Named for its ropy-looking long branches, Aplysina cauliformis, a coral reef sponge, provides a critical 3D habitat for marine organisms and helps to stabilize the foundation of coral reefs. However, these upright branching sponges are highly susceptible to breaking during storms, which increases sponge fragmentation and contributes to population clonality and inbreeding. Many sponges can survive severe damage and undergo frequent fragmentation, which is considered a mechanism for asexual reproduction. While fragmentation is a commonly utilized reproductive strategy in rope sponges, they also can reproduce sexually by producing larvae. How and whether they recolonize following extreme weather events is critical for the restoration and resilience of coral reef ecosystems.

Hurricanes Irma and Maria -- both in 2017 -- were two rapid succession storms that provided researchers from Florida Atlantic University's Harriet L. Wilkes Honors College and Harbor Branch Oceanographic Institute, and collaborators from the University of the Virgin Islands, the University of Mississippi and the University of Alabama, with a unique opportunity to address a priority concern -- the resilience of coral reef sponge populations after severe hurricanes. The researchers are the first to evaluate substrate recolonization by sponges in the U.S. Virgin Islands after these two catastrophic storms using genetic analyses to understand how much clonality verses sexual recruitment occurs on coral reefs post-storms. To date, studies of storm impacts have largely focused on scleractinian or stony corals.

Results of the study, published in the journal Molecular Ecology, reveal that populations of clonal marine species with low pelagic dispersion, such as A. cauliformis, may benefit from increased frequency and magnitude of hurricanes to maintain genetic diversity and combat inbreeding, enhancing the resilience of Caribbean sponge communities to extreme storm events.