Future resilient kelp forests: the role of diversity for ecosystem functioning and restoration under a changing climate

Why kelp is important

Kelp comprises several species of brown algae that can form dense forests several metres high just a few metres below the water’s surface. They are among the ocean’s most important inhabitants, purifying the water, absorbing carbon, and providing shelter and habitats for many other marine species.

Without the kelp forests, large areas of the seabed along Sweden’s coasts would be a barren rocky wasteland.

Climate change poses a threat

On the Norwegian side of the border, a large proportion of the kelp forests have disappeared or become much sparser, most likely due to rising water temperatures. This hits kelp seedlings particularly hard, as they do not thrive in warmer water.

Another explanation is the overfishing of larger fish, which has disrupted the balance of the food web. As predator numbers decline, their prey – such as sea urchins and snails, which graze on kelp – increase.

Hope lies in the genes

With high genetic diversity within a kelp community, there is a possibility that some individuals can tolerate higher temperatures better, or have stronger defences against grazers. If they can pass on their genes to future generations, the kelp will be better adapted to warmer waters or increased pressure from animals that feed on kelp.

Understanding genetic diversity and how it manifests itself in the composition of the kelp community and the sensitivity of individual kelp plants to high temperatures and grazing is therefore crucial if we are to protect, manage and restore kelp forests.

Activities

In this project, we will generate this knowledge by:

• Mapping the genetic diversity and population structure of all Swedish kelp populations.
• Estimating gene flow and the connections between Swedish kelp populations.
• Measuring species richness (biodiversity) among associated invertebrate grazers.
• Investigating whether high genetic or phenotypic (appearance-related) diversity in Swedish kelp is associated with a more species-rich and functional ecosystem.
• Experimentally testing whether there are genetic differences in temperature tolerance and grazing resistance within and between Swedish kelp populations.

Methods

To gather this knowledge, we will use a range of different methods:

• Studies of genetic diversity using a type of marker (known as SNPs) that is well suited to investigating genetic structure on a small scale.
• Using eDNA (environmental DNA), we will investigate whether the genetic composition of forests is also linked to the biodiversity of the animals living there. We will also describe the shape and structure of kelp plants and their chemical composition.
• ‘Common-garden’ experiments will be conducted to determine how sensitivity to temperature and grazing varies between different individuals.  

Expected outcomes

In the short term: The project’s findings can be used to inform conservation measures, promote engagement in marine resource management, and raise awareness of the ecological and economic importance of kelp forests.

In the long term: The project contributes to sustainable fisheries, increased resilience to climate change and the conservation of biodiversity, thereby improving ecosystem services such as carbon sequestration.

The project may also hopefully lead to the development of sustainable industries with both environmental and economic benefits, such as kelp-based biofuels and bioplastics.

Project team

Professor Gunilla Toth

Researcher Marina Panova

Project Assistant Ida Johansson

Partners

Västra Götaland County Administrative Board

Kosterhavet National Park