplinary research forces oceanographers and ecologists to devote substantial time and resources to acquiring essential frontal data.”
In 2020, a team led by Yu Haiqing, an associate professor at Shandong University, noticed that the distribution of saury fishing grounds in the northwest Pacific Ocean did not match observed and predicted ocean front locations.
They found that traditional ocean front identification methods were not very accurate in predicting fishing grounds and that the issue may lie in understanding which fronts are useful to predict, according to an article published last month by China Science Daily.
Mesoscale fronts are large, slow-moving features in the ocean that are tens to hundreds of kilometres wide, while submesoscale fronts are smaller features that can have more intense mixing of ocean elements but are short-lived.
The team found that existing algorithms incorporating satellite data identified numerous submesoscale fronts, which appeared to have a limited impact on saury fishing ground distribution, while mesoscale fronts became buried under the data.
“This prompted us to come up with a key conjecture: perhaps only those mesoscale fronts with a wide spatial range and long duration have a significant impact on the distribution of fishing grounds,” Yu told China Science Daily.
Using this knowledge, the team from Shandong University and Shanghai Ocean University generated the first publicly available, high-resolution daily global mesoscale ocean front dataset spanning 1982 to 2023.
“This daily frontal information can be easily integrated with biogeochemical data, plankton data, and fish and marine predator distribution data,” the researchers said.
“Additionally, our front data offer valuable references for the design of marine protected areas, considering the potential aggregation effects of human activities, protected species and floating marine debris.”
To create the dataset, the team used an improved version of an algorithm that is already widely used in marine ecology and fisheries research.
And to validate the reliability of their dataset, the team compared it to five independent datasets of sea surface measurements, including measurements taken from ships, which can provide a higher level of accuracy than satellite measurements.
“What we hope to provide is not just images or animations but high-credibility data that can be directly input into the model as variables and used for quantitative analysis,” Yu said. – South China Morning Post
