The forgotten forests of the sea: Are they also threatened by climate change?

By PhD Candidates Carolina Olguin Jacobson and Nur Arafeh Dalmau (Guest Co-Author)

Read Time: 449 words about 3 minutes.

Extreme climatic events, such as marine heatwaves, are threatening one of the most productive (but often forgotten) marine ecosystems; kelp forests. 

Sea lions among kelp forest in a remote island Cedros, in Baja California, Mexico. Photo by: Nur Arafeh Dalmau. 

The importance of terrestrial forests is well known, but their marine counterpart, underwater kelp forests, are equally important. Giant kelp forests are brown algae that can grow up to half a meter in a single day, they often form magnificent underwater three-dimensional structures. Kelp forests are considered one of the most productive ecosystems in the world, providing habitat for hundreds of marine species, coastal shoreline protection, nutrient cycling, commercial and recreational activities and their increasing important role in – carbon sequestration. However, kelp forests are globally decreasing due to extreme climatic events, particularly, marine heatwaves. 

A marine heatwave is a period where the temperature of the ocean is unusually warm and lasts for more than five consecutive days.

A marine heatwave is a period where the temperature of the ocean is unusually warm and lasts for more than five consecutive days. An example is the recent marine heatwave between 2014-2016 that damaged the giant kelp forest of Baja, California (Mexico) and California (USA). The combined thermal stress and reduction of giant kelp severely impacted kelp forest communities of fish, invertebrates and algae. In three islands of Baja, California, half of the fish and invertebrate species disappeared and invasive algae, previously absent, appeared. Still, after three years, these kelp forests have not recovered, and many areas have been replaced by sea urchins or smaller and less productive kelp species that have altered the whole ecosystem structure and function. 

A healthy kelp forest in Baja California, Mexico . Photo by: Robert Calderón

In our new letter in the scientific journal, Science, we highlighted these damaging events to the international community. If we desire to continue to benefit from the vital services of kelp forests and other marine ecosystems, we need to decrease future CO2 emissions to lower global temperatures and hopefully reduce extreme marine heatwaves. We also call for immediate management actions such as the exploration of climate- smart restoration sites. Importantly, if we want to succeed in halting the loss of giant kelp forests worldwide, we must build the required human capacity to do so. 

You can follow Carolina and Nur on Twitter:

Their handles are @JellyfishVibes and @ADalmauNur.

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