Monitoring the spread of non-indigenous species is fundamental to study global warming effects on marine biodiversity. A valuable tool is represented by the continuous updating of the geographic range expansion of non-indigenous species. Lamprohaminoea ovalis is a Lessepsian mollusc initially recorded in the Mediterranean Sea in 2001. This paper reports its range expansion over the last 20 years related to water warming. The first record of Lamprohaminoea ovalis from the Ligurian Sea (NW Mediterranean) is also reported. Two individuals (about 10 mm length) were observed on a sub-vertical rocky bottom at 26 m depth displaying potential trailing behaviour. This recent finding extends the currently known distributional range of Lamprohaminoea ovalis, representing the northernmost occurrence of this non-indigenous species in the western Mediterranean Sea.

We present a preliminary taxonomic survey of the metazoan parasites from meso- and bathypelagic fish hosts from the Perdido region, western Gulf of Mexico. In total, 187 individual fish were collected, belonging to five families and 12 species: Cyclothone acclinidens, Cyclothone alba, Cyclothone braueri, Cyclothone pallida, Cyclothone pseudopallida, Cyclothone sp., Manducus maderensis (Gonostomatidae), Notolychnus valdiviae (Myctophidae), Dibranchus atlanticus (Ogcocephalidae), Peristedion greyae (Peristediidae), Sternoptyx pseudobscura (Sternoptychidae), and Chauliodus sloani (Stomiidae). The metazoan parasites collected were the digenean Lethadena profunda from Cyclothone sp., four tetraphillidean larval cestodes from C. acclinidens, Cyclothone sp., C. sloani and P. greyae, a species of Echeneibotrium from D. atlanticus, a species of Anisakis from C. sloani, and the nematode Mooleptus rabuka from C. alba. Four of the parasite species found had already been previously recorded for the northern Gulf of Mexico. Additionally, we report two parasites not recorded before for meso- or bathypelagic fish in the entire Gulf of Mexico: M. rabuka from C. alba and Cyclothone sp.; and the copepods of the family Pennellidae from Cyclothone sp. and P. greyae.

The body condition of animals is an important indicator of their habitats and the effects of anthropogenic activities and pollution. Body condition indices calculated from morphometric measurements have been widely employed as they are easy to use and inexpensive. In sea turtles, Fulton's condition index, calculated as the bodyweight divided by the cube of straight carapace length (SCL), has been commonly used and it has been proposed that an index of ≥1.2 indicates a good body condition. However, comparing Fulton's condition index between different species and size classes is problematic as it does not consider the mass-length relationship. In this study, we conducted a meta-analysis to evaluate the differences between sea turtles. A literature review indicated that most studies reported the SCL-based Fulton's condition index for green turtles (Chelonia mydas), followed by loggerhead turtles (Caretta caretta) and hawksbill turtles (Eretmochelys imbricata). Therefore, we compared the values reported for healthy turtles of these three species. Meta-analysis supported the adequacy of 1.2 as a threshold in juvenile and adult green turtles and large juvenile and adult loggerhead turtles. High Fulton's condition index values were found for hatchlings and post-hatchlings of all three species and small loggerhead turtle juveniles. Low Fulton's condition index values were found for hawksbill turtles, particularly small juveniles. The differences in the Fulton's condition index between species and size classes indicated that it should be used carefully as a threshold for health condition evaluation.

Sowerby's beaked whale is a deep-diving cetacean species specialized to live in the deep waters of the North Atlantic, including offshore Irish waters. Sightings of Sowerby's beaked whales in this area are infrequent and a substantial increase in our knowledge of their presence comes from recent static acoustic monitoring (SAM) and passive acoustic monitoring (PAM). However, most information on this species has been derived from stranding records, which provide opportunistic insights into this elusive species' cryptic life history. Here we report on the live stranding of a 1200 mm long neonate and an adult 5 m female Sowerby's beaked whale in July 2015 and on the stranding of a 4.9 m pregnant female in September 2020 with a 495 mm long male foetus in the south-west of Ireland. These stranding events provide an important insight into the reproductive life history of this species and provide further evidence that Sowerby's beaked whales calve in offshore Irish waters.

