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Life cycle and life history traits of three species of Polygordius
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The life history of the polychaete Polygordius jouinae Ramey, Fiege, and Leander 2006 was studied in the sandy sediments of the LEO-15 research area off the coast of Tuckerton,
New Jersey (39°27.69′N, 74°15.81′W). Divers collected sediment cores biweekly, from February 2004 to November 2005 to examine
the temporal patterns of abundance and size–fre...
Citations
... Overall, the species that were recovered in high abundances in the grab samples (those that define biotopes and others) are known to occupy a range of substrate types, as documented in this study and in the literature (e.g., M. edulis (Maddock 2008);A. vadorum and A. verrilli (Dickinson et al. 1980); P. jouinae (Ramey 2008); O. fusiformis (Pinedo et al. 2000); G. gemma (Weinberg and Whitlatch 1983). Therefore, while sediment type is valuable for defining biotope boundaries and biotic-abiotic relationships, it should not be relied upon solely. ...
... M. edulis filters particles from the water column and enhances biodiversity in sediment-dominated environments (Maddock 2008), and M. lateralis is believed to contribute significantly to benthic production (Walker and Tenore 1984). Moreover, the motile deposit-feeding polychaete worm, P. jouinae, can be an indicator of changing sediment conditions and can impact sediment biogeochemistry (Ramey 2008). ...
In 2012, Hurricane Sandy created a new tidal inlet at Fire Island National Seashore (FIIS) in New York, USA, consequently altering environmental conditions within Great South Bay. This event presented a unique opportunity to establish new ecological baselines, assess resulting ecological change, and explore management implications. This study focuses on benthic mapping within the bayside of FIIS using acoustic, grab sample, and imagery data. Biotope (habitat) maps were developed describing relationships between macrofaunal communities and their environment. Additionally, biotopes were prioritized by “ecological value” based on user-defined criteria (presence of seagrass and potential for higher trophic level interactions) to guide management. While there are limited pre-Sandy data for comparison, findings from this study suggest the inlet has been a positive ecological influence on the nearby area. Dense concentrations of mature blue mussels (Mytilus edulis) documented near the inlet are considered ecologically beneficial and represent a post-Sandy distinction in ecosystem structure; M. edulis was last common when the inlet was previously open (early 1800s). The inlet is also likely responsible for seagrass expansion near the inlet but decline in other areas. This study advances the utility of the Coastal and Marine Ecological Classification Standard (CMECS) by including CMECS-defined data in analyses and expanding the definition of “dominance.” CMECS played a key role in developing map units, interpreting biotopes, and establishing statistically significant and ecologically meaningful biotic–abiotic relationships. This study also highlights the value and management applications of benthic mapping specific to FIIS and more broadly and advocates for similar studies elsewhere.
... Because of their rather simple organization, Polygordiidae were considered to represent a "primitive state", ancestral with respect to the "Chaetopodes" in Annelida (Hatschek 1878), and were the first group for which the former taxon Archiannelida was created. Alternate views suggested that they may be highly derived or secondarily simplified, but in either case they are well adapted for interstitial life (Hermans 1969, Westheide 1985, 1987, Worsaae and Kristensen 2005, Ramey 2008a). ...
... Limited knowledge of the behavior and general ecology of Polygordiidae mainly comes from studies of P. jouinae Ramey, Fiege & Leander, 2006 on the inner continental shelf off New Jersey, USA , Ramey 2008aRamey-Balci and Ambler 2014). Live observations indicated that this worm displays several behaviors that are particularly well suited to living in highly mobile sediments that are frequently resuspended into the water column. ...
... The relatively large size of this species (sexually mature adult body, 13-43 mm long and 0.23 to 0.38 wide) likely allows it to move with relative ease through coarse but not finer sediments. Patterns in distribution have been shown to be extremely patchy in time (i.e., seasonally and yearly) and in space, especially at small spatial scales of less than 1 m (Ramey 2008a, b, Ramey et al. 2009). Higher abundances of P. jouinae are associated with microhabitat features such as sandy rippled beds influencing the concentration of POM/food resources, with higher and more variable densities of this species in ripple troughs compared to crests (Ramey and Bodnar 2008). ...
