Site-specific factors override local climatic conditions in determining microalgae productivity in open raceway ponds

The response of microalgae to environmental variation affects commercial scale production of algal feedstocks. Regionally-resolved predictive models of biomass productivity use climatic factors such as temperature and light to estimate algal growth and identify the best locations for production sites. However, such predictions have rarely been validated at continental scales due to the lack of continuous robust datasets originating from multiple locations simultaneously. We established and maintained cultures of Nannochloropsis sp. in open raceway ponds in 150 to 260 L for >17 months at three locations: Kailua-Kona, HI; Las Cruces, NM; and San Diego, CA. We compared predicted biomass productivities, based on local weather conditions, with experimental field data. We found considerable deviations between predicted and observed productivities across and within sites. Although weather remains a pertinent driver of productivity, site-specific factors, such as local pest pressures, chemical/ biological contaminants, and differences in the surrounding environment heavily influence biomass productivities. Identifying and quantifying these local factors is key to formulating more accurate models to assess potential productivity and identify favorable sites for establishing algal production facilities.

Automated summary

The response of microalgae to environmental variation is crucial for commercial production of algal feedstocks. However, the current predictive models based on climate factors have rarely been validated at continental scales. This study compared predicted biomass productivities with experimental field data and found significant deviations, indicating the influence of site-specific factors on algal growth. Identifying and quantifying these factors is essential for more accurate models and locating favorable sites for algal production facilities.