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.

Reproduction in the shallow-water, sponge-dwelling, branching syllid Ramisyllis multicaudata exhibits several features unique among syllids and among annelids in general. We describe and illustrate the segmental asymmetry which intervenes between regions of symmetry, only found in branching annelids. We describe the morphology of the stolons and of the stolon stalks, which are unique to branching syllids but differ in detail from those of the other known branching syllid, Syllis ramosa. We also illustrate newly found paddle-shaped chaetae, which might indicate that these stolons do swim. We list the number of branch points and termini in an effort to gauge the extent of branching in a worm contained in a small sponge. The species appears to have separate sexes, but this cannot be proven. We compare R. multicaudata and S. ramosa as originally described and find new morphological differences between the branching syllid from Japan described as S. ramosa and R. multicaudata. We also compare the known stolons of branching syllids to those of other genera of the ‘ribbon clade’, a group including Trypanobia and Trypanosyllis, now known to be close relatives of R. multicaudata. Ramisyllis multicaudata is the first member of the ribbon clade, and one of few Syllinae, known to have sexually dimorphic stolons.

Hymedesmia (Hymedesmia) lindstroemae sp. nov. collected at 178–210 m depth off the western Swedish coast is described. This encrusting sponge is notably characterized by its unusually large sigmas. This new species brings the number of Hymedesmia (Hymedesmia) species in Swedish waters to 30. A key for all the North Atlantic Hymedesmia (Hymedesmia) species with sigmas (32 species) is included.

Dredging activity poses an environmental risk to sponges as sediments from the dredge or disposal site may smother the sponge surface, potentially affecting water filtration and light penetration. Dredge-related sedimentation effects may also vary between sponge morphologies, potentially impacting community structure and functioning. To test this, 10 sponge species encompassing four different morphologies (massive, erect, cup and encrusting), were exposed to a single pulse treatment of three different sediment concentrations (0, 250 and 500 mg l−1) and followed over 2 weeks, in 1000 l tanks. Total suspended solids (TSS) and sedimentation rates (SR) were recorded throughout the study. A sharp decrease in TSS was recorded within the first 2–3 h and a total settlement of sediments occurred within the first 48 h of the pulse exposure (0, 8 and 16 mg cm−2 in the control, medium and high sediment treatments, respectively). The effects of high sedimentation included mortality of cup-shaped Callyspongia confoederata and small areas of tissue necrosis in other species, with massive, encrusting and wide cup morphologies particularly affected. However, the sediment concentrations tested in this experiment did not cause changes in the concentration of sponge pigments or the structure of the symbiotic microbial community in any species. These results indicate that a single pulse of sediments less than 16 mg cm−2 is not detrimental to most of the sponge species studied.

Until recently, the only sponge-associated genera in the order Zoantharia were Parazoanthus (family Parazoanthidae), Epizoanthus and Thoracactis (family Epizoanthidae), both within the suborder Macrocnemina. The taxonomy of the genus Parazoanthus, as originally described, has been undergoing revision since 2010, with several species, genera and even families described. In 2015, multiple molecular markers were used in combination with morphological characteristics to erect the genus Umimayanthus inside the family Parazoanthidae. It included three species described from southern Japan, with other records for some of the species from the Great Barrier Reef, New Caledonia and the Red Sea. However, little is known of its distribution in the Pacific Islands. Here we report on the finding of Umimayanthus specimens in Palau, Micronesia, representing the first records for this region. A total of 32 specimens of Umimayanthus were collected from seven different locations; eight of the specimens were identified as Umimayanthus chanpuru, while the remaining 24 colonies were only identified to genus level.

Sponge samples were taken by scuba diving from six sites around Sea Lion Island (Sea Lion, Sea Lion Easterly and Brandy Islands), three sites south-east of East Falkland (Motley Island, Green Island and Triste Island) and six sites around Beauchêne Island. Nine new species are described: Iophon roseum sp. nov., Clathria (Microciona) tenebrosa sp. nov., Clathria (Microciona) cheeki sp. nov., Hymedesmia (Hymedesmia) laptikhovskyi sp. nov., Hymedesmia (Hymedesmia) croftsae sp. nov., Myxilla (Ectyomyxilla) beauchênensis sp. nov., Tedania (Tedania) livida sp. nov., Amphilectus fimbriatus sp. nov. and Isodictya cutisanserina sp nov. Additional information is provided on several species recently described from the Falkland Islands and Amphimedon marsei is newly reported. The biogeography of the sponge fauna of the southern Falkland Islands is discussed.

Here we report on the first records of the families Parazoanthidae and Microzoanthidae and by extension for the suborder Macrocnemina (Cnidaria: Anthozoa: Hexacorallia: Zoantharia) from the Red Sea. Despite a long history of zoantharian research in the region, previous records only reported species of the suborder Brachycnemina, from the genera Zoanthus and Palythoa. Both Parazoanthus sp. and Microzoanthus sp. specimens were first found from the same small coral cave at a reef at Jaz'air Sila, Saudi Arabia, and subsequently observed at another location in the northern Red Sea. Numerous Antipathozoanthus sp. colonies were observed at Marker 9 north of Yanbu, Saudi Arabia in association with antipatharians inside small caves. The Parazoanthus sp. was in association with numerous encrusting sponge species on the roof of the cave, similar to previously reported undescribed species in the Pacific Ocean. Microzoanthus sp. was found on hard rubble on the cave floor. These records represent large range extensions (e.g. thousands of kilometres) for each genus, demonstrating the overall lack of research on the order Zoantharia, especially within the Red Sea.

