Polychaete Diversity Research Articles

Assessment of polychaete diversity in selected tropical Islands and estuaries on the Southeast coast of India

Increased anthropogenic pressure on the marine environment leads to severe threats to resident biota, a global concern. The Gulf of Mannar (GoM) and Palk Bay (PB) on the Southeast coast of India are two notable ecological hotspots. However, increased industrialization, tourism, and fishing activities in recent years have contaminated the environment and biota of these two ecologically significant coastal zones. This study aims at the impact of seasonal dynamics on polychaete assemblages in four coastal areas (Kanyakumari, Thoothukudi, Ramanathapuram, and Cuddalore) along the southeast coast with different seasons (post-monsoon, summer, pre-monsoon, and monsoon). In all the collected parameters, salinity is the prime variable influencing the distribution of polychaetes greatly; they link to other environmental parameters. Results revealed that temperature, pH, chlorophyll, and total organic carbon all exhibited a strong positive correlation with salinity; others showed a negative correlation. According to a one-way ANOVA, the Kruskal-Wallis test and Pearson correlation have significant differences at the spatial scale (p<0.05). Overall, the multivariate analysis of PCA and CCA, followed by indices like Shannon diversity index and AMBI and M-AMBI indices results, revealed that spatial heterogeneity of the polychaetes was influenced by salinity, temperature, pH, DO, TN, TP, TOC, and clay (p<0.05). The environmental changes and anthropogenic activities are the reason for the spatial variation in the polychaetes.

Taxonomic richness and its relationship to the functional diversity of polychaetes in tropical estuaries

AbstractBiological diversity can be evaluated by the taxonomic and functional components. This study aimed to assess the relationship between taxonomic richness with the functional diversity components [functional richness (FRic), functional evenness (FEve) and functional divergence (FDiv)] and the functional trait dominance of polychaetes. In addition, we evaluated the environmental parameters that shape the functional structure in six tropical estuaries in north‐eastern Brazil. Three estuaries have a continuous environmental gradient (typical tropical), and the other three estuaries have no defined environmental gradient (semiarid tropical). We identified significant differences in the dominance of feeding strategy and habitat between estuaries, demonstrating that the functional space of the communities is not equally occupied. Also, the substrate particle size composition was correlated with the functional structure. FRic showed a positive relationship with taxonomic richness, regardless of the type of estuary. As taxonomic richness increases, the probability of different combinations of functional categories added to a community also increases. FEve and FDiv seem to be independent of taxonomic richness. Therefore, it is important to simultaneously evaluate diversity's taxonomic and functional components, considering the complementarity of the information provided by these diversity measures.

Site- and habitat-dependent variations in the diversity of polychaetes associated with golden kelp Ecklonia radiata holdfasts along the southeast coast of South Africa

Polychaetes are important components of the macrofaunal communities associated with golden kelp Ecklonia radiata holdfasts across different spatial scales. However, the polychaete component varies in different habitat types in response to varying environmental conditions. Here, we compared patterns of variation in Ecklonia radiata holdfast-associated polychaetes between rock pools and gullies along South Africa’s southeast coast. Eighteen species were found in gullies and 28 species in rock pools, with 13 and 16 families represented, respectively. The study sites at Cwebe, Dwesa and Nqabarha had 12, 11 and 20 species, respectively. The rock pools were more species-rich than the gullies, while Nqabarha was the most species-rich site. The composition of species varied both among habitat types and between sites, with a separation in polychaete composition observed between Cwebe and Dwesa. The species that contributed >60% to the distinction between habitat types and among sites were Lepidonotus semitectus, Cirriformia capensis, Eunice aphroditotis, Syllis sp., Chaetopterus variopedatus, L. durbanensis, Arabella iricolor, Lysidice natalensis and Gunnarea gaimardi. The polychaete distribution on kelp holdfasts was influenced by the sediment and geomorphological characteristics of the sampling sites. Our findings highlight the importance of sediment in creating habitat heterogeneity and how this facilitates high species richness in rock pools. However, physical factors explained a small proportion of the variance in the polychaete assemblages. Therefore, biological factors could be more important drivers than abiotic elements, particularly between habitat types.

