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In recent years, population outbreaks of the annelid Hermodice carunculata (Polychaeta, Amphinomidae) are recurrently detected along the coastal zone of the Salento peninsula (Southern Italy), with impacts on marine benthic ecosystems. Annelida are renowned for their remarkable regeneration potential, enabling them to reform lost body parts. A handful of studies have reported posterior regeneration of H. carunculata, but anterior regeneration has not been fully explored. In this study, we investigated the capacity of H. carunculata collected in shallow coastal areas (Ionian Sea, 40°08'26.9" N 17°58'44.1" E) to regenerate anterior body parts under different temperature conditions (22 and 14 °C) and considering two different body sizes (∼ 4 g and 25 g). In addition, histological analysis and lipid analyses were carried out to detect changes in the reproductive cycle and lipid storage during ongoing regeneration. The results suggest that small and large-sized specimens of H. carunculata can regenerate efficiently anterior body parts in 12–20 weeks post amputation when kept at 22 °C. Small-sized worms kept at 14 °C regenerated slower but died in 24 weeks post amputation before regenerating a mouth, while large-sized worms kept at 14 °C were affected by a 100% mortality during blastema formation. In addition, lipid extraction analyses show that H. carunculata can regenerate during extended periods of starvation by de novo synthesizing lipid reserves and regeneration in H. carunculata does not negatively impact the reproductive cycle, as gametogenesis occurs also during the regenerative processes. [ABSTRACT FROM AUTHOR]

Tylorrhynchus osawai, nereidid polychaete that is considered to support estuarine biodiversity, undergoes a unique epitokous metamorphosis for reproductive swarming. The reproductive swarming of this species has been observed in Japan for more than 100 years; however, the benthic phase of this species has not been well researched. In this study, we aimed to elucidate the morphological allometry and life history, specifically the reproductive swarming, of this species. To accomplish this, surveys were conducted to collect atokes and epitokes from a tidal river in Kyushu, Japan. A total of 1670 T. osawai specimens were collected and preserved in 80% ethanol. The body widths of these specimens were measured, while several intact specimens underwent additional measurements of body length and the number of chaetigers. The morphological allometry of this species differed between atokous and epitokous forms, indicating that its heteronereis form might be suitable for migration from a tidal river to the ocean. The survey results pertaining to the benthic phase of this species indicated that its lifespan was approximately one year or longer. In addition, the settlement, growth, and maturity of this species exhibited a degree of plasticity, potentially influenced by habitat landscapes and sediment conditions. Based on the surveys conducted on reproductive swarming, climate change could have caused the peak of reproductive swarming to shift slightly later than that of several historical observations. Our findings contribute to elucidating the ecological significance of epitokous metamorphosis in nereidid polychaetes and to conserving T. osawai populations. [ABSTRACT FROM AUTHOR]

The fatty acid (FA) composition of spionids co-occurring in shallow water and occupying various habitats was analyzed to characterize spectrum and diversity of their food sources and elucidate their feeding habits and trophic relationships. These included free-living and tube-dwelling species, and also opportunistic and specialized shell-borers and their hosts. A plot of principal component analysis (PCA) scores based on the FA compositions of nine spionid species recognized five distinct groups with different feeding strategies and revealed differences not only between the species, but also within the same species from various habitats. The predominance of 20:5n-3, C16 polyunsaturated FAs, and 16:1n-7 in suspension feeders indicated that they feed on diatoms. Benthic dinoflagellates and diatoms, as well as bacteria, constituted a major part in the diet of deposit feeders. On the basis of high 22:6n-3 and 18:1n-9 contents, Dipolydora commensalis was attributed to omnivorous with a predominance of animal dietary input. The selective detritivore Polydora glycymerica relies on a microbial food web. FAs of Laonice aff. cirrata indicated the importance of foraminifera in the diet of this subsurface feeder. Polychaetes were found to have a capability of changing their feeding habits depending on habitat. Specialized shell-borers adapt their feeding habits to the host's diet. The results obtained provide evidence that these species actually represent several non-overlapping groups characterized by different feeding strategies, which leads to weakening of their competitive relationships. Partitioning of food sources is regarded as one of the main mechanisms explaining the successful coexistence of spionid species. [ABSTRACT FROM AUTHOR]

Polychaetes belonging to the genus Capitella are known to represent a complex of opportunistic cryptic species that dominates the macrobenthos of organically enriched sediments, such as muddy areas particularly rich in sulfide. With the exception of the species, Capitella capitata (Fabricius) from West Greenland, Capitella spp. from the European Atlantic coast have never been accurately characterized both genetically and morphologically and were often reported as capitata in the literature. The life cycle of these European worms has not been described properly either, despite their widespread use as bio-indicators in ecological studies. The present study provides the first morphological description of Capitella specimens collected along the Brittany coast and the English Channel up to the entrance of the North Sea and their genetic diversification in this region. Both morphological and molecular data are congruent and support the co-occurrence of cryptic species at the tip of Brittany. The most frequent French mt lineages, C-Channel1, C-Atlantic and C-Channel2, although well distinct from Capitella teleta, are also divergent but closer to C. capitata initially described from Greenland. Following barcoding, the most abundant species (C-Channel1) was isolated and reared in the laboratory to describe its life cycle and predict both its dispersal ability and ecological success in the face of the sulfidic muddy habitats of the French harbors. [ABSTRACT FROM AUTHOR]

Polychaete worms are rich sources of polyunsaturated fatty acids (PUFA) and are increasingly incorporated into aquaculture broodstock diets. Conventionally, the build-up of PUFA in polychaetes was considered passive, with direct accumulation along the food web, originating with microalgae and other primary producers. However, it has been argued that polychaetes (and other multicellular eukaryotes) are capable of PUFA biosynthesis through the elongation and desaturation of precursor lipids. We further test this hypothesis in the ecologically and economically important nereid polychaete Alitta virens by adopting a stable isotope labelling approach. Worms were fed a 13C-1-palmitic acid (C16:0) enriched diet with the resulting isotopically enriched lipid products identified over a 7-day period. The data showed strong evidence of lipid elongation and desaturation, but with a high rate of PUFA turnover. A putative biosynthetic pathway is proposed, terminating with docosahexaenoic acid (DHA) via arachidonic (AA) and eicosapentaenoic acids (EPA) and involving a Δ8 desaturase. [ABSTRACT FROM AUTHOR]

Species distributions have been profoundly affected by past climate change, and are expected to change considerably in response to future environmental change. To better apprehend how future climate change is likely to affect genetic diversity in marine populations, it is essential to first evaluate the processes that have shaped the current distribution of genetic diversity in the sea. The honeycomb worm is a reef-building polychaete that hosts high biodiversity. Here we show that the genetic diversity in populations of S. alveolata is highest towards the edges of the current species range and lowest at its center. Pleistocene glacial cycles likely led to extirpations of S. alveolata from central populations in the Bay of Biscay, with coalescent-based estimates of post-glacial colonization dating to the beginning of the Holocene interglacial, from 10,000 to 14,000 years ago. Meanwhile, populations in the Irish Sea and English Channel likely persisted in glacial refugia since the Eemian interglacial, 120,000 years ago. Northern populations host at least two sets of divergent haplotypes, indicating that two refugia possibly existed in the north, with Ireland being a likely second refugium. Within biogeographic regions, populations were overall well-connected, but strong genetic differentiation suggests that little exchange occurs between regions. These two unexpected reservoirs of genetic diversity at the range edges deserve greater attention as warming temperatures threaten trailing edge populations, while greater climatic variability threatens leading edge populations. [ABSTRACT FROM AUTHOR]

Although destabilization and stabilization of soft sediments by macro-infauna are regarded as key to understanding benthic community dynamics, how component populations are affected concurrently by both agents was poorly investigated. On an intertidal sandflat, Kyushu, Japan during 1979 − 2014 (previous study) and 2015 − 2019, monitoring was made of the populations of the filter-feeding gastropod, Umbonium moniliferum, the burrow-dwelling ghost shrimp, Neotrypaea harmandi (destabilizer), and the tube-building polychaete, Mesochaetopterus minitus (stabilizer). Results revealed that gastropod population changes were driven by an interplay of shrimp, polychaete, and the stingray, Hemitrygon akajei, foraging for shrimp by sediment excavation. The gastropod went through high abundance (1100 m−2) in 1979, extinction during 1986 − 1997, two marked recoveries with peaks in 2001 and 2009, a slight recovery in 2016, and near extinction in 2019. These changes largely followed the fluctuation in shrimp density across a threshold of 160 m−2 inhibiting gastropod recruitment. The polychaete exhibited intermittent outbreaks with peaks in 2000, 2007, and 2016, with maximum densities of 15,000 − 24,000 m−2. Sandflat topography and sedimentary variables were measured during 2015 − 2017. Sediment stabilization by polychaete aggregations at the mid-tidal zone is suggested to have boosted gastropod recruitment. Release at sea and retrieval on shore of drift cards mimicking gastropod larvae with 3- to 9-day planktonic duration was conducted in 2008 − 2009 to specify source populations sending larvae to the present population. Potential source populations were censused in 1998 and 2017 − 2018. Their recent virtual extinction appears responsible for the present population's decline from 2011. This raises the need for metapopulation perspective to understand local dynamics. [ABSTRACT FROM AUTHOR]

