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The multifunctional catalytic hemoglobin from the terebellid polychaete Amphitrite ornata, also named dehaloperoxidase (AoDHP), utilizes the typical oxygen transport function in addition to four observed activities involved in substrate oxidation. The multifunctional ability of AoDHP is presently a rare observation, and there exists a limitation for how novel dehaloperoxidases can be identified from macrobenthic infauna. In order to discover more infaunal DHP-bearing candidates, we have devised a facilitated method for an accurate taxonomic identification that places visual and molecular taxonomic approaches in parallel. Traditional visual taxonomic species identification by the non-specialist, at least for A. ornata or even for other marine worms, is a very difficult and time-consuming task since a large diversity is present and the method is restricted to adult worm specimens. The work herein aimed to describe a method that simplifies the taxonomic identification of A. ornata in particular through the assessment of its mitochondrial cytochrome c oxidase subunit I gene by employing the DNA barcoding technique. Furthermore, whole-worm specimens of A. ornata were used to extract and purify AoDHP followed by an H2O2-dependent peroxidase activity assay evaluation against substrate 2,4,6-trichlorophenol. AoDHP isoenzyme A was also overexpressed as the recombinant protein in Escherichia coli, and its peroxidase activity parameters were compared to AoDHP from the natural source. The activity assay assessment indicated a tight correlation for all Michaelis–Menten parameters evaluated. We conclude that the method described herein exhibits a streamlined approach to identify the polychaete A. ornata, which can be adopted by the non-specialist, and the full procedure is predicted to facilitate the discovery of novel dehaloperoxidases from other marine invertebrates. [ABSTRACT FROM AUTHOR]

“Cirriformia tentaculata” is considered to be distributed throughout Japanese waters and is used as an indicator species of organic pollution in coastal regions. However, previous studies indicated that “C. tentaculata” from Japan contained cryptic or sibling species. In order to solve this taxonomic problem, we collected specimens of Cirriformia Hartman, 1936 from throughout Japan and conducted taxonomic analyses. Molecular phylogenetic analyses showed that the Cirriformia worms collected could be divided into twelve phylogroups. We conducted detailed morphological analyses of each phylogroup and found morphological differences between each. Ten species were considered new to science, and the remaining two had the morphology according to the original description of C. tentaculata (Montagu, 1808). Physio-chemical characteristics of their habitats were not identical between each species, which suggested that the so-called “C. tentaculata” in Japanese waters is not adequate as a pollutant indicator.

Despite significant improvements in the comprehension of neuro-regeneration, restoring nerve injury in humans continues to pose a substantial therapeutic difficulty. In the peripheral nervous system (PNS), the nerve regeneration process after injury relies on Schwann cells. These cells play a crucial role in regulating and releasing different extracellular matrix proteins, including laminin and fibronectin, which are essential for facilitating nerve regeneration. However, during regeneration, the nerve is required to regenerate for a long distance and, subsequently, loses its capacity to facilitate regeneration during this progression. Meanwhile, it has been noted that nerve regeneration has limited capabilities in the central nervous system (CNS) compared to in the PNS. The CNS contains factors that impede the regeneration of axons following injury to the axons. The presence of glial scar formation results from this unfavourable condition, where glial cells accumulate at the injury site, generating a physical and chemical barrier that hinders the regeneration of neurons. In contrast to humans, several species, such as axolotls, polychaetes, and planarians, possess the ability to regenerate their neural systems following amputation. This ability is based on the vast amount of pluripotent stem cells that have the remarkable capacity to differentiate and develop into any cell within their body. Although humans also possess these cells, their numbers are extremely limited. Examining the molecular pathways exhibited by these organisms has the potential to offer a foundational understanding of the human regeneration process. This review provides a concise overview of the molecular pathways involved in axolotl, polychaete, and planarian neuro-regeneration. It has the potential to offer a new perspective on therapeutic approaches for neuro-regeneration in humans. [ABSTRACT FROM AUTHOR]

The present study dealt with the extraction and purification of lectin from a marine polychaete collected from the Gadilam estuary. Polychaete samples were collected during the low tide mainly around the level of the mid tide. Collected polychaete species was identified using the standard identification keys described in the reference manuals as Perinereis cultrifera. Lectin was extracted from the polychaete and it was designated as 'PcL'. When the extracted PcL was tested for hemagglutination activity it showed a titer (as hemagglutination unit (HU) of 32 HU against rabbit erythrocytes, 1-2 HU against goat erythrocytes and no visible hemagglutination against the chicken erythrocytes. The effect of various sugars that inhibit the crude PcL's hemagglutination activity (sugar specificity) was tested against various sugars. The result showed galactose was the highest inhibitory among the other sugars tested with the lowest minimum inhibitory concentration (MIC) of 6.25 mM. Partial purification was done using 60% ammonium sulphate saturation. The total protein, carbohydrate and lipid content was 22 mg/ml, 4.6 mg/ml and 0.027 mg/ml respectively. Purification of lectin was doneusing DEAE-Cellulose and DEAE-Sephadex A-50 column chromatography. After each column purification steps, the specific activity was increased and it was 890.4 U/mg and 1280 U/mg after DEAE-cellulose and DEAE-sephadex column chromatography, respectively. Likewise, the fold of purity was 6.3 and 9 after the column purification. [ABSTRACT FROM AUTHOR]

The monotypic polynoid genus Arctonoella Buzhinskaja, 1967 comprises solely the type species A. sinagawaensis (Izuka, 1912), which was originally described from Tokyo Bay (central Japan), and subsequently recorded from China and the Russian Far East. The six specimens we collected together with the burrowing filter-feeding spoon worm Urechis unicinctus (Drasche, 1880) from three intertidal-flat sites in the Seto Inland Sea represent a new report for the western Japan, and the second for the country. Our morphological observations reveal that the shape of the cephalic peaks in the frontal prostomial margin is variable even within a local population, although this character has been considered as diagnostic for Arctonoella. This genus is closely related with Hesperonoe Chamberlin, 1919, both morphologically and phylogenetically. Hesperonoe urechis Marin and Antokhina, 2020, collected inside a burrow of U. unicinctus in the Russian Far East, is hereby deemed a junior synonym of A. sinagawaensis. This species morphologically resembles Hesperonoe adventor (Skogsberg in Fisher and MacGinitie, 1928), which inhabits spoon worm (Urechis caupo Fisher and MacGinitie, 1928 and Echiurus echiurus alaskanus Fisher, 1946) burrows along the northeastern Pacific coast of America. Therefore, we conclude that the Arctonoella-Hesperonoe species complex requires to be reviewed to determine the proper generic arrangement. Additionally, we revise the available data on the symbiotic fauna living inside the burrows of U. unicinctus and U. caupo.

