In the present study, we assessed the sponge fauna, sponge-associated, and planktonic prokaryotic communities residing in Burgers' Zoo Ocean aquarium, Arnhem, the Netherlands. The Ocean aquarium consisted of separate displays and life support systems, and included fish-only systems in addition to a large, 750,000 L tank containing a living, tropical coral reef ecosystem. Sponges were observed throughout the aquarium system and were identified as belonging to the genera Chalinula, Chondrilla, Chondrosia, Cinachyrella, Stylissa, Suberites and Tethya. There was a highly significant difference in composition between sponge-associated and planktonic prokaryotic communities. The tanks in which the sponges were sampled appeared to have a secondary structural effect on prokaryotic composition with sponges and water from the same tanks sharing several microorganisms. Both sponge-associated and planktonic prokaryotic communities housed prokaryotic taxa, which were highly similar to microorganisms previously recorded in sponges or coral reef environments, including taxa potentially involved in nitrification, denitrification, sulphur oxidation, and antibiotic biosynthesis. Several abundant microorganisms were only recorded in sponges and these may play a role in maintaining water quality in the aquarium system. Potential pathogens, e.g. related to Photobacterium damselae, and beneficial organisms, e.g. related to Pseudovibrio denitrificans, were also detected. The present study showed that Burgers' Zoo Ocean aquarium housed diverse free-living and host-associated prokaryotic communities. Future research should focus on identifying conditions and microbial communities conducive to a healthy aquarium environment.

The symbiotic relationship between the syllid polychaete, Haplosyllides floridana Augener, 1922, and the barrel-shaped sponge Xestospongia muta (Schmidt, 1870), originally documented solely in the Caribbean, is presumed to be species-specific. Recently, the host sponge has been found as a single species distributed across approximately 8000 km (from 26°N to 22°S). Herein we addressed new spatial and bathymetric population records of H. floridana to question the persistence of the association with X. muta, and whether, in the case of an association, the polychaete remains as a single species throughout this extensive distribution. Our findings change the restricted distribution of H. floridana, revealing a remarkable association with X. muta from Tropical north-western to south-western Atlantic including records in the Fernando de Noronha Archipelago and the Almirante Saldanha Seamount, at 270 m deep. The populations analysed in this study are morphologically consistent. The study underscores the need for further investigations into the connectivity of Xestospongia species, the presence of Haplosyllides in other ocean basins, and the shared evolutionary history between Xestospongia and Haplosyllides. The observed life cycle completion of H. floridana within the host sponge suggests a potential co-evolutionary relationship, offering insights into the intricate dynamics of symbiotic associations in marine ecosystems.

Lough Hyne (LH) Marine Nature Reserve in Ireland is a globally recognised biodiversity hotspot that hosts mesophotic-like communities in shallow water, however, major changes have occurred to most of the rocky cliff (>6 m) communities in one or more events between 2010 and 2015. To provide insights into these changes, we compared the sponge assemblage composition on the undersides of different sized, shallow (<1 m) subtidal boulders between 2000 and 2022 at two sites in LH. We also measured sponge species richness at seven sites in 2018. We found that unlike earlier reports from the deeper subtidal reef sponge assemblages, there was no evidence for changes in sponge assemblage composition on the undersides of boulders at either site. We also found high levels of sponge species richness at all seven sites sampled in 2018. We did find differences in sponge assemblages between sites and for different boulder sizes, which we propose is a result of site-specific environmental conditions and disturbance and size–area relationships. Since we found no changes in the shallow subtidal sponge assemblages between 2000 and 2022, our results support the hypothesis that changes to the deeper subtidal sponge assemblages at LH are driven by local processes associated with deeper water in LH, potentially related to the seasonal oxythermocline that forms within LH. Given the national and global importance of LH, understanding the drivers of change is critical to determine if management actions can prevent any future alterations to the LH sponge assemblages and support wider mesophotic community management.

