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The mitogenome sequence of the epitokous Nereis species (Phyllodocida, Nereididae) was determined first in the genus Nereis. The complete mitogenome is 15,667 bp in length, containing 13 protein-coding genes, two ribosomal RNAs, 22 transfer RNAs and a control region, and their gene order and structure is identical to those of other nereidid species. The mitogenome consists of 33.5% A, 20.0% C, 13.3% G, 33.1% T, showing a high content of A + T similar to the other phyllodocid polychaetes. These results will be useful for inferring the phylogenetic relationships among the members of Nereididae within the phyllodocids.

Some of the highest density pockmark fields in the world have been observed on the northwest Australian continental shelf (>700/km2) where they occur in muddy, organic-rich sediment around carbonate banks and paleochannels. Here we developed a semi-automated method to map and quantify the form and density of these pockmark fields (~220,000 pockmarks) and characterise their geochemical, sedimentological and biological properties to provide insight into their formative processes. These data indicate that pockmarks formed due to the release of gas derived from the breakdown of near-surface organic material, with gas accumulation aided by the sealing properties of the sediments. Sources of organic matter include adjacent carbonate banks and buried paleochannels. Polychaetes biodiversity appears to be affected negatively by the conditions surrounding dense pockmark fields since higher biodiversity is associated with low density fields. While regional bi-directionality of pockmark scours corresponds to modelled tidal flow, localised scattering around banks suggests turbulence. This multi-scale information therefore suggests that pockmark scours can act as proxy for bottom currents, which could help to inform modelling of benthic biodiversity patterns.

The sabellariid Phragmatopoma caudata (Kroyer, 1856), Morch, 1863 is widely distributed in the Americas and constructs large reef agglomerates that provide substrates for other benthic species. However, the difficulty in obtaining size data (especially length) hampers population studies, making it necessary to carry out morphometric studies as basis for studies of population dynamics. The objective of the present study is to determine the best morphological descriptor of length in P. caudata. A total of 17 morphometric variables were measured in specimens from four different populations. Measurements were performed using an ocular micrometer attached to a stereoscopic microscope. Correlations in the dataset were tested using Pearson's linear correlation coefficient, and the hypothesis of morphometric differences among populations was tested using MANOVA and principal component analysis. Correlation coefficients were different amongst populations, as well as in the measured traits . Moreover, the results suggest that populations differ more strongly in body size than in shape. Although populations presented different morphometric relationships, the length of the first thoracic chaetiger was one of the variables with highest correlation with total length. This result, as well as the fact that such region is located on the anterior portion of the body, suggests that this structure is a good length descriptor in P. caudata.

Global projections predict significant increases in ocean temperature and changes in ocean chemistry, including salinity variations by 2100. This has led to a substantial interest in the study of thermal ecophysiology, as temperature is a major factor shaping marine ectotherm communities. However, responses to temperature may be influenced by other factors such as salinity, highlighting the relevance of multiple stressor studies. In the present work, we experimentally evaluated the thermal tolerance of the marine ragworm Hediste diversicolor under predicted global change scenarios. Organisms were subjected to an experimental trial under control (24 °C), and two temperature treatment scenarios (ocean warming +3 °C – (27 °C) and heat wave +6 °C – (30 °C)), combined with salinity variations (20 and 30) in a full factorial design for 29 days. Environmental data from the field were collected during 2019 and 2020. At day 30 post exposure, upper thermal limits (Critical Thermal Maximum - CTMax), thermal safety margins (TSM) and acclimation capacity were measured. Higher acclimation temperatures led to higher thermal tolerance limits, confirming that H. diversicolor features some physiological plasticity, acclimation capacity and a positive thermal safety margin. This margin was greater considering in situ temperature data from 2019 than maximum temperatures for 2020 (CTMax > maximum habitat temperature–MHT). Moreover, smaller organisms displayed higher upper thermal limits suggesting that thermal tolerance is size dependent. Ragworms subjected to higher salinity also showed a higher CTMax than those acclimated to lower salinity. However, temperature and salinity showed an additive effect on CTMax, as no significant interaction was detected. We conclude that H. diversicolor can easily acclimate to increased water temperature, independently of salinity variations. Given the key role of ragworms in food webs in estuaries and coastal lagoons, substrate bioturbation and aquaculture, this information is relevant to support conservation actions, optimize culture protocols and identify thermal resistant strains. [Display omitted] • Hediste diversicolor specimens were subjected to predicted global change scenarios. • Hediste diversicolor had a positive acclimation capacity to temperature, independently of salinity. • Thermal safety margin was greater in 2019 than 2020. • Smaller specimens displayed higher thermal tolerance limits. [ABSTRACT FROM AUTHOR]

Cardicola opisthorchis is a blood fluke pathogen significantly affecting cultured Pacific bluefin tuna Thunnus orientalis in Japan. It is known that the intermediate host of C. opisthorchis is a terebellid polychaete Terebella sp. In order to study the intrapolychaete larval development of C. opisthorchis , we transplanted sporocysts, which contained a large number of cercariae, of C. opisthorchis obtained from Terebella sp. into sporocyst-free Terebella sp., which had been maintained at 20 °C. The transplanted sporocysts switched from cercarial to sporocystal production by 17 days after transplantation (d.a.t.) and daughter sporocysts were released into the polychaete body cavity at 25 d.a.t. Subsequently, the released daughter sporocysts produced daughter sporocysts again. Thereafter, daughter sporocysts that contained cercariae appeared at 38 d.a.t. and gradually increased. At 51 d.a.t., 136 sporocysts that had multiplied from the original two transplanted sporocysts were observed in the body of one polychaete, and cercariae were released from daughter sporocysts inside the polychaete body cavity. Subsequently the cercariae were found to be released outside the polychaete at 57 d.a.t. This is the first successful case of in situ observation of the development of a blood fluke within the intermediate host. [ABSTRACT FROM AUTHOR]

The present work analyzed three hard-bottom and two soft-bottom species of sabellid polychaetes to determine the content of several heavy metals in their branchial crown and body. The highest concentrations of heavy metals were recorded in the hard-bottom species Branchiomma bairdi, a recent Mediterranean introduction. Differences in the metal concentrations were most notable in the high trace metal levels of the branchial crown for all the studied species. Statistical analysis showed that the Mediterranean hard-bottom species were similar each other in their heavy metal content in the body as well as in the branchial crown and appeared separated from all the other species. Arsenic and vanadium hyperaccumulation in the branchial crowns of the considered sabellid species probably acts as a deterrent for predation. The observed differences among the examined species were discussed not only at the light of habitat colonization but also in terms of the phylogeny. [ABSTRACT FROM AUTHOR]

In this study, 169 lumbrinerids of the genera Ninoe and Cenogenus from the sublittoral zone of the Gulf of California and Gulf of Tehuantepec were analysed. Previous records in these regions of the Mexican Pacific included five species of Ninoe (N. chilensis, N. foliosa, N. gemmea, N. longibranchia and N. moorei) and two of Cenogenus (originally identified as Ninoe fusca and N. fuscoides). Ninoe jessicae and N. marthae are newly described. They are characterized by the presence of multidentate hooded hooks from chaetiger 1 and at least 7 branchial filaments in the best developed branchiae. N. marthae n. sp. differs not only from N. jessicae n. sp. but also from the other species of the genus Ninoe, because only four teeth are present in maxilla II, while in all the other described species, 6-8 teeth are present there. The new species Cenogenus eliae is characterized by the presence of branchiae starting at chaetigers 32-51 and simple multidentate hooded hooks in all parapodia.