Pelagic biofoulers such as barnacles or bryozoans settle and raft on natural debris like pumice or seeds. Recent influxes of marine debris into the world's oceans, especially plastic, have increased habitat availability for these biofoulers. Goose barnacles in the genus Lepas are some of the most common biofouling taxa globally, and play an important role in biofouling communities as foundation species. We examined community succession, growth rates and isotopic composition in Lepas and their associated biofouling communities in coastal waters of eastern Australia. Community succession on a fixed surface mooring showed an increase in species diversity over 25 weeks. Using the abundances of L. anserifera, L. anatifera, and the amphipods Caprella danilevskii and Jassa slatteryi, we created an equation to estimate minimum duration at sea. Predators such as the polychaete Amphinome rostrata may influence the biofouling community, as can beach scavengers once floating debris is cast ashore. We report a new maximum growth rate for L. anserifera of 1.45 mm−1, and our study is the first to report growth rates for any species of Lepas faster than 1 mm day−1. Lepas were larger on moored floats than on smaller, free-floating drifters. δ18O content of Lepas shells was a robust predictor of sea surface temperatures during formation for L. anatifera and L. anserifera. Our findings have important applications for estimating drift duration and trajectories of marine debris. [ABSTRACT FROM AUTHOR]

Stable isotopes are widely used to better understand dietary contributions and trophic interactions in benthic ecosystems. However, the traditional δC-δN bi-plots can only depict food-web structure for a single time period or space location. Various statistical approaches have now been developed to identify food-web changes in temporal or spatial scale. In the present study, three community-level statistical methods, including circular statistics, Layman et al.'s metrics and Bayesian Ellipses, were applied to compare natural abundance stable carbon and nitrogen isotope data from primary producers, meiofauna (nematodes and copepods), and macrofauna (polychaetes) in an intertidal area between summer and winter. Bayesian mixing model was also used to determine the food source contributions of consumers. In summer, data suggested that benthic microalgae were a dominant food source for most consumers, except for nematode Spilophorella sp. which mainly relied on seagrass detritus. While in winter, there was a significant increase in reliance on seagrass-based carbon for the consumers. The trophic positions of polychaete Eunice sp. and nematode Ditlevsenella sp. also differed between summer and winter, suggesting that they could change their feeding habits and behaviour according to time and availability of food. Using community-based statistics to quantitatively analyze stable isotope data can thus elucidate changes in food-web structure. In addition, considerable variations in food source utilization and trophic level for the same genus or species may imply that the feeding ecology of benthic infauna should be interpreted with caution and cannot be relied on buccal morphology alone. [ABSTRACT FROM AUTHOR]

High pCO environments, such as volcanic carbon dioxide (CO) vents, which mimic predicted near-future scenarios of ocean acidification (OA), offer an opportunity to examine effects of low pH conditions on marine biodiversity and adaptation/acclimatization of marine organisms to such conditions. Based on previous field studies in these systems, it is predicted that the stress owing to increasing CO concentrations favours the colonization by invertebrate species with a brooding habit. The goal of this study was to investigate the relative occurrence of the two sibling species Platynereis dumerilii (Audouin & Milne-Edwards, 1834) (free spawner) and Platynereis massiliensis (Moquin-Tandon, 1869) (egg brooder) in two shallow CO vents off Ischia and Vulcano islands (Italy, Tyrrhenian Sea), and in various areas with ambient pH conditions, where they represent one of the dominant genera. Phylogeographic analyses were integrated with reproductive biology and life-history observations on some selected populations thriving in the vent areas. This approach revealed the presence of four distinct Platynereis clades. Whereas two clades primarily inhabit CO vents and are presumably all brooders, the other two clades dominate the non-acidified sites and appear to be epitokous free spawners. We postulate that one of the brooding, vent-inhabiting clades represents P. massiliensis and one of the free spawning, non-vent-inhabiting clades represents P. dumerilii, although confirmation of the species status with sequence data from the respective-type localities would be desirable. [ABSTRACT FROM AUTHOR]

Ocean acidification is predicted to have negative effects on marine biota, resulting in the loss of biodiversity and changes in marine ecosystem structure and function. However, some species and life stages may be capable of thriving in low pH conditions, either due to their natural ability to tolerate stressful low pH-high pCO conditions and/or alteration of species interactions caused by changes in pH profiles, or due to evolutionary trade-offs. A better understanding of which species may be capable of tolerating ocean acidification can guide future research into the mechanisms for physiological and ecological resilience to future carbon dioxide (CO) conditions. We investigated the colonization of selected polychaete species along a pH gradient originating from shallow, coastal volcanic CO vents (Ischia, Italy). Colonization was quantified by exposing artificial invertebrate collectors attached to the substratum for 30 days during different periods of the year (late spring, fall and late winter). Three species, Amphiglena mediterranea, Platynereis dumerilii and Syllis prolifera, were present and abundant along the gradient throughout the year. All three species were significantly more abundant in the most acidified areas, confirming their high tolerance and capacity to cope with very low pH. Abundances of all three species were compared to data previously collected via collectors suspended in the water column. More individuals were found in the collectors attached to the substratum, suggesting that abundances may have previously been underestimated. This is likely due to the close proximity of these collectors with the natural rocky substratum. All three species exhibited similar temporal variability, consistent with their life cycle and reproductive biology. Our results demonstrate high tolerance of the species for low and variable pH and corroborate their use as robust models to explore the capacity to cope with low pH-high pCO conditions, both in the natural vent systems and in the laboratory. [ABSTRACT FROM AUTHOR]

Larvae of many sessile marine invertebrates settle in response to surface microbial communities (biofilms), but the effects of soluble compounds from biofilms in affecting larval behavior prior to settlement, attachment, and metamorphosis have been little studied. This question was addressed by videotaping the behavior of competent larvae of the serpulid, Hydroides elegans, above settlement-inducing biofilms. Adult worms were collected in Pearl Harbor, Hawaii, USA in November 2012 and spawned almost immediately. Six-day old larvae were placed in five replicated treatments in small cups: (1) with a natural biofilm; (2) with a natural biofilm on an 8-µm screen, 1 mm above the bottom of a clean cup; (3) with a natural biofilm beneath a clean screen; (4) in a clean cup; and (5) in a clean cup with a clean screen. Using the videotapes, larval swimming speeds and trajectories were quantified within 5 min of the larvae being placed in a treatment. Only larvae that touched a biofilm, i.e., in treatments (1) and (2), slowed their swimming speed and increased the amount of time spent crawling rather than swimming. This shows that under these conditions, any soluble cues emanating from a biofilm do not affect settlement behavior. Furthermore, after 24 h close to 100 % of larva in the two accessible biofilm treatments had metamorphosed and <15 % in treatments that included a biofilm under a clean screen and no biofilm at all, strongly suggesting that soluble cues for settlement were not produced by the biofilms over the longer time period. [ABSTRACT FROM AUTHOR]

Fatty acid profiles were determined in rocky intertidal suspension-feeders (mussels and polychaetes) and grazers (limpets and sea urchins) on a monthly basis over 1 year to assess potential dietary overlap between consumers occupying the same trophic guild, and any temporal shifts in diets. Both reproductive and non-reproductive tissues were assessed in an attempt to separate influences of food quality with those of life cycle. Relative variability in fatty acids over time could not be predicted from the feeding guild occupied by a consumer, and influential factors of the temporal shifts included both dietary and reproductive dynamics (even in muscle tissues). Species in the same trophic guild occupied separate trophic niches throughout the year, hence minimising competitive interactions regarding food acquisition. Based on overall variation in fatty acid profiles of muscle tissues, the suspension-feeders Perna perna and Gunnarea gaimardi and the grazing limpet Cymbula oculus occupied narrower feeding niches relative to the grazing sea urchin Parechinus angulosus. Our results provide compelling evidence for potentially large changes in the lipid composition of intertidal invertebrate populations over relatively small temporal scales (i.e. month to month), and these have important implications for short-term field collections intended for assessing invertebrate diets. [ABSTRACT FROM AUTHOR]