Polynesia is a hotspot for marine biodiversity in the South Pacific Ocean, yet the distribution of many invertebrate taxa in this region is still often poorly assessed. Information on the diversity and phylogeography of sponges in particular remains limited in spite of their importance for coral reef ecosystems. Recent expeditions to the island group of Wallis and Futuna enabled the first larger-scale assessment of the Wallis Island sponge fauna, resulting in the molecular identification of 82 unique Molecular Operational Taxonomic Units (MOTUs) from 339 sponge samples based on 28S C-region rDNA and CO1 mtDNA data. Faunal comparisons with both adjacent archipelagos and more distant Indo-Pacific regions were predominantly based on the MOTUs obtained from Wallis Island ecoregions, and suggest high levels of endemism of sponges in Wallis and Futuna, corroborating previous data on the biodiversity of sponges and other marine phyla in the South Pacific. The results of this molecular taxonomic survey of the Wallis and Futuna sponge fauna aim to lay solid foundations for a sustainable ‘Blue Economy’ in Wallis and Futuna for the conservation of their local coral reefs.

Sponges are important components of marine systems globally, and while sponges have generally been shown to tolerate ocean acidification (OA), most earlier studies have focused on demosponges with siliceous skeletons. In contrast, little is known of how calcareous sponges, with calcite or aragonite skeletons, may react to OA conditions. Here we measured tissue necrosis and respiration rate of the temperate New Zealand calcareous sponge Grantia sp. to simulated OA. Our treatment conditions were based on the IPCC RCP8.5 (pCO2 1131.9 ± 113 μatm) scenario over a 28 day experiment, and responses were compared to current day control conditions (pCO2 512.59 ± 23 μatm). Sponge respiration rate was not significantly different between the control and treatment sponges and there was no evidence of tissue necrosis over the course of the experiment. Overall, our study is consistent with earlier studies on demosponges, showing calcareous sponges to be resilient to OA.

Two new species of Haliclona (Chalinidae, Haplosclerida) are described here from Brazilian oceanic islands and the coast of Ceará State. They derive from collections undertaken between 1999 and 2014, and materials are deposited in the Porifera collection of Museu Nacional in Rio de Janeiro (MNRJ). Haliclona (Halichoclona) insularis sp. nov. can be distinguished from other Haliclona spp. in the western Atlantic by the combination of surface with light to deep red colour intermixed with white to beige areas (occasionally completely beige), white to beige choanosome, small fistular outgrowths, fragile consistency and blunt oxeas (90–175 × 1–5 μm) with irregular tips. Haliclona (Soestella) moraesi sp. nov. is the only western Atlantic species of Haliclona with the combination of thickly encrusting to cushion-shaped habit, purple or light pink colour, and a dense (sub)isotropic skeleton with rounded meshes, and without microscleres. Several attempts to amplify COI mtDNA and 28S C2–D2 rRNA for both species were unsuccessful, in spite of the initial successful extraction of genomic DNA. The number of Haliclona spp. known from the Brazilian coast is now 17. The long gap between species collection and formal description supports the concept of the taxonomic impediment, which is particularly marked in speciose taxa with little morphological disparity, as observed in Haplosclerida.

