Click on the Indicators below for More Information
Kelp Icon

Description of Kelp:

Kelp are a type of brown algae and consist of approximately 30 species worldwide and grow in cold water, nearshore submerged coastal zones. They form dense stands, known as “kelp forests”, which are some of the most diverse and productive ecosystems in the ocean. These kelp forest habitats are found along the entire west coast of the US and in some parts of the northeast. Where kelp forests form, they provide three-dimensional habitat, shelter, and food for invertebrates, fish, and marine mammals. Kelp forests are highly culturally valuable for coastal indigenous peoples, and have high socioeconomic value in aquaculture, food products, coastal protection, and cold water dive tourism. The density and area of kelp forests, known as “kelp canopy cover” changes year-to-year based on environmental conditions. Given the importance of these ecosystems, and the way they respond to the environment, kelp canopy cover often corresponds closely to ecosystem health, making it a reliable and important indicator of the overall health and status of the ecosystem.


Data Source:

Kelp biomass, area of canopy cover, and distribution data from Monterey Bay to San Diego were obtained from the Santa Barbara Coastal Long Term Ecological Research (SBC LTER) Project

Understanding the Gauge plots

The gauge plots that accompany the indicator time series are meant to reflect the current status of that ecosystem component at the regional or national level. The numerical scores are determined as the percentile rank of the average (mean) value of that indicator over the last five years of the time series, relative to the series as a whole. The values typically represent quantitative scores, with more desirable conditions in the darker blue. Thus, some gauges are "right-handed" with the higher values being in darker blue, whereas other gauges are "left-handed" with lower values being in darker blue (indicating that lower values are preferable). In some instances (e.g. climate measures), the scores represented are unitless and are presented as two-way gauges, indicating that either high or low scores are observed, implying neither higher nor lower values are necessarily preferred.

Lefthand Gauge
Left Hand Gauge
Righthand Gauge
Right Hand Gauge
Two-Way Gauge
Two-Way Gauge

Understanding the Time series plots

Time series plots show the changes in each indicator as a function of time, over the period 1980-present. Each plot also shows horizontal lines that indicate the median (middle) value of that indicator, as well as the 10th and 90th percentiles, each calculated for the entire period of measurement. Time series plots were only developed for datasets with at least 10 years of data. Two symbols located to the right of each plot describe how recent values of an indicator compare against the overall series. A black circle indicates whether the indicator values over the last five years are on average above the series 90th percentile (plus sign), below the 10th percentile (minus sign), or between those two values (solid circle). Beneath that an arrow reflects the trend of the indicator over the last five years; an increase or decrease greater than one standard deviation is reflected in upward or downward arrows respectively, while a change of less than one standard deviation is recorded by a left-right arrow.


Southern California Current

Santa Barbara Coastal Long-term Ecosystem Research (SBC LTER)

Kelp Area

Kelp is an important ecological indicator and habitat-building species in coastal regions of the U.S. We present the annual kelp biomass, distribution, and canopy cover for the US portions of the Southern California Current region.

Graph Data Interpretation:

This time series shows the average giant kelp canopy area for the Southern California Current from 1984 to 2021. During the last five years, there has been no notable trend and values are within the 10th and 90th percentiles, albeit near the lower end of the time series.

Indicator and source information:

Kelp play a key role as biogenic habitat builders in the coastal temperate waters along the west coast of the U.S. from California to Alaska, and along the New England coast as well. This kelp data provides important information for resource managers as they provide habitat complexity, shoreline protection, play a key role in food web dynamics, and support coastal economies.

Kelp biomass and area of canopy cover data were obtained from the Santa Barbara Coastal Long Term Ecological Research (SBC LTER) Project’s Landsat satellite imagery.  Kelp canopy area data consists of two kelp species: bull kelp (Nereocystis luetkeana) and giant kelp (Macrocystis pyrifera); whereas canopy biomass is giant kelp only. 


Data background and caveats:

The regional canopy cover and biomass shown here represent the spatial distribution, coverage, and biomass of kelp species. Canopy area estimates were derived from the fractional cover of kelp canopy which was determined from satellite surface reflectance.


Estimates of biomass (wet weight, kg) for giant kelp only, are derived from the relationship between giant kelp fractional cover determined from satellite surface reflectance and empirical measurements of giant kelp canopy biomass in long-term SBC LTER study plots obtained using SCUBA. 


Data and data documentation related to what is presented for this indicator can be obtained through the SBC LTER’s data portal: 

Santa Barbara Coastal LTER

The Santa Barbara Channel is a transition zone between the cold waters of the California Current and the warmer waters of Southern California, and is considered a transition zone between the Oregonian and Californian marine faunal provinces. Transition zones may be particularly susceptible to shifts in the composition of marine species driven by climate fluctuations. Pt. Conception (34.448 N, 120.471 W), at the western boundary of the Channel, is a major biogeographic and coastal oceanic boundary that strongly influences the physical and biological dynamics of the marine ecosystems within the Channel.

The mix of biogeographic provinces, warm and cool oceanic regimes and nearshore and offshore waters in the Santa Barbara Channel region results in a remarkably high biodiversity of marine organisms including marine mammals, seabirds, fish, invertebrates, plankton and algae. For example, at least 27 species of cetaceans have been recorded in the Santa Barbara Channel and 18 are considered resident, representing both northern and southern forms. Gray whales travel south through the channel in December and January, returning with calves on their northward trip from February to April as they migrate between feeding areas in the Bering Sea and breeding lagoons in Baja California, Mexico.

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