The importance life history plays in understanding population dynamics and the functional roles of species for predicting climate change scenarios are well established. Yet, in the marine environment, the complete life history is unknown for many species, especially the link between morphologically and ecologically distinct planktonic larvae, and their corresponding benthic adult forms. Integration of meroplankton abundance, benthic adult species, larval morphology, and molecular data was employed to unravel the complete life history of Polygordius, a dominant polychaete in sandy shelf sediments of the Mid-Atlantic Bight. Polygordius species are unusual, having two distinct planktonic larval forms: an exolarva and an endolarva. Extensive sampling in the southern Mid-Atlantic Bight with careful preservation of meroplankton (2006-2007) revealed the identity of multiple stages of exo- and endolarvae, and their spatial, seasonal, and vertical distribution. Molecular and morphological evidence indicated exolarvae are Polygordius jouinae and endolarva are an undescribed species. Structure and development of these larvae differed greatly. P. jouinae exolarvae were found off Delaware Bay to North Carolina. At some stations, they were abundant, with densities up to 4,013 m, comprising >90 % of the total meroplankton. Exolarvae spent up to a month in the plankton starting in March/May depending on year, settlement began in July when larvae were at least 2 mm in length, and by October were no longer observed in the plankton. These findings are consistent with the distribution patterns and life cycle known for adults. This is the first report of endolarvae north of Cape Hatteras. [ABSTRACT FROM AUTHOR]

Females of the polychaete Polydora hoplura (Claparède ) that produced planktotrophic and adelphophagic larvae were compared genetically to determine whether the different reproductive morphs represented sibling species or poecilogony. Worms were collected from Saldanha Bay, South Africa (33°0′37.71S, 17°56′59.74E), and cultured in a laboratory setting from November 2012 to April 2013. The results based on mitochondrial and nuclear DNA ( Cyt b and ATPSα, respectively) showed shared haplotypes between reproductive morphs for both markers. Additionally, variation in mtDNA sequences was significantly higher within morphs than between morphs (95.8 and 4.2 %, respectively). A comparison of developmental modes found that broods of planktotrophic larvae were larger than broods of adelphophagic larvae, while the latter had larger eggs and larvae at hatching. Developmental time from oviposition to settlement for planktotrophic and adelphophagic larvae was 40.2 and 16.6 days, respectively. Polydora hoplura represents the fifth confirmed case of poecilogony in the Spionidae. [ABSTRACT FROM AUTHOR]

Multivariate analysis of fatty acids (FA) profiles proved to be a useful tool for demonstrating feeding preferences of Arctic invertebrates belonging to several taxonomic groups collected during summer and winter seasons in the Spitsbergen fjords (Arctic). Within phytodetrivorous taxa, the enhanced proportions of 16:1n-7, C16 polyunsaturated fatty acids (PUFA) and 20:5n-3 in crustaceans clearly reflected selective ingestion of diatoms, while high amounts of 22:6n-3 and C18 FAs found in molluscs indicated flagellate-based nutrition. High levels of C20 PUFA and 16:1n-7 together with the typical bacterial FAs were found in winter specimens of deposit-feeding polychaetes showing their reliance on highly reworked organic matter during this season. Our results suggest that 18:1n-9 may not be a reliable marker of carnivory feeding within benthic taxa. Lipid signatures of omnivores and carnivores/detrivores usually originated from a variety of dietary sources, of which few possess highly characteristic FA features. Still, elevated levels of Calanus markers (20:1 and 22:1 moieties) characterized species linked to the pelagic food chains, while 20:4n-6 proved to be a useful indicator of foraminiferan consumption. We highlight the need for a multimethod approach, since complexity of benthic food webs along with general lack of unambiguous FA trophic markers prevents tracking of trophic relationships with use of FA analysis alone. Based on their FA composition, we showed that benthic species represent a source of essential PUFA and could play a fundamental role in the Arctic food webs transferring energy derived from variable pelagic and benthic resources to upper trophic levels. [ABSTRACT FROM AUTHOR]

The diet of three cooccurring abundant fish species ( Eucinostomus argenteus, Diapterus rhombeus and Micropogonias furnieri) and its ontogenetic changes in a mudflat area of a tropical bay in southeastern Brazil were described. The working hypothesis is that these three species shift the use of the available resources throughout their growth. Early juveniles of D. rhombeus and M. furnieri fed mainly on Cyclopoida copepods, shifting to Nematoda ( D. rhombeus) and errant Polychaeta ( M. furnieri) as they increased in size. In contrast, the early life stages of E. argenteus fed mainly on errant Polychaeta and Calanoida copepods, with increasing niche breadth as they grew. The relative degree of individual specialisation in resource use indicated specialism for M. furnieri and E. argenteus, and generalism for D. rhombeus. The largest intraspecific overlap was found for the smallest size classes. Niche breadth increased during ontogeny, with a higher average niche breadth at lower prey length/predator length ratios. Therefore, species-specific differences in diet across the resource gradient and increased niche breadth during ontogeny characterised the shifts of resource use, and probably account for the coexistence of these species in zones of sympatry in mudflat areas of southeastern Brazil. [ABSTRACT FROM AUTHOR]

The polychaete Pectinaria koreni exhibits a complex life cycle characterized by non-overlapping generations and widespread larval dispersal. To explore how 'local' metapopulation genetic structure varies spatially and temporally during population turnover, we combined observations on demography, larval dispersal through hydrodynamic modelling and population genetics of successive age cohorts in the Baie de Seine (eastern English Channel, France). Mature adults (March), newly settled (July) and later-stage juveniles (September) were sampled in 2003 on the edge and in the main demes of the metapopulation. Demes displayed an asynchronous dynamics due to variations in habitat quality affecting reproductive timing (e.g. three distinct spawning events observed) and in local larval supply linked to temporal fluctuations of hydrodynamism. Two-source populations were identified among dense areas with the greatest larval retention and self-recruitment rates: one with a single recruitment event, stable temporal genetic variation and a strong spatial genetic re-homogenization during turnover, and the other with two recruitment events and significant allele frequency changes over time. Sink habitats displayed single recruitment event and experienced strong inter-generational (juveniles vs adults) genetic changes due to genetic drift associated with strong winter mortalities. Altogether, results suggested that adult spawning asynchrony and sweepstakes reproductive success, together with genetic drift, played a greater role than hydrodynamics itself in determining effective recruitment rates at some sites and generating genetic patchiness. [ABSTRACT FROM AUTHOR]

The estuarine polychaete, Hediste diadroma (Nereididae), of eastern Asia was found at all six sites sampled in October 2009 in northeast Pacific estuaries, including the Columbia River, along a 300-km stretch of coastline in Washington and Oregon, USA. The immature worms were returned to the laboratory in Japan where 13 of them were cultured to sexual maturity after 5-7 months. These worms had the diagnostic, epitoke-specific spinigers that distinguish H. diadroma from all other Hediste species. Their egg sizes (140-170 μm), paragnath numbers on the proboscis, and chromosome number (2 n = 28) were also consistent with those previously reported for the Japanese population of H. diadroma. The widespread distribution of H. diadroma indicates that it is a successful invader of the North American Pacific and it may have long escaped detection because of its morphological similarity to the native species, H. limnicola. The long pelagic life of H. diadroma larvae could have facilitated its successful trans-ocean dispersal with ballast water of ships. [ABSTRACT FROM AUTHOR]

Three functionally different macrofaunal species (the filter- and/or surface deposit-feeding polychaete Hediste diversicolor, and the suspension-feeding bivalves Mya arenaria and Cerastoderma glaucum) were introduced as single- and two-species treatments into microcosms containing sandy sediment with a natural meiofaunal community. H. diversicolor is a burrowing species building a system of galleries, C. glaucum lives actively near the sediment surface acting as a biodiffuser and M. arenaria buries deeply and leads a sessile lifestyle. It is shown that H. diversicolor extended the vertical distribution of meiofauna into deeper sediment layers compared to the control and non- Hediste treatments. The response of the nematode community varied significantly among treatments and was dependant on the macrobenthic species composition but not on the species number. Nematode assemblages in all treatments with the polychaete, both in monoculture and with either bivalve, differed significantly from those recorded in other treatments and were more similar than replicates within any other single treatment. H. diversicolor also appeared to have stimulated nematode species diversity. The present study demonstrated that the impact of macrobenthic assemblages on meiofauna is not a simple summation of individual species effects but is species specific. [ABSTRACT FROM AUTHOR]

