Kelp off Chebeague Island in Maine.Gregory Rec/Portland portland Press Herald/Getty
Maine’s iconic kelp forests are facing a double threat, and the future of these underwater ecosystems hangs in the balance. Researchers have discovered that invasive red turf algae is preventing the regeneration of kelp, compounding the damage already caused by warming ocean temperatures.
A New Invasive Threat to Kelp Forests
Table of Contents
The rise of red turf algae, coupled with marine heatwaves, is jeopardizing kelp forests along the Maine coast and beyond.
- University of Maine researchers are documenting the decline of kelp forests in the Gulf of Maine.
- Red turf algae releases chemicals that inhibit the growth of juvenile kelp.
- Warming waters are exacerbating the problem, favoring the invasive algae over native kelp.
- The loss of kelp forests could have cascading effects on marine ecosystems and fisheries.
For the past three years, University of Maine Ph.D. student Shane Farrell has been diving off the coast of Maine, meticulously surveying the health of the region’s kelp forests. What he and his team at the Bigelow Laboratory for Ocean Sciences are finding is deeply concerning: a rapid decline in kelp cover, not just from warming waters, but from a newly identified aggressor-red turf algae.
The Chemical Warfare of Red Turf Algae
The team’s recent study, published in Science, revealed that this invasive algae releases waterborne chemicals that act as a potent deterrent to kelp regeneration. These allelopathic chemicals specifically target the gametophyte phase of kelp reproduction-the crucial stage when kelp spores develop into mature plants-hindering their ability to establish and survive on the seafloor.
“What was most shocking was that the types of chemicals found in the study are also found behind the lack of recovery in certain coral reefs and tropical rainforests,” Farrell said, highlighting the broader implications of this invasive species’ impact.
The proliferation of this red algae, originally from Asia, is directly linked to warming water temperatures. Doug Rasher,a senior research scientist at Bigelow’s Rasher Lab,explained that the current temperatures in the North Atlantic now match the algae’s native habitat,giving it a competitive advantage over cold-water kelp.
A Regional Crisis with Global Implications
Kelp forests are a vital component of Maine’s coastal ecosystem, stretching from Canada to Massachusetts. However,between 2004 and 2018,southern Maine experienced an alarming 80 percent decline in kelp cover,largely due to the region’s relatively warmer waters.
“This transition from kelp to turf algae is not just happening here in Maine. Its happening in places of rapid ocean warming around the world,” Farrell emphasized.
Beyond Algae: A Multifaceted Threat
The red turf algae isn’t the sole culprit in the kelp forest decline.
The Challenge of restoration
While physical removal of invasive algae has proven effective in some areas, like the Mediterranean, it’s a labor-intensive process. Witman noted that red algal turf, being filamentous, is much more difficult to remove than larger, more easily targeted species.
Rasher emphasized the need for further research into the long-term resilience of kelp forests, including identifying kelp cultivars that can withstand warmer ocean temperatures and developing strategies to improve reef receptivity by removing turf algae.
The research was funded by the National Science Foundation and the National Oceanic and Atmospheric Administration. Rasher noted that his lab is diversifying its funding sources to include foundational and philanthropic support, in addition to federal funding.
