The slow growth rates of sponges and the seasonal variations given in Zanzibar require evaluation periods of at least two years to allow a judgement for a sponge species’ suitability. The process comprises several phases:
- Collection of specimens of different sponge species in the wild (totally, more than 100 species were found and tested).
- Evaluation of each species’ suitability as bath- or cosmetic sponges (e.g. consistency, hardness, water absorption capacity, attractiveness). Promising samples were directly taken to potential customers to evaluate market acceptance.
- Growth tests of promising candidates (e.g. growth behaviour, growth rate, pest resistance, susceptibility to algal growth).
- Candidates will be subjected to propagation and farming tests (questions to be answered were: can the sponges be efficiently multiplied via segmentation; what are the chances of survival for a cutting; do the cuttings grow fast enough; how much maintenance is required; is the process profitable etc.)
The most important factors for a successful evaluation phase are sufficient funds, continuous local presence of project managers, reliable local partners, partners in academia, a lot of patience and the ability to pitch both project and product to future producers and buyers respectively.
The long period of two years it took to find a suitable sponge species and to establish of the cultivation method was the greatest challenge in the initial phase of the project.
Initially, the determination of growth rates was approached using quantitative methods (i.e. tracking volume, weight and environmental factors over time). Over time, however, it became clear that the factors influencing sponge growth are myriad while the people working on the projects are not used to work according to exact criteria. The quality and suitability of a sponge are appropriately assessed by close observation and by developing a feel for the various indicators.