Interactions of marine mammals and birds with offshore membrane enclosures for growing algae (OMEGA)

Abstract

BackgroundOMEGA is an integrated aquatic system to produce biofuels, treat and recycle wastewater, capture CO2, and expand aquaculture production. This system includes floating photobioreactors (PBRs) that will cover hundreds of hectares in marine bays. To assess the interactions of marine mammals and birds with PBRs, 9 × 1.3 m flat panel and 9.5 × 0.2 m tubular PBRs were deployed in a harbor and monitored day and night from October 10, 2011 to Janurary 22, 2012 using infrared video. To observe interactions with pinnipeds, two trained sea lions (Zalophus californianus) and one trained harbor seal (Phoca vitulina richardii) were observed and directed to interact with PBRs in tanks. To determine the forces required to puncture PBR plastic and the effects of weathering, Instron measurements were made with a sea otter (Enhydra lutris) tooth and bird beaks.ResultsA total of 1,445 interactions of marine mammals and birds with PBRs were observed in the 2,424 hours of video recorded. The 95 marine mammal interactions, 94 by sea otters and one by a sea lion had average durations of three minutes (max 44 min) and represented about 1% of total recording time. The 1,350 bird interactions, primarily coots (Fulica americana) and gulls (Larus occidentalis and L. californicus) had average durations of six minutes (max. 170) and represented 5% of recording time. Interactive behaviors were characterized as passive (feeding, walking, resting, grooming, and social activity) or proactive (biting, pecking, investigating, and unspecified manipulating). Mammal interactions were predominantly proactive, whereas birds were passive. All interactions occurred primarily during the day. Ninety-six percent of otter interactions occurred in winter, whereas 73% of bird interactions in fall, correlating to their abundance in the harbor. Trained pinnipeds followed most commands to bite, drag, and haul-out onto PBRs, made no overt undirected interactions with the PBRs, but showed avoidance behavior to PBR tethers. Instron measurements indicated that sea-otter teeth and gull beaks can penetrate weathered plastic more easily than new plastic.ConclusionsOtter and bird interactions with experimental PBRs were benign. Large-scale OMEGA systems are predicted to have both positive and negative environmental consequences.

Recent advances and fundamentals of microalgae cultivation technology

“…A prominent researcher of such microalgae applications is marine biologist Jonathan Trent, who was the head of the Offshore Membrane Enclosures for Growing Algae (OMEGA) project. [30,[97][98][99] The whole idea was to grow algae in the city's wastewater pumped through polyethylene tubes floating in the ocean. Thus, the waves supplied mixing, the towns supplied nutrients rich in nitrogen, and the sun produced light at no cost.…”

“…On the global scale, microalgae might help to feed the growing human population, [ 27 ] requiring less land for production than common crops or animals [ 28,29 ] and can be grown offshore. [ 30 ]…”

“…[25,26] On the global scale, microalgae might help to feed the growing human population, [27] requiring less land for production than common crops or animals [28,29] and can be grown offshore. [30] Microalgae have been used in wastewater cleaning [3] and were tested as pollutant scavengers [31,32] and as a fertilizer for agriculture. [33][34][35] Because certain strains of microalga have a very high lipid content, [36][37][38] they have been used for biodiesel production.…”

From the Ancient Tribes to Modern Societies, Microalgae Evolution from a Simple Food to an Alternative Fuel Source

“…The project was not a leading one in terms of innovative algae cultivation, but it established the usefulness of various equipment and apparatus to measure temperature, photosynthetic active radiation, and oxygenecarbon dioxide levels. In addition, the ecological aspects of the floating PBR on the sea surface were also discussed and evaluated (Trent, 2012;Hughes et al, 2014).…”

“…The system consisted of lightpenetrating plastic bag PBRs with specially designed osmosis membranes (Hughes et al, 2014). Algae cultures within the bags floating on the water surface used sunlight and nutrients in water to release clean water and oxygen back into the water environment.…”