The first insights on habitat and phylogenetic origin of a newly found population of Solen marginatus are provided in the mid-North Atlantic Azores archipelago, in the bay of Praia da Vitória, Terceira Island. Distribution is confined to the northern portion and most sheltered part of the bay down to 14.2 m depth. Densities with an average of 12.69 individuals/m2 were found at 8.4 m depth, using 4 × 20 sqm visual transects. Sizes of shell length between 10 and 12 cm comprised 60% of collected specimens (n = 118), ranging between 8.79 and 15.4 cm and averaging 11.28 cm. Considering shell length, the high densities and dispersion area, a settlement period above 20 years is estimated. Greater genetic affinity was found in the Ria de Aveiro (North of Portugal) and the Asturias populations (North of Spain). The source origin remains undetermined, with intentional or non-intentional anthropogenic introduction, as well as natural dispersion remaining possible, although more unlikely. Due to the commercial value of this species, a new clam fishery is likely to develop in the area, requiring further studies and immediate conservation measures.

The western Antarctic Peninsula harbours a diverse benthic marine community where dense canopies of macroalgae can dominate the shallow subtidal zone (0–40 m or greater). In the lower portion of this range (below 25–35 m depending on topography), invertebrates such as sponges and echinoderms can be found in greater abundance due to reduced competition for space from the algal species. Dendrilla antarctica (previously Dendrilla membranosa) is a common demosponge that thrives in both communities and is known for producing diterpene secondary metabolites as a defence against sympatric sea star and amphipod predators. Omnivorous mesograzers such as amphipods inhabit both communities; however, they are in greatest abundance within the macroalgal canopy. Due to the differences between habitats, it was hypothesized that specific amphipod species not susceptible to the defensive metabolites of D. antarctica would take refuge from predators in the chemically defended sponge. Analysis of the metabolome and amphipod communities from sponges in both habitats found correlations of metabolic profile to both abundance and habitat. These studies serve to inform our understanding of the complex ecosystem of the Antarctic benthos that stands to be dramatically altered by the rapidly changing climate in the years to come.

Surface physical properties, hydrodynamics, biochemical cues, orientation and temporal scales play an important role in invertebrate larval recruitment on artificial substrates. In the present study, invertebrate recruitment on four different substrates (acrylic, stainless steel, ceramic and concrete panels) was investigated in two different orientations (vertical and horizontal) in the central Red Sea. Results showed significant variations in the abundance of benthic invertebrates between the different substrates. While barnacles and bivalves preferred panels placed in vertical positions, the abundance of bryozoans was high on horizontal panels. Artificial panel submersion season plays a significant role in the recruitment of benthic invertebrates on surfaces in the Red Sea. In conclusion, this study supports the overall notion that marine invertebrate recruitment on hard substrates is regulated by a combination of factors which include substrate type, orientation and submersion season.

Rare and cryptic species can be easily missed during ecological surveys of coral communities. This study reveals a disparity in the reported geographic range of a rare species, Echinomorpha nishihirai, between three different sources; none of which are wholly consistent with the available published occurrence records. Discrepancies in the species ranges reported in two comprehensive online databases are greater for rare, compared with common, coral species, suggesting a need for a more cautious treatment of rare species in biogeographic studies.

The diversity and distribution of polychaete species under the families Nereididae, Syllidae and Eunicidae in sub-tidal fouling assemblage was studied by submerging wood as test substratum. Wooden panels were fitted onto a raft and submerged in Kudankulam coastal waters (south east coast of India) in pre-monsoon, monsoon and post-monsoon seasons from May 2003 to July 2005. Panels (in replicate) were retrieved from the raft at 15-day intervals. A total of 24 polychaete species belonging to the three families were identified from the test panels. Perinereis cultrifera, Platynereis dumerilii, Syllis variegata, Syllis truncata, and Eunice australis were the dominant species observed on the test panels. The abundance of major polychaete group was varied considerably between the panel series submerged in May 2003 (post-monsoon), November 2003 (monsoon) and July 2004 (pre-monsoon). The major difference in the polychaete community structure was the low abundance of both nereidids on pre-monsoon season panels and the eunicids on monsoon and post-monsoon season panels.