Capitella spp. are found in marine and estuarine benthos world‐wide. They are often treated as environmental sentinels because they occur in high densities in areas of anthropogenic disturbance and organic pollution. However, there are many cryptic species around the world, often grouped into the Capitella capitata complex. Historically, these have been differentiated using allozymes and developmental studies. Recently, single‐gene sequencing, especially cytochrome c oxidase subunit I, and phylogenetic methods have been used to characterise populations around the world. We present molecular support and provide descriptions for five new Capitella spp. from the Gulf of Mexico: Capitella gomexa sp. n., Capitella mandingensis sp. n., Capitella tampe sp. n., Capitella maculosa sp. n. and Capitella loucindae sp. n. Two were recently differentiated on the basis of larval development and morphology. Additionally, we present an updated look at global Capitella phylogeny. While no apparent patterns of phylogeography were recovered, we did find support for a single origin of thoracic acicular spines. [ABSTRACT FROM AUTHOR]

Johor Strait has received massive anthropogenic traffic in recent years, causing environmental alteration and inevitably harming macrobenthos on the seafloor. A comprehensive assessment was done in several key locations within the strait to identify macrobenthic inhabitants and possible driving factors attributing to differences in macrobenthic assemblages in these areas. Sediments were acquired using Ponar Grab in 13 key locations within the Johor Straits. Seven hundred thirty macrobenthic individuals and 46 known taxa were identified in sediments of 13 locations in the strait. Annelids Prionospio (n=295), Minuspio (n=95) and Mediomastus (n=82) were concentrated in the central zone. Molluscs dominated the Merambong Shoals area (Arcualuta, n=66), and amphipods dominated waters off Santi River (Leucothoe, n=26; Gammarus, n=11; Cymadusa, n=9). PERMANOVA analyses (p<0.05) showed significant differences in benthic taxa composition in all locations overall. BIOENV analyses (r=0.76, p<0.05) highlighted water acidity, chlorophyll-a, silts and total organic carbon as the main influences toward benthic assemblages throughout the study area. PCA graph indicated higher organic carbon and silts in the central area, implying favourable conditions for Sedentarian polychaetes to thrive. The east and west ends of the strait exhibited higher readings of water acidity and chlorophyll-a, which may directly contribute to a higher diversity of benthic communities in the areas. Lower oxygen levels in two locations in the central area (J3=2.97 mg/L, J4: 2.63 mg/L) exhibited Sedentaria polychaete-dominated region, but zero benthic organisms in another part of the central area (J5-J9, 2.97–0.99 mg/L). This study showcased the effectiveness of environmental monitoring using macrobenthos as an indicating subject. [ABSTRACT FROM AUTHOR]

In aquatic sediments, active ventilation of burrows is an important component of sediment metabolism, transporting solutes across the sediment–water interface. Within a burrow, the temporal and spatial structure of the flow velocity can dictate the flux of solutes across the burrow walls. However, it is difficult to measure the fine-scale flow dynamics within a burrow due to the opacity of marine sediments. Here, we allowed a nereid polychaete Alitta succinea, a cosmopolitan deposit feeder found in brackish to marine soft sediments, to construct burrows in a transparent, elastic sediment analog. This allowed the measurement of the temporal velocity structure of flow in the burrow using particle tracking velocimetry. We find that the flow within the burrow of this piston-pumping polychaete is unsteady and that oscillations in flow velocity are damped with distance along the tube. We also show that the flow velocity in a tube scales with worm size. Conversely, neither the unsteadiness of flow oscillations nor the stroke frequency of the worm pump scale with worm size. [ABSTRACT FROM AUTHOR]

The multifunctional catalytic hemoglobin from the terebellid polychaete Amphitrite ornata, also named dehaloperoxidase (AoDHP), utilizes the typical oxygen transport function in addition to four observed activities involved in substrate oxidation. The multifunctional ability of AoDHP is presently a rare observation, and there exists a limitation for how novel dehaloperoxidases can be identified from macrobenthic infauna. In order to discover more infaunal DHP-bearing candidates, we have devised a facilitated method for an accurate taxonomic identification that places visual and molecular taxonomic approaches in parallel. Traditional visual taxonomic species identification by the non-specialist, at least for A. ornata or even for other marine worms, is a very difficult and time-consuming task since a large diversity is present and the method is restricted to adult worm specimens. The work herein aimed to describe a method that simplifies the taxonomic identification of A. ornata in particular through the assessment of its mitochondrial cytochrome c oxidase subunit I gene by employing the DNA barcoding technique. Furthermore, whole-worm specimens of A. ornata were used to extract and purify AoDHP followed by an H2O2-dependent peroxidase activity assay evaluation against substrate 2,4,6-trichlorophenol. AoDHP isoenzyme A was also overexpressed as the recombinant protein in Escherichia coli, and its peroxidase activity parameters were compared to AoDHP from the natural source. The activity assay assessment indicated a tight correlation for all Michaelis–Menten parameters evaluated. We conclude that the method described herein exhibits a streamlined approach to identify the polychaete A. ornata, which can be adopted by the non-specialist, and the full procedure is predicted to facilitate the discovery of novel dehaloperoxidases from other marine invertebrates.

Three separate mangrove ecosystems in Kerala's Kannur district were examined for trace metal build-up in sediment and two polychaete species, Marphysa gravelyi and Dendronereis aestuarina. By classifying the areas according to the intensity of anthropogenic activity, metal deposition in polychaete tissue was investigated. ICP-MS was used to assess the heavy metal load and the accumulation of metals in sediment in the range of, Zn 24.37-59 mg/kg, Ni 23.67- 59.25 mg/ kg, Cu 11.27-38.6 mg/kg, Pb 4.5-16.4 mg/kg, Cd 0.1-1.8 mg/kg, Fe 1.25-3.67 %, and Al 0.65- 2.43 %. The soil sample's Zn concentration was at its highest and heavy metals accumulated in the pattern Zn>Ni>Cu>Pb>Cd. By just switching the concentrations of Ni and Cu, polychaetes' trace metal concentrations follow the same pattern as those found in soil, however, M. gravelyi was discovered to have larger amounts of accumulation when compared to D. aestuarina, mostly for metals like Zn and Pb. Based on data compiled from all stations, the average concentration of accumulation for Zn was 62.34 mg/kg & 43.45 mg/kg, and for Pb, it was 6.59 mg/kg & 1.86 mg/kg in M. gravelyi and D. aestuarina, respectively. Most metal buildup is found in mangrove soil, which has higher levels of organic carbon and clay particles. The findings imply that D. aestuarina is an organism that is sensitive to pollution and that M. gravelyi is a species that is extremely tolerant of pollution, suggesting that the species can be used to anticipate the state of its surrounding environment. [ABSTRACT FROM AUTHOR]

