Biology subjects

Zollmann, M.

Publications and source records attributed to Zollmann, M..

3 recordsLinked to original sources

bioRxiv2023

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

Offshore macroalgae production could provide an alternative source of biomass for food, materials and energy. However, the offshore environment in general, and specifically the Eastern Mediterranean Sea (EMS) offshore, is a high energy and low nutrients environment and thus is challenging for macroalgae farming. This study aims to understand the effects of season, depth, and fertilization duration on growth rates and chemical composition in offshore Ulva biomass production and develop a predictive model suitable to offshore conditions. We hypothesize that offshore Ulva growth rates and chemical composition will follow a seasonal trend and that applying rapid onshore fertilization could refill nutrient storages and enable continuous offshore cultivation. We test this hypothesis by measuring Ulva biomass and internal nitrogen in offshore experiments in the nitrogen-poor EMS a few kilometers offshore the Israeli coast. We construct a predictive cultivation model to estimate N concentrations in the sea during experiments. This study demonstrates the feasibility of growing Ulva sp. offshore the EMS with an onshore nutrient supply and develops a better understanding of seasonal growth dynamics and environmental effects (nitrogen, waves, depth, etc.). Furthermore, the study showcases the applicability of the macroalgae cultivation model in the offshore environment and its potential contribution throughout the whole lifecycle of seaweed cultivation.

bioengineering↗

bioRxiv2023

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

Macroalgae biomass production models that capture nutrient dynamics, temperature, light, and salinity are important for the design and operation of large-scale farms. The goal of this study is to understand how the nitrogen fertilizing regime, relating to fertilizing dose (M N week-1), amplitude (M N), and duration (hours), affects the dynamics of nitrogen content and biomass production of the Ulva sp. macroalgae. We hypothesize that the nitrogen fertilizing regime controls the Ulva Nitrogen Use Efficiency (NUE), defined here as the fraction of fertilizer nitrogen that is utilized and allocated to yield N, and, accordingly, also nitrogen assimilation in the biomass and the growth rate. We test this hypothesis by measuring internal nitrogen and biomass weight and by calculating NUE under various fertilization regimes in controlled photobioreactors. Based on this experimental data, we developed a biomass productivity model that predicts nitrogen and biomass dynamics in time over three weeks of cultivation. This study points out efficient fertilizing regimes and enables the development of a comprehensive understanding of the dynamic relationship between external N, internal N, and biomass production of the Ulva sp. macroalgae under varying external N levels, which is important for real-world agricultural applications. This study provides a better understanding of the external N-internal N-biomass triangle followed by an improved dynamic cultivation model, enabling better control of nutrient application and biomass production in macroalgae farming for a sustainable marine bioeconomy.

bioengineering↗

bioRxiv2020

Multi-Scale Modeling of Intensive Macroalgae Cultivation and Marine Nitrogen Sequestration

Multi-scale macroalgae growth models are required for the efficient design of sustainable, economically viable and environmentally safe farms. Here, we develop a multi-scale model for Ulva sp. macroalgae growth and nitrogen sequestration in an intensive cultivation farm, regulated by temperature, light and nutrients. The model incorporates a range of scales by incorporating spatial effects in two steps: light extinction at the reactor scale (1 m) and nutrient absorption at the farm scale (1 km). The model was validated on real data from an experimental reactor installed in the sea. Biomass production rates, chemical compositions and nitrogen removal were simulated under different seasons, levels of dilution in the environment and water-exchange rate in the reactor. This multi-scale model provides an important tool for environmental authorities and seaweed farmers who desire to upscale to large bioremediation and/or macroalgae biomass production farms, thus promoting the marine sustainable development and the macroalgae-based bioeconomy.

bioengineering↗