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.

The strontium-to-calcium ratio (Sr/Ca) in aragonitic shells and statoliths often depends on temperature, and has been investigated for its potential availability as a sclerochronological record of the temperatures experienced during the life of the animal. Only a few cephalopod species have been subjected to rearing experiments to validate the temperature dependence of statolith Sr/Ca despite the strong demand for estimating their historical ecology, particularly of migratory squid populations. In this context, we examined the relationship between temperature and statolith Sr/Ca in the spear squid, Heterololigo bleekeri, by maintaining wild-caught immature individuals at one of three constant temperatures: 12, 14 or 16°C. A portion of statolith precipitated during the experiment was optically identified by daily increment analysis, and then subjected to Sr/Ca measurement using an electron probe micro-analyser. Regression analysis (N = 29) demonstrated the dependence of statolith Sr/Ca on temperature and the relationship was estimated as an equation Y = 9.93 (±0.29) − 0.11 (±0.02) X. However, ~90% of the total residual variance was accounted for by the among-individual variation of statolith Sr/Ca within each temperature group. Consequently, the 95% confidence interval ranged over ± 7.85°C when the temperature was estimated by inserting a Sr/Ca value into this equation. The statolith Sr/Ca values are unlikely to provide reliable estimates for absolute temperatures, but it may allow reconstruction of a time-series of relative temperatures experienced by a particular individual.

The goose barnacle Conchoderma virgatum is a highly opportunistic epibiont, with observations of attachment to a wide range of marine organisms. Attachment to perciform fishes, however, is rarely observed. Observations of Conchoderma-osteichthyan associations in general are also rare in the southern hemisphere, especially in Australian waters. We present the first record of C. virgatum as an epibiont on an ephippid fish (Platax teira). This is also only the second known record of C. virgatum attached to a perciform fish in the Tasman Sea. We also summarize all previous known observations of C. virgatum in association with perciform fishes.

One new species of Caulleryaspis Sendall & Salazar-Vallejo, 2013 (Annelida: Sternaspidae), C. chicosciencei sp. nov., is described based on material collected in north-eastern Brazil. Specimens were collected in muddy bottoms in the Suape estuary complex in 7–16 m water depth. Caulleryaspis chicosciencei sp. nov. differs from the other known species by the combination of the following characters: small size, abundant cirriform papillae evenly distributed throughout body; chaetigers of introvert with 18–21 falcate hooks per bundle; ventral shield without ribs and undeveloped concentric lines, covered by long cirriform papillae with sediment particles adhered; marginal chaetal fascicles include eight lateral shield chaetae in an oval arrangement, and six posterior shield chaetae in slightly curved pattern. Caulleryaspis chicosciencei sp. nov. is the first species of the genus Caulleryaspis described from Brazil and it increases the number of sternaspids recorded from shallow water in the south-western Atlantic Ocean.

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.

Jellyfish are a well-known component of marine ecosystems. Here, we aimed to assess whether populations of the jellyfish species Mastigias cf. papua and Cassiopea ornata inhabiting different marine lakes and jellyfish species from open water habitat host ‘core’ symbionts and if there is evidence of species-specific host-microbial associations. Compositionally, jellyfishes hosted prokaryotic communities distinct from those found in water samples. All jellyfish samples across habitats and species exhibited a core OTU, assigned to the genus Endozoicomonas. This OTU was particularly abundant (>90% of all sequences) in C. ornata from one Papuan marine lake. Additionally, an OTU assigned to the Entomoplasmatales order was found in all but two jellyfish specimens, and was particularly abundant in marine lake specimens from Berau and Papua, Indonesia. Given the well-known relationship between Endozoicomonas and Symbiodinium spp., we tested for Symbiodinium presence in pooled specimens of M. papua from Berau. Our results showed that OTUs assigned to the genus Symbiodinium accounted for >99% of all sequences in jellyfish-associated microeukaryotic communities; these were closely related to organisms from Symbiodinium clade C. These results suggest the existence of a widespread and abundant jellyfish core symbiont, which may interact with symbiotic Symbiodinium populations to influence host fitness.

