Genetic research aims to safeguard the kelp forests of the future
Can the right genes save Sweden’s kelp forests? In the scientific community, there is growing concern about the future of large brown algae in Swedish waters. Research is now underway to investigate whether high genetic diversity can help the algae withstand both a warmer climate and hungry sea urchins.
More than half of the kelp forests in the world’s oceans have disappeared over the past 50 years. Close to home, there are examples from Norway’s west coast, where large populations of tangle have completely collapsed. Seabeds where kelp forests once swayed metres high and provided habitats for many other marine species now lie as barren as a rocky desert.
Sugar kelp has also declined sharply along the Norwegian south coast.
"If we look at developments in Norway, there may be reason to believe that kelp has also declined in Sweden. After all, the global trend is that kelp has declined sharply," says Gunilla Toth, Professor of Marine Ecology at the Department of Marine Sciences.
The greatest identified threats to kelp forests are man-made. Climate change is causing sea temperatures to rise, which is detrimental to sugar kelp, which thrives in colder waters. On Norway’s west coast, kelp has been grazed down by hungry sea urchins, whose numbers increased sharply from the 1970s onwards.
"The likely explanation there is that we humans have disrupted the food chain by catching too many fish that eat sea urchins. This, in turn, affects the kelp," says Gunilla Toth.
The answer may lie in the genes
Various restoration projects are underway around the world to restore the vital habitats of kelp forests. And the solution for viable kelp in a changing ocean may lie in the kelp’s genes.
"For a species to adapt to a changing environment, such as a warmer ocean, genetic variation is required. Species with greater genetic variation usually find it easier to adapt," says Gunilla Toth.
During the year, she is launching a new research project focusing on the three types of kelp: tangle, oarweed and sugar kelp.
Our understanding of the state of kelp in Swedish waters remains limited.
"The surveys carried out show that at least the common kelp has not declined. But we don’t have much data to go on, and that makes it difficult to say anything with certainty. It may well be that it has declined here too."
Important knowledge for restoration
She and her research team will, among other things, map the genetic diversity of Swedish kelp species. They will also test whether there are genetic differences in the kelp that affect its ability to cope with higher water temperatures and increased pressure from grazing sea urchins.
This knowledge will be vital should it become necessary to restore kelp forests in Sweden in the future.
"The hope is that our findings can be used as a basis for marine spatial planning and nature conservation. If we identify areas where kelp exhibits high genetic variation, these may be particularly important to protect, and during restoration work we can use this knowledge to select populations with key characteristics."
The project will run for four years, until 2030. Gunilla Toth is also looking forward to investigating the significance of kelp’s genetic diversity for the species richness found in the habitats formed by brown algae.
"In land plants, there are many studies showing that high genetic diversity within a species can be linked to greater species richness. For algae, our knowledge is still limited. It will be very exciting to see what we discover there,” she says.
Text: Mikael Andersson
The aim of the project is to map the genetic diversity and population structure of Swedish kelp beds, estimate gene flow between populations, and investigate the relationship between genetic variation and ecosystem function and species richness.
Methods used in the project include DNA analysis, environmental DNA (eDNA) and so-called ‘common-garden’ experiments to distinguish genetic effects from environmental influences.
Kelp are brown algae that form dense forests on rocky seabeds. The project covers three species: sugar kelp, tangle och oarweed.
Kelp plays a vital role as a habitat for many algae and animals; it provides important nursery and feeding grounds for fish, as well as areas where seabirds and seals forage.
The main threats to kelp are climate change (rising sea temperatures) and overfishing, which leads to an increase in the numbers of animals that graze on kelp.