Sponges, especially Calcarea, are minor components of benthic associations, especially during the Mesozoic. In the Lower Cretaceous of the Neuquén Basin, small calcareous sponges have been found building a small monospecific meadow. It is restricted to a marlstone lens-shaped bed in a quiet outer-ramp setting in the Cerro Marucho Locality (Picún Leufú depocentre), above a shell bed of small exogyrid oysters; oysters and sponges were the only preserved macrobenthic faunal elements. Individual sponges were small, under 4 cm high, and presented a sub-cylindrical morphology with one or more rounded, apical osculi, many inhalant openings and triactine spicules. Specimens studied here were assigned to Endostoma sp. aff. Endostoma nodosa. These sponges are quite commonly encrusted by exogyrid oysters, serpulids, sabellids, agglutinating foraminifers and cyclostome bryozoans. Overgrowths among sclerobionts were common, though no undoubtedly in vivo interaction has been recorded. Disarticulated left oyster valves were frequently bioclaustrated by the sponges, showing that in vivo settlement upon sponges was common. Many oysters settled in the periphery of the osculum suggesting a commensal relationship. The study of this sponge meadow and its sclerobiont community allowed the identification of different stages of ecological succession. The pioneer stage was characterised by sponge settlement on oyster valves, within an otherwise soft consistency bottom. High sedimentation or high nutrient inputs, either individually or in combination, could explain the great abundance of oysters. During the climax stage, sponges thrived and harboured several sclerobiont taxa, developing a relatively dynamic palaeocommunity. Finally, an intensification in either sedimentation rates or nutrient input (or both) past the tolerable threshold for sponges may have been the cause(s) of the meadow's demise. Endostoma and similar forms were up to now reported mostly from the Jurassic and Cretaceous of Europe as accessory builders, or as accompanying fauna in reefal settings. This new record shows that in rare occasions they could form low-relief meadows on their own.

Global climate change has aggravated the severity of space competition put up by marine sponges in the tropical coral reef ecosystems. We report here an outbreak of coral-killing sponge Clathria (Microciona) aceratoobtusa (Carter, 1887) over live coral colonies of the genus Turbinaria in an unprotected reef (mainland patch reef) in the Gulf of Mannar in India. An outbreak of this orange-reddish sponge was observed during an explorative dive in April 2020. Live coral cover in the reef was 62.06% (SD±3.36), which was dominated by the genus Turbinaria with 82.31%. Among the total of 549 Turbinaria colonies counted in five transects, 21.86% (n = 120) of colonies were found infested by the sponge. As the mainland patch reef lies outside the boundary of marine protected area, it is exposed to human-induced threats, apart from climate change implications. This report would serve as an evidence to indicate the intensity of the space competition waged by sponges in a disturbed reef ecosystem.

Sponges are major components of benthic marine ecosystems across the world. However, despite seagrasses being one of the key ecosystems in tropical environments, their associated sponge assemblages have been poorly studied. In this study we investigated seagrass and sponge assemblage composition in an Indo-Pacific seagrass meadow located surrounding Hoga Island in the Wakatobi National Park, South-east Sulawesi, Indonesia. We examined a continuous seagrass meadow, spatially separated into two sites, categorized into three zones based on the distance to the shore: high-shore, middle shore and near-reef-flat zones. We investigated the species richness, composition and abundance of both seagrass and sponge species across zones and sites. We found that the sponge assemblage composition was significantly different between sites and zones, while the seagrass assemblage was not. This suggests that the seagrass and sponge assemblages have different ecological drivers. Based on our observations, we propose that sponge adaptation to the prevailing environmental conditions in different seagrass zones may be reflected by sponge morphology. Furthermore, seagrass ecosystem management strategies should consider the different drivers of seagrass and sponge distribution patterns as they might be differentially affected by specific anthropogenic stressors.

We surveyed the shallow-water sponges of Ascension Island using scuba diving. In total, we collected 58 sponge specimens from 17 locations at depths of 0.5–30 m. In addition, we compiled historical records of sponges. We describe nine species new to science: Niphates verityae sp. nov., Petrosia (Petrosia) ernesti sp. nov., Monanchora downesae sp. nov., Svenzea weberorum sp. nov., Erylus williamsae sp. nov., Ircinia nolanae sp. nov., Ircinia richardsoni sp. nov., Ircinia simae sp. nov. and Chondrosia browningorum sp. nov. We provide molecular sequences for three of the new species. We have added 50% to the number of known species and added two new genera and one family to the known Ascension Island sponge fauna. Twenty-six species, from 16 genera, and 13 families, are now reported from Ascension's shallow waters. Many of these may be endemic to the island. We discuss the biogeographic affinities of Ascension Island and emphasize the need for additional survey of the sponge fauna of remote islands such as Ascension.

