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A SGSP is a basin of water where solar energy is trapped due to an artificially imposed salinity gradient. In a SGSP three zones can be identified: the surface and bottom zones that are both convective and an intermediate zone in between which is intended to be non-convective. This zone acts as a transparent insulation and allows the storage of solar energy at the bottom where it is available for use.A numerical model where the SGSP dynamics is described in terms of velocity , pressure , temperature and salt concentration is presented. It is based on the Navier-Stokes equations for an incompressible fluid coupled to one advection-diffusion equation for and one advection-diffusion equation for . The fluid density is taken to depend on and and the Boussinesq hypothesis is adopted: the fluid density appearing in the LHS of the NavierStokes equation is supposed constant and equal to some reference value whereas it is assumed to be variable in the RHS.The space discretization of the governing equations is based on the respective weak formulations and the discretization employs finite elements with a pressure correction method used to decouple velocity and pressure. Integration in time is accomplished by a BDF (Backward Differentiation Formula) method with the above PDEs treated sequentially within each time step. A computer code was developed employing the finite element class library deal.II.Comparisons with available experimental results are made to validate this numerical model.

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.