Ocean acidification is not happening in isolation but against a background of chronic low-level pollution for most coastal marine environments. The reproductive and larval stages of marine invertebrates can be highly sensitive to the impacts of both environmental pollutants and ocean acidification, but very little is currently known regarding the potential impacts of combined contaminant and high CO exposures on the health of marine organisms. Ocean acidification research to date has focused heavily on the responses of calcifying marine invertebrate larvae and algae, and as such the polychaetes as a group, despite their ecological importance, remain understudied. Here, we investigate the effects of elevated seawater CO (pH range 8.1-7.4, plus an extreme pH of 7.2 in the sperm motility experiments), in combination with the environmental pollutant copper (0.002 μM), on the early life history stages of the intertidal polychaete Pomatoceros lamarckii from two populations. P. lamarckii sperm appear to be robust to elevated seawater CO. Whilst all three of the sperm motility end points measured showed a response to elevated CO, these responses were small and not linear. The percentage of motile sperm and sperm curvilinear velocity were significantly reduced in the lower pH treatments of 7.4 and 7.2, whereas sperm straight-line velocity (VSL) was mostly unaffected except for an increased VSL at pH 8.0. Fertilisation success was investigated using two populations from the South West (UK), one from Torquay and one from Plymouth Sound. Fertilisation success was slightly but significantly reduced at the 7.6 and 7.4 pH treatments for both populations (a 9.0 % reduction in fertilisation success from pH 8.1 to 7.4 for Torquay), but with a greater effect observed in the population from Plymouth Sound (a 13.33 % reduction in fertilisation success). No additional impact of 0.002 μM copper exposure on fertilisation success was found. Larval survival was found to be much more sensitive to elevated CO than sperm function or fertilisation, and a significant interaction with copper exposure was observed. These results demonstrate the potential for polychaete larvae to be affected by predicted ocean acidification conditions and that chronic coastal pollutants, such as copper, have the potential to alter larval susceptibility to ocean acidification conditions. [ABSTRACT FROM AUTHOR]

Free crawling was an original life style, and the ability to build tubes and bore into shells evolved independently in various annelids and more than once within the family Spionidae. Absence of morphological differences between the shell-boring (SB) and tube-dwelling (TD) spionid worms and the innate ability of borers to build tubes raised a question whether the mode of life is fixed or flexible. Sequence data of three gene fragments of the mitochondrial 16S rDNA and nuclear 18S and 28S rDNA (in total 1,677 bp) have shown that SB and TD individuals of Dipolydora carunculata from the Sea of Japan were genetically identical, whereas those of Polydora triglanda from Taiwan were genetically distant and not conspecific. These data indicate that some species are constrained to a certain mode of life, while others are flexible and individuals can be either SB or TD depending on the place of settlement in the end of their larval development. [ABSTRACT FROM AUTHOR]

Larval settlement of the infaunal spionid polychaetes Polydora cornuta and Streblospio benedicti is mediated by sediment-associated microorganisms. To investigate if larval preference for certain sediment is guided by individual sediment-associated bacteria, 13 bacterial isolates (5 phyla) obtained from the natural habitat of adult polychaetes (Wadden Sea, Germany) in 2008 were screened in still-water, no-choice settlement assays. Two isolates (α- Proteobacterium-Strain DF11 and Flavobacterium-Strain 54) significantly triggered larval settlement in comparison with sterile sediment. In still-water, multiple-choice settlement assays comprising natural and sterile sediment and sediment re-inoculated with isolates DF11 and 54, significant preferences for natural sediment and sediment containing bacterial isolates at 10 cells g were observed. Larval settlement was influenced by bacterial abundance in sediment but the correlation was not strictly positive; thus, maximum larval settlement in response to single bacterial species may occur at certain optimum densities. Non-viable or suspended bacteria and water-soluble bacterial products did not induce larval settlement, suggesting that sediment-associated bacterial settlement cues for P. cornuta and S. benedicti were either produced in situ and/or consisted of heat-labile bacterial products. [ABSTRACT FROM AUTHOR]

The tube-building polychaete Lanice conchilega can form dense populations, often called reefs, which promote benthic community change and constitute feeding grounds for secondary consumers. The aim of this study was to quantify the role of the L. conchilega reef of the Bay of the Mont Saint-Michel (BMSM) for feeding waders, by combining macrobenthos data, bird counts and bird diet information. Wader densities in the reef were on average 46.6 times higher than in non-reef areas. According to faecal analyses, waders in the reef mainly selected the accompanying fauna and especially crustaceans. The attractiveness of the reef to feeding birds may be largely explained by the high abundance, richness and biomass of macrobenthic species in the reef compared with the rest of the BMSM. [ABSTRACT FROM AUTHOR]

Sublethal predation can be a significant trophic pathway in sediment communities, and the regeneration of damaged tissue affects the activity, growth, and reproduction of prey. A field experiment was conducted 12-18 July 2010 in the Tijuana Estuary, California (+32.56617°, −117.13152°), to measure in situ rates of body growth and palp regeneration of the polychaete Polydora cornuta after simulating sublethal predation by removing 2, 1, or 0 palps from labeled individuals. After 3 days in the field, individuals that had 2 palps removed grew significantly slower than worms that had 0 palps removed; 1-palp worms had intermediate growth. After 6 days in the field, rates of body growth were faster than those of worms recovered after 3 days, with similar trends among the three palp treatments. During the 3-day transplantation, removed palps regenerated to half the initial length of unmanipulated palps. After 6 days, palp lengths did not differ significantly among treatment groups, indicating complete regeneration. The regeneration rate of removed palps was significantly faster than the growth rate of undamaged palps, and palp regeneration rate did not differ significantly between worms that had 1 or 2 palps removed. [ABSTRACT FROM AUTHOR]

The spatial scale of life-history and demographic variation was investigated in the opportunistic polychaete Ophryotrocha labronica La Greca and Bacci. Individuals were collected along the Italian coasts from three thermally different biogeographical regions of the Mediterranean Sea. For each region, populations from four harbours were considered, and for each harbour, two sites were examined. Life-history and demographic traits were investigated after one generation under a common garden experiment, and their variation at the three spatial scales was assessed. All the traits showed high variability with regard to site. A number of life-history and all demographic traits also varied according to the biogeographical region. Conversely, no differences were found between harbours, suggesting that geographical isolation did not contribute to phenotypic variation. Results confirmed the central role of local conditions for the evolution of life history in species colonizing heterogeneous environments, but they also pointed to the importance of large-scale factors in shaping the phenotypic responses of O. labronica, demonstrating the need for a multi-scale approach for obtaining a good measure of natural variation in widespread opportunistic species. [ABSTRACT FROM AUTHOR]

Polychaetes constitute most of the benthic macroinvertebrates in estuarine and coastal environments. We investigated the utilization of organic matter in two polychaete species, Capitella sp. I and Perinereis nuntia brevicirris, living in different coastal habitats. The protease activity of Capitella sp. I (89.7 μg mg) was about 10 times that of P. nuntia brevicirris (8.0 μg mg) . High cellulase (endo-β-1,4-glucanase) activity was detected in P. nuntia brevicirris (3.2 μg mg), whereas scarcely any was detected in Capitella sp. I. We isolated cDNA clones of protease mRNA from Capitella sp. I and of cellulase mRNA from P. nuntia brevicirris. The high protease activity of Capitella sp. I enabled it to survive in the sediment under a fish farm, where it degrades organic matter. In contrast, the high cellulase activity of the estuary-dwelling P. nuntia brevicirris allowed it to degrade organic matter originating from terrestrial areas. [ABSTRACT FROM AUTHOR]

Cold seep communities in the Mediterranean Sea have only been discovered two decades ago, and their trophic ecology has been the subject of very few studies. We investigated the benthic food web of two deep chemosynthesis-based ecosystems on the Napoli and Amsterdam mud volcanoes (MVs) in the eastern Mediterranean Sea (~2,000 m depth). Seeping methane has been detected at the surface of both MVs during pioneering cruises and has been hypothesised to be assimilated by benthic fauna as observed in other oceans' margins. Given the extreme oligotrophic character of the eastern Mediterranean Sea, we a priori expected that chemosynthetic food sources, especially methane-derived carbon (MDC), played a major trophic role in these deep seep communities relative to what has been observed in other seep systems worldwide. We aimed at unravelling the trophic relationships on Napoli and Amsterdam MVs through the analysis of carbon, nitrogen and sulphur isotopes both in the dominant benthic invertebrates including the small endofauna (300 μm < size < 1 cm) and in the sedimented organic matter. In particular, we assessed the fraction of MDC in the tissue of several heterotrophic and symbiotic species. Low mean δS and δC values (0.4 ± 4.8‰ and −31.6 ± 5.7‰, respectively) obtained for mega- and macrofauna suggested that the investigated benthic food webs are virtually exclusively fuelled by carbon of chemosynthetic origin. A few grazer invertebrates (δS up to 11‰) depart from this trend and could complement their diet with sedimented and decayed phytoplanktonic organic matter. Faunal δC values indicated that the oxidation of sulphur is likely the predominant energetic pathway for biosynthesis on both MVs. Nevertheless, mytilid bivalves and small capitellid, ampharetid and spionid polychaetes were C-depleted (δC < −37‰) in a way indicating they assimilated a significant portion of MDC. For these later heterotrophic species, MDC ranged between 21 and 31% (lower estimates) and 97 and 100% (upper estimates). However, our results highlighted that the origin of assimilated carbon may be complex for some symbiotic species. The vestimentiferan tubeworm Lamellibrachia sp., which exclusively depends on its sulphur-oxidising endosymbionts, showed a ~20‰ inter-individual δC variability on a very small spatial scale (<1 m) at the summit of Napoli MV. This mostly reflects the variable isotopic composition of pore-water-dissolved inorganic carbon (DIC) and evidenced that tubeworms (and subsequently their endosymbionts) uptake DIC derived from multiple methane oxidation processes in varying proportions. The lower and upper MDC estimates for the vestimentum of Napoli's individuals were 11-38 and 21-73%, respectively. Finally, data on trophic ecology of Napoli and Amsterdam MVs clearly corroborate previous geophysical results evidencing the spatial heterogeneity of Mediterranean MV environmental conditions. [ABSTRACT FROM AUTHOR]