Fossils within early Cambrian phosphorites worldwide are often well preserved due to early diagenetic permineralization. Here, we examine the fossil record contained within phosphorites of the Lower Cambrian Pusa Formation (late Fortunian to Cambrian Stage 2) in Fontanarejo, central Spain. The sedimentology and age of these phosphorites have been controversial and are here reviewed and discussed, providing also an updated geological map. The Pusa Formation is composed of fine clastic sediments that are partly turbiditic, with channels of quartz-rich conglomerates and abundant phosphorites in the upper part of the succession. The microfacies and mineralogy of these channel deposits are studied here for the first time in detail, showing that they are mainly composed of subspherical apatite clasts, with minor mudstone intraclasts, quartzite and mica grains. Numerous sponge spicules, as well as entirely preserved hexactinellid sponges and demosponges, were collected within these phosphorites and likely represent stem groups. In addition to sponges, other fossils, such as small shelly fossils (SSF) of the mollusc Anabarella sp., were found. The phosphorites exhibit multiple evidence of intense microbial activity, including diverse fabrics (phosphatic oncoidal-like microbialites, thrombolites, stromatolites and cements) and abundant fossils of filamentous microbes that strongly resemble extant sulphur-oxidizing bacteria. Our findings strongly suggest that microbial processes mediated the rapid formation of most of the Fontanarejo apatite, probably accounting for the exceptional preservation of fragile fossils such as sponge skeletons. The apparent presence of taxonomically diverse hexactinellid and demosponge communities at the lowermost Cambrian further corroborates a Precambrian origin of the phylum Porifera.

We record for the first time a nominal species of the genus Microscleroderma in the Western Atlantic, and the first record of the genus Amphibleptula in Mexico. Two new species of ‘lithistid’ Tetractinellida are described: Microscleroderma mexica sp. nov. from crevices of two reefs in Veracruz, Mexico, and Amphibleptula aaktun sp. nov. from the anchialine cave El Aerolito, Cozumel Island, Mexico. Microscleroderma mexica sp. nov. is characterized by its tubular and cup-shaped to wavy laminar habitus, hirsute surface and two size categories of oxea diactines. Amphibleptula aaktun sp. nov. is characterized by its ficiform or lobular habitus with an exhalant area at the flat top of the body, divided into numerous vertical septa-like structures; its desmas have thinner epirhabds, and thinner oxea than those of Amphibleptula madrepora. This is the second species of Amphibleptula that has been described; hence, we propose the redefinition of the genus. Both species described have a shallow distribution (≤21 m depth); they are differentiated from each other by the disjunction between their habitats as well as by their morphology.

The poorly known sponge species Axinella vellerea (Topsent, 1904), Acarnus levii (Vacelet, 1960) and Haliclona poecillastroides (Vacelet, 1969) are reported from bottom-trawl samples off the Balearic Islands, Western Mediterranean. A re-description is provided for all three species and the Folmer fragment of cytochrome oxidase subunit I (COI) obtained for A. levii and H. poecillastroides. This is the second report of A. vellerea in the Mediterranean, the first time that A. levii is reported outside Corsica and the first time that H. poecillastroides is documented outside the Gulf of Lion, France. The systematic allocation of A. levii and H. poecillastroides is discussed based on a COI phylogenetic analysis and morphology. The poorly understood phylogeny of the Haplosclerida does not permit us to find a proper allocation for H. poecillastroides, although its current position in the genus Haliclona or the family Chalinidae is not defensible. On the other hand, A. levii currently fits best in the family Microcionidae, and seems related to some Clathria species with mixed features between Clathria and Acarnus. Considering that the species of the genus Acarnus shares a strong synapomorphy (the possession of Cladotylotes), it is plausible for all Acarnus species to be Microcionids. We conclude that H. poecillastroides needs to be reallocated to a new genus: Xestospongia poecillastroides comb. nov. (Petrosiidae). However, a reallocation of A. levii is not advisable for the moment, as this would imply major systematic changes such as the reallocation of the whole genus Acarnus to Microcionidae, and the redescription of Microcionidae and Acarnidae.

