What’s happening to kelp?

There has been a significant decline in kelp across Australia in recent years, with growing evidence of decline particularly in Western Australia, South Australia, Tasmania, Victoria, and New South Wales.

Research and monitoring has shown that the key stressors responsible for the decline of kelp include:

  • Ocean warming

  • Overabundance of herbivores (such as sea urchins), leading to destructive grazing

  • Urbanisation and pollution

As a consequence, many kelp forests around Australia have been lost and largely replaced by less complex and less productive turf algae habitats. In severe cases, urchin barrens have developed, creating underwater deserts devoid of other marine life.

Urchin barrens create underwater deserts devoid of other marine life (image courtesy of John Turnbull)

Urchin barrens create underwater deserts devoid of other marine life (image courtesy of John Turnbull)

 

Assessments of global status of kelp forests are hampered by a lack of data and high geographic variation at local scales.

The most comprehensive and recent analysis of the global status of kelp forests from 2016 found that 38% of studied regions had experienced significant declines in kelp forest cover over the past several decades - including in each Australian region examined in the study. Another 27% of study areas had increasing covers of kelp, while the remaining 35% of regions showed no significant changes in kelp forest cover.

The study demonstrated that loss of kelp forests was occurring in all regions of Australia where kelp has historically grown, with much of this caused by global climate change and anthropogenic stressors.

Krumhansl et al. (2016) conducted the first, globally comprehensive analysis of kelp forest change over the past 50 years.  Colour shading indicates number of sites in the dataset (n= 1,454) by ecoregion.   (full study available at  www.pnas.org )

Krumhansl et al. (2016) conducted the first, globally comprehensive analysis of kelp forest change over the past 50 years.
Colour shading indicates number of sites in the dataset (n= 1,454) by ecoregion.


(full study available at www.pnas.org)