Opheliid polychaetes collected by the United States Antarctic Research Program and additional material from South America were made available for study through the Smithsonian Institution, Washington, D.C., USA. The Opheliidae from Antarctic seas were treated by Hartman (1966, 1967, 1978), who summarized earlier work and also described several new species. Of the five genera she recorded, two (Travisia and Kesun) have since been synonymized and one, Ammotrypane, has been referred to Ophelina; Hartman’s records therefore encompass four genera, three of which are represented in the present collections. No representatives of Euzonus (Thoracophelia) were found. The following species were recorded from Antarctica in the present study: Ophelia algida n. sp., Ophelina breviata (Ehlers, 1913), Ophelina cf. cylindricaudata (sensu Hartmann-Schröder and Rosenfeldt, 1989), Ophelina nematoides (Ehlers, 1913), Ophelina scaphigera (Ehlers, 1900), Ophelina cf. setigera (Hartman, 1978), Ophelina syringopyge (Ehlers, 1901), Travisia antarctica Hartman, 1967 (emended 1978), Travisia kerguelensis McIntosh, 1885, Travisia kerguelensis gravieri Monro, 1930, Travisia palmeri n. sp. and Travisia tincta n. sp. The new species of Ophelia is distinguished by having branchiae starting on chaetiger 2 (rather than on or after chaetiger 8 as in most species of this genus). Travisia palmeri has 22 chaetigers and is distinguished by long branchiae. Travisia kerguelensis gravieri is raised to full species status and renamed T. monroi. Travisia tincta n. sp., distinguished by a distinctive Methyl Green staining pattern and long branchiae, is described from off Peru.

Linopherus beibuwanensis sp. n. is described based on six specimens deposited in the Marine Biological Museum of the Chinese Academy of Sciences, Qingdao, collected from the Beibu Gulf (Tokin Gulf ), South China Sea. The new species differs from all other Linopherus species by the shape of prostomium and caruncle. The posterior margin of prostomium is bilobed; the caruncle arises medially and confluently from the posterior margin of the prostomium, joining together with prostomium. A key to distinguish the known species of the genus is provided. [ABSTRACT FROM AUTHOR]

The aim of this paper is to measure metabolic rates of megafauna living in depths greater than 6000 m. Echinoderms, actinarians and a polychaete were captured by remotely operated vehicle (ROV) and inserted into respiration chambers in situ at depths of 4049 m, 7140 m and 8074 m in the region of the Kermadec Trench SW Pacific Ocean. Hadal research has moved into a new frontier as technological improvements now allow for a meticulous investigation of trench ecology in depths greater than 6000 m. The development of an in situ respirometer for use in these studies was deployed in the Kermadec Trench to obtain the first ever rates of basal metabolic rates of hadal megafauna. Typical deep-sea experiments of individual animal physiology must deal with covarying factors of pressure, temperature, light and food supply in this study investigated the effects of pressure and increased food supply on overall animal metabolism. In the Kermadec Trench, holothurian respiration rates (n=4), 0.079±0.011 (mean±SE) µmol-O 2 g −1 h −1 , were higher than those captured at abyssal depths (n=2), 0.018±0.002 µmol-O 2 g -1 h −1 , in the same region (p<0.001). When Q 10 adjusted to a common temperature of 2.5 °C trench holothurian respiration rates ranged between 0.068 and 0.119 µmol-O 2 g −1 h −1 . Anemone respiration rates were remarkably similar between abyssal and hadal specimens, 0.110 and 0.111 µmol-O 2 g −1 h −1 , respectively. Our results on echinoderm respiration when corrected for temperature and mass fall below the slope regression when compared with other in situ measurements at shallower ocean depths. [ABSTRACT FROM AUTHOR]

The polychaete Hediste diversicolor has a high physiological tolerance to extreme environmental factors, being easily farmed and reproduced in different types of conditions. Both in the field and under laboratory conditions, this worm can feed on different types of food. In order to highlight the potential of H. diversicolor for aquaculture, specific growth rate (SGR), daily growth rate (DGR), survival rate and fatty acid profile of juvenile worms, fed with three different diets, were assessed. The experiments were conducted using juvenile polychaete from a controlled reproduction with wild adults. H. diversicolor individuals were fed with two commercial diets, seabream dry feed ( Aquagold ) and semi-wet pellets for reared sole ( Moist Sole ), and with a non-processed diet consisting on mackerel's fillets ( Trachurus trachurus ). Juveniles fed with Aquagold had the highest final individual weight (0.89 ± 0.10 g). The SGR was higher in H. diversicolor fed with Aquagold and Moist Sole , (6.49 ± 0.30% d − 1 and 6.54 ± 0.06% d − 1 , respectively. The highest DGR was observed for juveniles fed with Aquagold (0.146 ± 0.02 g d − 1 ). The survival rate of ragworms under different treatments ranged from 96 to 100%. Regarding the protein content, the Moist Sole diet provided the highest percentage of protein in the reared worms (8.87%). Results showed that the total fat content of the diets was reflected in the fat content of the reared worms. The Moist Sole diet treatment had the highest fat content (2.25%) and individuals fed with seabream dry feed showed similar results (2.18%), while the lowest percentage was observed for the mackerel diet (0.85%). According to the fatty acid profile, the major fatty acids found in the juveniles fed with the three different diets were palmitic (C 16:0), with a higher value in the individuals fed with mackerel's fillets. Oleic (C 18:1 n9), eicosapentaenoic (C 20:5 n3), docosahexaenoic (C 22:6 n3) and stearic (C 18:0) acids presented high values in H. diversicolor fed with all the experimental diets. Statement of Relevance The common ragworm Hediste diversicolor is a potential high quality fatty acids source for reared fish and shrimp. Previous studies suggested that diet could be a relevant factor affecting the fatty acid composition of this polychaete (Luis and Passos, 1995). This study aimed to assess the effect of different diets on growth and survival of common ragworms juveniles ( H. diversicolor ), as well as the fatty acid profile and protein content in their tissues, aiming to find an appropriate diet to be used in commercial aquaculture. [ABSTRACT FROM AUTHOR]

Capitella capitata was traditionally used as a biological indicator species due to its ubiquitous distribution and high densities in disturbed and polluted marine and estuarine sediments. Based on allozyme and developmental studies, it is now clear that C. capitata is a species complex consisting of multiple distinct lineages worldwide, including the recently described C. teleta, a model species for spiralian development. The coast of the northern Gulf of Mexico, with its numerous bays and estuaries and frequently occurring natural and anthropogenic disturbances, provides an appropriate region for such studies. We sequenced a fragment of the mitochondrial cytochrome c oxidase subunit I gene for individuals of C. cf. capitata and C. cf. aciculata (distinguished by acicular spines on the first two chaetigers) collected from Texas and Florida coasts and analyzed them in conjunction with data available in GenBank. Our results indicate the presence of a Gulf of Mexico clade that is distinct from populations in Canada and the Indo-Pacific. Populations in the northern Gulf of Mexico are structured geographically, with support for Texas and Florida clades, and there do not seem to be clear boundaries between C. cf. capitata and C. cf. aciculata. This is corroborated by the fact that multiple specimens were morphologically intermediate between the two species. In future studies, we aim to clarify whether the intermediate morphologies represent ontogenetic stages, neutral morphological variation, phenotypic plasticity, or sexual dimorphism in a single species or whether several lineages with incomplete reproductive barriers are present. [ABSTRACT FROM AUTHOR]

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A new species of polychaete, Armandia sampadae was collected from shallow sandy sediments off Rutland Island (57 m depth) and off North Andaman (52 m depth) during a benthic survey along the continental shelf of Andaman and Nicobar Islands. The major character which distinguishes this species from other members of the genus Armandia is the presence of a pair of large, flattened, rounded, stalked, pigmented, leaf-shaped ventral papillae at the ventral base of the ringed anal funnel and the occurrence of a pair of sub-triangular black pigmented spots in the basal portion of the ventral papillae. [ABSTRACT FROM PUBLISHER]