... Polygordiids are thin interstitial worms which can reach impressive densities in shallow soft bottom habitats, where they can be the dominant benthic organisms (Ramey, 2008). The group is small, with only 20 valid species of Polygordius, the only genus in the family (Tustison et al., 2020). ...
The morphological diversity of marine annelid larvae is stunning. Although many of the larval forms have been categorized as trochophores or modified trochophores, there are a few groups with distinctive larval features that make them easy to distinguish from other annelid larvae. We collected 252 annelid larvae from the plankton, with particular emphasis on oweniids, polygordiids, and thalassematids (i.e., echiurans) and sequenced fragments of their cytochrome c oxidase subunit 1 and 16S ribosomal RNA genes. We found six oweniid, five polygordiid, and eight thalassematid OTUs. Thalassematids were found only in samples from the Pacific, and oweniids were found only in Caribbean samples. Among the oweniids we found two distinct morphotypes, one with a narrow, cloche shape and another that had a wider and more rectangular shape with clearly developed lappets. Among the polygordiids, we identified one larva as Polygordius eschaturus and several larvae as Polygordius jenniferae. All larvae, except for the P. eschaturus, which was at a stage too early to make a determination, were endolarvae. Among the thalassematids, we identified larvae of Ochetostoma edax and found seven unidentified OTUs. Finally, 150 miscellaneous polychaete larvae were sequenced, representing ~76 OTUs. Four rostraria larvae from the Caribbean, whose sequences confirm the long‐held assumption that they are amphinomids, could not be identified to species. In total only 5% of these OTUs could be identified to species with known sequences, and most could not be identified to genus or even family with reasonable certainty. It is clear that this poor coverage in the reference databases will limit metabarcoding efforts to document numbers of OTUs, and that DNA barcodes will be of limited use for identifying neotropical marine annelids until reference databases have improved their coverage of this group.
... Because of their rather simple organization, Polygordiidae were considered to represent a "primitive state", ancestral with respect to the "Chaetopodes" in Annelida (Hatschek 1878), and were the first group for which the former taxon Archiannelida was created. Alternate views suggested that they may be highly derived or secondarily simplified, but in either case they are well adapted for interstitial life (Hermans 1969, Westheide 1985, 1987, Worsaae and Kristensen 2005, Ramey 2008a). ...
... Limited knowledge of the behavior and general ecology of Polygordiidae mainly comes from studies of P. jouinae Ramey, Fiege & Leander, 2006 on the inner continental shelf off New Jersey, USA , Ramey 2008aRamey-Balci and Ambler 2014). Live observations indicated that this worm displays several behaviors that are particularly well suited to living in highly mobile sediments that are frequently resuspended into the water column. ...
... The relatively large size of this species (sexually mature adult body, 13-43 mm long and 0.23 to 0.38 wide) likely allows it to move with relative ease through coarse but not finer sediments. Patterns in distribution have been shown to be extremely patchy in time (i.e., seasonally and yearly) and in space, especially at small spatial scales of less than 1 m (Ramey 2008a, b, Ramey et al. 2009). Higher abundances of P. jouinae are associated with microhabitat features such as sandy rippled beds influencing the concentration of POM/food resources, with higher and more variable densities of this species in ripple troughs compared to crests (Ramey and Bodnar 2008). ...
... The most typical shape among the polychaete was the "banana larvae", which were eventually assigned to the Polygordius genus, whose larvae has been described in coastal waters of the eastern United States (e.g. Ramey et al. 2006;Ramey, 2008;Ramey & Bodnar, 2008;Ramey-Balci & Ambler, 2014). ...
... The total lengths (TL) of a subsample of fixed exolarvae were measured from the posterior stomach margin to the posterior pygidium (Fig. 4a-c). Exolarvae entering metamorphosis was measured from the anterior margin of the prostomium to the posterior margin of the pygidium, consistent with the measurements on benthic adults by Ramey (2008). All size measurements were taken using a high-resolution, 1.4 megapixel, Firewire color camera, Image MS Shot software. ...
