WP4: Environmental impacts of mussel mitigation culture

Objectives

  • To demonstrate the ecological feasibility of using mussel mitigation cultures in different environments.
  • To estimate the improvement of water clarity due to mussel filtration.
  • To estimate the impact of increased sedimentation below the mussel farms.
  • To develop methods to mitigate potential negative effects on the sediment.
  • To model effects on water quality indicators due to mussel filtration on spatial and seasonal scales.

Tasks


Measurements of water clarity and particle depletion around mussel farms

Institute of Oceanology will provide in-situ mapping of particle and fluorescence depletion around the mussel farms on scales down to 1 m during field campaigns at the four study sites. Combination of the collected information will allow for determination of the particle size and concentration spatial variability over the area, estimation of the particles origin (mineral or organic), vertical and horizontal evolution of the water transparency, and down-welling irradiance distribution. Developed algorithms linking satellite signal with concentrations of water constituents will allow to track the changes of water transparency and particles load over the time, beyond the fieldwork timeframe.

Measurements of sediment chemistry below mussel farms

Different chemical processes (denitrification, nutrient fluxes, hypoxia) will be measured under a range of environmental conditions at the four study sites during the field campaigns. Sedimentation under the farms and reference sites will be measured using sediment traps, general sediment characteristics (grain size, organic content, water content) analysed and the organic enrichment level of the sediment will be measure using silver-sulphide-sticks and the results will be related to the different environment conditions of the farms and to each other.

Develop methods for mitigation of sediment impacts

By studying changes in biogeochemical (nutrients, oxygen) fluxes across the sediment-water interface in laboratory experiments this task will investigate how different modes of bioturbation affects their potential as mitigators of sediments affected by biodeposits from mussel farms. Combined with assessments of how magnitude (i.e. different levels of organic enrichment) and composition of biodeposits affects potential success of mitigation measures this will provide valuable information for the development of sustainable mitigation methods of sediment impacts.

Modelling the impact of mussel farms on water quality

3D ecosystem modelling will be applied to estimate the mussel farm’s impact on water quality indicators (nutrients, Chl. a, oxygen, water clarity and sediment fluxes) on fine spatial and temporal scales in local set-ups of the Limfjorden, Horsens fjord and Greifswald Bay. The models will incorporate the collected data on sediment chemistry, as well as pelagic field and satellite data. The models will provide maps of impact magnitude and scales and will beused to demonstrate the feasibility of using mussel mitigation cultures in different environments and to optimize farm layout, mussel density to fulfil water quality targets.

Partners involved

  • Aarhus University
  • Technical University of Denmark
  • Leibniz Institute for Baltic Sea Research
  • University of Gothenburg 
  • Institute of Oceanology

 

 

WP4 lead

Marie Maar
Aarhus University
Find contact information

http://www.bonus-optimus.eu/about/work-packages/wp4
20 JUNE 2019