Latitudinal biodiversity gradients of rocky intertidal assemblages: Spatial scales and complex associations with environmental factors

AbstractLatitudinal biodiversity gradients vary across taxonomic groups and spatial scales, and various environmental factors have been associated with those patterns. However, it remains unknown whether taxonomic groups with strong ecological associations have similar or different latitudinal patterns. Macroalgae are foundation assemblages on rocky intertidal shores and are often inhabited by invertebrates, predominantly polychaetes. This study analysed latitudinal patterns of macroalgae and their associated polychaetes at different spatial scales and determined how environmental factors influenced those patterns. Macroalgae and polychaetes were collected from transects within 38 rocky intertidal shores of Western Australia at 14 latitudes between 18° S and 34° S. Latitudinal gradients in species richness, diversity (Simpson's diversity index) and abundance were evaluated at transect, site and latitudinal scales. Relationships between environmental factors and rocky intertidal assemblages were analysed using piecewise structural equation modelling based on direct, indirect and complex models. Macroalgae showed increases in species richness, diversity and abundance at transect and site scales towards high latitudes, but species richness and diversity patterns were unclear at the latitudinal scale where transect and site data were pooled. In contrast, polychaete diversity decreased towards high latitudes, although this pattern was unclear at the transect scale. Polychaete richness and abundance tended to follow parabolic patterns that peaked at 27° S. Relationships between environmental factors and rocky intertidal assemblages were best described by a complex model, with significant relationships more often at transect and site scales. Sea surface temperatures showed the strongest relationship with macroalgal and polychaete distributions.

Polychaete Diversity and Functional Trait Composition in Subtropical Mangrove Ecosystems

Polychaetes play a vital role in the structure and functioning of benthic communities in mangrove ecosystems. Nevertheless, our understanding of the diversity and functional structure of polychaete assemblages across different habitats in the mangrove ecosystems along the coast of the Persian Gulf and Gulf of Oman is limited. In this study, we investigated the species and trait composition of polychaetes and environmental variables, in vegetated and mudflat habitats of three subtropical mangroves. The results showed that Neanthes glandicincta was widely distributed across all regions and habitats. The three-factor ANOVA showed that the abundance and taxonomic diversity of polychaetes differed significantly between two habitats and three mangrove ecosystems. The abundance of polychaetes was observed to be higher in mud habitats than in vegetated habitats. There was a significant difference in species and trait composition between different regions and habitats. Vegetated habitats had higher proportions of crawler predatory species that are longer lived (3–5 years), with larger body size (80–100 mm), and are upward conveyors, whereas mudflat habitats had higher proportions of mobile (burrower) omnivore species that are moderately lived (1–3 years), with larger body size (&gt;100 mm), and are biodiffusers. The three-factor ANOVA showed a significant difference in the community weighted mean (CWM) index between two habitats and three mangrove ecosystems. Thus, the species and trait composition of polychaetes depend on the structural complexity of their respective habitats. The DistLM analysis showed that total organic carbon content of the sediment was the main predictor variable influencing species composition, while silt/clay content and salinity were the main predictor variables influencing the traits’ composition. The results showed how the composition of traits and the structure of polychaete communities change in mangrove ecosystems, which can be used for future studies on conservation strategies for mangrove ecosystems throughout the world.

Polychaetes (Annelida) of Cyprus (Eastern Mediterranean Sea): An Updated and Annotated Checklist Including New Distribution Records

The diversity and distribution of polychaetes in the coastal area and the EEZ of the Republic of Cyprus is presented based on both the literature records and new data acquired in a wide range of environmental monitoring programmes and research projects. A total of 585 polychaete species belonging to 49 families were reported in Cyprus waters; among them, 205 species (34%) were recorded based on the literature only, 149 (26%) were new records based on our own data, and a total of 231 spp. (40%) were recorded from both the literature and new data. A total of 51 polychaete species were identified as non-indigenous; among them, 32 were confirmed as alien species, 4 were considered cryptogenic, and 15 were considered questionable as there were doubts about their identity. The Indo-Pacific Schistomeringos loveni was reported for the first time in the Mediterranean Sea, while four species already reported in the literature, namely, Bispira melanostigma, Fimbriosthenelais longipinnis Leonnates aylaoberi, and Rhodopsis pusilla, were added to the list of non-indigenous polychaetes in the Mediterranean Sea. The current work highlights the importance of implementing environmental monitoring programmes and carrying out research surveys targeting benthic macrofauna assemblages.

