Better Together: Ex Situ Co-Culture of Seaweed and Two Mediterranean Demosponge Species

The interest in sponges is growing due to their environmental and economic potential such as bioremediation and aquariology and, therefore, so are the efforts to culture them. However, at the Mediterranean scale, few sponge species have been successfully reared under controlled conditions. Owing to their inorganic nutrient excretion, their co-culture with seaweeds (capable of assimilating these compounds) seems promising. In this work, the two Mediterranean demosponges Hymeniacidon perlevis and Aplysina cavernicola and the seaweed Cladophora prolifera have been successfully co-cultured ex situ for over three months. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$H$</tex>. perlevis and A. cavernicola increased their total Projected Surface Area (PSA) 34.9% and 9.46% at the end of the trial, respectively, while <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$C$</tex>. prolifera showed a significant wet-weight increasing trend at a mean monthly growth rate of 6% (± 4.4 SE). The presence of the seaweed served to maintain low levels of nitrates, nitrites and phosphates during the duration of the experiment. This work represents a step forward in the knowledge of the cultivation practices of these species in ex situ systems.