Spirorbinae, a ubiquitous group of marine calcareous tubeworms with a small body size as adults, have a fascinating diversity of brooding modes that form the basis for their taxonomic division into six tribes (traditionally subfamilies): in-tube incubation, with varying degrees of attachment to adult structures (four tribes), and external incubation in a modified radiole (opercular brood chambers; two tribes). We investigated the evolutionary transitions among these brooding modes. Phylogenetic reconstruction with molecular (28s and 18s rDNA) and morphological data (83 characters) among 36 taxa (32 ingroup spirorbins; 4 filogranin outgroups) of the combined data set, using maximum parsimony, maximum likelihood, and Bayesian analyses, inferred Spirorbinae to be monophyletic, with strong support for the monophyly for five tribes (Circeini, Januini, Romanchellini, Paralaeospirini and Spirorbini), but non-monophyly for Pileolariini. However, deeper relationships among some tribes remain unresolved. Neomicrorbis was found to be the sistergroup to all other Spirorbinae. Alternative coding strategies for assessing the ancestral state reconstruction for the reproductive mode allowed for a range of conclusions as to the evolution of tube and opercular brooding in Spirorbinae. Two of the transformations suggest that opercular brooding may be ancestral for Spirorbinae, and the tube-incubating tribes may have been derived independently from opercular-brooding ancestors. [ABSTRACT FROM AUTHOR]

Arabella iricolor (Montagu, 1804) was described with no diagnostic information for the characters used today to distinguish species within the genus. An updated description, together with genetic data, is provided using the holotype in conjunction with additional specimens collected at or near the type locality, to facilitate comparative analysis of other Arabella species and improve taxonomy within the genus. Arabella iricolor can be distinguished primarily through the long notopodial cirri that reach to or beyond the prechaetal lobes on chaetigers 1–9, in combination with unidentate maxilla I on both sides, four short digitiform pygidial cirri and gradually tapering ventralmost chaetae. The updated description and molecular information enabled the identification of a new species co-habiting with A. iricolor at the type locality and elsewhere. The new species, Arabella ampulliformis sp. nov., is characterised by two lateral pygidial lobes that extend into short cirri, appearing ampulliform in lateral view, in combination with a bifid left maxilla I, short left and long right maxilla II, short notopodial cirri and gradually tapering ventralmost chaetae. A new species from South Africa is also described, Arabella umgazanae sp. nov., distinguished through a bifid left maxilla I, short left and long right maxilla II, short notopodial cirri, two large lateral pygidial lobes and gradually tapering ventralmost chaetae along with additional characters relating to the chaetae, mandibles and maxillary apparatus. Problems surrounding the identification of Arabella species in South Africa are discussed in conjunction with details of the other species reported from the region.ZooBank: urn:lsid:zoobank.org:pub:9E60941E-7F95-4327-8884-5A56A5E7F309 [ABSTRACT FROM AUTHOR]

Pilargidae is a family of free-living and burrowing marine annelids. A lack of available molecular data for most of these species has precluded a molecular assessment of their phylogenetic relationships and has left uncertain the placement of Antonbruunia, which is hypothesized to be either a member of Pilargidae or its sister clade, the monotypic family Antonbruunidae. In this study, we describe the new species Antonbruunia milenae sp. nov., found at 845 m of depth off the coast of San Diego, California, USA, and we address the phylogeny of these organisms using 15 novel mitogenomes and multiple Sanger-sequenced loci. Our results show that Antonbruunia falls within Pilargidae, making Antonbruunidae a junior synonym of Pilargidae. Glyphohesione was transferred from Pilarginae to Synelminae, the previously unassigned genera Otopsis and Antonbruunia were shown to belong within Synelminae, and Hermundura was assigned to Phyllodocida incertae sedis. Sigambra was found to be non-monophyletic. Four different mitogenome gene orders were found among Pilargidae. Changes between the gene orders and the ancestral state gene order of the family were inferred. Two species have introns within the COI gene. These efforts represent a significant expansion of the available molecular resources for pilargids, as well as the basis for a more stable taxonomy. [ABSTRACT FROM AUTHOR]

Lipid quality during frozen storage of the low trophic marine resource polychaete (Alitta virens) was evaluated after blanching, vacuum packing, and different storage temperatures (−23°C vs −27°C). In non-blanched samples, free fatty acid (FAA) reached a level of 15–20% after 12-months of frozen storage. 1H and31P nuclear magnetic resonance (NMR) analyses showed that the increase in FFA could be attributed to both hydrolysis of phospholipids and triacylglycerols. Vacuum packing prevented lipid oxidation. Blanching hindered lipid hydrolysis and is thereby recommended to preserve valuable phospholipids during long-term frozen storage of polychaete, a resource that has attracted growing interest for use in aquaculture. [ABSTRACT FROM AUTHOR]

The deep seafloor of the Northeastern Pacific Ocean between the Clarion and Clipperton Fracture Zones (CCZ) hosts large deposits of polymetallic nodules that are of great commercial interest as they are rich in valuable metals such as manganese, nickel, copper and cobalt. However, mining of these nodules has the potential to severely affect the benthic fauna, whose distribution and diversity are still poorly understood. The CCZ is characterized by strong gradients in sea surface productivity and hence changes in the amount of organic carbon reaching the seafloor, decreasing from mesotrophic conditions in the southeast to oligotrophic conditions in the northwest. Uncovering and understanding changes in community composition and structure along this productivity gradient are challenging but important, especially in the context of future mining impacts. Here, we summarize published data on benthic annelids (polychaetes), a major component of macrobenthic communities in the CCZ. Unlike previous studies, we attempt to explore all available data based on both morphology and genetics collected by box corer and epibenthic sledge. In this regard, we specifically aimed to (a) summarize and compare morphological and molecular data in relation to surface water nutrient conditions and (b) provide recommendations to advance the studies of polychaete biodiversity. Although initial studies on polychaetes in the CCZ were performed as far back as the 1970s, there are still large data gaps further explored in our review. For example, most of the current data are from the eastern CCZ, limiting understanding of species ranges across the region. An association between polychaete communities and the available food supply was generally observed in this study. Indeed, mesotrophic conditions supported higher abundance and species richness in polychaetes as a whole, but for certain groups of species, the patterns appear to be opposite — illustrating that relationships are likely more complex at lower taxonomic levels. A better understanding of biogeographical, ecological and evolutionary processes requires a concerted effort involving increased sampling and sharing of data and material to close existing knowledge gaps. [ABSTRACT FROM AUTHOR]

The doublesex-mab3-related transcription factor (Dmrt) gene family is a class of crucial transcription factors characterized by one or several DM domains. Dmrt family genes play important roles in sex determination/differentiation. Polychaete annelids are critically important in most marine ecosystems. However, to date, the genome-wide characterization and analysis of Dmrt genes in polychaetes have not been investigated. In this study, the identification and analysis of Dmrt genes were performed in three representative polychaetes, including Capitella teleta, Dimorphilus gyrociliatus, and Owenia fusiformis. A total of 12 Dmrt genes have been found, and the number of Dmrt genes in different polychaetes ranges from 3 to 5. The phylogenetic tree showed that all identified Dmrt genes were classified into 4 classes: Dmrt2/11E, Dmrt3/93B, Dmrt4/5/99B, and DSX. Furthermore, the selection pressure analysis suggested that all the Dmrt genes underwent strong purifying selection pressure. The spatiotemporal expression profile in O. fusiformis suggested that Dmrt genes have diverse functions, and the Dmrt2/11E-like gene may play an important role in the sex determination/differentiation of polychaetes. In general, this study provides a molecular basis for polychaete Dmrt genes and may serve as a reference for in-depth phylogenomics. [ABSTRACT FROM AUTHOR]