The benthic microbial food web can be responsible for a large proportion of benthic carbon cycling yet there are few data on the trophic interactions between this food web and macrobenthos. A large-scale field experiment was conducted to investigate effects of eliminating the polychaete Arenicola marina on benthic microbes (prokaryotes, heterotrophic and autotrophic protists) and metazoan meiofauna in a marine intertidal flat of the North Sea, Germany. Over a period of 2 years, quantity and composition of micro- and meiobenthos from unmanipulated sites were compared to those from sites deplete of lugworms. These grazer treatments were cross-classified with different sediment characteristics (low- and mid-intertidal areas). Lugworm removal resulted in an initial increase in abundance of prokaryotes and nanoflagellates, which became less pronounced in the second year. Ciliates were not affected quantitatively, but in the absence of lugworms, diversity and the proportion of carnivorous forms increased. Meiobenthos (nematodes, ostracods and copepods) were affected only moderately. The observed changes are probably due to a combination of release from grazing/predation pressure, changes in the species composition of higher trophic levels (namely large polychaetes) and altered environmental conditions (such as depth of the oxygenated layer and sediment grain size). Spatial differences between sites of different tidal exposure/grain size appeared to be as large as temporal differences during the 2 years following the manipulation of the system. We conclude that in intertidal sediments, indirect effects due to habitat transformation are as important as direct biological interactions (grazing pressure and competition) for the dynamics of the benthic microbial food web. [ABSTRACT FROM AUTHOR]

Eurythoe complanata (Pallas 1766) has been considered a cosmopolitan species with a great morphological similarity across its geographic range. To elucidate whether E. complanata is actually a single species, genetic (cytochrome oxidase subunit I and allozymes) and morphological differences were compared among specimens from the Pacific, Caribbean, and South Atlantic Oceans. Large levels of COI divergence (10–22%) and diagnostic allozyme loci identified three cryptic species: one in the eastern Pacific and two in the Atlantic, with one being morphologically differentiated and found only in islands. COI sequences between Pacific and Atlantic lineages were much more divergent than those of other transisthmian invertebrates, indicating their split before the Panama Isthmus closure or a faster evolutionary rate of COI for this species. The existence of two Atlantic species may be a consequence of parapatric speciation followed by a secondary invasion or even a sympatric speciation in the Atlantic oceanic islands. [ABSTRACT FROM AUTHOR]

There are many reported associations between mussels and other invertebrates, such as pea crabs, polychaetes, turbellarians and copepods, which live in their mantle cavities. The boundary between commensalism and parasitism is often indistinguishable because of insufficient knowledge or because the interaction is variable. Preliminary evidence led to a closer examination of the relationship between the mussel, Mytilus edulis platensis, and an isopod, Edotia doellojuradoi, previously described as commensalism. Monthly intertidal samples of mussels were taken from September 2004 to August 2005 at Caleta Cordova Norte (45°43′S, 67°22′W) in southern Argentina and assessed for the prevalence and abundance levels of isopods. Mussels with and without isopods were measured, examined for evidence of gill damage and their condition (soft tissue dry weight) was determined. The overall isopod prevalence in mussels was 57.9% and infestation varied with mussel length, with maximum occurence at 30.2 mm (medium-sized mussels). Experimental evidence indicated that the position of the isopod inside the mussel depended on the feeding activity of the mussel. Female isopods were observed grasping the ventral food groove of the gill demibranchs and feeding on the mucous food strand produced by the mussel. Juveniles and males were observed clustered together on the dorsal side of the single female in each occupied mussel, suggesting extended maternal care. Gill damage was observed in 58.2% of mussels at the Argentine site and was significantly associated with isopod occurrence. Categorical regression analysis showed that the most important factor associated with the degree of gill lesions was the number of male and juvenile isopods per mussel, followed by the length of female isopods and the developmental stage of juveniles. Conversely, the degree of gill damage decreased with increasing mussel length. Overall, E. doellojuradoi had a significant effect on mussel condition throughout the year, with low flesh weight in mussels with isopods, except during the austral summer and early autumn. In contrast to previous studies, which concluded that the isopod was a commensal, the present study clearly demonstrates that E. doellojuradoi is a parasite of M. edulis platensis. Other symbiotic interactions formerly classified as commensal might not be innocuous on further investigation, especially if samples are taken at multiple sites and at different times of the year. [ABSTRACT FROM AUTHOR]

Lamellibrachia luymesi and Seepiophila jonesi are co-occurring species of vestimentiferan tubeworms found at hydrocarbon seepage sites on the upper Louisiana slope of the Gulf of Mexico. Like all vestimentiferans, they rely on internal sulfide-oxidizing symbiotic bacteria for nutrition. These symbionts produce hydrogen ions as a byproduct of sulfide oxidation, which the host tubeworm needs to eliminate to prevent acidosis. The hydrothermal vent tubeworm Riftia pachyptila uses a high activity of P- and V-type H+-ATPases located in its plume epithelium to excrete protons. Unlike R. pachyptila, the seep species grow a posterior root, which they can use in addition to their plumes as a nutrient exchange surface. In this study we measured the ATPase activities of plume and root tissues collected from L. luymesi and S. jonesi, and used a combination of inhibitors to determine the relative activities of P- and V-type H+-ATPases. We found that the total H+-ATPase activity of their plumes was approximately 14 μmol h−1 g−1 wet weight, and that of their roots was between 5 and 7 μmol h−1 g−1 wet weight. These activities were more than ten times lower than those measured in R. pachyptila. We suggest that seep tubeworms might use passive channels to eliminate protons across their roots, in addition to ATP-dependant proton pumps located in their plumes and roots. In addition, we found strong differences between the types of ATPase activities in the plumes of L. luymesi and S. jonesi. While the H+-ATPase activity of L. luymesi plumes is dominated by P-type ATPases, S. jonesi has an unusually high activity of V-type H+-ATPases. We suggest that S. jonesi relies on its high V-type H+-ATPase activity to drive carbon dioxide uptake across its plume surface. L. luymesi, on the other hand, might rely partially on bicarbonate uptake across its root. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the reproductive and gametogenic cycle of the spionid polychaete Scolelepis goodbodyi (Jones). Every 15 days, in the upper level of the intertidal zone on Barequeçaba Beach in southeastern Brazil, a 100 m2 area was delimited and within it three points were selected and sampled using a core sampler 0.01 m2 in area × 0.2 m long. Each sample was divided into three sub-samples: surface (2 cm) and middle (8 cm), which were sieved through 0.5, 0.25 and 0.125 mm mesh sieves; and lower (10 cm), sieved through 1.0 and 0.5 mm mesh sieves. Males, females and undetermined individuals were separated, and the width of the third setiger was measured. The gonadal development of each individual was classified based on external features of the gametogenic setigers. Ten to 20 adults from each sampling period were classified according to their gonadal development stage and then analyzed histologically for gametogenic studies, for comparison with the former classification. Some of the ripe females were used for fecundity evaluation. The diameters of the oocytes were measured prior to spawning. Eight hundred and twenty-eight females (29.70%), 848 males (30.42%) and 1,112 undetermined individuals (39.89%) were analyzed. The sex ratio did not differ significantly from unity (χ2 = 0.24; df = 1 ; P < 0.05). Males and females were more abundant in May 2002 (ca. 80%) and between November 2002 and May 2003 (between 77 and 90%); the proportion of undetermined individuals did not represent recruitment alone, but also a high incidence of adults with recovering gonads. Fecundity varied from 134 oocytes in a 0.54 mm W3 individual to 289 oocytes in a 0.4 mm W3 individual, with a mean of 220 (SD = 57) oocytes per female and 19 (SD = 5) oocytes per gametogenic setiger. Oocytes were ellipsoid, and ranged in size from 150 × 80 (to 220 × 120 μm (mean ± SD = 173 × 113 ± 15 × 11 μm). Neither a well-defined gametogenic cycle nor synchrony in the reproductive period was observed, because many gonadal development stages occurred in each month. Nevertheless, peaks of maturity were observed between October–December 2002 and April–May 2003. [ABSTRACT FROM AUTHOR]

