Deep Water Nutrient Supply for an Offshore Ulva sp. Cultivation Project in the Eastern Mediterranean Sea: Experimental Simulation and Modeling

Modeling of growth ofUlvasp. macroalgae in a controlled photobioreactor based on nitrogen accumulation dynamics

“…Each sleeve, 17.8 cm in diameter and 0.036 m 2 of illuminated area, was filled up with 5L of ASW (38)(39)(40) PSU) composed of distilled water (TREION, Treitel Chemical Engineering Ltd, IS) and 212.5g of sea salt (Red Sea Ltd). ASW baseline nutrient concentrations were 1.35, 1.89, 2.35, 0.09, and 0.19 µM for silicate, ammonium, nitrate, nitrite, and phosphate, respectively 10 . Air bubble mixing was provided from the bottom at a rate of 1 L min -1 (flowmeter, 0.5-8 L min -1 , Dwyer Instruments, USA).…”

“…Macroalgae biomass production models relate to several main a-biotic parameters, including light, temperature, salinity, water flow and nutrients [8][9][10] . Among these parameters, nutrients, and specifically nitrogen (N), are the main input stream required for successful macroalgae cultivation, often limiting growth in natural environments 11 .…”

“…Thereafter, we use model simulations and experimental results to analyze the effects of the fertilizing regime, specifically the amplitude (added N concentration) and frequency of fertilizing, the total weekly fertilizer dose, and the duration of each fertilizing event, on N Use Efficiency (NUE), defined here as the fraction of fertilizer nitrogen that is utilized and allocated to yield N 41 , level of internal N and the Daily Growth Rate (DGR). NUE, which is an established metric used to benchmark N management 41 but is rarely addressed in macroalgae cultivation studies, implies on the efficiency and sustainability of the process, specifically how much energy and resources are used per unit of produced biomass 42 or protein 10 and is an important characteristic of the cultivation process.…”

Cultivation ofUlvasp. offshore the Eastern Mediterranean Sea in experimental bioreactors: seasonal growth dynamics and environmental effects

“…The copyright holder for this this version posted January 18, 2023. ; https://doi.org/10.1101/2023.01. 15.524102 doi: bioRxiv preprint Experience from terrestrial agriculture shows that dynamic models that aim to predict the field yield significantly improve the economics and long-term sustainability of food supply systems 21 . Such detailed models, which combine biomass productivity, crop yields, sustainability, and economics, are not yet available for macroalgae offshore farms.…”

“…The current offshore marine biomass cultivation concepts include Near Farm Concepts for kelp growth 10 , Tidal Flat Farms, Floating Cultivation 10 , Ring Cultivation 11 , wind-farm integrated systems 12 , and air mixed cages 13 . Artificial fertilizing is generally not recommended but if needed, can be performed via integration to fish farms in an Integrated Multitrophic Aquaculture (IMTA) 14 or artificial upwelling of nutrient-rich deep water 15 . Another potential fertilizing solution, although logistically challenging, to utilize Ulva's high uptake rates (up to 470 μmol N g -1 D.W. h -1 ) [16][17][18][19][20] and recharge critical nutrients by rapid fertilizing in a designated fertilizing tank, which can be performed on or offshore.…”