Rhynchospio glandulosa is a common polychaete living in silty tubes in soft sediments in temperate shallow waters in the Northwest Pacific. Worms are simultaneous hermaphrodites. Spermatogenesis occurs in the coelomic cavity. Spermatids are joined in 16-cell clusters. The spermatozoa have a dome-shaped acrosome 1.2 µm long, an elongated nucleus 2.9 µm long, midpiece 2.4 µm long with subspherical mitochondria, and a flagellum about 44 µm long. The acrosome is a complex structure with five internal parts. The nucleus is concave anteriorly and has a short fossa posteriorly which accommodates the basal body of the axoneme. The flagellum is strengthened by two circles of microtubules in addition to the central axoneme. Oogenesis is intraovarian. Developed oocytes are about 130 µm in diameter, with an envelope about 0.8 µm thick, consisting of three layers of extracellular matrix: the thickest basal layer penetrated by unbranched microvilli each about 0.4 µm long, a homogenous intermediate layer with the highest electron density, and the outer brush-like layer with numerous extensions each about 0.3 µm long. The oocytes are spawned to the parent's dorsum where they are loosely held by flat branchiae and long dorsal capillaries. In this "hatchery" larvae develop until the four-segment stage, then leave the parent and continue development in sea water. The general morphology of long-headed spermatozoa and thin-envelope oocytes of R. glandulosa is similar to that of other brooding spionids, but the details of their gamete ultrastructure are different. [ABSTRACT FROM AUTHOR]

Originally described from the northern Norway, Laonice cirrata (M. Sars, 1851) has been considered cosmopolitan and widely distributed in the North Pacific. To clarify the taxonomic status of the Pacific worms, we obtained the genetic characteristics of L. cirrata from Grøtsund Fjord, near Tromsø, one of the sites where Michael Sars collected worms to describe this species. The phylogenetic analysis of sequences of five gene fragments (mitochondrial COI and 16S rDNA, nuclear 18S rDNA and 28S rDNA, and Histone 3) showed significant difference between the Norwegian worms and worms from the north-western part of the Sea of Japan (Russia) earlier identified by morphology as L. cirrata. Common inhabitants of shallow waters in the Sea of Japan, these worms are assigned to the new species Laonice kasyanovi sp. nov. Both Northeast Atlantic and the Northwest Pacific populations exhibit high and overlapping variability of the diagnostic morphological characters of adults, and thus the two species can be considered as siblings. The distribution of these two species in the North Pacific remains uncertain and can only be elucidated by molecular data. Adults and one larva from the White Sea were also sequenced and found to be genetically identical to L. cirrata from Norway. The trochophores of L. cirrata are described and illustrated. They are characterized by two circles of large vesicles in the thick egg membrane and have been incorrectly referred to Aonides by previous authors. [ABSTRACT FROM AUTHOR]

In aquatic sediments, active ventilation of burrows is an important component of sediment metabolism, transporting solutes across the sediment–water interface. Within a burrow, the temporal and spatial structure of the flow velocity can dictate the flux of solutes across the burrow walls. However, it is difficult to measure the fine-scale flow dynamics within a burrow due to the opacity of marine sediments. Here, we allowed a nereid polychaete Alitta succinea, a cosmopolitan deposit feeder found in brackish to marine soft sediments, to construct burrows in a transparent, elastic sediment analog. This allowed the measurement of the temporal velocity structure of flow in the burrow using particle tracking velocimetry. We find that the flow within the burrow of this piston-pumping polychaete is unsteady and that oscillations in flow velocity are damped with distance along the tube. We also show that the flow velocity in a tube scales with worm size. Conversely, neither the unsteadiness of flow oscillations nor the stroke frequency of the worm pump scale with worm size.

Nereididae is among the most familiar of marine annelid families, common and well-studied in most marine environments but paradoxically no recent key or identification guide exists to the world's genera. Here updated generic descriptions, a list of characters, a linear key to genera, and minimal diagnoses that distinguish each genus from all others in the family are provided. This information is generated from a Delta database of 186 morphological characters and a link is provided to downloadable software allowing the same data to be interrogated using the open-source Delta program Intkey - a nonlinear multiple entry point computerised interactive key. For each genus the recent literature is also summarised, comments on taxonomic status provided, and published keys to species cited. Nexus format matrices are provided for all 45 genera and 158 Nereididae species, representing all genera, scored for 146 multistate characters from the same character list to facilitate future phylogenetic studies. [ABSTRACT FROM AUTHOR]

Marine transportation requires maintenance dredging of navigation channels to allow large ships access to inland ports. These dredging activities have repercussions on the benthic habitat, modifying the bottom topography and inducing habitat degradation. In this study, we analyzed the polychaete community composition before, during, and after a maintenance dredging carried out in the tropical estuary of Buenaventura Bay. Transparency, salinity, and dissolved oxygen exhibited temporal variation (p < 0.05) before, during, and after the maintenance dredging. Significant variation in sediment granulometric composition and OM content (p < 0.05) was observed in E1 and E2. Gravel (%), coarse silt (%), organic matter (%), transparency (cm), and disolved oxygen (mg L−1) were the most influential environmental parameters on the polychaete community composition. Polychaete density varied from 0 to 3050 ind. m−2 in E1 and 25 to 1350 ind. m−2 E2. The families Cossuridae, Maldanidae, Lumbrineridae, and Capitellidae were dominant during dredging. The species diversity index (H′) was slightly higher in E1 compared to E2. The NMDS showed differences in the ordination of the polychaetes community composition in at least one of the three seasons. In this study, the observed temporal variations in the polychaete community composition and the environmental variables were mostly driven by the natural disturbances associated with the river discharges and the dredging activities. [ABSTRACT FROM AUTHOR]

Adult Scolelepis are unique among spionids in having an elongated, pointed snout, used for digging in sediment. Earlier studies have suggested that the pointed part of the larval head was a peristomial extension. Despite this, modern authors characterize larvae and adults of Scolelepis as having an elongated, pointed prostomium. Based on new observations, as well as on literature data, I show that the pointed medioventral process of the head in larvae is formed by lateral peristomial lips, elongated and fused anteriorly, each supported internally by conspicuous fibres. During settlement and metamorphosis, the anterolateral parts of the prostomium extend ventrally and overgrow the basal part of the peristomial process in a tube-like manner, forming a typical adult snout. Thus, in adult Scolelepis , only the wide basal part of the snout is formed by the prostomium, while the anterior, pointed part of the snout (the rostrum) is of peristomial origin. The ventral peristomial lip does not develop in Scolelepis larvae, and the ventral part of the mouth in adults is formed by the anterior extensions of the first and second segments. The diverse composition of the mouth region of different spionids is illustrated, as well as other details of the morphology of Scolelepis. [ABSTRACT FROM AUTHOR]