Effect of the alien octocoral Carijoa riisei on benthic fauna assemblages on natural and artificial substrates

AbstractCarijoa riisei is an invasive octocoral whose dispersal in the tropics has increased considerably in recent years. This study evaluated the changes in the benthic fauna assemblages associated with C. riisei growing on rocks from a sea port and on the metal of a submerged shipwreck in the bays of Manzanillo, Colima, in the Mexican Central Pacific. Quarterly samples were collected between April 2021 and January 2022, with the presence or absence of C. riisei. The effect of C. riisei on the benthic fauna according to the type of substrate was evaluated with PERMANOVA models. The presence of C. riisei was found to affect taxonomic diversity. In the absence of the octocoral, 209 species were recorded, whereas in its presence, 190 were found. The decline of taxa occurred at the level of families, genera, and species. The interaction of the presence/absence of C. riisei and substrate generated significant changes in the Shannon (1D) and Simpson (2D) diversity indexes. However, the presence of C. riisei coincided with higher abundances of Ophiothela mirabilis, Ericthonius brasiliensis, and Pseudobranchiomma schizogenica. In conclusion, the snowflake coral favors the dominance of some species and reduces the biological diversity of several taxa, mainly mollusks, polychaetes, sipunculids, and anthozoans, generating significant changes in the structure of benthic communities. This study highlights the need to evaluate species composition in areas where the octocoral grows, to determine whether its presence has an ecological impact and whether control measures are required.

Latest Ordovician jawed polychaetes, chitinozoans and depositional environments of the Levín section, Prague Basin, Czech Republic

Jawed polychaetes evolved and diversified extensively during the Ordovician. However, Ordovician polychaete jaws (scolecodonts) have remained poorly documented for many regions. This applies for the Prague Basin of peri-Gondwana, from where the previous study on Late Ordovician scolecodonts was published more than 70 years ago, with just two species preliminarily identified. The aim of the present paper was to fill this research gap and to study organic-walled microfossils from the boundary interval of the Králův Dvůr and Kosov formations (uppermost Katian and lowermost Hirnantian) at the Levín locality. As a result, a diverse assemblage of scolecodonts and chitinozoans was discovered. Chitinozoans are represented by at least 24 species from 15 genera, i.e., a relatively diverse assemblage whose species composition points toward the Ancyrochitina merga and Tanuchitina elongata biozones. The recovered jawed polychaete fauna contains at least 19 species from 14 genera. Taxa with labidognath and prionognath type maxillary apparatuses predominate in samples, whereas placognath and ctenognath taxa are relatively rare. A similar pattern is typical for the Laurentian samples but contrasts with the Baltic polychaete faunas. Polychaetaspids dominate in the Levín assemblage, followed by other families such as ramphoprionids, paulinitids, and atraktoprionids. The studied interval in the Levín section is represented by a succession of thin-bedded silty shales with diamictite beds, practically devoid of shelly fossils and with a variable degree of bioturbation. The deposits are interpreted as distal turbidites and debrites, reflecting sea-level changes driven by the growth and retreat of glacial ice and possibly also local tectonics. Reduced diversity and abundance of scolecodonts was recorded in the uppermost part of the Králův Dvůr Formation, which correlates with less bioturbation and finer silt fraction. The reported discovery shows wide geographical distribution and diversity of jawed polychaetes before and during the Hirnantian glaciation and mass extinction.

Soft-bottom polychaetes in a chronic eutrophic bay on the coast of Alexandria

Context The polychaetes are the major benthos in the soft bottom of the eutrophic Eastern Harbour of Alexandria, Egypt. Aim Investigate the quantitative and qualitative dynamics of polychaete community in the Harbour. Methods Polychaetes were collected bimonthly from August 2018 to June 2019, by using a 29- × 16-cm grab. Key results In total, 54 polychaete species were identified, belonging to 27 families and 51 genera. The family Syllidae was represented by eight species, Spionidae by five species, and Cirratulidae by five species, against one to three species from all other families. Eleven alien species were recorded, including four new to the Mediterranean Sea (Caulleriella cristata, Armandia casuarina, Spio blakei and Prionospio lighti). The polychaete community displayed pronounced temporal variations in both species diversity and numerical abundance at the two sampled sites. Conclusion This study showed high diversity and abundance of polychaetes in such eutrophic basin. Implications The eutrophication may play a role in the structure and count of polychaetes in the Eastern Harbour.