Globally, introductions of non-indigenous species have caused dramatic economic and ecological damage. Most research on marine invasions has occurred in locations easily accessible by researchers, but much less is known about introductions to remote islands. In the central Pacific, Palmyra Atoll represents one of the last remaining quasi-pristine reef systems left in the world. In the 1940s the Atoll underwent extensive military modifications, potentially making it susceptible to invasive species. Here we describe the presence of five non-indigenous invertebrate and algal introductions at Palmyra, including two sponges, Haliclona (Sigmadocia) caerulea and Gelliodes fibrosa; one bryozoan; Zoobotryon verticillatum; one hydroid, Pennaria disticha and one macroalga, Acanthophora spicifera. The Hawaiian Archipelago is the most likely source of the introductions via shipping or yachting activity to the Atoll. Currently, the impacts of these introductions remain unknown although future monitoring will assess the influence of these non-indigenous species on this remote reef system.

Sponge samples were taken by SCUBA diving from four sites around Stanley and nine sites at the Jason Islands in the Falkland Islands. Twelve new species are described: Iophon pictoni sp. nov., Lissodendoryx (Ectyodoryx) jasonensis sp. nov., Phorbas ferrugineus sp. nov., Phorbas shackletoni sp. nov., Myxilla (Styloptilon) acanthotornota sp. nov., Amphilectus fleecei sp. nov., Amphilectus dactylus sp. nov., Mycale (Aegogropila) nodulosa sp. nov., Scopalina erubescens sp. nov., Scopalina bunkeri sp. nov., Amphimedon calyx sp. nov. and Pachychalina erinacea sp. nov. Information is also provided on the distribution and external appearance of other sponge species: Iophon proximum Ridley, 1881, Clathria (Dendrocia) tuberculata Burton, 1934, Tedania (Tedania) mucosa Thiele, 1905, Tedania (Tedania) murdochi Topsent, 1915, Halichondria (Eumastia) attenuata Topsent, 1915, Siphonochalina fortis Ridley, 1881 and Haliclona (Soestella) chilensis Thiele, 1905. The biogeography of the Falklands' sponge fauna is discussed.

Desmapsamma anchorata has been recorded overgrowing Tubastraea coccinea and Tubastraea tagusensis on two sites at Ilha Grande, Rio de Janeiro, Brazil. The records of D. anchorata overgrowing and killing T. coccinea and T. tagusensis showed that this native sponge could be an important competitor for the invasive corals.

The sponge genus Strongylodesma is reviewed and redefined, and now accommodates eight closely related species. The type species of Strongylodesma Lévi is redescribed and an additional two new species are described from the Indo-Pacific: S. novaecaledoniae sp. nov. and S. tongaensis sp. nov. Several specimens previously identified as species of Batzella (Poecilosclerida: Chondropsidae) have been re-assigned to Strongylodesma, as the new species S. purpureus sp. nov. and S. nigra sp. nov. With the description here of new species from the Pacific Ocean and Caribbean Atlantic, the biogeographical distribution of Strongylodesma now appears to be generally tropical with a subtropical South African component, whereas previously it was only known from South Africa. Although species of Strongylodesma have not previously been recorded from the intermediate locations (Western Indian Ocean, South-east Asia, central west Pacific, and New Zealand), re-evaluation here will facilitate more readily the recognition of taxa in these intermediate regions, if they exist, in the future. The species are not widespread, except perhaps along the south-east coast of South Africa, and where they occur they are not abundant. Species occur over a wide depth range, from the intertidal in Tsitsikamma, South Africa, to 140 m in the Caribbean.

Studies were continued to investigate the ability of secondary metabolites sequestered in Antarctic sponges to cause feeding deterrent responses (tube foot retractions) in a common predator of Aritarctic sponges, the sea star Perknaster fuscus. Lipophilic (dichloromethane/methanol) and hydrophilic (methanol/water) extracts of 15 new species of Antarctic marine sponges were tested for their ability to induce sustained tubefoot retraction. One additional species, Cinchyra antarctica, was re-tested from a previous study because we discovered a colour morph that was of comparative interest. Employing established protocols, sponge extracts were imbedded in silicone and presented to an extended tube-foot on the tip of a glass rod. Extracts of ten of the 15 new species of sponges (67%) caused significantly longer tube-foot retractions than controls. Among all sponges tested, significant tube-foot retraction activity was primarily associated with dichloromethane/methanol extracts (eleven sponge species or colour morphs), while significant tube-foot retraction activity was less common in response to methanol/water extracts (three sponges species or colour morphs). Both lipophilic and hydrophilic extracts from the sponges C. antarctica (yellow morph) and Scolymastia joubini elicited significant tube-foot retraction activity, suggesting that more than one compound from these speciesmight elicit tube-foot retractions in P. fuscus. Overall these findings lend considerable support to the hypothesis that there has been significant evolutionary selection for chemical defences among Antarctic marine sponges in McMurdo Sound, in contrast to earlier biogeographic selection models that predicted low levels of chemical defences in polar marine invertebrates.