Promastobranchus Gallardo, 1968 is a small genus in the polychaete family Capitellidae, and the available records are largely reported from the Indo-West Pacific region. Although Gallardo (1968) and Green (2002) noted that Promastobranchus species had intraspecific variation in the number of thoracic chaetigers when they described the two previously known species, this variation has not been corroborated using molecular evidence. In this study, a new Promastobranchus species, Promastobranchus variabilis sp. nov., is described based on 29 specimens collected from the Beibu Gulf, South China Sea. The new species is mainly characterized by having a tessellated epithelium in the anterior thorax, nine teeth in three rows above the main fang in the abdominal hooks, four pairs of genital pores located on the intersegmental grooves between chaetigers 9 and 13, and its unique methyl green staining pattern. Comparisons of multiple gene markers (16S, 18S, 28S, and H3) revealed no genetic divergence (K2P < 0.003) among these type specimens with 9-13 thoracic chaetigers. In other words, the new species exhibited morphological variability in the number of thoracic chaetigers during ontogeny, and this character was unsuitable to differentiate Promastobranchus species as the ranges overlap among Promastobranchus species. This is the third Promastobranchus species known in the world, and it is now recorded along the Fujian coast. [ABSTRACT FROM AUTHOR]

The potential of polychaetes for the bioremediation of aquaculture sludge gained more attention in recent years. These organisms can reduce organic matter and nutrients contained in the sludge of several aquaculture species, improving the sustainability of these activities. The aim of this study was to evaluate the removal performance of Perinereis gualpensis (Jeldes, 1963) being fed with aquaculture sludge produced by a recirculating system cultivating Atlantic salmon. The experiment involved adding different amounts of sludge (10% and 20% with respect to total substrate) at a density of 300 organisms m−2 during 30 days. A treatment without sludge served as a control, using natural substrate. The highest removal rate of total organic matter (TOM) (23.95 ± 13.19 g m−2 day−1) was achieved by P. gualpensis with 20% sludge addition, a reduction of about 36% compared to the total amount added at the beginning of the trials. The organisms fed with aquaculture sludge presented higher nitrogen (8–9%) and carbon (40–43%) contents, with a maximum organic carbon assimilation of 32% in relation to the total content in the sludge. The high survival (88–95%) and positive growth rates (0.28% day−1) achieved by P. gualpensis indicated that this species can be sustained with salmon sludge as the only source of food. These results indicate that P. gualpensis is a promising candidate for removing nutrients from salmon effluents. Moreover, the protein contents achieved by the organisms (52–58%) meet the dietary protein requirements of several aquaculture species. Further research is needed to determine the maximum bioremediation capacity of this species and to evaluate the lipid content and fatty acid profiles of P. gualpensis to determine its potential application in aquaculture feed. [ABSTRACT FROM AUTHOR]

Podarkeopsis chinensis sp. nov. (Annelida, Hesionidae) is described based on specimens collected from the coast of southeast China. It is the first Podarkeopsis species described from the Indo-Pacific, although there are already nine valid Podarkeopsis species known from other parts of the world. This new species can be distinguished from the other Podarkeopsis species in having a palpostyle as long as the palpophore and double aciculae in both notopodia and neuropodia, and in bearing bifid furcate chaetae which have a smooth base on the shorter tine. A phylogenetic analysis based on the concatenated sequences of five gene fragments (COI, 16S rRNA, 18S rRNA, 28S rRNA, and histone H3) from 18 specimens of P. chinensis sp. nov. showed that they formed a monophyletic clade that is sister to P. levifuscina. K2P genetic distances indicated that the four gene fragments (COI, 16S rRNA, 18S rRNA, and 28S rRNA) of P. chinensis sp. nov. diverged from the corresponding sequences of the closest related species of Podarkeopsis in GenBank and BOLD Systems by 21.1-27.5%, 20.3-23.1%, 0.1-0.2%, and 2.1-3.2%. An identification key is provided for species in the genus Podarkeopsis. [ABSTRACT FROM AUTHOR]

Polychaetes are important benthic macrofauna that lives in sediments, usually in intertidal flats with high organic content and high sulfide. It has been suggested that polychaete bioturbation could perform environmental remediation. During the process, the microbial community plays important roles. Here, we used high-throughput sequencing technology to study the bioturbation effects on the bacterial community in the polychaete (Perinereis aibuhitensis) burrows at different tidal positions in intertidal flat. The results showed that the bacterial communities were dramatically influenced by the polychaete bioturbation. The ACE, Chao, and Shannon indices of the polychaete burrows increased in summer. Dominant phyla in the polychaete burrows were Proteobacteria, Campilobacterota, Desulfobacterota, Chloroflexi, and Bacteroidota, and the dominant bacterial families were Sulfurvaceae, Flavobacteriaceae, Rhodobacteraceae, Woeseiaceae, Desulfobulbaceae, and Sulfurimonadaceae. Results of linear discriminant analysis effect size (LEfSe) showed that groups that include organic matter degraders, such as Bacteroidota, Flavobacteriaceae, Rhodobacteraceae, Woeseiaceae, and groups that include sulfur oxidizers, such as Campilobacterota, Sulfurovaceae, Rhodobacteraceae, Desulfobulbaceae, and Sulfurimonadaceae, were significantly increased due to the polychaete bioturbation. The polychaete bioturbation reduced the complexity of the bacterial co-occurrence network while increased its modularity and homogeneity. The polychaete bioturbation also changed the functional groups, which significantly enhanced in functional groups of aerobic nitrite oxidation, nitration, dark thiosulfate oxidation, dark sulfur oxidation, and dark sulfite oxidation, while nitrogen respiration and nitrate respiration decreased. These results provide insight into the impact of bacterial communities under the intertidal polychaete bioturbation. [ABSTRACT FROM AUTHOR]

The monotypic polynoid genus Arctonoella Buzhinskaja, 1967 comprises solely the type species A. sinagawaensis (Izuka, 1912), which was originally described from Tokyo Bay (central Japan), and subsequently recorded from China and the Russian Far East. The six specimens we collected together with the burrowing filter-feeding spoon worm Urechis unicinctus (Drasche, 1880) from three intertidal-flat sites in the Seto Inland Sea represent a new report for the western Japan, and the second for the country. Our morphological observations reveal that the shape of the cephalic peaks in the frontal prostomial margin is variable even within a local population, although this character has been considered as diagnostic for Arctonoella. This genus is closely related with Hesperonoe Chamberlin, 1919, both morphologically and phylogenetically. Hesperonoe urechis Marin and Antokhina, 2020, collected inside a burrow of U. unicinctus in the Russian Far East, is hereby deemed a junior synonym of A. sinagawaensis. This species morphologically resembles Hesperonoe adventor (Skogsberg in Fisher and MacGinitie, 1928), which inhabits spoon worm (Urechis caupo Fisher and MacGinitie, 1928 and Echiurus echiurus alaskanus Fisher, 1946) burrows along the northeastern Pacific coast of America. Therefore, we conclude that the Arctonoella-Hesperonoe species complex requires to be reviewed to determine the proper generic arrangement. Additionally, we revise the available data on the symbiotic fauna living inside the burrows of U. unicinctus and U. caupo. [ABSTRACT FROM AUTHOR]

