Giant Kelp
Macrocystis pyrifera
Giant kelp look like underwater plants with their green color, large blades, and holdfasts (or root-like structures that anchor them to the ocean floor). However, they are not plants at all! Giant kelp are one of the largest species of marine algae. They use their large blades to collect sunlight and absorb nutrients from the water. Gas bladders keep them upright, letting them stretch from the ocean floor to the ocean’s surface. Once they reach the surface they continue to grow, creating a kelp canopy. Giant kelp forests are home to many marine species including sea otters and are food for sea urchins. Giant kelp are incredibly important in maintaining a healthy ecosystem.
Credit: Aquarium of the Pacific / Andrew Reitsma
SPECIES IN DETAIL
Giant Kelp
Macrocystis pyrifera
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE:
Geographic Distribution
Giant kelp can be found off the coasts of South America, Western North America, South Africa, Australia, and New Zealand.
Habitat
With their holdfast and rapid growth rate of 60 centimeters (2 feet) per day, this algae is best suited to survive in rocky reefs with high wave activity. Giant kelp can grow as deep as 30 meters (100 feet) below the surface of the ocean.
Physical Characteristics
At the bottom of giant kelp are holdfasts which anchor the algae to rocky reefs. Out from the stipe (center stalk) grow large leaf-like structures to collect sunlight and pneumatocyst (bulbs filled with gas) to keep the algae upright.
Size
Depending on environmental conditions this algae can grow anywhere from 30 to 53 meters (100 to 175 feet) in their lifetime.
Diet
This is the largest marine algae, feeding off of sunlight and nutrients in the water through photosynthesis.
Reproduction
Giant kelp reproduces in two stages through spores and gametes. The adult giant kelp has fronds at the base which create packets of spores (sori). These packets release spores into the water and can be released year-round but mostly happen in the spring and summer. The spores usually settle within 10 meters (33 feet) of the parent algae. When the spores settle on hard surfaces like rocks, they start their second stage and form male and female gametophytes. These produce eggs and sperm. Fertilized eggs will grow into new kelp.
Behavior
This algae grows in dense groups called kelp forests. The kelp forest canopies offer protection for a variety of marine species including sea otters.
Adaptation
This algae has several adaptations that allow them to thrive in their environment. Firstly, the structure itself contains gas bladders to keep themselves upright, blades to collect sunlight, and holdfasts that anchor them down. Secondly, they have a fast growth rate at about 60 centimeters (2 feet) per day in ideal conditions.
Longevity
With the right conditions giant kelp will survive for a maximum of 7 years. However, their lifespan can be reduced in an area with high wave activity or an increase in sea urchin populations.
Conservation
Currently, there is no limit on the harvest of giant kelp with the exception of restrictions in Marine Protected Areas. Some countries, like New Zealand, have limited their giant kelp harvest (mainly for abalone blister pearls) to 1500 metric tons (3,306,934 lbs) a year.
Special Notes
Pneumatocysts are the gas filled bulbs that keep the kelp upright.
Dense groups of giant kelp create underwater forests. The kelp structure is a hiding place for fish, invertebrates and is food for urchins.
Giant kelp is not a plant but rather a large marine algae.
SPECIES IN DETAIL | Print full entry
Giant Kelp
Macrocystis pyrifera
CONSERVATION STATUS: Not evaluated
CLIMATE CHANGE:
Giant kelp can be found off the coasts of South America, Western North America, South Africa, Australia, and New Zealand.
With their holdfast and rapid growth rate of 60 centimeters (2 feet) per day, this algae is best suited to survive in rocky reefs with high wave activity. Giant kelp can grow as deep as 30 meters (100 feet) below the surface of the ocean.
At the bottom of giant kelp are holdfasts which anchor the algae to rocky reefs. Out from the stipe (center stalk) grow large leaf-like structures to collect sunlight and pneumatocyst (bulbs filled with gas) to keep the algae upright.
Depending on environmental conditions this algae can grow anywhere from 30 to 53 meters (100 to 175 feet) in their lifetime.
This is the largest marine algae, feeding off of sunlight and nutrients in the water through photosynthesis.
Giant kelp reproduces in two stages through spores and gametes. The adult giant kelp has fronds at the base which create packets of spores (sori). These packets release spores into the water and can be released year-round but mostly happen in the spring and summer. The spores usually settle within 10 meters (33 feet) of the parent algae. When the spores settle on hard surfaces like rocks, they start their second stage and form male and female gametophytes. These produce eggs and sperm. Fertilized eggs will grow into new kelp.
This algae grows in dense groups called kelp forests. The kelp forest canopies offer protection for a variety of marine species including sea otters.
This algae has several adaptations that allow them to thrive in their environment. Firstly, the structure itself contains gas bladders to keep themselves upright, blades to collect sunlight, and holdfasts that anchor them down. Secondly, they have a fast growth rate at about 60 centimeters (2 feet) per day in ideal conditions.
With the right conditions giant kelp will survive for a maximum of 7 years. However, their lifespan can be reduced in an area with high wave activity or an increase in sea urchin populations.
Currently, there is no limit on the harvest of giant kelp with the exception of restrictions in Marine Protected Areas. Some countries, like New Zealand, have limited their giant kelp harvest (mainly for abalone blister pearls) to 1500 metric tons (3,306,934 lbs) a year.
Pneumatocysts are the gas filled bulbs that keep the kelp upright.
Dense groups of giant kelp create underwater forests. The kelp structure is a hiding place for fish, invertebrates and is food for urchins.
Giant kelp is not a plant but rather a large marine algae.