This study aimed to evaluate the possible remedial effects of three marine benthic annelids on organically polluted sediments from the waters of Hatsukaichi Marina, Hiroshima, Japan. Two polychaetes, Perinereis nuntia and Capitella cf. teleta , and an oligochaete, Thalassodrilides sp., were incubated in sediments for 50 days. Their effects on physicochemical properties such as organic matter (loss on ignition), redox potential (Eh), acid volatile sulfides (AVS), and degradation of polycyclic aromatic hydrocarbons (PAHs) were assessed. The polychaetes P. nuntia and C. cf. teleta significantly increased Eh level and decreased AVS level compared with the oligochaete Thalassodrilides sp. and control (without benthic organisms). Total PAH concentration significantly decreased from the initial level with all three groups; Thalassodrilides sp. had a marked ability to reduce PAHs in sediment. These results indicate that benthic organisms have species-specific remediation properties and ecological functions in organically polluted sediments. [ABSTRACT FROM AUTHOR]

Several authors identified polychaetes as a group of marine invertebrates that respond rapidly to anthropogenic stressors. Furthermore, several studies have demonstrated that environmental pollution lead to the impoverishment of benthic communities with species replacement and biodiversity loss, but very few studies have investigated biochemical and physiological alterations that species undergo in response to Arsenic (As) exposure. Therefore, the present study assessed the toxicity induced in the polychaete Diopatra neapolitana after a long-term (28 days) exposure to different As concentrations (0.0, 0.05, 0.25 and 1.25 mg/L). For this biochemical and physiological alterations were evaluated. Biochemical analysis included the measurement of different biomarkers such as glutathione S-transferase (GST), lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and oxidized glutathione (GSSG) were assessed in order to evaluate oxidative stress. Physiological analyzes included the observation of polychaetes regenerative capacity and the quantification of organisms total protein (PROT) and glycogen (GLY) content. The results obtained allowed to confirm the suitability of these biomarkers to identify the toxicity caused by As and moreover revealed that D. neapolitana is a good bioindicator of As pollution. [ABSTRACT FROM AUTHOR]

Recent offshore petroleum exploration has increased the risks of oil spills worldwide. We investigated biomarker responses to diesel oil exposure in two tropical and subtropical species, the clam Anomalocardia flexuosa and the polychaete Laeonereis culveri. Animals were exposed to oil-spiked sediment at two different concentrations (0.5 L and 1.0 L m). Activities of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx); glutathione transferase (GST); and lipid peroxides (LPO) were assessed in bivalve digestive glands and polychaete whole-body homogenates at 36 and 60 h of exposure. Significant variation in enzymatic antioxidant activity depended on the sampling time after exposure. No similar response patterns, either increases or decreases, were detected for the two target species, and biomarker responses were species-specific. L. culveri showed clearer patterns in its antioxidant response and should be prioritized over other species in biomonitoring studies involving oil exposure. Understanding the temporal variability of these biomarkers is a necessary action before implementing them as indicators measures in oil contamination biomonitoring programs. Our results provide a better understanding of biomarker responses in subtropical species, evidencing their potential use as sentinels of oil contamination. [ABSTRACT FROM AUTHOR]

We examined diet of nonbreeding Semipalmated Plovers ( Charadrius semipalmatus Bonaparte, 1825) in the Cumberland Island estuary, Georgia, USA, through fecal sample analysis. We also examined prey size selectivity by Semipalmated Plovers for the most common prey item found in the fecal samples, which are polychaetes in the family Nereidae (= Nereididae). We compared the size distribution of polychaetes in Semipalmated Plover fecal samples from salt marshes and mudflats with the size distribution of polychaetes sampled from the two habitats. Semipalmated Plovers foraging on mudflats had less variable diets than those foraging on salt marshes, although the mean number of prey per Semipalmated Plover fecal sample was similar between the two habitats. Size selectivity by Semipalmated Plovers of nereid (= nereidid) polychaetes varied as a function of habitat, with Semipalmated Plovers eating larger polychaetes in salt marshes than in mudflats, although in both habitats Semipalmated Plovers avoided extremely small and (or) large ones. Semipalmated Plovers took fewer of the available prey groups and were more selective in sizes of the dominant prey group on mudflats, where prey densities were the highest. These observations are consistent with predictions from optimal foraging theory. [ABSTRACT FROM AUTHOR]