High polychaete diversity in the Gulf of Guinea (West African continental margin): The influence of local and intermediate scale ecological factors on a background of regional patterns

The Tropical East Atlantic is one of the least studied areas in the world's oceans, and thus a blank spot on the map of marine studies. Shaped by dynamic currents and shifting water masses, it is a key region in discussions about marine ecology, biodiversity, and zoogeography, while facing numerous, poorly understood, and unmonitored threats associated with climate change, acidification, and pollution. Polychaete diversity was assessed along four transects along the Ghana coast, from shallow to deep bottoms and distributed along the whole upwelling marine ecoregion. Despite high sampling effort, steep species accumulation curves demonstrated the necessity of further sampling in the region. We observed zonation of fauna by depth, and a decrease in species richness from 25 m to 1000 m depth. Polychaete communities were influenced by sediment type, presence of oxygen minimum zones, and local disturbances caused by elevated barium concentrations. Similar evenness along the depth gradient reflected the importance of rare species in the community structure. Differences in phylogenetic diversity, as reflected by taxonomic distinctness, were small, which suggested high ecosystem stability. The highly variable species richness at small scale (meters) showed the importance of ecological factors giving rise to microhabitat diversity, although we also noticed intermediate scale (50–300 km) differences affecting community structure. About 44 % of the species were rare (i.e. recorded only in three or fewer samples), highlighting the level of patchiness, while one fifth was distributed on all transects, therefore along the whole upwelling ecoregion, demonstrating the influence of the regional species pool on local communities at particular stations. Our study yielded 253 species, increasing the number of polychaetes known from this region by at least 50 %. This casts doubt on previous findings regarding Atlantic bioregionalization, biodiversity estimates and endemism, which appear to have been more pronouncedly affected by sampling bias than previously thought.

Functional and taxonomic diversity of macroinvertebrates present opposite patterns in tropical estuarine ecosystems

The determination of the processes that act in the assembly of the communities is a theme of growing interest among ecologists. Different processes (e.g., environmental filtering and biotic interactions) can shape the structure of communities depending on the spatial scale analyzed. In this study, we partitioned the functional and taxonomic diversity of polychaete and molluscs communities of tropical estuaries from the hot and humid region, named as typical, and from the semi-arid region into the alpha, beta, and gamma components. The biological communities were sampled in three typical tropical estuaries (Paraíba do Norte, Mamanguape and Passos) and three semi-arid estuaries (Galinhos, Tubarão and Casqueira) once in each dry and rainy period. We used Rao's quadratic entropy and Simpson's index, respectively, to partition the functional and taxonomic diversity. Our results showed that when functional diversity was considered, the alpha component (diversity within sites) presented higher proportions in relation to beta diversity. For taxonomic diversity, the opposite occurred, with higher proportions of beta diversity (diversity between sites). This trend was observed in both seasonal periods. Our results indicate that different processes act in the assembly of the functional and taxonomic diversity of molluscs and polychaetes at different spatial scales. More specifically, biotic interactions seem to be more important in the assembly of functional diversity, while environmental filtering and dispersal limitation seems to have a greater effect on taxonomic diversity. Therefore, functional and taxonomic approaches provided complementary results on the distribution patterns of estuarine communities at different spatial scales.

The diversity of polychaetes (Annelida: Polychaeta) in a long-term pollution monitoring study from the Levantine coast of Turkey (Eastern Mediterranean), with the descriptions of four species new to science and two species new to the Mediterranean fauna

ABSTRACT During a relatively long-term pollution monitoring study between 2015 and 2021 (annually between 2015 and 2019; triennially after 2019), a total of 257 polychaete species belonging to 40 families were identified at 17 soft bottom stations (depth range: 11–89 m) along the Levantine coast of Turkey. Among them, four species belonging to Hesionidae (Oxydromus digitifera sp. nov.), Orbiniidae (Leitoscoloplos mediterranea sp. nov.), Paraonidae (Paraonis lobulata sp. nov.) and Capitellidae (Barantolla cryptogenica sp. nov.) are new to science, two species belonging to Cirratulidae (Chaetozone elakata) and Ampharetidae (Anobothrus amoureuxi) are new additions to the Mediterranean fauna and 28 species are new additions to the marine fauna of Turkey. Among the families, Spionidae (29 species), Syllidae (22 species) and Paraonidae (22 species) accounted for 28% of the total number of species, and Capitellidae, Lumbrineridae and Spionidae comprised 45% of the total number of individuals. The most dominant species in the region were Lumbrineris geldiayi, Notomastus mossambicus and Prionospio saccifera. A total of 20 alien species belonging to 12 families were found in the region, with N. mossambicus and P. saccifera accounting for more than 85% of the total number of individuals of alien species. The new species are described and compared to the closely related species. http://www.zoobank.org/urn:lsid:zoobank.org:pub:8E09CE08-AA44-46F4-A59B-3DE19D42EB4B

