In a troubling development for marine ecosystems, a harmful bloom of the microalgae species Karenia mikimotoi has wreaked havoc off the coast of South Australia. So far, this bloom has endured for three months! It is resulting in tremendous non-target marine life mortality, particularly to ray-finned fish and sharks. Now, scientists working in the Earth Life Interaction Center for T14 are studying the environmental conditions that might have caused this phenomenon.
The explosive bloom of Karenia mikimotoi has devastated marine life. Its settlement has dramatically changed the underwater scenery surrounding the Edithburgh Jetty on the Yorke Peninsula. Though this invasive microalgae is harmless to humans, the ecological ramifications on local marine biodiversity have been devastating. That led to a huge die-off, which has been attributed to the bloom. Nearly 50% of the dead marine animals are species of ray-finned fish and 25% sharks and rays.
The Impact of Karenia mikimotoi
Karenia mikimotoi is a species of microalgae often responsible for harmful algal blooms (HABs). These blooms can produce extremely powerful toxins which heavily damage marine fauna. The current bloom off South Australia has led to widespread mortality among various marine species, signaling a pressing ecological crisis.
Just recently, scientists released some especially frightening news. This bloom has released enough toxins that fish are being poisoned and oxygen levels in the water are so low they create dead zones. This toxic, unregulated stormwater runoff wreaks havoc on our aquatic life, resulting in millions of marine organism deaths each year. The state of the waters there has raised alarm among environmentalists and marine biologists about what this means for local ecosystems in the long run.
Unprecedented sea surface temperature anomalies are amplifying the impacts. This has resulted in temperatures since September at 2.5°C above average. It is these higher temperatures that are believed to serve as triggering factors for the expansion of harmful algal blooms, like Karenia mikimotoi. Experts, including the National Oceanic and Atmospheric Administration, have long attributed increasing sea temperatures to climate change. That trend, in turn, would make future blooms more likely to occur often.
A Broader Ecological Concern
The consequences of the algal bloom go well beyond the immediate fish kill. As loss of keystone species tip the balance of the ecosystem. Flipping this balance can set off a ripple effect across the entire food web. In turn, this dramatic loss of ray-finned fish and sharks breaks down important predator-prey dynamics. This drop puts other species, including federally threatened species that depend on these fish for food, at risk.
“High toxin algal blooms are becoming widespread due to a lack of monitoring and enforcement,” said UAMS researcher and co-author Dr. Understanding the mechanisms behind their occurrence can aid in developing effective strategies for managing and mitigating their impact on marine ecosystems.
Future Implications and Research Directions
The persistent study of Karenia mikimotoi and its kin is essential to observing their place within marine ecosystems. Microalgae, such as Karenia, are essential contributors to our atmosphere. They generate an estimated 60% of the oxygen we breathe, highlighting their importance well beyond just favorite food web, ecological interactions.
As scientists continue to investigate the relationship between changing environmental conditions and harmful algal blooms, there is hope for gaining insights into preventing future crises. Greater collaborative efforts among local officials, academic researchers, and environmental advocacy groups will be necessary to meet this ascendant threat.