Abstract
Abstract. There is increasing interest in macroalgae farming in European waters for a range of applications, including food, chemical extraction for biofuel production. This study uses a 3-D numerical model of hydrodynamics and biogeochemistry to investigate potential production and environmental effects of macroalgae farming in UK and Dutch coastal waters. The model included four experimental farms in different coastal settings in Strangford Lough (Northern Ireland), in Sound of Kerrera and Lynn of Lorne (north-west Scotland) and in the Rhine plume (the Netherlands), as well as a hypothetical large-scale farm off the UK north Norfolk coast. The model could not detect significant changes in biogeochemistry and plankton dynamics at any of the farm sites averaged over the farming season. The results showed a range of macroalgae growth behaviours in response to simulated environmental conditions. These were then compared with in situ observations where available, showing good correspondence for some farms and less good correspondence for others. At the most basic level, macroalgae production depended on prevailing nutrient concentrations and light conditions, with higher levels of both resulting in higher macroalgae production. It is shown that under non-elevated and interannually varying winter nutrient conditions, farming success was modulated by the timings of the onset of increasing nutrient concentrations in autumn and nutrient drawdown in spring. Macroalgae carbohydrate content also depended on nutrient concentrations, with higher nutrient concentrations leading to lower carbohydrate content at harvest. This will reduce the energy density of the crop and thus affect its suitability for conversion into biofuel. For the hypothetical large-scale macroalgae farm off the UK north Norfolk coast, the model suggested high, stable farm yields of macroalgae from year to year with substantial carbohydrate content and limited environmental effects.
Highlights
1.1 Background, aims and approachWorldwide macroalgae production is in excess of 28 million tons per year and has doubled between 2000 and 2014 (FAO, 2014)
The model was forced with tidal constituents derived from TOPEX-POSEIDON satellite altimetry (Le Provost et al, 1998); atmospheric forcing from ECMWF ERAInterim (Dee et al, 2011; Berrisford et al, 2011; www. ecmwf.int/en/research/climate-reanalysis/era-interim); interpolated river runoff from a range of observational data sets
Compared with in situ SmartBuoy observations (Greenwood et al, 2010), modelled suspended particulate matter (SPM) concentrations showed a reasonable representation of the seasonal cycle but over-estimated peak values
Summary
Worldwide macroalgae (seaweed) production is in excess of 28 million tons per year and has doubled between 2000 and 2014 (FAO, 2014). The majority of this production ( > 95 %) is from the southeast Asian region where macroalgal cultivation is well established (FAO, 2014; West et al, 2016). J. van der Molen et al.: Modelling potential production of macroalgae farms. There has been increasing interest in the potential of macroalgae cultivation across the Northern Hemisphere and Europe (Van der Burg et al, 2016), partially driven by research on biofuel technologies (Kerrison et al, 2015). A further advantage is that such third-generation biofuels do not need additional freshwater and do not compete for agricultural land like many existing biofuel sources
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call