This systematic review analysed scientific publications to identify relevant research about the impact of alien polychaete species around the world, using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analysis) guide. The criterion for inclusion was studies published in English, with the key terms (e.g. ‘impact’, ‘alien species’, ‘polychaetes’) in the title, abstract and keywords. The literature search was conducted in Scopus and Web of Science from April to December 2020. The search resulted in 150 papers that included information about impact of alien polychaete species. Of these studies, 98% were published in the last 25 years, reporting on the impact of 40 species in 18 regions of the world. Sixty-one per cent of the research was conducted in the Baltic Sea, South-west Atlantic and Mediterranean Sea. The most frequent type of study was field surveys (46%) and the most studied system was open coast areas (36%). The species with the highest number of publications about their impacts were Ficopomatus enigmaticus, Marenzelleria viridis, Sabella spallanzanii and Boccardia proboscidea. Based on evidence of their most severe documented impacts in their introduced ranges, the impact mechanisms (IMos) of the alien polychaete species were strongly related to their biology and lifestyles. We found that species that build conspicuous reefs and tube-dwellers mainly showed physical and structural impact on ecosystems; shell-borers, mainly parasitism and infauna species, showed mainly chemical, physical and structural impacts on ecosystems. Some recommendations for the study of alien polychaete species are discussed.

The concentrations of organotin (OT) compounds, butyltin (BT) and phenyltin (PT), in aquatic organisms from Merambong and Tinggi Island, Malaysia, which differ in industrial and economic activities, were measured. Tributyltin (TBT) compounds among BTs ranged from 2.9–28 and <0.1–21 ng g−1 ww in aquatic organisms from Merambong and Tinggi Island, respectively. Triphenyltin (TPT) compounds among PTs ranged from <0.1–25 ng g−1 ww and <0.1–61 ng g−1 ww in aquatic organisms from Merambong and Tinggi Island, respectively. A survey of OT concentrations among the species of OT compounds revealed that the concentrations of BTs and PTs in crabs and clams were high while those in fish were low. Correlation analysis with stable nitrogen isotopes suggest that OT compounds did not accumulate in aquatic organisms through the food web. The measurement of OT compounds in tissues and organs of fish revealed that BT concentrations in liver were higher than those in muscle and that BTs were detected in eggs of fish.

Deep-sea ecosystems are generally oligotrophic because they lack photosynthesizing producers. On deep-sea slopes near land, however, various terrestrial plant remains flow to and are deposited on near-shore deep bottoms. From a depth of 300 m off the Pacific coast of Owase, central Japan, we collected an onuphid polychaete, Anchinothria cirrobranchiata (Annelida: Onuphidae), which lives in a dorsoventrally flattened portable tube. The polychaete tubes were made of sand, as well as leaves and twigs of terrestrial evergreen trees. The leaves glued on the portable tubes were chartaceous, blackish and tough; they belonged mainly to two genera of Fagaceae, Castanopsis and Quercus, which are dominant components of coastal evergreen oak forests. In aquaria, the polychaetes fed on the leaves on their tubes, as well as autochthonous sedimented leaves, suggesting utilization of terrigenous plant litter as food. As to the evolution of Anchinothria, a molecular phylogenetic analysis suggests that Anchinothria is monophyletic with other Hyalinoeciinae (Nothria, Leptoecia, Hyalinoecia).

Fisheries constitute a major threat to marine mammals globally. To evaluate the impact of small-scale fisheries (SSF) on regional under-studied marine mammal populations, we tested a novel and cost-effective approach at three data-limited locations of the central and eastern Mediterranean Sea. Using off-the-shelf GPS loggers to track SSF activities and systematic surveys to map the distribution of marine mammals, we assessed the probability of co-occurrence between SSF and marine mammals by reporting areas of spatial overlap. Spatial overlap between SSF and the core zones of marine mammal distribution (ranging between 21.85–35.4%) was observed in all three locations, indicating potential interaction hotspots. The probability of co-occurrence in those areas varied from 0.5–2.9% depending on the species. The resulting overlap between fishing activity and marine mammals may pose a threat in both directions: higher risk of species entanglement and economic burden on fishers due to gear damage. Despite the spatial and temporal limitations of this pilot study, the proposed approach can provide baseline information on SSF-marine mammal co-occurrence, particularly in financially limited regions. If applied on a larger scale, our method may be used to inform future conservation actions with the aim to reduce pressure on key populations.