... Polygordius larvae are large and planktonic (Fig. 5a-c), with juveniles reaching lengths of up to 9 mm (Ramey-Balci & Ambler, 2014). The smallest P. jouinae individual recorded by Ramey (2008) was 2 mm TL and provides an initial estimate of size at recruitment. Average lengths of specimens collected during CIMAR 16 and 18 was 2.87 ± 0.81 mm TL, with individuals of 2.0-2.4 mm TL being relatively common, and the largest exolarva being 3.2 mm TL. ...
Integration of meroplankton abundance and hydrographic data was employed to relate the Polygordius exolarvae spatial dynamics with different salinity gradients in order to define the factors that regulate the abundance and spatial distribution along the large estuarine system from southern Chile. The present study aims: i) record the abundance and spatial distribution of Polygordius neustonic exolarvae along of the estuaries with different gradients of salinity located between Guafo Channel, southern Chiloé Island (44° S) to Navarino Island (55° S), Chile; ii) connect this distributional pattern to oceanographic parameters to determine if members of this genus have adapted to euryhaline or stenohaline conditions, and iii) establish a comparison between the abundance of Polygordius and others meroplanktonic taxa collected during CIMAR Cruises 16, 18 and 20 Fjords. Neustonic samples were collected during three oceanographic cruises along southern Chilean fjord/channel systems (~ 1,700 km) with different freshwater supply regimes (CIMAR 16: October/November, 2010, 52° to 55° S; CIMAR 18: June/July, 2012, 44° to 47° S; CIMAR 20: October, 2014, 47° to 50° S), providing evidence to relate the influence of surface salinity on the Polygordius exolarvae spatial distribution of abundance. Polygordius exolarvae (average length=2.9 ± 0.8 mm), the most abundant meroplanktonic taxa within the neustonic community (54.04% of total abundance; 66,228 individuals; NTotal=26 stations), was represented at 81% of stations sampled in CIMAR 16 (mean salinity=30.7 psu), showing higher abundance (1,518 ind. x 5 min of horizontal drag) than for other polychaete larvae (10 types) and other meroneustonic taxa; 60% of the abundance of exolarvae during CIMAR 16 was collected around Dawson Island, Magellan Strait. In CIMAR 18 cruise (mean salinity=24.28 psu), abundance of exolarvae was low (3 ind. x 5 min of horizontal drag) and were collected only at 5 stations along the Moraleda Channel (NTotal=31 stations); no exolarvae were collected duringTCotaIlMAR 20 (Ntotal=39 stations) (mean salinity= 23.26 psu). Polygordius exolarvae have narrow haline/thermal requirements during their pelagic life, where sills and island mass effect could produce a restricted and aggregated spatial distribution in some areas of the study zone.
... Polygordius species have a strong affinity for highly energetic habitats with coarse sandy sediments in intertidal to subtidal and continental shelf/slope https://doi.org/10.1016/j.ympev.2018.06.039 Received 12 August 2017; Received in revised form 25 June 2018; Accepted 25 June 2018 environments worldwide (Ramey, 2008;Ramey-Balcı et al., 2013). The relatively larger interstitial spaces afforded by coarser sediment grains allow for larger body size. ...
... indirect as sperm structure is consistent with external fertilization via broadcast spawning (Franzén, 1977;Ramey, 2008). Development is also indirect with a planktotrophic larval phase that has two distinct, species-specific forms (i.e., exolarvae vs. endolarvae) which differ in structure and development (e.g., Fig. 1D-E) (Agassiz, 1867;Cowles, 1903;Hatschek, 1878;Herrmann, 1986;Lovén, 1843;Ramey-Balcı and Ambler, 2014;Woltereck, 1902). ...
