Marine biodiversity
New ERANET Project

Will rising sea temperatures increase the impacts of invasive seaweeds?

Sargassum muticum in Øygarden
Sargassum muticum in Øygarden
Mette Eilertsen

Main content

Introduced and invasive seaweeds can come to dominate and even replace native species. With increasing sea temperatures due to climate change, this impact can be worse.

Associate Professor Kjersti Sjøtun from the research group, Marine Biodiversity, will coordinate a new ERANET project entitled:  Invasive seaweeds in rising temperatures: Impacts and risk assessments (INVASIVES). The project will last 3 years, 2013-2016.

According to Sjøtun, the idea behind INVASIVES is based on the fact that Europe is a hot-spot for the introduction of aquatic species. Thus far, around 600 different introduced and established taxa have been registered. Among the most well-known invasive macro-algae species are Sargassum muticum, Codium fragile subsp. fragile, Gracilaria vermiculophylla, Bonnemaisonia hamifera and Heterosiphonia japonica.

Sjøtun says that these, in addition to other introduced species, can be so numerous that they come to dominate over native species in local environments, and can thereby partially or even completely replace these local species. The invasion, however, can lead to a potential negative domino effect throughout the local ecosystem by influencing food-webs and productivity.

One of the reasons that the ERANET project was established was because the researchers involved have concerns that climate change and rising sea temperatures could aggravate the impact of invading species. They will try to learn more about the potential impact in a variety of ways.

  • Evaluating the effect of temperature variability on the incidence and dispersal / spreading of introduced species
  • Evaluating how invasive or potentially invasive macro-algae affect given local ecosystems under different temperatures

INVASIVES involves 7 different partners from 5 different countries covering the European North Atlantic coast from Portugal to Norway. Together, they will study the effects of introduced macroalgae on local biodiversity using a combination of different methodologies including modelling, field-work, ecology studies and molecular biology technologies. The work will focus particularly on selected macroalgae that are considered either invasive or potentially invasive. The effects of changing temperatures will be studied in the various partner labs, in the field and through modelling.

The project began March 2013 and is organised into 6 sub-projects. Each sub-project has its own research goals. Sjøtun explains that the first 2 sub-projects consider potential vectors for introducing and facilitating the spreading invasive macro-algae under different climatic conditions. The next 2 consider impacts on local marine ecosystems. The last 2 will consider how invasive macro-algae adapt to potential new environments in Europe. The specific aims under each of the sub-projects are as follows:

  1. Assess the importance of new pathways of alien seaweeds to European coasts,
  2. Develop niche models which predict the potential range of alien seaweeds, under present and future climatic conditions,
  3. Investigate the ecological processes responsible for substituting native seaweeds with invasive ones,
  4. Assess impact of alien seaweeds on native seaweed-associated fauna and food webs,
  5. Study how acclimation and adaptation processes can influence the success of invasive seaweeds
  6. Study how climatic variation affects the biochemical adaptation of invasive seaweeds. The results will be used in risk assessments of range extension, establishment and impacts on biodiversity.