The activity and surface sediment displacement by the terebellid polychaete Eupolymnia nebulosa were monitored, using new image acquisition and image analysis procedures. We used a video sensor mounted on a motorized table, to acquire adjacent images of the whole studied aquarium within about 2 s. These images were then grouped within a composite image acquired every 15 s. Consecutive composite images were compared to infer activity and surface sediment displacement. This procedure proved efficient for E. nebulosa as indicated by (1) the continuity of the tentacles within composite images, and (2) the direct comparison of images and detected activities. There were important temporal changes in the relative importance of the three main types of activity: feeding, tube-building and (both partial and total) emergence from the tube, accounting, respectively, for 75, 15 and 10% of the entire experiment duration. Activity intensity (cm2 min-1) was assessed through the surface of pixels with grey levels differing by more than 20 (on a 0–255 scale) between two consecutive images. Feeding was associated with low activity intensity, whereas tube-building and emergence from the tubes were associated with high activity intensities. Surface sediment displacement mostly resulted from tentacle activity both during feeding and tube-building and was almost zero when worms emerged from their tube. We used our experimental set up to assess spatial changes in activity intensity and particle displacements along the tentacles. Most of the activity occurred within the first 4–6 cm from the tube aperture. Particle loss during their transfer along the tentacles preferentially affected larger particles as postulated by the model of particle selection and transport in tentaculate deposit-feeders. Moreover, the speed of the particles along the tentacles correlated negatively with their size. This contributed to increase in the residence time of larger particles on the tentacles and thus, to further enhance their probability of being lost. The size distributions of particles during feeding and tube-building did not differ significantly although visual observations confirmed the preferential use of larger particles for tube-building. This suggests the existence of a sorting step occurring elsewhere than on the tentacles as already demonstrated for spionid polychaetes. [ABSTRACT FROM AUTHOR]

The diversity of soft-bottom polychaete assemblages in one Antarctic (Admiralty Bay) and two Arctic (Kongsfjord and van Mijenfjord) localities was compared. The data sets included 79 (Admiralty Bay), 80 (Kongsfjord) and 44 (van Mijenfjord) samples collected with use of 0.1 m2 van Veen grab. The number of species per sample in Kongsfjord (mean 19.9 ± 8.0 SD) was higher than that in Van Mijenfjord (13.7 ± 8.3) or Admiralty Bay (15.7 ± 9.4). The differences in species numbers reflected differences in numbers of individuals in samples: 310.4 ind/0.1 m2 ± 178.0 in Kongsfjord, 132.7 ind/0.1 m2 ± 88.7 in Van Mijenfjord and 138.9 ind/0.1 m2 ± 91.5 in Admiralty Bay. The Hurlbert diversity for 50 individuals ( ES [50]) was similar at all sites: 10.7 ± 3.4 in Kongsfjord, 9.7 ± 4.2 in van Mijenfjord, 10.5 ± 4.9 in Admiralty Bay. The shape of species accumulation curves was also similar for all localities. There was no significant difference (at P < 0.05) either in the total number of species or in species richness as estimated by Chao1 and Chao2 estimators. The generic and family richness at three sites was also similar. We found no substantial differences in the distribution of species among families. At both poles Terebellidae, Ampharetidae, Maldanidae, Spionidae and Polynoidae were dominant in terms of species numbers. The similarity of infaunal polychaete diversity at the polar sites studied contrasts with the substantial differences reported for epi-megafauna. Our study suggests that the patterns of diversity of polar benthic communities are shaped by patterns of habitat heterogeneity which appears to mask any historical processes. [ABSTRACT FROM AUTHOR]

The aim of this work was to define the phylogeographic patterns of the two species of polychaete Eunicidae, Lysidice ninetta Audouin and Milne Edwards and Lysidice collaris Grube, both associated as sheath borers to the Mediterranean seagrass Posidonia oceanica, and with reference to their different origin and their actual geographic distribution. L. ninetta is distributed in the Atlantic and in the Mediterranean Sea while L. collaris is a tropical species, whose introduction into the Mediterranean Sea through the Suez Canal (lessepsian migrant) has been hypothesized in recent years. The two species have been often confused in the past, although they appear morphologically distinct. They share the same microhabitat ( Posidonia sheaths) and they co-exist along a broad bathymetric range (1–30 m). Several populations for both taxa were sampled all along the coast of the Mediterranean basin. A variable no coding region of nuclear DNA (rDNA, ITS1) and a portion of a more conservative coding region of mitochondrial DNA (sub-unit one of citochrome oxidase, COI) were used as molecular markers. Both markers confirmed the separation between the two species. Low intraspecific polymorphism was present in L. collaris, together with absence of phylogeographic structure. In L. ninetta, instead, the presence of intraspecific cryptic lineages, sympatric in some sites, was recorded. Clustering of single populations in the two main clades was not always consistent between markers. The mitochondrial COI region showed more resolution at the given spatial scale. Our results suggest that Lysidice collaris could be recently introduced into the Mediterranean Sea from one or more separate events. On the other hand, for L. ninetta one could presume a re-colonization of the Mediterranean basin from the Atlantics, after the Messinian crisis (dry-out of the Mediterranean Sea, 5.5 my) with the subsequent separation of intraspecific lineages. The phylogeographic patterns of both Lysidice spp. are disjoined with respect to that of the host plant, P. oceanica. The obtained results suggest that environmental constraints and evolutionary history of these polychaetes and their host plant act in different ways to determine their actual genetic spatial structure. [ABSTRACT FROM AUTHOR]

Phragmatopoma spp . are marine, reef-building polychaetes that inhabit the intertidal and shallow subtidal zones of both coasts of the Americas. Phragmatopoma californica is found in the Pacific Ocean along the California coast south to Mexico, while Phragmatopoma caudata inhabits the Caribbean islands and Atlantic Ocean from the Florida coast south to Brazil. Although apparently geographically isolated, P. californica and P. caudata have been found to interbreed (Pawlik ) and thus their specific taxonomic relationship has been unclear. In this study, two genes, cytochrome c oxidase subunit I (COI) and the first internal transcribed spacer region (ITS-1), were sequenced to assess the specific status of P. californica and P. caudata as well as Phragmatopoma virgini. Comparison of sequences revealed that samples of P. californica shared no COI haplotypes or ITS-1 sequences with P. caudata. Phylogenetic analyses, including maximum parsimony and Bayesian methods, clustered each species in separate, well-supported clades with genetic distances between them being greater than between either contested species or the uncontested, valid species, P. virgini. Thus, the molecular data support that P. californica and P. caudata are separate species. However, the sample of individuals of P. virgini included one genetically divergent individual, whose morphology was found to match that of a species formerly recognized as P. moerchi but since synonymized with P. virgini. Divergences among lineages were dated using the COI sequences, after adjustment for non-clock-like behavior. Consequently, we suggest that P. virgini and P. caudata are sister taxons and that P. californica diverged from the P. virgini/P. caudata clade ∼5.7 mya with P. virgini diverging from P. caudata ∼3 mya. [ABSTRACT FROM AUTHOR]

Most spionid polychaetes switch from deposit feeding to suspension feeding as current speed and the flux of suspended food increase. Growth rates of juvenile Polydora cornuta are strongly affected by flow and can be as rapid as 60% day−1 in moderate currents. Feeding palps that extend above the sediment–water interface during suspension feeding are especially vulnerable to sublethal predation, but individuals with damaged posteriors are also common. We performed a series of laboratory flume experiments to test the effects of sublethal tissue damage on the growth and regeneration rates of P. cornuta juveniles. Replicated experiments were conducted at three flow speeds in counter-rotating annular flumes containing field-collected sediment and a nonliving algal slurry as deposited and suspended food. In the first set of experiments, we removed 2, 1, or 0 of worms’ two feeding palps and measured the relative growth rates of worm bodies and palps after 3 days in the flumes. Worms that lost both palps grew significantly slower than the other two groups, but the growth rate of worms that had one undamaged palp was not significantly different from worms that had two undamaged palps. Faster flow speeds significantly increased rates of body growth, and there was a significant interaction between flow and the effect of palp loss. During the 3-day experiments, damaged palps fully regenerated and often grew larger than they were prior to being removed. Damaged palps also grew significantly faster than undamaged palps. The second set of experiments tested the effects of removing a worm’s posterior region (~18% of body volume). The growth rates of these damaged and undamaged worms did not differ significantly. By the end of a 3-day flume experiment, damaged worms had grown 6× larger than they were prior to the posterior damage. The rapid regeneration of damaged palps and posterior tissue in moderate flows that allow suspension feeding suggests that sublethal predation on spionids might be more frequent than previously estimated and will have little impact on the growth of juvenile recruits. [ABSTRACT FROM AUTHOR]