In the deep ocean, whale falls (deceased whales that sink to the seafloor) act as a boost of productivity in this otherwise generally food-limited setting, nourishing organisms from sharks to microbes during the various stages of their decomposition. Annelid worms are habitual colonizers of whale falls, with new species regularly reported from these settings and their systematics helping to resolve biogeographic patterns among deep-sea organic fall environments. During a 2017 expedition of the Australian research vessel RV Investigator to sample bathyal to abyssal communities off Australia's east coast, a natural whale fall was opportunistically trawled at ~1000 m depth. In this study, we provide detailed taxonomic descriptions of the annelids associated with this whale-fall community, using both morphological and molecular techniques. From this material we describe nine new species from five families (Dorvilleidae: Ophryotrocha dahlgreni sp. nov. Ophryotrocha hanneloreae sp. nov., Ophryotrocha ravarae sp. nov.; Hesionidae: Vrijenhoekia timoharai sp. nov.; Nereididae: Neanthes adriangloveri sp. nov., Neanthes visicete sp. nov.; Orbiniidae: Orbiniella jamesi sp. nov.), including two belonging to the bone-eating genus Osedax (Siboglinidae: Osedax waadjum sp. nov., Osedax byronbayensis sp. nov.) that are the first to be described from Australian waters. We further provide systematic accounts for 10 taxa within the Ampharetidae, Amphinomidae, Microphthalmidae, Nereididae, Orbiniidae, Phyllodocidae, Protodrilidae, Sphaerodoridae and Phascolosomatidae. Our investigations uncover unique occurrences and for the first time enable the evaluation of biogeographic links between Australian whale falls and others in the western Pacific as well as worldwide. [ABSTRACT FROM AUTHOR]

Simple Summary: Transoceanic shipping and global development of aquaculture are the main vectors for the introduction of marine organisms, as adults or their larvae, to new remote locations. Recent invasions by large species may be well known and documented, while older and smaller-bodied invasions are often hidden and more difficult to detect. In the present study, we investigated, using molecular methods, marine worms that bore into the shells of commercial molluscs on four continents. We have identified them as Polydora hoplura, a species originally described from Italy. The highest genetic diversity was detected in South African population. While high genetic diversity is often regarded as indicative of a species' natural range, our analysis of the worldwide discovery of P. hoplura calls into question its natural distribution in South Africa. The high genetic diversity of P. hoplura in this region may be the result of a complex dispersal history by ships and aquaculture. We tentatively propose the Northwest Pacific, or at the most the Indo–West Pacific, as its home region, not the Atlantic Ocean or the Eastern Pacific Ocean, and call for further exploration of this hypothesis. The spionid polychaete Polydora hoplura Claparède, 1868 is a shell borer widely occurring across the world and considered introduced in many areas. It was originally described in the Gulf of Naples, Italy. Adult diagnostic features are the palps with black bands, prostomium weakly incised anteriorly, caruncle extending to the end of chaetiger 3, short occipital antenna, and heavy sickle-shaped spines in the posterior notopodia. The Bayesian inference analysis of sequence data of four gene fragments (2369 bp in total) of the mitochondrial 16S rDNA, nuclear 18S, 28S rDNA and Histone 3 has shown that worms with these morphological features from the Mediterranean, northern Europe, Brazil, South Africa, Australia, Republic of Korea, Japan and California are genetically identical, form a well-supported clade, and can be considered conspecific. The genetic analysis of a 16S dataset detected 15 haplotypes of this species, 10 of which occur only in South Africa. Despite the high genetic diversity of P. hoplura in South Africa, we tentatively propose the Northwest Pacific, or at the most the Indo–West Pacific, as its home region, not the Atlantic Ocean or the Eastern Pacific Ocean. The history of the discovery of P. hoplura around the world appears to be intimately linked to global shipping commencing in the mid-19th century, followed by the advent of the global movement of commercial shellfish (especially the Pacific oyster Magallana gigas) in the 20th century, interlaced with continued, complex dispersal by vessels and aquaculture. Given that P. hoplura has been detected in only a few of the 17 countries where Pacific oysters have been established, we predict that it may already be present in many more regions. As global connectivity through world trade continues to increase, it is likely that novel populations of P. hoplura will continue to emerge. [ABSTRACT FROM AUTHOR]

BackgroundThe unusual holopelagic annelid Poeobius meseres Heath, 1930 (Flabelligeridae) was first collected from Monterey Bay, California and has been subsequently recorded across the northern Pacific from Japan to the Gulf of California. Rare occurrences in the eastern tropical Pacific have extended as far as 7° S off Peru.New informationUsing molecular phylogenetic analysis of a newly-collected specimen from the Salas y Gómez Ridge off Chile, we extend the known geographic range of P. meseres southwards by 2040 km. This subtropical specimen showed higher genetic similarity to a specimen from the type locality (< 1.5% pairwise COI distance) than to representatives from the Aleutian Islands and Japan (5-6%), establishing the first genetically-confirmed occurrence of this species in the Southern Hemisphere. The latitudinal range of P. meseres encompasses the sole collection locality, off Ecuador, of Enigma terwielii Betrem, 1925, a pelagic annelid which has been compared to P. meseres, but is indeterminable due to an inadequate description. We therefore suggest that the earlier sole record of E. terwielii may have been an occurrence of what is known now as P. meseres.

Este estudio tiene como objeto proporcionar una actualización del conocimiento de poliquetos bentónicos registrados en Ecuador Continental. Se realizó una revisión de la información disponible sobre especies registradas desde 1865 hasta el 2020, de lo cual, se obtuvo el número de géneros y especies por familias proporcionando un listado de poliquetos bentónicos para el país. Se han reportado 143 especies en total, en donde, 20 han sido registradas anteriormente con su sinonimia. Existe un importante aumento en la biodiversidad de poliquetos para el país y su taxonomía ha tenido muchas controversias, lo que se ve reflejado en ciertas familias. Se menciona que, El Golfo de Guayaquil es el área donde se ha encontrado un mayor número de registros de poliquetos. Con las nuevas tecnologías y disponibilidad de información, se podría incrementar este dato; es necesario considerar la distribución biogeográfica de las especies para una mejor identificación, además de, con ayuda de análisis de ADN y la opinión de especialistas, esto permitiría realizar una actualización viable sobre el conocimiento taxonómico de las especies de poliquetos para Ecuador

Here, we report the complete mitochondrial genome of sabellid Pseudopotamilla reniformis (Bruguière, 1789) (16,408 bp) and comprised of two ribosomal RNAs, the ubiquitous set of 13 protein-coding sequences, and 22 tRNAs. The order of protein-coding genes is consistent with the proposed conserved pattern, which contradicts recent discovery in other members of the family (Sabella spallanzanii in Daffe et al., and Bispira melanostigma in Hornfeck et al., ).