We report on the relationships between some conspicuous Mediterranean photophilous sponge species and Caulerpa cylindracea, a non-indigenous species. A diversification of defence strategies and behaviour is highlighted in target species belonging to different orders of Demospongiae from a western Mediterranean Marine Protected Area (NW Sardinian Sea). Caulerpa cylindracea displays a strongly invasive behaviour during body colonization of the Irciniidae Sarcotragus spinosulus and Ircinia retidermata (order Dictyoceratida). These sponges possess pre-adaptive defensive morpho-functional and physiological traits enabling them to partly withstand algal invasion. Also Aplysina aerophoba (order Verongiida) seems to be able to control colonization. Successful anti-Caulerpa strategies characterize the rarely affected Crambe crambe (order Poecilosclerida). Species-specific competitive strategies are displayed at different levels of body architecture, behaviour and physiology by native sponge species. The invasion patterns on sponges, the invasion dynamics in 2016–2017 and topographic distribution of C. cylindracea on S. spinosulus confirm this algal species as a threat, with potential long-term effects on sponge assemblages. Data suggest other kinds of poorly investigated synergic stressors affecting these habitat-forming species. Defence strategies of sponge species take the form of: (1) passive deterrence by morpho-functional pre-adaptive traits as growth form, biomass amount, surface traits, and microhabitat within the sponges' aquiferous system; (2) active physiological defence, whereby the morphology/anatomy of the sponge body is adapted to control invaders, by body remodelling and regenerative processes within the aquiferous system and at the sponge surface; (3) presumed active chemical defence by exudation processes of bioactive compounds.

The three-dimensional coral scaffolds formed by the skeletons of the cold-water corals Madrepora oculata and Lophelia pertusa represent an important deep-sea hard substratum and create an optimal shelter for a rich associated fauna in which the contribution of Porifera has still not been fully considered. The taxonomic analysis of sponges collected from two Sardinian canyons (Nora and Coda Cavallo, 256–408 m) and associated with the dead coral matrix resulted in 28 species, including new records for the Mediterranean Sea, Italian fauna or Central Tyrrhenian Sea. In addition, for many species this is the first finding associated with the coral framework or the first documentation of the in situ morphology. The taxonomic comparison with sponge assemblages associated with coral frameworks from Santa Maria di Leuca, Strait of Sicily and Bari Canyon, gave the opportunity to evaluate the similarities among geographically separated banks. Overall, the percentage of exclusive species (recorded only in one site), is very high (81%) and only one species is shared by all four sites, suggesting a low connectivity among the sponge communities. The percentage of shared species is higher for the Maltese community, supporting the role of the Sicily Channel as a crossroads between the communities of the eastern and western Mediterranean basins. Here, 55% of the sponges associated to the coral framework are also reported in shallow-water coralligenous assemblages, indicating a high bathymetric connectivity as well as an ecological plasticity allowing these species to occupy a wide range of small, dark refuges.

Climate change and heavy anthropic pressures are giving rise to important modifications in the rocky benthic communities of the Mediterranean Sea. In particular, sponge assemblages have been deeply affected due to the susceptibility of some species to dramatic phenomena such as mass mortalities or widespread variations in the abundance of other species. For this reason, long-term biodiversity monitoring of the sponge assemblages is important for understanding the direction of changes over time. We studied the sponge fauna living off Tricase Porto (Otranto Strait) and compared its composition with the results of a study conducted in the same area 50 years ago. The comparison indicated that the sponge diversity of this area has strongly increased in the last 50 years and a large number of the sponges recorded in the old survey are still present in the recent community. This evidence matches with other results obtained from different localities of the Mediterranean Sea indicating an increase of sponge diversity, possibly due to the present water warming. The description of two new Demosponge species, Diplastrella boeroi sp. nov. and Spirastrella angulata sp. nov., is also provided.

