Hopp til hovedteksten
Algae (Skeletonema)
Skeletonema
Photo: Stig Bjarte Haugen
Print friendly version

Sustainment from the controlled upwelling of nutrient rich deepwater

Plants form the basis for life on earth. In the ocean plants are termed algae. Algae can be microscopic and float freely in the water or attach to the substrate as seaweeds do. The algae need sunlight and nutrients to thrive and grow. Sunlight is rapidly absorbed and spread in turbid sea water, leaving the deep water in darkness. The growth of algae is therefore limited to shallow water.

Most Norwegian fjords have nutrient-poor waters following the algae bloom in spring. Since light irradiation is sufficient in summer, it is lack of nutrients that limits the growth of algae. Micro-algae comprise the main food source to many suspension feeders and a limited supply decrease the production carrying capacity to the fjord.

Strong northerly winds induce upwelling of nutrient rich deep water along the Norwegian coast. Such upwellings stimulate the production of algae, but are irregular and typically short in duration. We have mimicked these natural upwelling events and taken control of the nutrient supply to the Lysefjord in Rogaland. Using simple technology, and fresh water, we can control the upwelling of nutrients. This is an efficient method to support biological production, to capture the greenhouse gas CO2, restore the nutrient supply in fjords with hydroelectric power plants, and to provide unique knowledge of the fjord ecosystem.

Fjord cultivation – from desert to farmland

Over the next 40 years there is a need to double food production on Earth. In Norway, we have large areas and volume of water in the coastal zone suited to produce substantially more seafood. The challenge for most of the Norwegian fjords is the limited access to nutrients that cause a low production of plankton algae. We have a solution to this in the Lysefjord. With forced upwelling of nutrient rich deep water, we can triple the amount of plankton algae in large parts of the fjord (Figure / link report). The area of influence can also sustain three times higher biomass of marine animals that feed on phytoplankton.

Areas, worldwide, that produce large amounts of bivalves are characterized by high food concentrations. For example, the production of algae is almost 20 times higher in the Spanish Rias compared to Norwegian fjords. Algal production in the Spanish Rias is based on coastal upwelling of nutrients. It is likely that we can achieve similar results for many Norwegian fjords, just by increasing the capacity of the method used in the Lysefjord. Forced upwelling of nutrient-rich deep water has an enormous potential to increase food production in our fjords.

Mussel
Photo: Øivind Strand

Capture the greenhouse gas CO2

Plants and animals are mainly composed of carbon, nitrogen and oxygen. Plants use inorganic carbon from seawater to build organic molecules. An increased production of algae in fjords will thereby bind more inorganic carbon. The algal bound inorganic carbon from sea water is replaced by CO2 from the atmosphere. So by increasing the biomass of algae, we will contribute in decreasing the greenhouse gas CO2 in the atmosphere.

Exactly how much greenhouse gas we bind is still unclear. This is primarily because we do not accurately know how large proportions of the bound carbon that is kept in the system, either as biomass, dissolved organic carbon or as long-term deposits to the seabed. With the current upwelling of nutrient-rich deep water in the Lysefjord, our first calculations indicate that we remove approximately 2100 tons of CO2 per season. This represents the emission of CO2 from approximately 2000 cars that travels around 10 000 km per year. If we increase the capacity of the upwelling system (e.g. force down more fresh water) we might bind about 12 000 tons of CO2 per season if we can achieve the algal production obtained in the Spanish Rias.

Restore fjords after affected by hydro power plant

Fjords with hydropower plants receive less nutrients when the phytoplankton needs it. The hydropower plants emit large amounts of fresh water during winter when it is cold and dark and demand for electricity is high. Emission is reduced in summer compared to the natural situation. Thus, less nutrients are available to the algae in the fjord when they need them, when there is sufficient light for fast algal growth. Controlled upwelling of nutrient-rich deep water can compensate the reduced nutrient availability induced by hydropower plants.

Unique ecosystem laboratory – understanding the effect of nutrient supply

Nutrients are essential for plants to grow and thrive. Norwegian fjords are typically nutrient poor with low production and have a potential to increase in biodiversity. However, too high nutrient concentration may result in adverse effects and undesirable changes in the ecosystem. The Lysefjord is currently the only ecosystem where natural nutrient concentrations can be manipulated and studied under controlled conditions. This makes the Lysefjord a unique large scale ecosystem laboratory.

Mussel

What about the future?

The Institute of Marine Research aims to develop this research facility in order to improve essential knowledge about fjord ecosystems, the effects of human activities on fjords, and demonstrate the potential applications by using fresh water to lift up the deeper nutrient-rich sea water to the upper layers with sufficient light. It is important to document the potential on how this method can increase food production and capture the greenhouse gas CO2. This unique fjord laboratory can be expanded to involve studies on several components of the ecosystem providing essential knowledge about a variety of other aspects related to the enhanced phytoplankton production demonstrated so far.

Facts: Forced upwelling of nutrient rich deepwater

  • Deepwater has a naturally balanced composition of nutrients
  • Forced upwelling of deep water lift nutrients up and into the light so the nutrients can be utilized by the phytoplankton
  • In the area of influence the production of phytoplankton and suspension feeders (e.g. blue mussel) can be tripled
  • Increased phytoplankton production bind the greenhouse gas CO2

Animation


Animation.

 

Projects

Contact

Tore Strohmeier
907 20 754
Øivind Strand
473 08 955
Jan Aure
913 22 983