Freshwater polychaetes are relatively rare and little-studied members of the benthos of lakes and rivers. We studied one polychaete species ( Manayunkia speciosa) in Lake Erie near the mouth of the Detroit River. Abundances at one site were determined between 1961 and 2013 and life‐history characteristics at two sites were determined seasonally (March–November) in 2009–2010 and 2012–2013. Life‐history characteristics included abundances, length‐frequency distributions, presence/absence of constructed tubes, sexual maturity, and number and maturation of young-of-the-year (YOY) in tubes. Long-term abundances decreased in successive time periods between 1961 and 2003 (mean range = 57,570 to 2583/m 2 ) but few changes occurred between 2003 and 2013 (mean = 5007/m 2 ; range/y = 2355–8216/m 2 ). Seasonal abundances varied substantially between sites and years, but overall, abundances were low in March–April, high in May–August, and low in September–November. Although reproduction was continuous throughout warmer months, en masse recruitment, as revealed by length–frequency distributions, occurred in a brief period late‐June to mid-July, and possibly in early-September. All life-history characteristics, including tube construction, were dependent on water temperatures (> 5 °C in spring and < 15 °C in fall). These results generally agree with and complement laboratory studies of M. speciosa in the Pacific Northwest where M. speciosa hosts parasites that cause substantial fish mortalities. Although abundance of M. speciosa near the mouth of the Detroit River was 33-fold lower in 2013 than it was in 1961, this population has persisted for five decades and, therefore, has the potential to harbor parasites that may cause fish mortalities in the Great Lakes. [ABSTRACT FROM AUTHOR]

Members of Calamyzinae, a clade of free-living and ectoparasitic chrysopetalids, are mainly associated with deep-sea chemosynthetic environments. The three currently known free-living calamyzin species are placed in Vigtorniella. A new free-living calamyzin species similar to these is described here. Phylogenetic analyses of Calamyzinae using mitochondrial (cytochrome c oxidase subunit I and 16S rDNA) and nuclear ( Histone H3 and 18S rDNA) loci showed that Vigtorniella and the new species form a grade with respect to an ectoparasitic clade, requiring two new genera to be erected. All free-living calamyzins show a similar anterior end and chaetal morphology. Micospina auribohnorum gen. et sp. nov. is described for the small-bodied new species from deep-sea whale falls off California and methane seeps off Costa Rica. The maximum-likelihood and Bayesian analyses show Micospina gen. nov. as sister to the ectoparasitic clade. Boudemos gen. nov. is named for the clade of two larger-bodied species: Boudemos flokati gen. et comb. nov. and Boudemos ardabilia gen. et comb. nov., which is sister group to all other Calamyzinae. Vigtorniella is retained for the type species, Vigtorniella zaikai (Kiseleva, 1992), with the adults found amongst bacterial mats at the boundary of the hydrogen sulphide zone in the Black Sea. Micospina gen. nov., Boudemos gen. nov., and Vigtorniella form a grade of free-living taxa that is associated with feeding on organic-enriched sediments, and the latter two taxa display ontogenetic jaw change. Jaws are absent in Micospina auribohnorum gen. et sp. nov. and most of the calamyzin clade of parasitic forms. [ABSTRACT FROM AUTHOR]

Polychaete annelids (segmented worms) dominated the macrobenthos in sediments located 6–9 km from the Deep Water Horizon (DWH) Oil Spill site five months after the event, based on nine 0.2 m 2 box core samples. Numbers of species, abundance, and biodiversity indices in the polychaete taxa were significantly lower than pre-spill values from similar depths in the eastern Gulf of Mexico (GoM). Both non-selective and selective deposit feeders were the most frequent feeding guilds, as expected, but their abundances were significantly lower. An increase in the number of carnivorous Sigalionidae may be a response to an accumulation of petroleum hydrocarbons on the sediment. The concentration of oil in the sediments was low and the source of the oil remains equivocal. Multivariate analyses illustrated the differences between communities near the DWH and those from prior studies in similar deep GoM habitats. In summary, Deep Water Horizon Oil Spill appears to have had a measurable impact on the polychaetes. [ABSTRACT FROM AUTHOR]

