3.3.2. Algal controlled systems
3.3.2.1. Microalgae availability.Aquaculture ponds are eutrophic
with a primary production of 1–3 g C/m2
/day in temperate regions
and 4–8 g C/m
2
/day in the tropics and subtropics. Nearly all algae
are mineralized within the pond. In addition, aquafeeds also act as
a fertilizer. If the total primary production would constantly be harvested from ponds, the amount of fertilizer needed to maintain the
productivity would be prohibitively high. Pond management aims
to maintain production and consumption in equilibrium. Nevertheless, even if only a few percent of the primary production could be
harvested and used as feed or biofuel (Cadoret and Bernard, 2008),
the impact on the biobased economy would be significant. Direct
harvesting of algae is difficult. New techniques like flocculation
maybe will lead to a breakthrough (Lee et al., 2009).