How are the underwater rainforests of the world faring in the face of global change? The NCEAS Global Impacts of Climate Change on Kelp Forest Ecosystems Working Group sought to answer this question by collecting and analyzing kelp forest data sets from around the world and spanning the past half-century to determine long term trends of kelp populations. The findings were recently published in the Proceedings of the National Academy of Sciences.
The working group results identified that kelp in 38% of the regions analyzed are in decline but in other regions, kelp has increased (27%) or shown no detectable change (35%). These regional differences demonstrate that the magnitude of responses to global change vary regionally based on local conditions and sources of stress. Globally, there has been a small 1.8% global decline per year.
“Our study highlights that maintaining the health of kelp forest relies on understanding what is happening on local scales. Each region is unique. In fact – each forest is unique. Managing stressors on local scales has a key role to play in maintaining the health of kelp ecosystems in the face of increasing global pressures”
- Kira Krumhansl, Simon Fraser University and lead author
The result of this study is strikingly different from the consistent declines in species abundance most ecosystems are experiencing worldwide. Kelp is doing better than other key coastal ecosystem-forming species, such as coral reefs and seagrasses, which highlights the unique ability for kelp to resist and recover quickly from disturbances. Detecting future changes in the population of this culturally, economically and scientifically important species is best achieved through the continuance of long-term monitoring.
Global patterns of kelp forest change over the past half-century
Krumhansl, K.A., Okamoto, D.K., Rassweiler, A., Novak, M., Bolton, J.J., Cavanaugh, K.C., Connell, S.D., Johnson, C.R., Konar, B., Ling, S.D., Micheli, F., Norderhaug, K., Pérez-Matus, A., Sousa-Pinto, I., Reed, D., Salomon, A., Shears, N.T., Wernberg, T., Anderson, R.J., Barrett, N., Buschmann, A.H., Carr, M.H., Caselle, J.E., Derrien-Courtel, S., Edgar, G., Edwards, M.E., Estes, J., Goodwin, C., Kenner, M.C., Kushner, D.J., Moy, F.E., Nunn, J., Steneck, R.S., Vásquez, J.A., Watson, J., Witman, J., Byrnes, J.E.K.
PNAS, November 2016, doi: 10.1073/pnas.1606102113
- Kelp forests globally resilient, but may need local solutions to environmental threats, Phys.org
- Underwater health check shows kelp forests are declining around the world, The Conversation
- OSU scientists release findings in global kelp ecosystem study, KVAL
For more information about the participants and products of the Global Impacts of Climate Change on Kelp Forest Ecosystems working group