Projections based on optimal PBR [photobioreactor] conditions suggest an annual yield of 99.54 gigatons of microalgae biomass.
Notably, Australia leads in microalgae biomass production, with an annual output of 16.19 gigatons, followed by significant contributions from Kazakhstan, Sudan, Brazil, the United States, and China, showcasing the diverse global potential for microalgae bioenergy across varying ecological and geographical landscapes. Through this rigorous investigation, the study emphasizes the strategic importance of microalgae cultivation in achieving sustainable energy solutions and mitigating climate change, while also acknowledging the scalability challenges and the necessity for significant economic and energy investments.
An Inverted Food Pyramid on Earth
Our analysis reveals that the global marine biomass pyramid contains more consumers than producers, thus increasing the scope of previous observations on inverse food pyramids. Finally, we highlight that the mass of humans is an order of magnitude higher than that of all wild mammals combined and report the historical impact of humanity on the global biomass of prominent taxa, including mammals, fish, and plants.
In fact, humans and livestock outweigh all vertebrates combined, with the exception of fish. Even though humans and livestock dominate mammalian biomass, they are a small fraction of the ≈2 Gt C of animal biomass, which primarily comprises arthropods (≈1 Gt C; SI Appendix, Tables S13 and S14), followed by fish (≈0.7 Gt C; SI Appendix, Table S15).
When analyzing trophic levels, the biomass of primary producers on land is much larger than that of primary and secondary consumers. In stark contrast, in the oceans, ≈1 Gt C of primary producers supports ≈5 Gt C of consumer biomass, resulting in an inverted standing biomass distribution as shown in Fig. 2C. Such inverted biomass distributions can occur when primary producers have a rapid turnover of biomass [on the order of days (34)], while consumer biomass turns over much more slowly [a few years in the case of mesopelagic fish (35)]. Thus, the standing stock of consumers is larger, even though the productivity of producers is necessarily higher.
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