Nutrient Loading Due To Eutrophication In Areas Of Aquaculture: Macroalgae as an inorganic Nutrient filter

Alexander Kristensen & Elijah Aighobahi

Studenteropgave: Semesterprojekt

Abstrakt

It is known that the fish farm industry is ever growing. They account for over 30% of the fish consumed in today’s world. However there is also a growing issue of Eutrophication due to the extra nutrients being added into the aquatic ecosystem. This is causing problems like harmful algal blooms in all ecosystems and low dissolved oxygen concentration in ecosystems of shallow water. Corresponding with these two types of ecosystems, the two case studies taken under consideration are a shallow water Danish fish farm and a deep water Norwegian fish farm. Both ecosystems present different variables that will affect algal growth in the vicinity of the fish farms. The aim of this project is to take four macroalgaes and analyze them, then an educated assumption is made matching the algaes that best take up the nutrient load from the fish farms in the conditions presented by the case studies. The four algaes that are under scrutiny are, A. esculenta, S. latissima, U. lactuca and C. sericea. All of their assets will be taken into consideration, including their nutrient sequestration, biomass, prefered salinity, temperature and depth conditions. To take account for all of the nutrients released by the fish farms there will need to be 0.82 Kg of Alaria esculenta grown to account for all the N deposits and 0.78 Kg to take up all of the P deposits per kilogram of fish. For Saccharina latissima there will have to be 1.56 Kg grown to take up all of the N and 1.67 Kg to take up all of the P deposited per kilogram of fish. A. esculenta and S. latissima are in ratios of dry weight calculated based on the numbers from the Norwegian case study, the numbers will vary for the Danish case study. Next, there will need to be 0.647 Kg of Ulva lactuca to take up all of the nitrogen in the water for the Norwegian case study and 0.730 Kg of Ulva lactuca to take up all the N in the Danish case study per kilogram of fish produced. Then there will need to be 3.03 Kg of Ulva lactuca to take up all of the P in the Norwegian case study and 2.77 Kg in the Danish case study per kilogram of fish produced by the farms. Lastly Cladophora sericea will need 0.470 Kg to take up all of the N from the Norwegian case study and 0.530 Kg in the Danish case study. As for the excess P Cladophora sericea will need to be produced at a ratio of 2.39 Kg of seaweed to one kilogram of fish for the Norwegian case study 2.19 Kg of seaweed to one kilogram of fish for the Danish case study presented. Using this information compared with the data provided from the two case studies, it was concluded that the algaes Ulva lactuca and Cladophora sericea are not effective in taking up inorganic nutrients in the areas surrounding fish farms at all. In fact it would be surprising if they were able to even survive. However, the algaes Alaria esculenta and Saccharina latissima would both thrive in the conditions provided by both case studies. Although Alaria esculenta would be more efficient in taking up the nutrient load in the Norwegian case study than Saccharina latissima would be, and Saccharina latissima is more effective in sequestering the nutrient load presented by the Danish case study than Alaria esculenta. Knowing this information, there is a possibility of bringing a new light on the industry of aquaculture. By using macroalgae to get rid of the inorganic nutrients from eutrophication it can allow for the growth of the aquaculture industry which is already such an important source of food all around the world.

UddannelserBasis - International Naturvidenskabelig Bacheloruddannelse, (Bachelor uddannelse) Basis
SprogEngelsk
Udgivelsesdato22 jan. 2014
VejledereSøren Neilsen

Emneord

  • Macroalgae
  • Fish Farms
  • Aquaculture
  • Eutrophication