Ficopomatus Southern, 1921 is a serpulid genus currently composed of six species, two of which (F. enigmaticus and F. miamiensis) are reef-builders. The former has invaded subtropical and warm-temperate estuaries worldwide, causing environmental and economic harm. In this study, Ficopomatus miamiensis and F. uschakovi are reported from brackish-water coastal localities in both Atlantic and Pacific sides of Mexico, including a Biosphere Reserve, estuaries, as well as shrimp and oyster farms. Ficopomatus miamiensis is reported from Veracruz (southern Gulf of Mexico, Mexico territory) and Sinaloa (southern Gulf of California). Ficopomatus uschakovi is reported for the first time in the southern Gulf of Mexico (Mexico territory) and repeatedly recorded in Chiapas (southern Mexican Pacific). There are no phenotypic differences between specimens of F. miamiensis from both coasts of Mexico. Comparison of mitochondrial cytochrome b (Cytb) DNA sequences further support the notion that F. miamiensis from the type locality (Florida) and Atlantic coasts of Mexico is also found along the Pacific coast of Mexico. Morphological variability within specimens of F. uschakovi from a single locality (either Laguna del Ostión or La Encrucijada) in Mexico suggest potential presence of multiple cryptic species. Molecular genetics studies are needed to confirm the taxonomic and invasive status of F. uschakovi.

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.

A new location record for the night shark, Carcharhinus signatus, is reported for Puerto Rico. DNA barcoding was used to confirm the photo identification of a shark captured incidentally by a small-scale commercial fisher. The adult female night shark was recovered from a depth of 330 m entangled in hook and line gear used in the deep-water snapper and grouper fishery. This record is the first confirmed sighting for Puerto Rico, increasing the shark species reported for the island and supporting its range up to the Mona Passage in the eastern Caribbean Sea.

The recruitment of the endangered limpet Patella ferruginea in the Chafarinas Islands (SW Mediterranean) was studied over a 17-year period (1999‒2015). A total of 8115 recruits <20 mm in maximum diameter were counted in 95 transect censuses sampled during the study period. The presence of recruits began at the end of winter or beginning of spring (March‒April), when they reached a maximum shell diameter (MD) of at least 4 mm, with a peak in abundance occurring in spring. Smaller recruits were found on the lower midlittoral on the fringe of the vermetid gastropod Dendropoma lebeche and the crustose coralline algae Neogoniolithon brassica-florida, which suggests that settlement occurs at this shore level. Recruits reach 12‒27 mm at the end of their first year of life. A regular recruitment was detected for all studied years, with an average of 11.71 recruits m−1 across the study period. However, recruitment exhibited high interannual variability and did not occur evenly along the coastline of the islands. Higher recruitment was observed in 2001, 2011 and 2012, with a maximum density of 69.07 recruits m−1 in one transect in 2012. The density of recruits decreased in summer. No significant correlation was found between the density of recruits and adults. Between 1999‒2010, 29.29% of recruits were ‘phoretic’ on the shell of adults (1.81 recruits per host on average). Recruits climbed on to adults sometime after settlement, thus we suggest that ‘phoresy’ could favour the survival of young limpets instead of being due to selective settlement on adults. To improve and standardize recruitment monitoring in future studies, we propose that recruits are considered as those specimens <20 mm in MD and that recruitment censuses are carried out in spring, with additional censuses after summer to detect juvenile mortality. Additionally, we propose that 1 mm interval size classes are used for growth studies based on size‒frequency analyses.

Otoliths are an excellent tool in studies on ecological connectivity of fish species populations. Opsanus beta is an invasive species introduced on the Brazilian coast, but not native from the Gulf of Mexico. The present study aimed to compare the otolith contours of specimens collected in Mexico (Celestún, CEL) and in two Brazilian estuaries (Santos Bay, STB, and Paranaguá Estuarine Complex, PEC). In the laboratory, 99 otoliths were extracted, photographed and compared using wavelet analysis. The otolith contours varied between sites (39 from CEL, 26 from STB and 34 from PEC). The linear discriminant analysis correctly reclassified 87.9% of otoliths by sites, with the best reclassifications in the CEL (97.36%), followed by PEC (88.23%) and SBT (73.07%). MANOVA showed significant differences in otolith contours between sites (F = 5.37; P < 0.005). The otolith contour from CEL was significantly different from those from the PEC and SBT. However, the otolith contour of the two Brazilian estuaries did not significantly differ among them (MANOVA, P > 0.005). Our results indicate O. beta populations on the Brazilian coast are connected, and probably isolated from the Mexican population.

