All About Bull Kelp

Bull kelp is a marine brown algae but can often appear green in colour. The stripe grows upward and is typically around 10m tall. It is hollow and is around 1 cm in diameter, getting wider at the top (called the float). The float (aka the pneumatocyst) is filled with gas which can contain up to 10% carbon monoxide). The float carries two bunches of up to 64 blades, and since the float often reaches the surface, these blades spread out along the surface of the water where the photosynthetic rates are higher. The blades can reach up to 10 m long and 15 cm wide and grow continuously from a meristem located at their base. The older, outer tips of the blades slough off and the detritus formed by the sloughing has been shown to be an important source of carbon for inshore intertidal ecosystems. 

Names

Habitat:

Bull kelp is commonly found in areas with high current or moderate wave action where it anchors itself to the rocks by its fingerlike projections (known as the holdfast). It can be found in both the inertial and subtidal zones, attaching to rocks up to 20m deep. This kelp tends to grow in relatively high densities forming what is known as a kelp forest. Bull kelp thrives in the cold water temperatures of the Pacific Northwest.

Bull kelp plays a key role in marine ecosystems, creating a forest that provides both food and shelter for other species. Even when the forests die off in the winter the floating masses of dead bull kelp continue to be important for many species.

Distribution: 

Bull kelp can be found along the West Coast from Alaska down to central California. 

Conservation:

Elders have expressed the importance that kelp species have on both the ecosystem as well as First Nations’ ways of life. There is an inherent connection between the health of the land and the health of the peoples who have stewarded those lands since time immemorial. If there is continued loss and degradation of the kelp forests and marine ecosystems there will be a concurrent loss of culture for those coastal Nations that are so closely tied with the marine environments (Turner, 2001)

Extreme climatic events such as marine heat waves have impacted marine ecosystems around the world including foundational species such as coral and kelp. Bull kelp has declined in some areas along the Pacific Northwest Coast where there has been persistently warm water temperatures and nutrient poor conditions (Rogers-Bennett & Catton, 2019)

Indigenous Knowledge and Uses:

There is a close relationship between kelp and many of the Pacific Northwest First Nations peoples. Kelp has been referred to as both an ecological and cultural foundation species, which highlights the significance that a loss of kelp would have on both the ecosystems as well as cultural knowledge (Turner, 2004). Traditional ecological knowledge serves as an integral component to the recovery and conservation of kelp throughout the Pacific Northwest Coast. 

Bull kelp was a valued marine plant material for many nations along the Northwest Coast (Turner, 2001). It was used for many purposes such as anchor lines and as fishing lines (Turner, 2001). To make fishing lines, the stripes were cut by divers and were then cured by alternatively soaking in freshwater and saltwater and then drying and rubbing them with dogfish oil (Turner, 2001). This process could take up to a year according to John Thomas, a Ditidaht cultural specialist (Turner, 2001). Before the lines were used they would be soaked in water again and sections of the line were joined together using knots that allowed them to be long enough for deep sea fish such as halibut (Turner, 2001). Bull kelp was also used to make ropes, anchor lines, harpoon lines and fishing nets (Turner, 2001). 

The hollow bulbs and adjoining stalks of bull kelp were also used in the process of steaming wood for bending and shaping. The Kwakwaka’wakw nation used this process as a source of making steam in  making bentwood cedar boxes (Turner, 2001).