Kelp Forests

image of kelp forest by chad king

Kelp forests are among the most unique and ecologically diverse ecosystems in coastal temperate oceans and are found globally. In the eastern Pacific ocean, they occur from Alaska and Canada to the waters of Baja California in the northern hemisphere, and along the southern coast of Chile in the southern hemisphere. Kelp forests need rocky coastlines where their holdfasts can take anchor, and cool (50 – 64 °F), clear, nutrient rich water to grow. These forests are tiered like a terrestrial rainforest with a canopy and several understory layers below. 

Kelp forests of the eastern Pacific coast are dominated by two canopy-forming, brown macroalgae species, giant kelp Macrocystis pyrifera and bull kelp Nereocystis leutkeana. Both species are highly productive. For example, when conditions are ideal, the giant kelp’s average growth in spring can range from 27 to 61 centimeters (10 to 24 inches) per day. These tiered forests create attractive habitat to a diversity of fishes, invertebrates and other algae as refuge from predators and as a source of food.

Much of the extraordinary production of kelp falls to the ocean floor, like leaf litter in terrestrial forests. There, it either remains to support productive and species rich detritus-based forest food webs, or is exported by currents to adjacent ecosystems where it fuels food webs on sandy beaches, deep rocky reefs or submarine canyons. Among the many species that inhabit kelp forests are a wide variety of economically important species such as sea urchins, abalone, lobster, sea cucumbers, rockfishes and other finfishes, as well as some endangered species including abalone and southern sea otters. The kelp itself is harvested to feed abalone in aquaculture facilities and for use in a number of human products. The forests also support economically important eco-tourism, including kayaking, bird and marine mammal watching and scuba diving.

PISCO’s kelp forest monitoring programs are designed to reveal geographic patterns of the structure and functions of this important ecosystem through quantification of the abundance of the macroalgae, invertebrates and fishes that constitute kelp forest communities. Our approach allows us to quantify large- and small-scale spatial patterns of structure of the kelp forest communities as well as characterize changes over time. This information provides insight into the causes and consequences of changes in species abundance resulting from natural and anthropogenic factors and as such forms the basis of ecosystem-based management of kelp forest communities. Read about: