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Aspects of the nutrient-uptake physiology of Porphyra dioica (Brodie et Irvine) from Porto, Portugal were investigated under laboratory conditions. The capacity for uptake and accumulation of nitrogen (N) by P. dioica was determined for two different N sources, ammonium and nitrate (). The influence of the light–dark cycle and of the simultaneous presence of and , as well as the effects of phosphorus (P) enrichment, on the growth, nutrient uptake, and accumulation were also evaluated. Porphyra dioica was able to take up, accumulate, and grow equally well using both sources of nitrogen when presented separately. The photosynthetic pigment levels increased significantly with the increase of the availability of N, for both sources. The chlorophyll a content was higher in thalli that used as source of N, while this difference was not seen for phycobiliprotein content. When both N sources were available (NO3 : NH4 = 6 : 1), P. dioica preferentially removed , with a clear diurnal difference. During the light period, the algae removed 70% of the available, while only 35% was removed during the dark period. Phosphorus enrichment did not influence the growth rate or the amount of P removed from the medium, suggesting a limited capacity to store P. These results indicate that P. dioica is a good candidate for application in an integrated multi-trophic aquaculture (IMTA) system.

Since 2011, Dr. Charles Yarish and colleagues have experimented with growing seaweed on long lines at the head of New York's Bronx River Estuary, along with ribbed mussels suspended from a raft. They have raised a summer crop of the native red seaweed, Gracilaria tikvahiae, that grew up to 16.5% a day in July and a winter crop of sugar kelp, Saccharina latissima, that grew up to 8 feet in six months. Yarish says he has been surprised by the profigious growth in an area with low salinity and an overload of "a suite of nutrients" from a nearby waste water treatment plant and non-point runoff from the land and river. 

Offshore grown macroalgae biomass could provide a sustainable feedstock for biorefineries. However, tools to assess its potential for producing biofuels, food and chemicals are limited. In this work, we determined the net annual primary productivity (NPP) for Ulva sp. (Chlorophyta), using a single layer cultivation in a shallow, coastal site in Israel. We also evaluated the implied potential bioethanol production under literature based conversion rates. Overall, the daily growth rate of Ulva sp. was 4.5 ± 1.1%, corresponding to an annual average productivity of 5.8 ± 1.5 gDW m−2 day−1. In comparison, laboratory experiments showed that under nutrients saturation conditions Ulva sp. daily growth rate achieved 33 ± 6%. The average NPP of Ulva sp. offshore was 838 ± 201 g C m−2 year−1, which is higher than the global average of 290 g C m−2 year−1 NPP estimated for terrestrial biomass in the Middle East. These results position Ulva sp. at the high end of potential crops for bioenergy under the prevailing conditions of the Eastern Mediterranean Sea. We found that with 90% confidence, with the respect to the conversion distribution, the annual ethanol production from Ulva sp. biomass, grown in a layer reactor is 229.5 g ethanol m−2 year−1.This translates to an energy density of 5.74 MJ m−2 year−1 and power density of 0.18 W m−2. Growth intensification, to the rates observed at the laboratory conditions, with currently reported conversion yields, could increase, with 90% confidence, the annual ethanol production density of Ulva sp. to 1735 g ethanol m−2 year−1, which translates to an energy density of 43.5 MJ m−2 year−1 and a power density 1.36 W m−2. Based on the measured NPP, we estimated the size of offshore area allocation required to provide biomass for bioethanol sufficient to replace 5–100% of oil used in transportation in Israel. We also performed a sensitivity analysis on the biomass productivity, national CO2 emissions reduction, ethanol potential, feedstock costs and sizes of the required allocated areas.

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.