Low morphological diversity among interstitial taxa makes it difficult to delimit species and their geographic boundaries based solely on morphology and molecular data often reveal cryptic species. Polygordius (Annelida, Polygordiidae) have low morphological diversity, but are unusual among interstitial species in their comparatively large size due to their elongated form, high fecundity, and potential for long-distance dispersal via a planktotrophic larval stage. Polygordius species collected from 14 localities in the Northwest Atlantic, Mediterranean Sea, and Southwest Atlantic including several of the respective type localities were analysed. This study presents the first phylogeny of the genus Polygordius and combines molecular data, sequences of COI, 16S and ITS1/2 genes, and morphological data for a systematic re-evaluation focusing on Atlantic species, with an emphasis on populations from European waters. Phylogenetic analyses recovered six valid species (P. appendiculatus, P. lacteus, P. neapolitanus, P. triestinus, P. jouinae, and P. eschaturus) and their distinctness is confirmed by haplotype network analyses. Thus, molecular data supported the validity of the previously recognized morpho-species and no new species were present. P. erythrophthalmus and P. villoti are invalid species being synonymous with P. lacteus. Subtle differences in head and pygidial morphology and larval type (endolarva vs. exolarva), were useful characters for discrimination. Yet seemingly significant variation in characters among individuals in some species was not diagnostic (e.g., number of pygidial cirri). Highly similar species based on adult morphology were shown to be sister taxa occurring in allopatry. Present day distribution patterns of species are summarized in light of this study.
... While Pisioninae have not always been regarded as interstitial taxa, Struck et al. (2005) favoured keeping this designation due to similar adaptations in other interstitial groups (i.e. Polygordiidae, Protodrilidae, Saccocirridae; Ramey, 2008;Di Domenico et al., 2014;Mart ınez et al., 2015), including a long and narrowed body form, reduction or loss of notopodia, reduced length in chaetae, reduced dorsal and ventral styles, presence of adhesive glands in the modified stylode (apomorphy; see Appendix 1), presence of terminal prostomial appendages and presence of paired external copulatory organs ( Akesson, 1961;Yamanishi, 1991Yamanishi, , 1998. ...
Aphroditiformia represents one of the most successful radiations of annelids, and is therefore an interesting model to understand morphological and functional evolution. Previous phylogenetic analyses yielded most families as monophyletic but excluded anchialine and interstitial species while failing to recover relationships within Sigalionidae. Here we address these shortcomings through the analysis of four molecular markers and 87 morphological characters sampled across 127 species under the assumptions of parsimony and model-based methods. Of the 34 newly sequenced taxa, five anchialine and 24 interstitial species were included, with increased representation of Sigalionidae. An additional 28 elusive Sigalionidae taxa were included, represented only by morphological partitions. Molecular and morphological partitions were evaluated under exhaustive sensitivity
analyses, testing the effects of alignment algorithms and optimization criteria on tree topologies. Our trees congruently recovered six clades corresponding to the families within Aphroditiformia: Acoetidae, Aphroditidae, Eulepethidae, Iphionidae, Polynoidae and Sigalionidae, respectively. An anchialine polynoid lineage was nested among strictly deep sea species, and interstitial pisionids and pholoids formed two independent clades nested within Sigalionidae. Additionally, Sigalionidae resulted in four clades, defined by combinations of apomorphies, and hereby we propose the subfamilies Pelogeniinae, Pholoinae, Pisioninae, Sthenelanellinae, as well as the provisionally included polyphyletic Sigalioninae.
... Polygordius was reported on one (swash zone of Estaleiro Beach) of six sandy beaches in the states of Santa Catarina and Paraná, Brazil (Di Domenico et al. 2009). Conversely, the European and North American species inhabit sublittoral coarse sands or gravel zones (Villora-Moreno 1997, Ramey 2008, Martins et al. 2013, while one species even occurred in muddy bottoms of the Adriatic Sea (Rota and Carchini 1999). ...
... Most published studies address the systematics and morphology of this genus (see Lehmacher et al. 2016 and references therein). Its physiology has received little attention but some data on life cycles are available (Ramey 2008). ...
Specimens of Polygordius eschaturus from a reflective sandy beach were tested in the laboratory for tolerance to salinity and temperature and for their response to light, gravity and oxygen tension. After 192 h at 10°C, almost all specimens died at salinities of 10, 20 and 50 psu and were slow moving from 30 to 40. At 20°C and 30°C, all specimens died when salinity was 10; few showed abnormal behaviour at 50 and all presented normal behaviour from 20 to 40. At 40°C, all specimens died within 24 h. In our experimental conditions, the observed migration patterns corresponded to photonegative geopositive behaviours, but also indicated a positive response to a higher oxygen tension. These patterns, together with euryhalinity and eurythermy, are in accordance with the typical habitat of the species, from 10 to 20 cm depth in coarse sand above the swash zone. In the intertidal zone of the tropical beach where the worms were originally found, the combined behaviour leading to an attraction to well-oxygenated, dark subsurface sediment layers results in successful protection from the strong changes in salinity and temperature of the more superficial layers.
