|Effects of hydrodynamics on the biomass allocation and biochemical composition of Saccharina latissima|
Arminaite, E. (2018). Effects of hydrodynamics on the biomass allocation and biochemical composition of Saccharina latissima. NIOZ Royal Institute for Sea Research: Yerseke. 63 pp.
This study focuses on brown kelp Saccharina latissima, and the effects of hydrodynamics and nutrient availability on its biomass and biochemical content (carbon and nitrogen ratio, percentage of carbon, nitrogen and protein per dry weight of sample). It was previously seen, that the biomass of brown kelps might depend on those two factors. Two experiments were performed in order to research this topic. In the first experiment large individuals (size ranging from 0.4-1.1 meters) were grown under conditions of wave/no wave, high/low nutrient for two months and harvested in May 2017. In the second experiment, starting with microscopically small sporophytes of S. latissima, the individuals were exposed to low, medium or high current and high/low concentrations of nutrients. The latter experiment lasted for 4 months and the ultimate harvest of biomass took place in January 2018. The effects of nutrient availability and hydrodynamics were tested by measuring the biomass and biomass density of the individuals, measuring the nitrogen and carbon contents in percentage of dry weight by Thermoscientific Flash2000 Organic Elemental Analyzer, calculating the CN ratio, as well as total protein content in percentage of DW by using N-to protein conversion factor of 5. It was found, that hydrodynamics and nutrient availability had a great effect on the biomass and biochemical content of Saccharina latissima. The biomass of an individual of Saccharina latissima was higher when hydrodynamic factor was present and when nutrient availability was high. The biomass density within the blade was found to be more consistent in environments with a hydrodynamic factor, as a protective response to potential harm that hydrodynamic factor could cause. The carbon content (%, W/W) in fully grown individuals (experiment 1) was lower when nutrient availability was high, whereas in young individuals, the carbon content was lower when nutrient availability was low. No effects of hydrodynamics were observed. Nitrogen content (%, W/W) was higher in high nutrient environments while hydrodynamic factor or an increase of its strength reduced the nitrogen content. The inorganic nitrogen in individuals grown in high nutrient environments appeared in higher percentages of total nitrogen content (%, W/W), than in low nutrient environments. The CN ratio in individuals grown with low nutrient availability increased, whereas when nutrients were widely available, the ratio decreased. Without the presence of a hydrodynamic factor, the CN ratios were lower. The protein content (%, W/W) in Saccharina latissima was higher when the nutrient availability was high and decreased as hydrodynamic activity increased. However, it was also found, that when nutrient availability is higher, the strength of the hydrodynamics does not influence the parameter.