Polychaete diversity in Tunisian waters as of 2021: an update with special emphasis on Non-Indigenous species

The last inventory of Tunisian polychaetes diversity by Ayari et al. (2009) is updated. New records were acquired from the literature and from the current study concerning species collected in the tidal channels of the Gulf of Gabès (2016-2017) and the re-examination of some species deposited in the collection of the Tunisian National Institute of Marine Sciences and Technologies. This inventory, reviewing the taxonomy, nomenclature, and biogeographic distribution of the Tunisian polychaetes, includes 390 species belonging to 52 families, among which the Serpulidae (41 species) and Syllidae (36 species) are the most diverse. In total, 37 species previously reported are currently removed from the Tunisian polychaetes list. An additional 121 new species are added, including 23 species collected in the tidal channels and 6 species in the reference collection previously misidentified as their congeners. Morphological differences between the latter are briefly discussed and figured. Among these species, Laonice bahusiensis, Laonice norgensis, and Scolelepis neglecta are extending their Mediterranean distribution, while Sternaspis thalassemoides and Caulleriella mediterranea are probably reported for the first time after their original description. In addition, this current inventory allows us to discuss the establishment status of 17 Non-Indigenous polychaete species (14 established, 1 casual, and 2 cryptogenic) found in Tunisian waters.

Seasonal carbonate system vis-à-vis pH and Salinity in selected tropical estuaries: Implications on polychaete diversity and composition towards predicting ecological health

Salinity and pH play a fundamental role in structuring spatial patterns of physical properties, biota, and biogeochemical processes in the estuarine ecosystem. In this study, the influence of salinity-pH gradient and carbonate system on polychaete diversity in Ennore, Uppanar, Vellar, and Kaduvaiyar estuaries was investigated. Water and sediment samples were collected from September 2017 to August 2018. Univariate and multivariate statistical analyses were employed to define ecological status. Temperature, salinity, pH, and partial pressure of carbon-di-oxide varied between 21 and 30°C; 29 and 39 ppt; 7.4 and 8.3; and 89.216 and 1702.558 µatm, respectively. PCA and CCA results revealed that DO, chlorophyll, carbonate species, and sediment TOC have a higher influence on polychaete community structure. Forty-two species such as Ancistrosyllis parva, Cossura coasta, Eunice pennata, Euclymene annandalei, Lumbrineris albidentata, Capitella capitata, Prionospio cirrifera, P. pinnata, P. cirrobranchiata, and Notomastus sp. were found dominantly in all estuaries. Shannon index values ranged between 1.619 (UE-1) and 3.376 (VE-2). Based on these findings, high levels of carbonate species and low pH have a greater impact on polychaete diversity and richness values. The results of the AMBI Index revealed that stations UE-1, UE-2, UE-3 in Uppanar, EC-1, EC-2 in Ennore indicate “moderately disturbed”, while other stations are under the “slightly disturbed” category. This trend was quite evident in M-AMBI as well.

Diversity and distribution patterns of macrofauna polychaetes (Annelida) in deep waters of the Southwestern Gulf of Mexico

The distribution and composition at the genus level of polychaetes greater than 500 μm of 54 sites in the southwestern Gulf of Mexico in a depth range of 185–3762 m were analyzed. Samples were collected on board the R/V Justo Sierra (Universidad Nacional Autónoma de México) in two cruises carried out in June 2015 and September 2016. Sixty-nine genera belonging to 33 families were recorded. The families with the highest abundance were: Spionidae, Paraonidae, Pilargidae and Capitellidae. Spionidae, Capitellidae and Paraonidae families presented the highest genus richness. The highest abundance was observed in the southern region of the study area and in the upper bathyal zone while the highest taxonomic richness was registered in the Campeche Bay, in the northwestern region of the study area and in intermediate depths. Polychaeta community functional diversity (bioturbation traits and feeding guilds) was also analyzed. A general decrease in functional diversity was observed as depth increased, presenting a partial biodiffusors and deposit-feeders dominance in the deepest zones. Distribution was highly related with depth, sediment granulometry, temperature and dissolved oxygen concentration of the bottom water.

