Restoring Biscayne Bay, One Sponge at a Time
The Biscayne Bay Aquatic Preserves (BBAP), with funding from the Environmental Protection Agency (EPA), launched a pilot sponge propagation study in the Venetian Basin of Northern Biscayne Bay to explore the viability of using sponges to enhance water quality and ecosystem health. The nursery focused on four native high-volume sponge species—Spheciospongia vesparium, Ircinia campana, Ircinia felix, and Spongia tubulifera—selected based on filtration efficiency and ecological relevance. These species were propagated using internationally recognized techniques, with guidance from DEP’s Sponge Advisory Board, resulting in exceptionally high survival rates: Spongia tubulifera (90%), Ircinia felix (88%), Spheciospongia vesparium (86%), and Ircinia campana (84.78%). Notably, no donor sponge mortality was observed throughout the project.
Key innovations driving this success included data-driven site selection, careful fragmentation and healing processes, and the use of suspended paracord bundles (16 bundles across 50 pilings) to support 200 sponge fragments. Protective berry baskets were tested to enhance healing, and water quality was rigorously monitored to assess environmental compatibility. These measures created ideal conditions for sponge growth and long-term survival in an urbanized marine setting.
From mid-May to early July 2025, all four sponge species demonstrated measurable tissue growth, with volume increases ranging from modest to substantial. Spheciospongia vesparium grew from 426 cm³ to 484 cm³, Ircinia campana from 74 cm³ to 162 cm³, Ircinia felix from 120 cm³ to 286 cm³, and Spongia tubulifera from 136 cm³ to 199 cm³. These early growth patterns indicate strong compatibility with local conditions and validate the functionality of the nursery system.
In terms of ecosystem services, the 200 sponge fragments are already filtering tens of thousands of liters of water daily. If even 25% of the fragments reach full maturity, the nursery could filter approximately 18.75 million liters of water per day. With 50% and 100% maturation, filtration potential rises to 37.5 million and over 75 million liters per day, respectively. These figures underscore the scalable impact of sponge propagation not just for water filtration but also for broader ecological benefits, including habitat formation and nutrient sequestration.