The paper describes the first report of Kandelia candel (Rhizophoraceae), a rare mangrove from Bhavanapadu, a coastal village in Srikakulam district in Andhra Pradesh, India. This species is relatively less abundant along the east coast of India. During our study covering all the 41 mangrove patches in the state of Andhra Pradesh, 16 mangrove species were observed throughout the state and the Kandelia candel was seen only in Bhavanapadu (patch 2). The plant sighted was identified using taxonomic keys and confirmed using DNA barcoding. The identified specimen is deposited in the museum repository at ICAR-Central Marine Fisheries Research Institute (CMFRI), Kochi (accession no. MB.1.1.1.1) and its gene sequence is deposited in National Center for Biotechnological Information (NCBI) (accession no. MH243746). Patch 2 where K. candel was observed is separated away from the other clusters in the principal component one, with the patch showing an average dissimilarity of about 71.79% from the other patches. K. candel is a mangrove highly sensitive to changes in salinity. The presence of a lone member of a rare species in the state at the sampling location raises questions on its endurance in the region. The study underlines the relevance of monitoring the mangroves and advocate adequate conservation measures for proper protection, proliferation and management of this globally dwindling resource.

Deployment of artificial wreck reefs (AWRs) near natural reefs can influence fish assemblages on both reefs. Here, we assessed fish attitudes (abundances, biomass and species richness) according to different level complexity areas of wrecks, feeding guilds of fish and body size of fish of two identical AWRs deployed at the same depth (36.6 m) and different distances from natural reefs. Scuba divers used visual census method to sample fish communities at wrecks for two years. An average of 2346 individuals per dive belonging to 52 species were observed on wrecks combined. Both mean fish abundance and mean biomass did not differ significantly between wrecks. Mean species richness was significantly greater at 9 Eylül than Alaybey. Planktivore was the most abundant feeding guild on wrecks, and its abundance statistically differed between AWRs. The comparisons of fish assemblages at the different level complexity areas of the wrecks show differences, the highest mean abundances were recorded at the areas of low complexity of the wrecks. The results of this study show that although deploying artificial wreck reefs near to natural rocky reefs catalyses fish colonization, it does not present an exact influence on the fish communities of AWRs. We have not known yet how creating an artificial wreck reef affects fish community of natural reefs. With giving extra importance to the choice of deployment area, AWR applications may transform to win-win projects for both the marine environment and recreational users, such as divers and anglers.

Kelp forests are regarded as important nursery and foraging habitats for commercially important species of finfish and shellfish despite an absence of fishery-independent data in many regions. Here, we conducted targeted surveys at 12 subtidal reefs, distributed across 9° of latitude in the UK, using three complementary techniques (Underwater Visual Census (UVC), Baited Remote Underwater Video (BRUV) and deployment of prawn pots) to quantify the abundance of crustaceans within kelp forests. Commercially important species were recorded at all sites; Cancer pagurus (brown/edible crab) and Necora puber (velvet swimming crab) were the most abundant and commonly observed, although Maja brachydactyla (spider crab), Homarus gammarus (European lobster) and Palaemon serratus (common prawn) were also recorded. The abundance of some species exhibited pronounced regional variability, with higher abundances of C. pagurus within northern regions and, conversely, higher abundances of M. brachydactyla and P. serratus within southern regions. Each sampling technique yielded similar spatial patterns for the most abundant species but had varying sensitivity to some species. Most individuals observed were juvenile or sub-adults, suggesting kelp forests serve as important nursery grounds for commercially and ecologically important crustaceans. Further monitoring efforts, conducted across greater spatiotemporal scales and in different habitat types, are needed to provide a robust baseline against which to detect changes and to inform management and conservation actions.

The annelid mitochondrial genomes (mitogenomes) have been well documented, and phylogenetic analyses based on the mitogenomes provide insightful implications for annelid evolution. However, the mitogenomes of some families remain unknown. Herein, we determined the complete mitogenome of the lugworm Abarenicola claparedi oceanica (15,524 bp), representing the first mitogenome from the family Arenicolidae. The gene order of this species is the same as the various lineages in Sedentaria. The maximum likelihood phylogenetic analyses were performed based on six different datasets, including 43 ingroups (oligochaetes, hirudineans, echiurans and closely related polychaetes) and two outgroups (Siboglinidae), namely, aligned and trimmed datasets consisting of the nucleotide sequences of protein-coding genes (PCGs) and rRNAs, and amino acid sequences of PCGs. Phylogenetic analyses based on the nucleotide sequences yielded trees with better support values than those based on the amino acid sequences. Arenicolidae is clustered with Maldanidae in all analyses. Analyses based on nucleotide sequences confirm the monophyly of Terebellidae, which was paraphyletic in recent mitogenomic phylogenetic studies. We also performed the phylogenetic analysis based on the RY-coding of the nucleotide sequences of PCGs only to yield phylogeny with generally low support values. Additional mitogenome sequences of related ingroup species would be needed to comprehensively understand the phylogenetic relationship, which was not present in this study.