Twenty-one immature Kemp's ridley sea turtles ( Lepidochelys kempii) were collected following incidental capture or entanglement in recreational hook-and-line gear during 2005-2008 in Galveston County, Texas, United States. Turtles consumed primarily swimming crabs (common blue crab, Callinectes sapidus, and Callinectes spp.), walking crabs (calico box crab, Hepatus epheliticus; mottled purse crab, Persephona mediterranea; and hermit crabs), and polychaete worm tubes. Macroalgae ( Sargassum spp.) was also consumed by nearly half of the sampled turtles, presumably incidentally and likely as benthic detritus. The upper Texas coast and local fishing piers provide diverse foraging opportunities for immature Kemp's ridleys but also put the species at risk for interactions with human activities, including gear interactions and ingestion of anthropogenic debris. [ABSTRACT FROM AUTHOR]

Diplocirrus nicolaji is a flabelligerid worm originally described from shallow waters of Peter the Great Bay, Sea of Japan. Later, this species was also recorded from Japan, but detailed data were not provided; thus the occurrence of D. nicolaji in Japan needs to be confirmed based upon additional material. The collection of 20 D. nicolaji individuals from four localities along Japanese coasts (the Sea of Japan and western Pacific Ocean), allowed us to provide detailed morphological observations using stereoscopic and scanning electron microscopy. Partial cytochrome c oxidase subunit I sequences were obtained for phylogenetic analysis. Although the morphological analysis detected a few variations in palp length and body colour in ethanol among the local populations, the phylogenetic analysis confirmed their conspecificity with little genetic divergence. This is the first report of D. nicolaji from the western Pacific Ocean and extends its distribution southward. [ABSTRACT FROM AUTHOR]

Bioremediation is a promising method for remediating environmentally polluted water. We investigated the abilities of two benthic annelid species to biotransform 1-nitronaphthalene, a nitrated polycyclic aromatic hydrocarbon. We used an oligochaete, Thalassodrilides sp. (Naididae), collected from the sediment beneath a fish farm and a polychaete, Perinereis nuntia , which was obtained from a commercial source. Populations of both organisms were exposed to 1400 μg L −1 of 1-nitronaphthalene in seawater for 3 days in the dark at 20 °C. The concentration of the pollutant decreased to 12 μg L −1 in the seawater containing the Thalassodrilides sp. and to 560 μg L −1 in the seawater containing P. nuntia . The 1-nitronaphthalene concentration in the bodies of the animals increased from 12 to 94 μg kg −1 in Thalassodrilides sp. and from 0.90 μg kg −1 to 38,000 μg kg −1 in P. nuntia . After 3 days, 99% and 40% of the 1-nitronaphthalene had been biotransformed in the Thalassodrilides sp. and P. nuntia experimental groups, respectively. We then tested the acute toxicity of residual 1-nitronaphthalene from the same water using mummichog (fish) larvae. After the larvae had been exposed for 96 h, the percentage of apparently unaffected larvae remaining was 83.3% in Thalassodrilides sp. group but only 16.7% in the P. nuntia group. Clearly, of the two species we studied, Thalassodrilides sp. had a superior ability to convert 1-nitronaphthalene into substances that were nontoxic to mummichog larvae. Therefore, we recommend the use of this species for bioremediation of chemically polluted sediments. [ABSTRACT FROM AUTHOR]

Fish blood flukes (Aporocotylidae) are important pathogens of farmed finfish around the world. Among them, Cardicola spp. infecting farmed tuna are considered to be serious threats to tuna farming and have received tremendous attention. We conducted periodical samplings at a tuna farming site in Japan between January and May, 2015 to determine the life cycle of Cardicola spp. We collected over 4700 terebellid polychaetes from ropes, floats and frames of tuna culture cages and found nearly 400 infected worms. Sporocysts and cercariae found in Nicolea gracilibranchis were genetically identified as Cardicola orientalis by 28S and ITS2 ribosomal DNA sequences. This was the first discovery of the intermediate host for this parasite species. Infection prevalence and the abundance of N. gracilibranchis significantly varied between sampling points and the highest number of infected terebellids were collected from ropes. We also demonstrated morphologically and molecularly that asexual stages found in a single Amphitrite sp. (Terebellidae) and adult worms isolated from farmed juvenile tuna were Cardicola forsteri . This is the first report of C. forsteri in Pacific bluefin tuna (PBT) Thunnus orientalis in Japan. Our results demonstrated that all three species of Cardicola orientalis , C. forsteri and Cardicola opisthorchis exist in Japanese farmed PBTs and that they all use terebellid polychaetes as the intermediate hosts. [ABSTRACT FROM AUTHOR]

