Dutch researcher Nicole de Voogd has investigated the possibilities for rearing sea sponges in Indonesia. Some of these sponges contain substances of interest to the pharmaceutical industry. As these are increasingly difficult to obtain, there is growing interest in alternative methods of exploitation, such as rearing sponges.
For her research, De Voogd described three new species of sponges and examined the interactions of four sponge species with possible spatial competitors. She discovered that as soon as certain sponge species grow over corals, the coral develops necrotic tissue. From this she concluded that the sponges concerned produce their bioactive substances to defeat spatial competitors. This is important, as in an environment without spatial competitors, such as in a sponge culture, a lower concentration of the substances of interest to the pharmaceutical industry might be produced.
The researcher tried to rear 9 of the 151 species of sponge observed but was successful with only 3 species. Although the survival rates of these species were generally very high, the growth rates were very slow and unpredictable. Moreover, the reared sponges produced less of the biologically-active substances than their natural counterparts.
Although Indonesia has a very high diversity of sponge species, and therefore a large number of biologically-active substances with pharmaceutical potential, most of the species occur in relatively low densities compared to species in temperate areas. De Voogd discovered that as a result of this low natural density, surprisingly few Indonesian species are suitable for sea rearing.