We can lose sight of the central role that seaweed plays in the coastal habitat of Northern California. For while often present before our eyes, the problems of mapping often submerge seaweed forests with any fixity is mirrored by the threatened disappearance of offshore kelp beds in an amazingly rapid timeframe, as creating an actual image capture able to register the extent of kelp forests poses challenges to the diminishing kelp beds off the California coast. The rise of “sea urchin barrens,” where the near coastal waters are cleared of seaweeds and kelp, is a global problem, from Norway to Japan to but the decline of natural predators of urchins in California has made their sudden rise along the coast While the decline of kelp forests seems as radical as the clear-cutting of redwoods, it is both far more rapid and far more environmentally disruptive, if far less visible to the human eye.
For in recent decades, increasingly warming waters and out of whack ecosystems have led to a massive decline of seaweed, decimated by a rise in the sea urchin population to by 10,000 percent off the California coast over only last five years, shrinking kelp forests that stand to catapult us to a future for which we have no map. The long-term decline in sea otters and sea stars, natural predators of the urchins, have removed constraints on urchin growth, which warming waters has encouraged, reducing a historical abundance of kelp in the near coastal waters across California.
This has perhaps been difficult to register due to the problems of mapping seaweed, and indeed registering kelp forests’ decline. The advance of sea urchin populations that have created barrens in coastal waters stands to disrupt and overturn some of the most abundant ecological niches in the global oceans. How has this happened under our eyes, so close tho shore and lying just undersea? We have few real maps of seaweed or kelp, lurking underwater, rather than above land, and leave out kelp from most of our maps, which largely privilege land. But the abundance of kelp that produce most of the global oxygen supply live in underwater ecotones–sensitive places between land and sea, in-between areas of shallow water, abundant sunlight, and blending of land and sea–an intersection, properly understood, between biomes, on which different biological communities depend.
Looking at the offshore seaweed near Santa Cruz, CA, I wondered if the predominantly passive registration of location–onshore registration of sites remotely by satellites, familiar from the harrowing images of the spread of fires, provided a basis to register our states of emergencies that was spectacularly unsuited to the contraction of coastal kelp, despite the huge advances of mapping techniques, and left us without a map to their contraction, or to register the subtle if radical consequences of kelp loss, and the almost as devastatingly rapid progress of their advance as populations of urchins have mowed down underseas kelp beds. For even as we strike alarms for the the decline of global kelp populations and seaweed forests as a result of the warming of offshore temperatures that place the near offshore regions at special risk of atmospheric warming–
–we lack maps of the place of seaweed and kelp beds in their ecotone, and indeed have no adequate maps of seaweed populations under threat that is comparable, say, to the devastation of forests by fire, whose growth we can witness, terrifyingly, with each overhead passing of a satellite in the recent forest fires, and whose decimation by loggers in earlier generations we can also map. The tree-loss reduced habitats, but I worry we can barely chart save metaphorically the reduction of kelp beds.
We cannot help, however, but to be reminded by maps showing the loss of seaweed with great rapidity of the rapid advance of the burn perimeters of Yosemite wildfires of 2013, North Bay Fires, or the disastrous Camp Fire of 2018. The rapid pace of the loss of these forested lands seems eerily echoed in the shrinking of coastal beds of kelp along Northern California, and correlates to the advance of warming climes.
If we have developed tools to map the continuity, intensity, and growth of forest fires by satellite and drones, the problem of passively registering the loss of kelp forests, and its relation to the advance of urchin beds, removes a part of coastal environments we are in need of mapping. The scale of maps of the destruction of seaweed beds on the California coast are less rooted in real time, but have advanced in striking fashion over ten years, although the ravages of destruction for now seem to remain undersea. But we are less skilled to communicate their crucial place in offshore environments.