Megabenthic soft bottom communities of trawlable grounds have been studied since the first few decades of the last century, thanks to trawl fishing technologies. Despite providing an extensive amount of presence data, trawling cannot be considered reliable from a quantitative point of view, frequently giving only weak information about sessile species density, large and small-scale distribution and main habitat features. The recent development of visual technologies on remotely operated vehicles (ROVs) can give a more accurate approach for the study of mega-epibenthic communities. The present study reports the application of both ROV imaging and trawling approaches for the study of a large aggregation (i.e. field) of the red sea pen Pennatula rubra in the Ionian Sea. Density, biomass and population structure were studied in the same population of P. rubra. The density assessed by ROV was significantly higher than that estimated with a three-year series of trawling surveys. Trawling gear efficiency in the removal of P. rubra was low overall. Incidental mortality can be very high due to damage to those specimens that encounter the trawl net but are not directly captured. However, sampling of several colonies by trawling was necessary to establish biometric correlations to estimates of size and biomass from ROV imaging. Trawling catch abundance/biomass data could be useful to identify areas of higher concentration of sea pens, while ROV imaging can be used to monitor these fields in a non-destructive manner that would be consistent with protection measures.

A new species of corallivorous goniasterid, Evoplosoma watlingi n. sp., from Bear Seamount in the North Atlantic is described in conjunction with an overview of other species within the genus Evoplosoma. Hippasteria tasmanica McKnight, 2006 is re-classified within Evoplosoma. In situ images of Atlantic deep-sea Goniasteridae, including Evoplosoma spp., Hippasteria phrygiana and Circeaster americanus, are presented herein. Observations of several Evoplosoma species and the Atlantic C. americanus are documented for the first time, recorded by the R/V Okeanos Explorer. The feeding duration of C. americanus is also documented for the first time.

Based on material collected during oceanographic campaigns in the western Atlantic from 1958 to 2011, two species of primnoid octocorals belonging to the genus Callogorgia were identified: Callogorgia americana and Callogorgia arawak sp. nov. These species are described and illustrated herein and their geographic and bathymetric are given. This is the first record of the genus in the south-western Atlantic. Additionally, the elevation of C. americana americana and C. a. delta to species level is proposed, keeping Callogorgia gilberti, C. delta and C. americana as separate species.

Community structure, species composition, and changes over time after disturbances are frequently studied using common descriptors. We used rank abundance distribution plots (RADs), Rényi entropy plots, common theoretical community models, ordination analysis of similarities (ANOSIM and Clusters), and abundance spectra analyses to study the effects of a gradual natural population decline and an anthropogenic punctuated disturbance on the structure of octocoral communities in Panama, considered a hot spot area for octocoral diversity in the Tropical Eastern Pacific. Over a 17-month period, no significant change was found in community structure after a natural yearly population decline of 25.2%. After a disturbance, however, different recovery trajectories were observed in various coral communities. Possible physical and biological explanations for the observed differences include initial local species diversity and abundance, species life history patterns, colony morphology, and the geographical location of the community. Differences in community structure between study sites were best described using a combination of community descriptors, RADs, and abundance spectra. Rényi plots were useful in identifying changes in community structure, whereas the extent of the changes was best evaluated using ANOSIM and cluster analysis.

The first record of the plexaurid genus Psammogorgia from the shallow waters of Peru is reported here. A new species (Psammogorgia hookeri sp. nov.) is described from Isla San Gallán, Paracas National Reserve. The new species was morphologically analysed using light microscopy and scanning electron microscopy. It is distinguished from the others in the genus by its small size; prominent calyces with wide lips around polyp apertures and without a special type of sclerites, but with a concentration of irregular, thorny spindles and wart-clubs around the calyx rim; coenenchymal sclerites that do not reach more than 0.2 mm long; the occurrence of conspicuous star-like radiates; and the colour of the colony and coenenchymal sclerites, which is coral red. The results increase species richness within a genus that has not been studied for more than a century, and contribute to the establishment of characters for further morphological studies. Additionally, the new species adds value to existing protected areas and to the octocoral biodiversity records for the Peruvian region and the eastern Pacific.

A survey of the distribution, percentage coverage, and diversity of octocoral fauna on the south-west coast of India yielded fourteen species from six families: Clavulariidae, Nephtheidae, Melithaeidae, Plexauridae, Gorgoniidae and Ellisellidae. This study produced ten new zoogeographical records of octocoral species to India, two species which were first records to the shallow water fauna (11–12 m depth), and one found to be a potential new record to the Indian coast. Octocoral coverage was <1% at all sites and diversity ranged from 6–13 species among the five study sites.

Hydroids symbiotic with octocorals in the Bunaken Marine Park and in the Lembeh Strait (North Sulawesi, Indonesia) were studied. Four species, Hydrichthella epigorgia, Ralpharia neira, Pteroclava krempfi and Zanclea timida sp. nov. were recorded and are described. The new species Z. timida is the only one of the genus associated with an octocoral. It is characterized by a naked hydrorhiza producing nematocyst knobs and by polyps which are able to retract into their own rigid, cup-shaped, basal region. The relationship between epibiontic hydroids and their octocoral hosts affects the morphology of both partners. The hydrorhiza of Hydrichthella epigorgia is naked when associated with Anthoplexaura dimorpha, but perisarc-covered when growing on other gorgonian host species. Vice versa, the hydroid is also able to affect the host morphology: Ralpharia neira induces Ellisella sp. to develop new branches, with the inner skeleton enveloping the hydroid stem.

Leptogorgia christiae is a rarely collected new species found at 15–30 m depth at Roca Hacha, a rocky outcrop near Coiba Island characterized by its high diversity of octocorals. The branching pattern and combination of asymmetric blunt spindles, abundance of capstans, and a low occurrence of acute spindles are distinct characteristics of the new taxon. The new species is described, illustrated and compared to the other species of the genus reported from Pacific Panama; thus increasing the total of Leptogorgia species to 17, which encompasses over 70% of the shallow water species for the eastern Pacific.

Sampling scale and lack of attention to taxa other than scleractinian corals have limited the capacity to protect coral reefs and coral communities in Pacific Panama. The distribution of coral habitats (live coral cover) and their species richness in the largest marine protected area of Panama, the Coiba National Park (270 125 ha), is described using quadrat transects and manta tows. The species richness of scleractinian corals and octocorals was lower in coral reefs than in coral communities, and a close relationship between richness and live coral cover was observed only in coral communities. The distribution of high live coral cover in coral communities overlapped with areas of high coral species richness. Average live coral cover in communities was 64%, compared to 28% in reefs, whereas algae cover was 30% and 49%, respectively. Twenty-two coral and 34 octocoral species were observed, many only now detected in Panama as endemic or new species. Analysis of satellite imagery showed 80% of terrestrial habitats were mostly primary forest, and coral reefs and coral communities covered 1700 ha, about 2% of marine habitats. Shallow marine environments (< 20 m) had up to 60% calcareous red algae cover (rhodolite beds). Based on the distribution of live coral cover and species richness, three conservation units were identified as priority, with the southern and northernmost sides of the marine protected area as the most significant. These three areas encompass most of the rare and endemic species or populations, as well as species previously regarded as endangered.