Description 

This species of kelp forms extensive canopies and forests and is one of the largest and most complex macroalgae.  It is usually yellow to deep brown in color, and anchors itself to rocks via a flattened holdfast that spreads over rock surfaces with small finger-like projections (haptera).  The stipe extends from the holdfast and splits numerous times to form a multi-branched individual with hundreds of tapered blades projecting out along the entire lengths of the split stipe, eventually reaching 20 meters in length in warmer, more sun-lit waters.  The corrugated blades are flattened with serrated edges and are typically 25 to 35 centimeters long and up to 5 centimeters wide, with a small elongated pneumatocyst or float at the base or stipe-end of each blade.  These blades (or lamina) are wrinkled or grooved in an irregular pattern, and gradually taper towards the end and are abruptly rounded at the base.  The ultimate shape of the blade is dependent on the degree of water motion it is exposed to during its growth cycle: wave-exposed sites produce blades that are narrow, with a highly corrugated surface and marginal spines that are flush with the blade edge, whereas more sheltered sites produce wider blades, with few surface corrugations and marginal spines that arise at irregular angles to the blade.  The blades grow throughout the length of the stipe instead of only at the terminal region near the surface.  Macrocystis integrifolia has long internodes between the blades at the base of the stipe and short internodes at the top. In the water column the blades are arranged spirally, whereas at the surface the blades are in an alternate arrangement.

It does not seem to grow in areas with salinity lower than that of the open coastal waters, so it is not found very far inland in larger straits, and it prefers minimal seasonal variability in temperature.  Macrocystis integrifolia occurs in the very lowest portion of intertidal and in subtidal waters 7 to 10 meters deep, on rocky substrates.  It favors areas exposed to the open sea but somewhat sheltered from the full force of heavy wave action.  It is a perennial, and can grow in exposed outer coasts, although it may have a shortened lifespan of only one or two years due to wave action, compared to four or more years in more protected habitats.

Macrocystis integrifolia is currently regarded as a taxonomic synonym of Macrocystis pyrifera, but for now a separate page is being maintained as so many products have specifically listed Macrocystis integrifolia as an ingredient.

 

Names 

aracanto, canutillo, giant sea kelp, huiro canutillo, huiro flotador, huiro pato, huiro pito, long bladder kelp, macro

 

Phylum Classification 

Ochrophyta

 

Geographic Distribution 

Macrocystis integrifolia grows along the Pacific coast of South America between Concepción and Arica, and in North America from Baja California north to the Kodiak Archipelago in Alaska.

 

Uses 

Macrocystis integrifolia has industrial, food, and commercial uses. Its principal industrial use is the production of algins and alginates for use in various textiles industries such as paper and cardboard, paint, pharmaceuticals, and plastics.  It is a rich source of iodine and potassium and is valued for its mineral content, so it is used as a nutrient supplement for both humans and farm animals. It is also used in different types of agricultural and gardening fertilizers.  It is used in spa products such as masques, salts, moisturizing mists, and bath soaks.  Currently at least 14 companies across Canada, Peru, Chile, Italy are known to produce over 35 types of products from Macrocystis integrifolia.

 

Harvesting 

Harvesting of Macrocystis integrifolia occurs in Chile, Peru, California, and British Columbia.

 

Harvesting Techniques 

Macrocystis integrifolia is harvested by hand, either at low tide on foot, or by boat.  Since this species is predominantly sub-tidal, harvesting is usually performed with a boat.

 

Ecosystem 

Macrocystis integrifolia can grow intermingled with Macrocystis pyrifera, and are similar in appearance.  A key distinguishing characteristic is that Macrocystis integrifolia has a flattened, rhizome-like holdfast, and Macrocystis pyrifera has a conical holdfast.  Further north Macrocystis integrifolia grows in the neighborhood of Nereocystis luetkeana, and after the first large storms in the autumn, Macrocystis will end up in tangled masses with Nereocystis on the beaches.  Floating at or near the sea surface, Macrocystis integrifolia forms extensive masses of beds with rich-brown leaf-like blades.  Thus a dense forest is established which serves as a valuable habitat for hundreds of invertebrate, fish, and seaweed species which depend on this valuable canopy for shelter, food and protection, the same role canopy trees play in a tropical rain forest.  Residents include gastropods, ophiuroids, amphipods and bryozoans.  Along the Pacific coast of South America, Macrocystis integrifolia and Lessonia trabeculata form vast kelp beds providing a three-dimensional habitat for diverse invertebrate and fish fauna off northern Chile and Peru.  Unattached, drifting kelp plants are consumed by abalone, sea urchins, and other grazers.  Macrocystis integrifolia also exudes dissolved organic matter that is available for consumption by filter and suspension feeders.  Another reason this species is valuable and important is that herring lay their row on this kelp, which is part of a larger marine ecosystem and the broader fishing and seafood industry.