Nephtyidae (Annelida: Polychaeta) from the Sea of Marmara and Black Sea, with descriptions of two new species.

The present paper deals with the diversity of nephtyid polychaetes (Nephtyidae) from the Sea of Marmara and the Black Sea. Three species belonging to two genera (Micronephthys and Nephtys) were found in the Black Sea (coast of Turkey) and six species belonging to three genera (Inermonephtys, Micronephthys and Nephtys) were found in the Sea of Marmara. The material includes two species new to science, Inermonephtys turcica n. sp. and Nephtys sinopensis n. sp., and a species record (Nephtys kersivalensis McIntosh, 1908) new to the Sea of Marmaras marine fauna. Nephtys sinopensis n. sp. is mainly characterized by having 14 geniculate chaetae in the postacicular position of the parapodia; digitiform antennae, palps, and ventral cirri at chaetiger 1 with swollen tips; small and cirriform branchiae present from chaetiger 4 to the end of the body; poorly developed parapodial prechaetal lamellae in median and posterior chaetigers and long ventral cirri along the body. Inermonephtys turcica n. sp. is mainly characterized by having cushion-like palps with digitiform tips; well developed neuropodial postchaetal lamellae; barred chaetae in preacicular position of the anterior and median parapodia; and branchiae first appearing between chaetiger 3 and 13 (depending on body size).

Polychaete (Annelida) Diversity Patterns in Southern Gulf of Mexico: The Influence of Spatial Structure and Environmental Variables

A comprehensive database was built to examine the spatial diversity patterns of polychaete species from the continental shelf in Southern Gulf of Mexico. Using Cluster and nMDS analysis we found the composition of polychaete species to be different between the terrigenous and carbonate regions of the Gulf. To test the relative importance of spatial and environmental components in the polychaetae community structure in the Southern Gulf of Mexico, we examined the spatial relationships between polychaetae assemblages and environmental variables over broad geographical scales. A distance-based redundancy analysis (dbRDA) and variation partitioning was used to quantify the relative importance of these explanatory variables on the spatial variations of species richness and composition. Variation partitioning is an important tool to investigate the importance of spatial structure to species distribution in communities, but it has not yet been used in marine ecosystems. The significance level of spatial and environmental components to the distribution of polychaete species showed that the combined effect of spatial processes and sediment characteristics explained a higher percentage of variance than those parameters could alone.

Консорты брюхоногого моллюска Rapana venosa (Valenciennes, 1846) в северной части Чёрного моря. Часть V: Annelida (Polychaeta)

