Here you see the lowering tide in Great Cove yesterday hard at work exposing the intertidal zone and its colorful colony of Ascophyllum nodosum, the seaweed commonly called “rockweed”:
Rockweed is a species of brown algae that gets its common name from growing on rocks and other hard surfaces. It anchors itself there by a “holdfast,” an adhesive foot-like growth.
Rockweed is a valuable member of the wildlife community. Its fronds and the cells that it releases are important food sources for marine organisms and sea birds. At low tide, it protects crabs and other marine animals from predators and the sun; at high tide, it’s an underwater forest that shelters many organisms. It also is a photosynthesizer that consumes harmful carbine dioxide.
Nonetheless – and here’s the rub – it also has significant commercial uses. These include conversion into fertilizers, use as a moist packing material (e.g., for bait and lobsters), and being a source for the food-thickening agent alginate.
The risks and benefits of commercial harvesting of rockweed in Maine have become controversial issues. Under Maine law, coastal upland owners also own and control the intertidal area (with certain irrelevant exceptions). Commercial interests need permission from the owners of the land before harvesting its rockweed.
The rockweed harvesters are lobbying to change that law to allow them to cut the seaweed without permission and environmentalists are seeking stronger applications of the law and other conservation efforts relating to rockweed. If you’re interested in getting more information about the concerns, I suggest that you start with the Blue Hill Peninsula Rockweed Forum: https://rockweedforest.org/.
(Images taken in Brooklin, Maine, on November 25, 2024.) The owner of the intertidal land shown here has refused to permit its harvesting.