Females of the spionid polychaete Streblospio benedicti (Webster) produce either small eggs (60–70 μm diameter) and planktotrophic larvae, or large eggs (100–200 μm) and lecithotrophic larvae that reportedly do not feed. This intraspecific polymorphism, a form of poecilogony, is potentially useful in studies of larval ecology and evolution, but necessary data on larval form and function are lacking. This study describes the morphology and nutritional biology of larvae obtained from Atlantic (South Carolina) and Pacific (California and Washington) populations from 2003 to 2005. The two types of larvae produced by Atlantic S. benedicti differed greatly in length (229±22 μm SD for planktotrophs vs. 638±40 μm for lecithotrophs) and chaetiger number (2–5 vs. 10–11) at release from the female’s brood pouch. Planktotrophic larvae bore long provisional chaetae on their first chaetiger; provisional chaetae were absent in lecithotrophic larvae. Larvae from Pacific populations were all of the lecithotrophic form, and were similar to their Atlantic counterparts in all respects. High-speed video microscopy revealed that both types of larvae used opposed bands of cilia to capture suspended particles and transport them to the mouth, where they were often ingested. Lecithotrophic larvae reared with suspended phytoplankton ( Rhodomonas sp., 104 cells ml−1) for 2 days grew significantly faster than sibling larvae reared without added food, indicating that these larvae can digest and assimilate ingested food. Larvae of S. benedicti that develop from large eggs are thus facultative planktotrophs instead of obligately non-feeding lecithotrophs, a result that affects the interpretation of comparative studies of the ecology and evolution of larvae in S. benedicti and certain other marine invertebrates. [ABSTRACT FROM AUTHOR]

The Mediterranean endemic seagrass Posidonia oceanica forms beds characterised by a dense leaf canopy and a thick root-rhizome ‘matte’. Death of P. oceanica shoots leads to exposure of the underlying matte, which can persist for many years, and is termed ‘dead’ matte. Traditionally, dead matte has been regarded as a degraded habitat. To test whether this assumption was true, the motile macroinvertebrates of adjacent living (with shoots) and dead (without shoots) matte of P. oceanica were sampled in four different plots located at the same depth (5–6 m) in Mellieha Bay, Malta (central Mediterranean). The total number of species and abundance were significantly higher (ANOVA; P<0.05 and P<0.01, respectively) in the dead matte than in living P. oceanica matte, despite the presence of the foliar canopy in the latter. Multivariate analysis (MDS) clearly showed two main groups of assemblages, corresponding to the two matte types. The amphipods Leptocheirus guttatus and Maera grossimana, and the polychaete Nereis rava contributed most to the dissimilarity between the two different matte types. Several unique properties of the dead matte contributing to the unexpected higher number of species and abundance of motile macroinvertebrates associated with this habitat are discussed. The findings have important implications for the conservation of bare P. oceanica matte, which has been generally viewed as a habitat of low ecological value. [ABSTRACT FROM AUTHOR]

The southern oyster drill, Stramonita (= Thais, Kool 1987) haemastoma, is a common intertidal and subtidal predator in the southeastern United States. It uses specialized feeding structures and foraging strategies to bore holes through the shell of its bivalve prey. However, on the east coast of Florida, S. haemastoma, is common on sabellariid worm reefs constructed by the polychaete Phragmatopoma lapidosa (Walton Rocks Beach, Florida, 27°17′N, 80°12′W), a habitat where the snail’s typical prey are scarce. From 1999 to 2001, we examined the feeding habits of S. haemastoma on sabellariid reefs and the behavioral and morphological responses of S. haemastoma that accompanied switching from a diet of bivalves to sabellariids. On worm reefs S. haemastoma feeds on P. lapidosa by inserting the proboscis deep into a worm’s tube. Worm-feeding snails had longer proboscises (~3.7 times shell height) than bivalve-feeding conspecifics (~2.0 times shell height). Snails raised on different diets showed significant differences in proboscis length suggesting that the proboscis length is phenotypically plastic. Whereas typical oyster drills must bore holes for days before ingesting prey, S. haemastoma on worm reefs avoids boring and attacks and consumes worms in 15–50 min. In the laboratory, oyster drills consumed 1.7 worms per day, spending <1 h each day feeding. On sabellariid reefs, differences in feeding, handling costs, and prey value, are likely to have a significant effect on the ecology and life history of S. haemastoma in this habitat . [ABSTRACT FROM AUTHOR]

Early development was examined, under various salinities, for two sympatric nereidid polychaetes, Hediste japonica and H. diadroma, which participated in a simultaneous reproductive swarming in an estuary of the Omuta-gawa River in Ariake Sea, Japan. The eggs of both species were isotonic to the medium of 27.5–30 psu salinity. The egg diameter in the isotonic salinity was 180–205 μm in H. japonica, and 130–160 μm in H. diadroma. Successful development of most embryos was observed in a salinity range of 22.5–30 psu in both species, while successful fertilization occurred in wider ranges of salinity, i.e., 10–34 psu in H. japonica and 10 to 30 psu in H. diadroma. In both species, free-swimming larval life started from the indistinct hatching of trochophores out of a jelly layer capsule. The lecithotrophic development appeared to run to the 4-setiger nectochaetes in H. japonica, while to 3-setiger nectochaetes in H. diadroma, resulting in a shorter pelagic larval life in H. japonica. In a comparison of larval morphology among Hediste species, we found a definite negative correlation between the prostomium width, which represents the larval size and depends on egg size, and relative length of chaetae to the prostomium width: the relative length of chaetae was the longest in H. diadroma (with the smallest egg size and long pelagic life), intermediate in H. japonica (intermediate egg size, short pelagic life), and the shortest in H. atoka (largest egg size, no true pelagic life). We also examined the possibility of hybridization between H. japonica and H. diadroma through cross-insemination experiments. The gametes of the two species were reciprocally compatible, and viable hybrid offspring were produced by the laboratory crosses. The hybrid larvae expressed intermediate phenotypes, but with a greater maternal influence in characteristics such as the relative length of chaetae and the lecithotrophic larval duration. [ABSTRACT FROM AUTHOR]

The analysis of genotypic shifts in field-exposed populations has been proposed as a tool for monitoring the environmental impacts of contaminants. Previous laboratory experiments showed the occurrence of genotypic shifts induced by copper exposure in samples of Hediste diversicolor from the Pialassa estuary (North Adriatic Sea, Italy). In order to test if genotype-tolerance responses observed were consistent at larger spatial scales, populations of H. diversicolor were sampled in three haphazardly chosen estuaries along the Italian coast (Comacchio, Pialassa, Serchio) and exposed to 0.48 mg 1-1 Cu2+ under laboratory conditions. Survival analysis procedures were used to test for possible relationships between time-to-death and genotypes at three allozyme loci (ALD, FH, PGI). Genotype-tolerance responses observed at locus ALD were consistent among populations up to 2500 km distant, with genotype ALD102/102 associated with the shortest survival times. Comparisons with previous laboratory experiments showed that responses to copper stress at locus ALD were also consistent in time, with genotypes ALD102/102 and ALD100/102 associated with higher 96 h mortality ratios. Results suggested the occurrence of stable relationships between genotypes at locus ALD and tolerance responses of H. diversicolor to copper stress. Conversely, genotype-tolerance responses at loci PGI and FH were not consistent either in space (among populations from the three estuaries) or in time (between laboratory experiments), being possibly affected by site-specific features of populations or stochastic factors. Results show that genotype-tolerance responses should be carefully verified at different spatial and temporal scales, before considering genotypic shifts among the possible tools for monitoring the effects of environmental stressors. [ABSTRACT FROM AUTHOR]