... Although originally described as segmented Gordian worms by Schneider (1868), external segmentation is almost invisible. The absence of typical polychaete characters such as parapodia and chaetae in combination with their ability to move rapidly through the sediment (Ramey 2008) by antagonistic action of well-developed longitudinal musculature and a strong, smooth iridescent cuticle has led to confusion with nematodes. Morphological characters used for species distinction are limited to details of the prostomium and pygidium and require detailed study using scanning electron microscopy. ...
... Alternatively, they may be considered highly derived or secondarily simplified. In any case, they appear well adapted for interstitial life (Hermans 1969b;Westheide 1985Westheide , 1987Worsaae and Kristensen 2005;Ramey 2008). ...
The systematic position of Polygordiidae is still under debate. They have been assigned to various positions among the polychaetes. Recent molecular analyses indicate that they might well be part of a basal radiation in Annelida, suggesting that certain morphological characters could represent primitive character traits adopted from the annelid stem species. To test this hypothesis, an investigation of the muscular and nervous systems by means of immunological staining and confocal laser scanning microscopy and transmission electron microscopy was conducted. With the exception of the brain, the nervous system is entirely basiepidermal and consists of the brain, the esophageal connectives, the subesophageal region, the ventral nerve cord and several smaller longitudinal nerves. These are connected by a considerable number of ring nerves in each segment. The ventral nerve cord is made up of closely apposed longitudinal neurite bundles, a median and two larger lateral ones. Since distinct ganglia are lacking, it represents a medullary cord. The muscular system mainly consists of longitudinal fibers, regularly distributed oblique muscles and strong septa. The longitudinal fibers form a right and a left unit separated along the dorsal midline, each divided into a dorsal and ventral part by the oblique muscles. Anteriorly, the longitudinal musculature passes the brain and terminates in the prostomium. There is no musculature in the palps. In contrast to earlier observations, regularly arranged minute circular muscle fibers are present. Very likely, a basiepithelial and non-ganglionic organization of the ventral nerve cord as well as an orthogonal nervous system represent plesiomorphic characters. The same applies for the predominance of longitudinal muscle fibers.
... Of the organisms targeted with molecular probes, polychaete larvae exhibited the clearest patterns. Polychaetes comprise the largest component of soft-sediment infauna, yet the complete life history is known for only about 5% of the > 8000 described species (Ramey 2008). Presence/absence of polychaete larvae within/outside INL samples suggests that INLs function as transport vehicles for their larval stages. ...
Predicting when and where key oceanic processes will be encountered is problematic in dynamic coastal waters where diverse physical, chemical, and biological factors interact in varied and rapidly changing combinations. Defining key processes often requires efficient sampling of specific water masses and prompt sample return for subsequent analyses. This compound challenge motivated our efforts to develop mobile autonomous process sampling (MAPS) for use with autonomous underwater vehicles (AUVs). With this system, features are recognized by artificial intelligence that integrates AUV sensor data to estimate probabilistic states for adaptive control of survey navigation and triggering of targeted water samplers. To demonstrate the utility of the MAPS/AUV system, we focused on intermediate nepheloid layers (INLs), episodic transport events that may play a role in zooplankton ecology. During multiple field tests in Monterey Bay, California, the MAPS/AUV system recognized, mapped, and sampled INLs. Invertebrate larvae contained in the water samples were subsequently characterized with molecular probes developed for high-throughput screening. Preliminary results support the hypothesis that INLs function as vehicles for episodic larval transport. Applying MAPS within a greater coastal ocean observing system permitted description of regional oceanographic dynamics that influenced the patterns and scales of INL and larval transport. © 2010, by the American Society of Limnology and Oceanography, Inc.
