ISSUES: Is Rockweed harvesting damaging our marine ecosystem? And why should you care?

by artmackay

This series of articles provides information and resources for common marine plants and animals found along the North Atlantic coast. Great resources for explorers and teachers

ROCKWEED. There are a number of different species of algae that we call "rockweed". This article is about the most common species Ascophyllum nodosum. It's the abundant species that you see growing on intertidal rocky surfaces everywhere along the coast of New England and the Atlantic Provinces. It is so abundant in fact that most folks don't realize that it is a keystone species that is vital to many marine creatures that depend on it directly or indirectly. This article will help you understand the importance of rockweed and, perhaps, actions that you can take to ensure our marine coasts are properly managed.

Bags of rockweed ready to go to the buyer.
Bags of rockweed ready to go to the buyer.
Art MacKay

Ascophyllum nodosum

Common Names: Rockweed, Knotted Wrack

Phylum: Heterokontophyta (Brown seaweeds)

Class: Phaeophyceae

Order: Fucales

Family: Fucacae

Distribution: All coasts of the North Atlantic

Credit: Wikipedia











Habitat: Ascophyllum nodosum is found intertidally on rocky shores in a wide range of exposures but most abundantly at sheltered rocky sites in the mid-littoral where it is usually the dominant species.

Credit Wikipedia

Description: Ascophyllum nodosum is olive-brown. It has long fronds with large dominant air-bladders that occur at regular intervals.The stocks are somewhat flattened and have no mid-rib.

Plants can reach 2 m or more and are attached to the rock surface by strong holdfasts. They create a virtual forest when the tide is high and cover and protect the rock surface and it's other inhabitants when the tide falls. 

Uses: Rockweed has always been known as a garden fertilizer, mulch and soil conditioner. Today, growth-promoting compounds are extracted to produce a liquid "foliar feed" that can be sprayed directly on the crops. It is also processed into kelp meal, a nutritious feed for livestock and compounds called "alginates" which serve as a stabilizer and thickener in thousands of commercial products ranging from paints, to cosmetics to puddings.

Rockweed is frequently used in baitworm and lobster shipments to provide a moist environment while these live animals make their way to various domestic and international locations.


The Rockweed Coalition

If you would like to learn more about rockweed harvesting, the most active coalition can be found at:

Topics covered include:

2014-2015 STATE (DMR) Rockweed Management Plan Development.

LEGAL ISSUE: Who owns the rockweed? The intertidal shore to Mean Low Water is privately owned in Maine. Is cutting vegetation on private property "fishing"?


Is rockweed harvesting "sustainable"?

Canadian government report: rockweed has been overharvested in Nova Scotia and the rockweed harvest must be regulated more carefully to be more "sustainable"!

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Ecology and Management of Maine's Eelgrass, Rockweeds, and Kelps

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Updated: 02/18/2016, artmackay
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