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Mayne Island Conservancy Society

Kelp Mapping Project

Photo of Bull KelpBull Kelp bulbs floating on the surface in Miners Bay
Photo credit: Rheanna Drennan

About Kelp Beds

Bull Kelp (Nereocystis luetkeana) is an annual marine seaweed that is common throughout the Gulf Islands. Its range extends from Alaska to California, and it provides important habitat for many kinds of marine life. The plant consists of a long stipe (up to 36 m long), attached to the ocean floor by a holdfast and buoyed at the ocean's surface by a float, which allows the cluster of smooth blades to obtain light. Kelp beds look like forests underwater, and create habitat for crustaceans, plankton, snails, juvenile salmon, rockfish, surf smelt, and other marine life. Predators such as harbour seals, sea lions, sea birds, and even orcas hunt around these kelp forests. Kelp swept away by storms can wash up on shore where it is then eaten by decomposers or may sink into deeper water and feed other food webs.

Kelp beds may be negatively impacted by changes in the ocean floor composition or by changes in salinity and temperature of the water. A loss of animals that feed on dead material and remove silt and debris, such as sea cucumbers, and an increase in herbivores such as sea urchins, can also have a negative effect.

Kelp Mapping Methodologies

The Mayne Island Conservancy has been mapping kelp beds in the island's coves and bays for three seasons. Staff consulted experts in the field to develop a methodology for mapping by kayak which is described in a this PDF document. It has been prepared for the Seagrass Conservation Working Group, a consortium of community groups, biologists, consultants, First Nations and government agencies who work to conserve nearshore habitats like eelgrass and kelp

This document will be of interest to those undertaking similar activities and they are welcome to make fair use of the information. Appropriate credit will be appreciated! Community group that would like to be trained to map and monitor bull kelp habitat should contact Leanna Boyer at lboyer@shaw.ca.

Bull Kelp Facts

Parts of the kelp plant
  • Grows Quickly - Entire growth occurs spring to fall, up to half a meter per day. Can grow to 60 meters in ocean waters, but in protected Salish Sea, bull kelp often reaches 10 metres

  • Huge Holdfasts - Attaches to rocks below low tide level with holdfasts bigger than your hand, up to 40 centimetres wide

  • Gas Floats - Bulbous float at the end is filled with gas containing carbon monoxide

Bull Kelp AKA: Ribbon kelp, Bulb kelp, Giant kelp, Sea kelp, Horsetail kelp, - descriptive for sure, but not as colourful as "Sea Otter's Cabbage"

Why Map & Monitor

On almost any rocky shore around Mayne, clusters of bull kelp can be seen offshore, growing in the subtidal zone. Kelp beds provide a resting and feeding area for otters, gulls, herons, loons, scoters, grebes, goldeneyes, and buffleheads, and other waterfowl. Underwater kelp forests shelter snails, crabs, shrimp, starfish, sea anemones, sea cucumbers, brittle stars, sea squirts, and many other marine creatures.

Rafts of kelp help reduce beach erosion. Kelp forests soften the force of waves against the shoreline. This protection can be seen along the Strait of Juan De Fuca where large kelp beds form bay-like areas along the shoreward side. In addition, kelp forests are a significant carbon sink, sequestering mega-tonnes of CO2 equivalent in the Pacific North West.

Anecdotal evidence is showing a decline in bull kelp in the Salish Sea. Measuring change in area of kelp beds over time (monitoring) will enable us to detect declining populations and determine why.

Experimental research shows that bull kelp ceases to grow with an increase in temperature. The federal government reports that Salish Sea ocean temperatures are increasing at all depths due to climate change effects. Grazing from sea urchins can also decimate kelp beds.

Kelp Studies at the University of Victoria

A paper published by UVic as part of the Salish Sea Survival Project investigates the extent of bull kelp (Nereocystis leutkeana) floating canopy area on our shores using satellite based near infra-red photography validated by ground-truthing wherever possible. The Conservancy's extensive and continuing annual kelp surveys on the rocky points and promontories of Mayne Island have been used in this way and cited in the report:
At present, kelp mapping is conducted manually via transects and aerial photography (Cavanaugh et al., 2010; Sutherland et al., 2007; Field, 1996). In British Columbia, the Ministry of Environment has conducted kelp surveys in allocated areas along the coast since the 70’s using field transects and infrared aerial photos (Sutherland, 1990; Sutherland et al., 2007; Lucas et al., 2007). Localized kelp inventory initiatives have also been established recently in the Gulf Islands area, such as through the Mayne Island Conservancy Society and the citizen science group Help the Kelp on Gabriola Island...
Read the completed study here

MICS Mapping Kelp Pics

Mapping kelp by kayak - summer 2012

Photo of the surface portion of some kelp
Floating Kelp from a Kayak
Photo of a kayaker engaged in kelp mapping
Kayaker Inspects a Bed
Photo of a kelp holdfast
Some as big as yer 'and
Photo of a kelp mapper's equipment
Data, GPS, Camera, Waterproof Bag ...
Photo of damp data sheets
..Still the mapping team has hangups!

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