Toxicity testing is an important tool for risk assessment of sediment contamination in estuaries. However, there has been a predominant focus on fitness parameters as toxic endpoints and on crustaceans as test organisms, while effects at the sub-organismal level and on other benthic taxa have received less attention. Also, interactions between sediment contamination and natural stressors such as oxygen are often neglected in traditional toxicity tests. Here we conducted a toxicity test of sediments from the Elbe and Oder (Odra) estuaries under three weeks of continuous and intermittent oxygenation, using biomarkers in an annelid, the ragworm Hediste diversicolor. Contaminated sediments affected worm survival and some biomarkers of antioxidant defense, electrophilic stress, and energy status with response ratios of above 20%. Toxic effects were most pronounced in sediments from the upper Elbe estuary, which contained high levels of heavy metals and organic chemicals. Oxygen regimes hardly changed the sediment effects, suggesting the robustness of the biomarker-based toxicity test with ragworms. • Sediments from the Elbe and Oder estuaries contaminated with various chemicals. • Sediment toxicity tested under continuous and intermittent oxygenation. • Ragworm survival and several biomarkers affected by contaminated sediments. • Toxic effects frequently observed in sediments from the upper Elbe estuary. • Sediment toxicity largely independent of oxygen regimes. [ABSTRACT FROM AUTHOR]

Dorvilleids belonging to Ophryotrocha Claparède & Mecznikow, 1869 are known from deep-sea hydrothermal vents in the Pacific, Atlantic, Indian and Southern Oceans. However, how they colonized and diversified in these ecosystems has not been assessed in detail. Here, a collection of Pacific hydrothermal vent Ophryotrocha was examined using morphology and DNA markers (COI, 16S and H3). Five new species were revealed, largely expanding the diversity of the group at this habitat type. They are Ophryotrocha charlottae sp. nov., O. kailae sp. nov., O. marinae sp. nov., O. pruittae sp. nov. from eastern Pacific, and O. bohnorum sp. nov. from the western Pacific. Phylogenetic analyses based on the concatenated alignments of all three genes suggest vent habitants have been colonized several times independently within Ophryotrocha. One clade of six vent species was recovered, indicative of diversification following a colonization of hydrothermal vents, likely in the eastern Pacific. An Indian Ocean species, O. jiaolongi, was nested inside this clade and was closely related to one of the new species from the Gulf of California, diverging from it by less than 4% on COI.

Early annelid evolution is mostly known from 13 described species from Cambrian Burgess Shale-type Lagerstätten. We introduce a new exceptionally well-preserved polychaete, Ursactis comosa gen. et sp. nov., from the Burgess Shale (Wuliuan Stage). This small species (3–15 mm) is the most abundant Cambrian polychaete known to date. Most specimens come from Tokumm Creek, a new Burgess Shale locality in northern Kootenay National Park, British Columbia, Canada. Ursactis has a pair of large palps, thin peristomial neurochaetae and biramous parapodia bearing similarly sized capillary neurochaetae and notochaetae, except for segments six to nine, which also have longer notochaetae. The number of segments in this polychaete range between 8 and 10 with larger individuals having 10 segments. This number of segments in Ursactis is remarkably small compared with other polychaetes, including modern forms. Specimens with 10 segments show significant size variations, and the length of each segment increases with the body length, indicating that body growth was primarily achieved by increasing the size of existing segments rather than adding new ones. This contrasts with most modern polychaetes, which typically have a larger number of segments through additions of segments throughout life. The inferred growth pattern in Ursactis suggests that annelids had evolved control over segment addition by the mid-Cambrian.

Here, we sequenced and annotated the complete mitochondrial genome for the terebellid polychaete, Neoamphitrite affinis (Malmgren 1866). The complete mitogenome of N. affinis is 15,823 bp, with 33.4% A, 18.2% C, 11.5% G, and 37.0% T. The circular N. affinis mitochondrial genome comprises 13 protein-coding genes (PCGs), 23 transfer RNA (tRNA) genes including 2 methionine tRNA genes, 2 ribosomal RNA (rRNA) genes, and a non-coding region. Phylogenomic analysis based on 26 in-group taxa belonging to the two main clades, Sedentaria and Errantia, is congruent with published phylogenetic relationship for annelids, which N. affinis was grouped with Pista cristata (Terebellida; Terebellidae). This mitogenome resource will be useful for future phylogenetic studies of families belonging to Sedentaria.

We deployed jaws of the common thresher shark (Alopias vulpinus) on the seafloor at ~1000 m depth off Monterey California for 8 months. The jaws disintegrated, with all the hyaline cartilage disappearing, leaving some fragments of tessellated cartilage and the teeth. Two different Osedax species, O. packardorum and O. talkovici were found to have bored into the roots of some of the teeth, and were using the dentin pulp, which is rich in collagen, as a food source. The enameloid crowns of the shark teeth and the tessellated cartilage showed no signs of Osedax activity. This is the first demonstration of Osedax exploiting a source of food that is not bone. This raises questions as to the original food source of Osedax 'bone worms'. Examination for the presence of Osedax in the skeletons and teeth of Mesozoic and possibly even Palaeozoic fossil sharks, bony fish and reptiles is warranted. [ABSTRACT FROM AUTHOR]

The bearded fireworm Hermodice carunculata is a conspicuous omnivorous benthic invertebrate distributed in the wider Atlantic Ocean, Mediterranean Sea and the Red Sea. Questions were raised in the past regarding the taxonomic status of amphiatlantic fireworm specimens but subsequent analysis of morphological data with new molecular data reconfirmed the presence of only one species, H. carunculata with amphiatlantic distribution. Hermodice carunculata has been the subject of several taxonomic and genetic studies but there are still questions regarding the genetic diversity and population structure of the species throughout its range. We contributed to the genetic studies of H. carunculata with ~200 new samples from over 20 locations in the Caribbean, Eastern Atlantic Ocean and the Mediterranean Sea. We sequenced the mitochondrial markers Cytochrome c oxidase Subunit I (COI) and Cytochrome b (Cytb) from each polychaete to examine the patterns of genetic diversity of H. carunculata. Our data revealed a significant population structure between the Caribbean H. carunculata including those from Brazil compared with those from the eastern Atlantic (Tenerife, Canary Islands) and eastern Mediterranean (Greece and Malta). We inferred rates of gene flow between eastern and western Atlantic populations by estimating the bidirectional effective migration rate (Nem). We corroborate previous studies indicating the existence of one species with genetically distinct populations. However, the biological significance of the observed population divergence should be evaluated with cross-breeding experiments. [ABSTRACT FROM AUTHOR]

