Reproductive output and productivity of filamentous tropical Ulva over time

Abstract

The production of macroalgae in the tropics requires robust species that tolerate temperature and salinity fluctuations. The widely distributed macroalga Ulva sp. 3 is tolerant of these environmental challenges; however, a reliable source of seedlings and a consistent production of biomass are critical for the sustainable long-term cultivation of this species. Therefore, the objective of this study was to quantify the reproductive output and productivity of multiple cultivation cycles of the asexually reproducing Ulva sp. 3 seeded onto ropes using the harvested biomass of each cycle as the seedstock for each successive generation. The seedstock of three independent collections was assessed across multiple asexual generations in outdoor culture to investigate generational and environmental effects. This study, for the first time, has demonstrated that Ulva sp. 3 can be cultivated successfully over multiple (up to seven) successive generations and highlighted the importance of generational and environmental effects. Notably, there was an order of a magnitude decrease in reproductive output and greater than 4-fold decrease in biomass productivity across generations, while the decrease across cultivation cycles was more pronounced with a greater than 20-fold decrease in reproductive output and an order of a magnitude decrease in biomass productivity. The marked decrease in reproduction and productivity was driven by a generational effect in combination with environmental effect across the multi-generational study and both require consideration for the intensive production of biomass.

Reproductive sterility increases the capacity to exploit the green seaweed Ulva rigida for commercial applications

“…The green seaweed Ulva is an increasingly important food (Ortiz et al, 2006), feed (Ahmed et al, 2015;Cyrus et al, 2015), and biofuel feedstock (Bruhn et al, 2011), as well playing a role in the delivery of crucial wastewater and CO2 remediation services (Chung et al, 2011;Al-Hafedh et al, 2015). Interest in Ulva as a source of bioproducts and bioprocesses has driven concomitant efforts to optimize Ulva cultivation (Hiraoka & Oka, 2008;Bolton et al, 2009;Carl et al, 2016). Ulva species should, in theory, be ideal cultivation candidates given their cosmopolitan distribution (Kirkendale et al, 2013), very high growth rates (Bruhn et al, 2011), and broad environmental tolerances (Luo & Liu, 2011).…”

Recent advances in seaweed seedling production: a review of eucheumatoids and other valuable seaweeds

“…Over the last decade, numerous studies on the use of micropropagated seedlings for seaweed cultivation have been published, with many of them emphasizing the im-species (Gupta et al 2018). Researchers may develop a combination of various abiotic factors to induce reproductive maturity and eventual sporulation independent of the natural life cycle based on their understanding of seaweed reproductive biology (Carl et al 2014(Carl et al , 2016. However, rigorous, long-term experimentation is needed to optimize the conditions that can trigger maturity and ling rearing facility until they reach the appropriate plantlet size for transplantation.…”