Kelp restoration trial

Bringing back underwater forests

Seaweeds are of immense value for marine ecosystems. Kelp, the largest of them all, form spectacular underwater forests that provide habitat for fish, clean the water and sequester carbon. Unfortunately, large swaths of these subaquatic forests have disappeared from the coast of many European countries. Although many factors appear to be contributing to this trend, there is still a lot we don’t know about the ecosystems engineered by seaweeds and this makes it difficult to carry out effective conservation and restoration work. We have partnered with SeaForester to come up with 3 projects designed to make large scale restoration of seaweed forests along the coast of Portugal a reality. Our members could choose between carrying out a kelp restoration trial, acquiring a sonar setup for seafloor mapping or acquiring a dropdown camera for seaweed monitoring. The kelp restoration trial was the option that won the vote.

Kelp restoration trial

Kelp are large brown seaweeds belonging to the order Laminariales and are widely known for the impressive subaquatic forests that they form. In order to bring back these kelp forests to the areas from which they have disappeared it is important to test and refine available techniques. This project involves carrying out a trial to test the “spore bag” seeding technique to bring back furbellow kelp (Saccorhiza polyschides) to the coast of Cascais, Portugal where it used to be very abundant. Reproductive structures of the plant are collected from donor populations, placed in mesh bags and attached to the rocky reef identified for restoration. The idea is for the spores to be released from the reproductive structures, to settle on the underlying bedrock and create new patches of kelp forest.

Jan Verbeek, a marine biologist from SeaForester demonstrating the spore bag technique at the project area.
Jan Verbeek, a marine biologist from SeaForester demonstrating the spore bag technique at the project area.

Learn more about the context behind this project

Disappearing seaweed forests

The world’s shallow coastal areas, where sunlight penetrates, are the cradle of the ocean. Here seaweed forests grow supporting a rich and diverse assemblage of marine fauna and flora by providing highly productive three-dimensional habitats. Unfortunately, European seaweed forests are disappearing at an alarming rate. Although we lack the data to figure out the actual causes for this decline, these are likely to be important drivers in many areas:

  • Water pollution
  • Climate change affecting water temperatures
  • A build up of sediment as a result of both human and natural causes
  • Increases in herbivory rates due to overfishing and its impact on coastal ecological communities
  • Increased storm intensity
A kelp forest on the coast of Portugal.
Kelp forests have been disappearing at an alarming rate globally and the coast of Portugal is no exception.

Pioneering seaweed restoration work

Unlike land-based deforestation which has received a lot of attention, the loss of marine forests tends to go mostly unnoticed. This may be due to the fact that the underwater-world is out of sight for most of us and its deterioration is therefore not as obvious. As result, there are still very few seaweed restoration projects in Europe and there is a great need to develop greater know-how in this area. This is where our partnership with SeaForester comes in.

SeaForester is an initiative that aims to reverse the alarming disappearance of seaweed forests in the world in order to safeguard the oceans’ vital role of carbon sequestration, maintaining fish stocks and securing the planet’s wellbeing. Along the coastline of the municipality of Cascais they are pioneering the work to identify the reasons for the decline in seaweed populations and to test seeding techniques. Therefore this project will not be carried out in isolation but will be integrated with other efforts to restore the area. 

Sources & further reading

Peer Reviewed Research Section
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    the team behind the project

    Team Member

    Tiago de Zoeten, Conservation Biologist at Mossy Earth

    Team Member

    Jan Verbeek, Marine Biologist at SeaForester

    Team Member

    Inês Louro, Marine Biologist at SeaForester

    Sources & further reading

    Peer Reviewed Research Section
    1. Status, trends and drivers of kelp forests in Europe: an expert assessment - Biodiversity and ConservationExternal linkIcon Peer Review
    2. The role of kelp species as biogenic habitat formers in coastal marine ecosystems - Journal of Experimental Marine Biology and EcologyExternal linkIcon Peer Review
    3. Threats and knowledge gaps for ecosystem services provided by kelp forests: a northeast Atlantic perspective - Ecology and EvolutionExternal linkIcon Peer Review