Solar Pond devices: free energy or bioreactors for Artemia biomass production?

Abstract

The recent exponential growth in industrial aquaculture has led to a huge increase in Artemia biomass production in order to meet increased fish production needs. The present study explores the potential use of salt gradient solar ponds (SGSPs) for production of Artemia nauplii. An SGSP is a basin of water where solar energy is trapped and collected via an artificially imposed gradient. Three zones can be identified in an SGSP: upper and lower zones, which are both convective, and a middle zone, which is intended to be non-convective. The latter acts as a transparent insulation layer and allows for storage of solar energy at the bottom, where it is available for use. The combination of salt, temperature and high transparency could make SGSPs promising bioreactors for the production of Artemia nauplii. Using particle image velocymetry (PIV) and Shadowgraph visualisation techniques, the behaviour of Artemia nauplii under critical cultivation parameters (namely, salinity, temperature and light) was monitored to determine movement velocity, and how movement of Artemia affects the salt gradient. It was observed that Artemia nauplii constantly follow light, irrespective of adverse salinity and/or temperature conditions. However, despite the substantial displacement of Artemia following the light source, the salt gradient is not disrupted. The suitability of SGSPs as bioreactors for Artemia biomass production was then tested. The results were disappointing, probably due to the lack of sufficient O(2) for Artemia survival and growth. Follow-up trials were conducted aimed at using the SGSP as a green and economically attractive energy source to induce faster hatching of cysts and improved Artemia nauplii growth. The results of these trials, and a case study of Artemia nauplii production using an SGSP, are presented. The authors constructed a Solar Pond device, which they suggest as a novel way of supplying thermal energy for Artemia biomass production in an aquaculture enterprise. Finally, the authors suggest a method of producing and collecting Artemia biomass, and of heating a fish larval tank, in an 'ideal' Solar Pond device, profiting from the low investment costs of using a decommissioned salt works.

The Dunaliella salina organelle genomes: large sequences, inflated with intronic and intergenic DNA

“…D. salina was selected for genome sequencing because of its potential as a feedstock producer for biofuels production [23] and its model status for studying saline adaptation. All of the D. salina whole genome shotgun sequencing (WGS) trace files that the DOE JGI produced are publicly available at the GenBank Trace Archive [24]; soon a complete assembly of the D. salina nuclear DNA (nucDNA) will be made public.…”

Brazilian solar saltworks - ancient uses and future possibilities

“…The consumption of fish and derivatives has been documented as having beneficial effects on human health due to the presence of omega-3 polyunsaturated fatty acid (PUFA) [7]. For the poor populations from coastal regions of the semiarid which suffer from nutritional deficiency, artisanal fisheries are one of the only sources of supply and obtaining income.…”

“…Dormant cysts of Artemia are available year-round in large quantities along the shorelines of hypersaline lakes, coastal lagoons and solar saltworks spread over the five continents [7]. …”

“…Prices have risen exponentially, turning Artemia into a bottleneck for the expansion of the hatchery aquaculture of marine fish and crustacean. In particular, many developing countries can barely afford to import the very expensive cysts [7]. …”