Forecasting the impacts of changes in water quality on broadcast spawning aquatic organisms is a key aspect of environmental monitoring. Rapid assays of reproductive potential are central to this monitoring, and there is a need to develop a variety of methods to identify responses. Here, we report a proof-of-concept study that assesses whether quantification of “Sperm Accumulated Against Surface” (SAAS) of tissue culture well-plates could be a rapid and simple proxy measure of fertilisation success. Our results confirm that motile sperm (but not immotile sperm) actively accumulate at surfaces and that the pattern of accumulation reflects fertilisation success in the model oyster species Crassostrea gigas . Furthermore, we confirm these patterns of SAAS for another marine species, the polychaete Galeolaria caespitosa , as well as for a freshwater species, the fish Gasterosteus aculeatus . For all species considered, SAAS reflected changes in sperm performance caused by experimentally manipulated differences in water quality (here, salinity). These findings indicate that SAAS could be applied easily to a range of species when examining the effects of water quality. Measurement of SAAS could, therefore, form the basis of a rapid and reliable assay for bioassessments of broadcast spawning aquatic organisms. [ABSTRACT FROM AUTHOR]

The Ctenodrilidae is a species-poor family of the Annelida with an often debated affiliation, ranging from constituting a distinct annelid order to being part of the Cirratulidae. Furthermore, relationships of the included genera and species are not resolved. Ctenodrilus serratus, by far the most common member of this taxon, appears to have a worldwide distribution. As molecular data are lacking for most reports, it is unknown if this species is cosmopolitan, or a complex of potentially cryptic species. Here we describe the first discovery of C. cf. serratus from Kleinzee oyster farms (South Africa). Besides morphological characterization, we analyzed the CO1 sequence in comparison to C. serratus from Helgoland (Germany, North Sea). Additionally, we included several cirratulid sequences with a special focus on Dodecaceria and another ctenodrilid, Raricirrus beryli, to illuminate the relationship of C. serratus and the Ctenodrilidae in general. Our findings support the idea that both investigated ctenodrilids represent progenetic members of the Cirratulidae but do not support monophyly of the former Ctenodrilidae. Whereas C. serratus is closely related to Dodecaceria (or possibly nested within), R. beryli is recovered as a sister taxon to the multi-tentaculated cirratulid genera Cirratulus, Cirriformia and Timarete. Finally, the similarity of C. serratus to larvae of D. concharum is discussed, supporting the hypothesis of progenetic evolution. [ABSTRACT FROM AUTHOR]

The serpulid annelid Ficopomatus enigmaticus is found as a non-indigenous species in many subtropical and temperate habitats, where it often has major effects on the physical structure and community ecology of invaded habitats. In the northeastern Pacific, it has been present in northern California since about 1920, but clearly established populations have not previously been reported from southern California. We describe a large population of F. enigmaticus in the intertidal zone of the Los Angeles River, near Long Beach, California, and a much smaller population in the nearby Port of Los Angeles. Both reproductive adults and new recruits were common in the Los Angeles River population, suggesting that it is well established. We also describe previously unpublished observations of two additional populations in isolated lagoons in Santa Barbara County. Broader surveys aimed at establishing the distribution of this serpulid in central and southern California are needed to evaluate hypotheses on its pathway and timing of introduction to southern California, to evaluate risks of intraregional spread, and to begin to explore management strategies. [ABSTRACT FROM AUTHOR]