Изучение таксоцена Annelida (Polychaeta), эпибионтов брюхоногого моллюска — вселенца Rapana venosa, продолжает цикл по описанию состава консорции самого крупного брюхоногого моллюска черноморского бентоса. Консорция R. venosa до сих пор является мало исследованной и неучтённой компонентой в структуре биоценозов шельфа Чёрного моря. Цель данной работы — изучить комплекс полихет консорции R. venosa. Задачи этого этапа: составление списка таксонов Annelida (Polychaeta) — эпибионтов рапаны; изучение биогеографической и трофической структуры таксоцена; исследование экологических связей полихет с ядром консорции. Для изучения консортного сообщества рапаны были осуществлены сборы в семи районах северной части Чёрного моря: 1 — Мамайя, Румыния; 2 — северо-западная часть Чёрного моря, Крымский сектор; 3 — Севастополь; 4 — Алупка; 5 — Ялта — Алушта; 6 — Карадаг; 7 — Керченский пролив. Сбор R. venosa в прибрежной зоне до глубины 15 м проводили тотально с использованием легководолазного оборудования, в более глубоководной зоне (до 40 м) — дночерпателем «Океан-50» с борта НИС «Профессор Водяницкий». Каждый экземпляр (пробу) рапаны помещали в отдельный пластиковый пакет с указанием района, глубины и биотопа. Всего отобрано и проанализировано 2411 проб, из них 977 — скальной рапаны и 1434 — песчаной. Покрытие эпибионтами раковины R. venosa (интенсивность обрастания) оценивали в процентах от общей площади внешней поверхности раковины. Таксоцен Polychaeta консорции R. venosa включает 31 вид, представляющий 31 род 15 семейств 2 подклассов. Бόльшая часть видов (18) относится к Errantia, половину из них составляют представители семейств Nereididae и Syllidae. К Sedentaria относятся 13 видов; наибольшее их количество (4) принадлежит семейству Serpulidae. Таксоцен Polychaeta консорции рапаны представлен тремя биогеографическими группами: аборигенные виды средиземноморско-атлантического генезиса (84 %), эндемики Чёрного моря (10 %) и современные виды-вселенцы различного географического генезиса (6 %). На песчаной рапане обнаружен 31 вид полихет, а на скальной — только 5. Показатели развития фауны полихет значительно различаются по глубинам и районам исследований. Наиболее разнообразны полихеты в бухтах г. Севастополя (район № 3) на глубинах 2–10 м; максимальная глубина обнаружения полихет (40 м) соответствует наибольшей глубине отбора рапаны. Площадь покрытия раковины рапаны полихетами достигает 70 %, встречаемость в отдельных районах составляет до 95 %. Максимальное число видов, обнаруженных на отдельном экземпляре рапаны, — 8; в среднем на особях R. venosa отмечено 2–4 вида полихет. Таксономическое разнообразие и обилие Polychaeta определяют их значимость в консорции R. venosa. Благодаря инвазионному хищному моллюску R. venosa полихеты получают дополнительные возможности для распространения на шельфе Чёрного моря.

Sponge-Associated Polychaetes: Not a Random Assemblage

Polychaetes are among the most common marine organisms, and in many habitats they dominate both in species richness and abundance. They are often found in association with other organisms. Specifically, sponges with their complex three-dimensional internal architecture, are known to host a great diversity of polychaetes. Due to the fact that a large number of sponge-associated polychaete species are known to be common on other substrates, most studies agree that they represent an opportunistic part of the sponge-inhabiting assemblage, without any selection of species tightly associated with sponges. The current study aimed to shed light on polychaetes affinity to sponges. We applied Clarke and Warwick’s taxonomic distinctness indices and test for random assembly, to a dataset compiled of 13 publications that provided polychaete species lists from massive-sponges across the Mediterranean Sea, and compared them with benthic-polychaete species lists from all of the Mediterranean and its zoogeographical regions. These indices are considered to be independent of sampling efforts and setting, and can be applied on presence/absence data, making it possible to compare data from multiple studies. We further compared the trophic structure of sponge-associated polychaetes between the Mediterranean’s zoogeographical regions. Our results show that the trophic structure of the sponge-associated polychaete community, was found to be stable across the entire Mediterranean Sea. Moreover, randomization tests showed that at almost all observational scales (e.g., study, region, Mediterranean) the phylogenetic diversity is not assembled at random, and that sponge-associated polychaete communities are composed of taxonomically related species. These results support the statement that polychaete assemblages inhabiting sponges are not a transient facultative assembly of species, but rather stable, diverse and specialized communities which are well adapted for life in this habitat.

Polychaete Diversity Related to Different Mesophotic Bioconstructions along the Southeastern Italian Coast

In the different mesophotic bioconstructions recently found along the Southeastern Italian coast, polychaetes have been proved to show high species richness and diversity, hitherto never investigated. In the present study, the species composition and functional role of polychaete assemblages were analysed; the updated key to identification of the Mediterranean species of genus Eunice was presented and some taxonomic issues were also discussed. On the total of 70 species Serpulidae and Eunicida were the dominant polychaetes. Facing similar levels of α-diversity, the polychaete assemblages showed a high turnover of species along the north-south gradient, clearly according to the current circulation pattern, as well as to the different bioconstructors as biological determinants. Indeed, Serpulidae were dominant on the mesophotic bioconstructions primarily formed by the deep-sea oyster Neopycnodonte cochlear, while the Eunicida prevailed on the mesophotic bioconstructions mainly built by scleractinians. Lastly, the record of Eunice dubitata was the first for the Mediterranean and Italian fauna and proved this species to be characteristic of mesophotic bioconstructions.