A variety of nereidid species have been reported from the South China Sea, although little is known about the deep-sea species in this area. Recently, two specimens belonging to a novel nereidid polychaete were collected from a sedimentary habitat during an environmental survey to a deep-sea basin where cold seeps occur. This new species, Nereis tricirrata sp. nov., is described herein, based on morphological and molecular analyses. The most noteworthy feature is the absence of eyes on the prostomium; it can be distinguished from other eyeless Nereis species by the arrangement of conical paragnaths on the pharynx, the nature of homogomph falcigers and the shape of notopodial lobes in posterior chaetigers. The reconstructed phylogenetic tree, using concatenated sequences of mtCOI, 16S, and 18S rRNA, showed that all Nereis species included in this study form a monophyletic clade with full support. The mtCOI-based interspecific comparisons revealed a high genetic divergence (23.1%-37.3% K2P) from four-eyed Nereis species with the available sequences. This is the first record of an eyeless Nereis species in the South China Sea. [ABSTRACT FROM AUTHOR]

Urban developments in estuarine areas affect benthic organisms, notably the macrobenthos, by physically modifying the territory and generating waste. The polychaete assemblages and the environmental parameters in the estuarine area of Sungai Terengganu were examined based on nine stations along a salinity gradient from oligohaline to polyhaline. Samples were collected using a Smith McIntyre grab and yielded 1886 individuals, from 43 species grouped into 24 families. The fauna was mainly dominated by Composetia sp. (39.48%) and Cossura sp. (31.87%); the former in oligohaline areas and the latter in the polyhaline areas. The densities of both species had significant positive correlations with salinity, temperature, and silt, clay, and gravel contents. This study will benchmark the polychaete community distribution in this tropical estuary, which could be similar to environments along the east coast of Peninsular Malaysia (South China Sea). [ABSTRACT FROM AUTHOR]

Polychaete serves as aquafeed for most aquaculture species and as bioremediation agent of organic waste. Polychaete used for broodstocks of finfish and crustaceans stimulates gonadal maturation and endocrine system in penaeid shrimp, therefore overcoming the shortfall in juvenile production of animals and securing reliable production of aquaculture harvests. Commercial feed has gained the most ground in polychaete farming. Microalgae’s essential nutrients and favorable morphology are ideal for polychaete larviculture. Home-made feed is less attractive due to its complex structural fibre but applicable as co-feed in polychaete nourishment. High organic matter waste is competitive as polychaete feed although it might lack adequate nutrients. The ideal feeds for polychaete growth, distinguished by the different life stages, are poorly studied. This review studies the fitness of microalgae in larviculture, nutritional value of commercial feed, and home-made feed as co-feed option, in polychaete nourishment; and the bioremediation benefit from polychaete’s waste-feeding behaviour.

Ophryotrocha craigsmithi (Wiklund, Glover & Dahlgren, 2009) has repeatedly been observed in high densities at salmonid fish farms in Norway and has been shown to feed on the organic waste released during fish production. This species has therefore been pointed out as a candidate for the benthic component of integrated multitrophic aquaculture (IMTA). Little is known about the life history traits of Ophryotrocha species found at greater depths in temperate waters. Insight into life traits is of key importance in evaluating the bio-mitigation and harvest potential of (benthic) species within IMTA systems. In this study, we aimed to describe key life history traits for O. craigsmithi, such as growth, reproductive pattern, and offset of reproduction. The main findings are as follows: (I) O. craigsmithi exhibits early sexual maturation and rapid growth, going from 5 to 16 mm in length in 8 weeks; (II) their estimated lifetime is approximately 15 weeks with a generation time of 4 weeks; (III) there are strong indications that they are gonochoric semicontinuous spawners; (IV) the majority of mature eggs ranged from 120 to 150 µm; and (V) the larvae developed into a free-swimming stage after approximately 1 week. To this end, we present a framework for assessing the suitability of deposit-feeding polychaetes as candidate species in IMTA, considering environmental adaptiveness, production potential, as well as carbon and nitrogen mitigation capacity. On the basis of this, O. craigsmithi shows a high suitability as an extractive farmed species in benthic IMTA.

The methane ice worm Sirsoe methanicola is the only marine polychaete species observed to colonize the methane hydrates of the Gulf of Mexico. Methane hydrates are ephemeral features of deep-sea cold seeps, and finding worm-colonized hydrates is rare; thus, little is known about these organisms. Recent metagenomic analysis predicted prokaryotic taxa and pathways from S. methanicola gut contents and worm fragments. Here, we increase the genetic information known about S. methanicola by assembling its nuclear rRNA genes (18S rRNA and 28S rRNA), mitochondrial genome (mitogenome), and other protein-coding genes from metagenomic data. Assembled 18S rRNA and 28S rRNA gene sequences of S. methanicola were near-identical to previously reported S. methanicola sequences. The 17,403-bp mitogenome of S. methanicola is the first mitogenome sequence of the family Hesionidae, consisting of 39.03% G+C content, 13 protein-coding genes, 24 tRNAs (including two split trnM genes), and 2 rRNA genes. Protein-coding genes in the S. methanicola metagenomes assigned to the phylum Annelida were involved in cell adhesion, signaling, ubiquitin system, metabolism, transport, and other processes. From the metagenomes, we also found 42 homologs of the cytochrome P450 (CYP) superfamily putatively involved in polycyclic aromatic hydrocarbon (PAH) metabolism. Our results encourage further studies into the genetic adaptations of S. methanicola to its methane hydrate habitat, especially in the context of deep-sea ecology and nutrient cycling.

Three new species of Marphysa Quatrefages, 1866, Marphysa banana sp. nov., Marphysa papuaensis sp. nov., and Marphysa zanolae sp. nov. are described from deep-sea sunken vegetation off Papua New Guinea, using both morphology and molecular data (for two species). With the presence of compound spinigers only and the branchiae present over many chaetigers, Marphysa banana sp. nov. belongs to the group B2. This species is characterised by the presence of eyes, the presence of branchiae starting from chaetiger 20, and by the presence of three types of pectinate chaetae and bidentate subacicular hooks starting from chaetigers 13-52. With the presence of compound falcigers only and the branchiae restricted to a short anterior region, Marphysa papuaensis sp. nov. belongs to the group C1. This species has a bilobed prostomium but no eyes, has branchiae from chaetigers 7 to 14-16 with up to 16 filaments. Marphysa papuaensis sp. nov. is also characterised by the presence of bidentate subacicular hooks from chaetiger 20 and by a single type of pectinate chaetae. Finally, Marphysa zanolae sp. nov. belongs to the group C2, with the presence of compound falcigers only and the branchiae present over many chaetigers. This species is characterised by the absence of eyes, by the presence of branchiae with a single long filament starting from chaetiger 31, by unidentate subacicular hooks starting from chaetiger 28 and finally by one type of pectinate chaetae with very long outer teeth. [ABSTRACT FROM AUTHOR]