The comparative kinetics of the accumulation of the trace metals copper, zinc and cadmium have been measured in the estuarine burrowing polychaete worm Nereis (Hediste) diversicolor from two sites: (a) a metalrich site, Restronguet Creek, Cornwall, UK, which hosts a copper- and zinc-tolerant population of worms, and (b) the Blackwater estuary, Essex, UK as a control site. A sediment transfer experiment showed that the Blackwater worms responded to the increased copper bioavailability in Restronguet Creek sediment by accumulating significantly increasing copper concentrations over 50 days. The Restronguet Creek worms showed no significant change in copper concentration over 50 days in sediment from either site or in sand. Nevertheless, electron microscopy showed that some Restronguet Creek worms do appear to excrete accumulated copper, probably in association with renewal of the cuticle over a long time scale. The Blackwater worms did not accumulate extra zinc from the zinc-rich Restronguet Creek sediment, in probable reflection of the regulation of body zinc concentration by N. diversicolor. Radiolabelled zinc and cadmium were accumulated from labelled sediment and labelled solution by worms from both sites. The rate of uptake of labelled zinc from sediment was significantly greater in the Restronguet Creek worms, as was the rate of uptake of labelled cadmium from 10 μg 1-1 dissolved exposure; other rates of uptake did not differ between populations. Mucus, which is secreted by Restronguet Creek worms in response to enhanced copper exposure, adsorbed very small proportions of zinc and cadmium present in solution, indicating that the mucus does not act as an adsorption barrier against excessive metal uptake by these worms. [ABSTRACT FROM AUTHOR]

This study reports on the reproduction activity of Exogone naidina Örsted, 1845, followed on a hard-bottom population located at a site along the coast of Bari (South Adriatic Sea), during a year of study from November 2000 to October 2001. Population structure was analysed together with the reproductive state of individuals over time. The interpretation of frequency histograms computed on the total worm length was not easy because of the almost complete lack of juvenile forms. Ripe individuals were present for most of the year, covering a large range of sizes. The reproductive season extended from April to December, with two peaks of activity: one from April to June and one in September–October. Life span was hypothesized to be up to 1 year, with generational change clearly visible only in late summer. However, the prolonged reproductive period produces an overlapping of generations. The link between population density and the reproductive cycle of the species with food availability is also discussed. [ABSTRACT FROM AUTHOR]

Differences in protein patterns of the soluble protein fraction among the sibling speciesMarenzelleria viridis(formerly type I) andM.neglecta(formerly type II) were investigated under common environmental conditions using two-dimensional gel electrophoresis (2D-PAGE). Protein expression was determined using general protein staining with Coomassie-blue and compared with radioactive labeling of proteins. In the well-resolved region of stained gels an average of 319 protein spots forM.viridisand 241 spots forM.neglectacould be detected. High sensitivity of radiolabeling allowed separation of an average of 517 and 496 spots forM.viridisand forM.neglecta, respectively. Differences in protein expression between both species could be attributed mainly to qualitative differences in protein patterns. Triplet pattern was used to calculate the genetic similarity of the two species. Thus, 373 protein spots were scored for this analysis; whereas 304 spots were invariant, 36 spots were specific forM.viridis, while 33 spots were specific forM.neglecta. The genetic similarity (F) of the twoMarenzelleriasibling species was 0.815. Apart from presence and absence, differences between both species resulted either from slight changes in the isoelectric point or from molecular weight, but rarely from both. Genetic variability was found only among specimens ofM.viridis. The experimental conditions to perform two-dimensional electrophoresis for these polychaete species were established for subsequent investigations on a proteomic level. Using 2D-PAGE we expect further insight into the evolutionary adaptation inMarenzelleriaspp. [ABSTRACT FROM AUTHOR]

The structure, diversity and temporal distribution of the infaunal polychaetes associated withCymodocea nodosameadows were studied in Tenerife (Canary Islands). The samples were collected monthly throughout a year, to depths of 13-16 m. The sediment was extracted by means of PVC cores, in which four layers were separated (i.e. 0-5 cm, 5-10 cm, 10-20 cm and 20-30 cm). A total of 1,167 polychaete specimens, belonging to 69 taxa were collected, representing one of the most dominant groups in the benthic assemblage throughout the entire year. The most common families were Syllidae, Paraonidae and Spionidae, both in terms of abundance and species richness. The dominant species wereStreptosyllis bidentata,Aricidea assimilisandExogone parahomoseta mediterranea, representing also the only constant species throughout the year. The highest values of species richness, diversity, equitability and abundance of polychaetes occurred in September. The multifactorial analysis of abundances (i.e. cluster analysis and non-metric, multi-dimensional scaling) indicated temporal segregation of the samples from July, August and September (i.e. the warmest months) with respect to those from the rest of the year, due to structural differences in the assemblage. Polychaete species have been found to a depth of up to 30 cm in the sediment. Nevertheless, most of them (89%) occurred in the upper 5 cm of the sediment, with an increase of specimens in deeper layers in February (i.e. due to sporadic episodes of higher hydrodynamics). To compare the vertical distribution of polychaetes, additional core samples were collected in two seagrass meadows (i.e.C.nodosaandRuppia cirrhosa) at Ebro’s Delta (NW Mediterranean); these were separated into five layers (i.e. 0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm, 20-25 cm). The results obtained for theR.cirrhosameadow (98% of the polychaetes within the upper 5 cm) agree with those for the CanarianC.nodosameadow, while the polychaetes reached up to 15 cm depth in the MediterraneanC.nodosameadow (i.e. ~39% between 0 and 5 cm, ~41% between 5 and 10 cm, ~20% between 10 and 15 cm). Our results indicated that the structural characteristics of the assemblages appeared to be more strongly controlled by the combined characteristics of the sediment (i.e. lack of oxygen, granulometry and degree of compaction) than by the seagrass species building the meadow. [ABSTRACT FROM AUTHOR]

In this paper, we evaluate the influence of the burrowing crabChasmagnathus granulatuson the feeding behavior, body condition, burrowing activity, and fecal production of the deposit-feeding polychaeteLaeonereis acuta. Previous results and ours show that, due to crab activity, sediment organic matter decreases with depth outside a crab bed, but there were no differences inside. Also, particle sizes were smaller inside the crab bed. Polychaetes showed better body condition inside the crab bed, suggesting higher energy gain. They fed on the surface more frequently outside the crab bed than inside. However, feeding rate was higher inside the crab bed, which is consistent with the larger weight and volume of fecal pellets found inside crab bed. In both areas, the bedload sediment transport was not similar to the sediment ingested by this polychaete. A 1-month exclusion/inclusion experiment performed outside and inside the crab bed showed that the body condition of polychaetes changed between areas but that this was not directly due to crab manipulation. Thus, our results suggest that the higher sediment quality inside a crab bed can positively affect the feeding behavior of the deposit-feeding polychaeteL.acuta, increasing its feeding rate and consequently enhancing its body condition. [ABSTRACT FROM AUTHOR]

Deployment of artificial substrata is a common method of investigating early community development and recruitment, but rarely are such experiments of long enough duration to include even year time scales. We placed replicate, machined-slate panels (15×15 cm) in the intertidal and at depths of 6 and 12 m at two sites of differing flow rate at Lough Hyne, SW Ireland. These were serially replaced every 30–60 days for a period of 5 years (1997–2002), except in the intertidal (2000–2002). The number and identity of all recruits were recorded. Recruitment varied over several orders of magnitude both on temporal and spatial scales. The greatest source of variability was between the intertidal (with few species or recruit numbers) and the subtidal zones (many species, some with thousands of recruits per panel per 30 days). Highest levels of recruitment occurred at the low-flow site (Labhra Cliff). Here, recruitment was dominated by the serpulid polychaete, Pomatoceros sp., reaching ~4000 individuals per panel per 30 days. Highest species richness occurred, however, at the high flow site (Whirlpool Cliff). At this site more colonial forms (e.g. bryozoans) settled. Season was found to be the dominant pattern explaining subtidal recruit and species number variability. Year, however, was the dominant temporal pattern explaining change in diversity (Shannon–Wiener H′). In space, depth explained most variability of recruit numbers, whereas site explained more variation in species richness. Both these spatial factors contributed similarly to variability of diversity (H′). Recruitment has long been known to vary considerably over large spatial scales, such as with latitude and isolation, but we that show changes of a similar magnitude in recruitment can occur across small spatial scales. Individual taxa showed varied temporal patterns of recruitment including continuous, regular seasonal fluctuations and irregular pulses in particular years. [ABSTRACT FROM AUTHOR]

Analysis of the displacements and activity of larval stages of the terebellid polychaete Eupolymnia nebulosa were carried out on different sediment types collected in the Bay of Banyuls-sur-Mer (western Mediterranean). Results indicated sediment recognition by the larvae. Time devoted to exploration and settlement trials were significantly longer when sediments of similar granulometry had been previously reworked by adults. There were increased responses of settling larvae if the tentacles of adults of the same species had previously been in contact with the tested sediment. The early settlement activity was stronger at the sediment boundaries and increased in the coarse sediment. Our results suggest that larvae are able to recognize biologically bioturbed sediments and modify their behaviour accordingly. There is a larval settlement before the competent stage. Possible consequences of early settlement and the limitation of dispersal in Eupolymnia nebulosa larvae are discussed together with the results of automated measurements of early larval swimming. [ABSTRACT FROM AUTHOR]