With all I wrote in my previous series of posts, I still had not answered the question people ask me most often about our kelp forests: what happened to them? How and why did they disappear in the first place?
So I went back to my sources with that question and wrote a short article that appeared in our monthly local paper, The First Edition.
Here is the article.
What happened to the kelp?
This was the most-asked question when Conservancy Hornby Island held an open house on October 22, presenting a series of maps of the marine values around the island.
One map showed the eelgrass beds, and the sites where the forests of bull kelp used to be. That ‘used to’ took a lot of people by surprise.
Is it really all gone? What happened?
I asked Amanda Zielinski from Hornby Island Diving, who volunteers for the local kelp restoration project.
The decline has been going on for decades, all over the Pacific Coast, but it is most obvious throughout the Salish Sea, where there is not as much water movement as on the open coast.
Amanda moved here in 1998, and by then the vast majority of the kelp beds were already gone. Rob Zielinski had long ago mapped the areas where they used to be, and this is the data that was on view at the Community Hall.
As with many things in nature, there are several factors at work.
Kelp is very sensitive to sea temperatures. The temperatures have risen most of all near the surface, and that is where the kelp’s reproductive tissues are formed, on the leaf-like blades that we can see at low tide. Warmer water also speeds the growth of various other algae and sea creatures that can engulf the kelp before it is large enough to outgrow them.
Kelp is also sensitive to increases in UV radiation… And of course that is mostly felt at the surface too, where those delicate reproductive structures are.
Kelp is sensitive to many man-made pollutants. Think about the eight pulp mills around the Salish Sea that poured out untreated waste, 24 hours a day, 365 days a year, for most of a century. Mill closures and tightened regulations about the disposal of waste water have helped this situation, but not a moment too soon. Treated-lumber manufacture and storage on the Fraser River has also been implicated.
Kelp is sensitive to sedimentation. Upland development and logging have increased the amount of silt released into our waters. This would affect the kelp most at its microscopic stages but an increase in sediments suspended in the water also means a decrease of light, so this would slow down the growth of the kelp at all stages.
Kelp is also affected by grazers. Sea urchin numbers are increasing. Aside from Sea Otters, whose numbers crashed almost two hundred years ago and who may not have populated the Salish Sea anyway, other animals control sea urchins. The most notable is the Sunflower Star, a huge, many-armed sea star. Disease wiped out our area’s Sunflower Stars three years ago. In the few years before then, there had been a little bit of kelp regrowth at Gravelly Bay, near the ferry dock, and the last large kelp bed near Chrome Island was showing signs of recovery, but after the demise of the Sunflower Star these areas crashed again. This year Rob searched the area and found not a blade.
Since 2011, the Zielinskis and Amanda’s father, biologist Bill Heath, have been working on a kelp restoration project, one of many that have started on both sides of the border. These projects have increased our knowledge of how the kelp grows. Is it too late to restore our kelp forests? What else is here, in that ocean surrounding us, unnoticed and possibly threatened as we go about our daily lives?
