2024’s Bumper Southern Upwelling
Southern Australia is currently experiencing one of its most significant upwelling events in recent years, according to marine researchers.
Nutrient-Rich Waters
The phenomenon, which brings nutrient-rich waters to the surface, is vital for the marine ecosystem, supporting a diverse range of marine life, including the enigmatic blue whales.
Images: IMOS
Great Southern Coastal Upwelling
The Great Southern Coastal Upwelling System plays a pivotal role in this natural spectacle, acting as the engine behind the nutrient cycling that underpins the region's marine biodiversity.
Each year this system pumps nutrient-rich water from the deep sea toward the ocean's surface across southern Australia. In these shallow, sunlit waters this natural fertilisation process boosts the growth of algae and phytoplankton, the primary producers at the base of the oceanic food web, which in turn supports a more extensive array of marine life.
Photosynthetic Flourish
Kirsten Rough, a seasoned researcher with the Australian Southern Bluefin Tuna Industry Association has an intimate understanding of the upwelling and offers valuable insights into this year's significant upwelling event.
According to Rough, "The upwelling is really about bringing the nutrients, which are necessary for plant life to grow from the deep dark depths of the ocean floor up into surface waters where the sunlight can actually enable the plants to use them and grow."
Highlighting the extent of this year's upwelling, Rough notes, "This year with such a strong upwelling, we’re seeing an increase in algae growth over a much wider area than usual." Consequently Rough’s team, with the assistance of spotter planes have observed huge numbers of southern bluefin tuna, dolphins, whales and even sometimes rarely seen species including giant squid.
Algal Arteries
Rough highlights this economic significance of the phenomenon, noting, "The seasonal upwellings in this area are key to supporting some of Australia's most valuable fisheries”.
In light of this year's exceptional upwelling event, Rough underscores a crucial point “Probably the only thing we do know is we don’t understand everything. We only see a small part of what’s going on; we don’t see what’s happening at depth”. Her words reinforce the crucial need for further exploration and study of these under-researched waters.
While the spectacle of tuna shoals and shimmering waters highlights the immediate visual impact of this year’s strong upwelling event, it's the broader ecological implications that underscore the significance of this event. A Big upwelling means the system is able to sustain more herbivores, in this case, zooplankton which is a wonderful food source for juvenile and larval fish, jellyfish right up to the biggest creatures on the earth, the blue whales.
Image: Bazz Hockaday
Bumper Upwelling Insights
Dr Pete Gill, founder of the Blue Whale Study, a seasoned scientist with decades of experience in whale research, shared his insights on this year's exceptional upwelling. "We're having a cracker upwelling this year. It's a bumper," he stated, attributing the phenomenon to sustained southeast winds that have been stronger and more persistent than usual.
Pete's fascination with blue whales has been a driving force behind his long-standing research career. He embarked on this journey with a profound interest in these majestic creatures, leading him to pursue a PhD focused on their behaviours and ecology.
During his studies, Pete made groundbreaking discoveries, notably the intricate relationship between blue whales and the upwelling system.
Blue Whale Abundance
Reflecting on a particularly remarkable day, Pete recalled, "There was one day we recorded 70 sightings of blue whales within a ten nautical mile area."
This extraordinary event underscored the abundance that the upwelling can bring to the region and highlighted the critical importance of these nutrient-rich waters in supporting the dense congregations of blue whales.
Elusive Giants
Despite the excitement around this year's upwelling, in a recent aerial survey, Pete and his team observed only a single blue whale. Despite this seemingly sparse observation, Pete isn't overly concerned, he remarked "There's a lot going on because of the big upwelling this season, but we don't know where the biggest aggregations of krill are yet".
Drawing from his extensive research history, he knows that blue whale sightings can fluctuate. “We're kind of looking in these small windows into what is really a very big picture," he explained, underscoring the need for more comprehensive studies to understand the full impact of the upwelling on marine life.
Data-Driven Discoveries
As the season progresses, researchers like Pete hope to gather more data to shed light on the intricate relationships between the upwelling, krill populations, and blue whales. Such research is vital for understanding and protecting these complex and delicate marine ecosystems, which face increasing threats from human activities and climate change.
Learn more about Pete’s work and the Blue Whale Study at https://bluewhalestudy.org/
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