Abstract Sponge-ophiuroid ecological associations, which are important in the dynamics of marine populations and communities, have been recorded for a long time. In this study, we report new records of interactions between sponges and ophiuroids, which were obtained by analyzing biological collections, to increase knowledge about the associations between these animals. The study observed 14 interactions between sponges and ophiuroids, eight of which are new to science: Ophiocnida scabriuscula and Agelas sp., Ophiothrix sp. and Monanchora arbuscula, Ophiactis quinqueradia and M. arbuscula, O. quinqueradia and Callyspongia ( Cladochalina) aculeata, Ophiactis savignyi and Agelas dispar, O. savignyi and M. arbuscula, O. savignyi and Topsentia ophiraphidites, and O. savignyi and Dysidea etheria. The specimens found were collected in four areas of the northeastern Brazilian coast (tropical southwestern Atlantic), including a conservation area and a mesophotic coral ecosystem. Thus, the continuation of studies and the implementation of conservation strategies for these environments are essential. Finally, the importance of biological collections as a crucial data source for biodiversity studies is reinforced. Spongeophiuroid Sponge ophiuroid communities time ophiuroids animals 1 science sp arbuscula M O Cladochalina aculeata dispar ophiraphidites etheria tropical Atlantic, Atlantic , Atlantic) ecosystem Thus essential Finally reinforced

Abstract Marginal reefs can provide meaningful information about the structure and dynamics of ecosystems under suboptimal environmental conditions. In addition to their different characteristics, these environments can also occur in urbanized areas. In this note, we characterize marine animal forests (MAFs) on turbid-zone reefs on an urban coast in the equatorial southwestern Atlantic. Overall, the sandstone ferruginous reefs (6-10 m depth) exhibited a flat topography and gentle slope (1-2 m above the seabed). Benthic cover is composed mainly of sponge gardens and ascidians. In addition, we found a low-relief coral carpet with only one massive reef-building coral (Siderastrea stellata) and Zoantharia. The ascidians and sponges had a higher diversity (at least 15 species) than the cnidarians (two species) in these forests. The main animals forming this seascape are weedy and stress-tolerant species adapted to challenging environmental conditions, such as swell waves, mesotidal regimes, moderate turbidity waters, and periodic burial. In this regard, these conditions and human impacts have shaped a unique MAF. Remarkably, the studied formations seem similar to high-latitude marginal reefs or low-latitude reefs under the influence of upwelling, which sustains soft corals and non-framework building coral communities along with sponges and ascidians. In particular, the shallow MAFs along the semi-arid coast of Brazil seem to lack some of the characteristics of low-latitude reefs under high sedimentation, whose structure was described as coral rubble within sedimentary matrices. This suggests that factors other than periodic burials and low light availability affected these MAFs. These overlooked forests are widespread in this area and have been neglected in studies, despite their richness (> 31 taxa) and valuable ecosystem goods and services. In the context of urbanized areas subject to climate change and pollution impacts, jetties, and dredging activities, it is necessary to consider these lush forests in impact assessments and conservation policies. note (MAFs turbidzone turbid zone Atlantic Overall 610 6 10 (6-1 depth 12 1 2 (1- seabed. seabed . seabed) lowrelief relief reefbuilding reef Siderastrea stellata Zoantharia at two stresstolerant stress tolerant waves regimes waters burial regard MAF Remarkably highlatitude latitude lowlatitude upwelling nonframework non framework particular semiarid semi arid sedimentation matrices studies > ( 3 taxa services jetties activities policies 61 (6- (1 (6