DNA barcoding based on the cytochrome c oxidase subunit I (COI) gene in mitochondrial DNA has been adopted as a global biological identification system for animals due to its accuracy compared with other classical taxonomic methods. The objective of this study was to establish a reference library with generated barcodes. A total of 84 fish specimens belonging to 37 commercially important marine fish species, representing five orders, 14 families and 30 genera, were sampled along the Tunisian coast and barcoded for the first time, obtaining 637 bp sequences. The average Kimura 2-parameter (K2P) distances within species, genera and families were 0.52, 6.86 and 14.60%, respectively. The Maximum likelihood (ML) tree revealed distinct clusters in concurrence with the taxonomic status of the species. Our results confirmed the authentication of the barcode approach for the identification of the species examined and provide valuable information that would help ichthyologists to achieve better monitoring, conservation and management of fisheries in Tunisia.

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 present study enhances knowledge of the biodiversity of diatoms in Chuuk, Micronesia following our 2018 study on the seaweed-associated diatoms. We collected planktonic samples of diatoms from five sites of reef flats using a 20 μm mesh net, and two samples of seaweeds with epiphytes by hand from an islet on the barrier reef. In addition, the seaweed-associated diatoms from our 2018 study were analysed using scanning electron microscopy. A total of 109 diatom taxa are documented in the present study. Of these, 70 species were from net samples, and 39 species from the seaweed-associated diatoms. Thirty-one species are newly recorded from Micronesian waters. Most taxa are benthic or tychoplanktonic; euplanktonic diatoms were rare. The occurrence of benthic diatoms from the water column might be related to the Chuuk environmental conditions which include shallow water, strong light intensity and high grazing pressure, to which benthic diatoms seem to be able to better adapt than planktonic diatoms.

An opportunistic sighting of an Indo-Pacific humpback dolphin (Sousa chinensis) was reported in the nearshore waters off the east Liaodong Peninsula, China. This is the first at-sea sighting in this area, and the northern-most sighting record of this species with a distance >3000 km away from the nearest described conspecific population located in the mid-China. The present sighting occurred in close proximity to the location at which another Indo-Pacific humpback dolphin was found by-caught in 2003. The sighted individual could not be identified through the existing photo-identification catalogues of this species in China (>3500 individuals). Therefore, we suggest that a population of Indo-Pacific humpback dolphins that was never reported might exist in the north of the Yellow Sea.

This study was carried out throughout 10 fishing seasons between 2002 and 2018 to monitor the population and stock variations of Engraulis encrasicolus (L., 1758) on the south-eastern Black Sea coast of Turkey. Asymptotic length (L∞), growth constant (K) and growth performance indexes (φ) were calculated to be between 12.86 and 15.79 cm, 0.69 and 0.99, 2.10 and 2.29, respectively. Theoretical birth ages were determined to range between (to) −0.15 and −0.27, the maximum ages (tmax) ranged between 3.03 and 4.35, total mortality rates (Z) between 2.19 and 2.66, natural mortality rates (M) between 0.93 and 1.26, the fishing mortality rate (F) between 0.93 and 1.47, and the optimum fishing mortality rate (Fopt.) between 0.37 and 0.62. Fishing mortality rates (F) were estimated to be higher than the optimum fishing mortality rates (Fopt). Z/K ratios were determined to range between 1.91 and 3.43. Current exploitation rates (Ecurr.) were calculated to range between 0.42 and 0.62. The first recruit lengths (Lr) and first capture lengths (Lc50) were estimated to range between from 5.25–7.75 and from 7.66–8.74 cm, respectively. The first maturity lengths (Lm50) of E. encrasicolus ranged between 8.57 and 10.53 cm. The maximum sustainable exploitation levels (Emax) were determined to range between 0.72 and 0.83. These data indicate that if current levels of fishing pressure continue, anchovy stocks will collapse in the near future.