New Records of Invasive Calcareous Sponge (Porifera, Calcarea) Heteropia glomerosa on the Coast of São Paulo, Brazil

Calcareous sponges are marine animals that play an important role in the ecology of coastal environments by serving as a substrate and shelter for several small invertebrates, as well as being crucial in the uptake of dissolved organic matter in reef systems, making them available in the form of particulate organic matter. Due to the subsampling and the limited number of specialists around the world, understanding the distribution of this class of sponges remains a persistent challenge. Throughout the Western Atlantic, the Caribbean sea, expected as a hotspot region for many marine taxa, is still poorly understood concerning the diversity and distribution of the class Calcarea, with the Brazilian coast being the region with the highest number of described species. Despite this, there are still large areas of the Brazilian coastline that need investigation. In this work, we present preliminary data from our exploration in one such area, where the presence of the invasive Heteropia glomerosa was observed on different beaches along the coastline of São Paulo, including São Sebastião (Toque Toque Pequeno Beach), Ilhabela (Beach of Pedras Miúdas), and Ubatuba (Saco da Ribeira). Notably, a specimen was living associated to a native sea squirt, Phallusia nigra, demonstrating a strong ecological interaction of the invasive sponge to local fauna. All records herein are from previously unrecorded beaches, which is an advancement in understanding the invasion biology of these animals along the Brazilian coastline. Additionally, the sponges were found on natural substrates, which is noteworthy since previous observations indicated colonization most frequently on artificial substrates, such as ropes and docks. These records from São Paulo demonstrate the potential capacity of this species to colonize the southern coastline and the risk of habitat suppression for indigenous sponges. Further investigations are needed to understand the spread and environmental impacts of these animals, including environmental monitoring over time.