Sponges are important components of intertidal marine communities. There is a lack of information about intertidal marine sponge diversity in the western coast of Portugal (North-east Atlantic). In the present work we identified the most common intertidal sponges of the western coast of Portugal, and made a comprehensive list of the intertidal species described so far for this region. Sponges belonging to the Classes Calcarea and Demospongiae were identified, the former class for the first time at these locations. Demospongiae are the most common intertidal sponges, present in all sampling locations. We used an integrative approach for Demospongiae identification, using both morphological and molecular characters. Molecular identification, using a CO1 marker proved to be helpful in the identification to the genus level, despite some limitations, such as difficulty in amplification experienced for sponges as well as non-target organisms. A total of 170 specimens were collected. Seven specimens (five species) belonged to the Class Calcarea and 163 specimens (23 species) to the Class Demospongiae. The demosponge Hymeniacidon perlevis was present at all sample locations. Calcarean species were primarily found in samples taken along the south-western coast.

The Pentland Hills sponge fauna (Llandovery, Telychian) consists of an unusual, aberrant assemblage, but of low diversity. A new specimen of a unique sponge, Eoghanospongia carlinslowpensis gen. et sp. nov., is described from the classic locality of R82. The mushroom-shaped, probably stalked body (peduncle attachment to body not exposed) resembles that of some living rossellids, especially Caulophacus. The sponge also shows prominent projecting pentactins and monaxon derivatives – a spicule type diagnostic of the Rossellidae among living taxa, albeit in a robust form not described from extant sponges, including Caulophacus or other pedunculate lyssacinosidans. Certain attribution to the Rossellidae is not possible from the single specimen, largely because of weak preservation of the primary spicule skeleton, but no other fossil or modern sponges show any significant similarity to it. Although similarly early relatives of the Rossellidae have recently been described from elsewhere, the new sponge is even more unexpected in being from a shallow-water environment, making the absence of rossellids through the rest of the Palaeozoic much more problematic.

Mesophotic ecosystems have been relatively poorly studied in the Indo-Pacific and in particular within the Coral Triangle region. Here we used a mini-ROV to explore the changes in major benthic groups at two sites (~200 m apart) in the Wakatobi Marine National Park, SE Sulawesi, Indonesia spanning shallow water coral reefs (5 m) to deeper water mesophotic ecosystems (80 m). We found very similar patterns at both sites where coral cover peaked at 15 m, declined rapidly by 30 m, and was virtually absent at 50 m. As coral declined there was a marked increase in sponges, soft corals and other encrusting organisms (including ascidians, bryozoans, tubeworms, gorgonians and molluscs). Importantly, our results differ from most previous studies in other geographic locations where hard corals extend much deeper. It is unclear what drives this difference but it may be related to higher levels of turbidity and therefore reduced light penetration in the Wakatobi compared with other areas, which limits the vertical extent of coral development.

Boring sponges are an important component of bioeroder assemblages in tropical coral reefs. They are considered as a potential threat for coral reef health, and the increase of dead corals is expected to promote their abundance. The relationship between the availability of dead coral substrata and the development of boring sponge assemblages was evaluated during El Niño 2015–16 at five reefs from Zihuatanejo, Guerrero, Mexico. Environment and substrate quality were assessed. Overall, environment conditions remained normal in relation to previous studies in the area. Only water temperature showed unusually high records at all sites and coincided with bleaching and mortality of corals, possibly caused by the effects of the El Niño event. Abundance of boring sponges in dead corals and coral rubble was lower than during previous studies. Although sponge abundance was not directly related to cover of both dead corals and coral rubble, cover of dead corals showed a high correlation with the variation in the structure of sponge assemblages across sites. Cliona vermifera dominated sponge assemblages at all sites, and its abundance was high under conditions of high cover of live corals and low cover of bleached corals. Since overall sponge abundance responded in a similar way, these results suggest that boring sponge assemblages dominated by C. vermifera are enhanced by conditions favourable for corals. Our results imply that El Niño events in the Mexican Pacific are not likely to cause immediate population outbreaks of boring sponges.