Tube-forming polychaetes enhance invertebrate diversity and abundance in sandy sediments of Mozambique,Africa

In marine soft-bottom systems, polychaetes can increase habitat complexity by constructing rigid tubes (e.g. several onuphid species) that contrast with surrounding topographically flat sediments. These structures can provide predation refuges and increase larval settlement and thereby increase the richness and abundance of fauna. We collected invertebrate samples from an intertidal flat with low onuphid tube density (2.7 m^–2) in Mozambique and document that more organisms (70 times higher mollusc abundances) and more species (15 times more mollusc species) were found associated with solitary tubes of an onuphid polychaete compared with surrounding sand habitats. These results are in agreement with tube versus sand comparisons from soft-bottom systems in the North Atlantic where polychaete tube densities are often much higher.     

Polychaete tubes create ephemeral community patterns: Lanice conchilega (Pallas, 1766) associations studied over six years

On intertidal sandflats spatial patterns of benthic communities are influenced by biogenic habitat structures such as mussel beds or seagrass meadows. These structures represent ecological islands hosting a different and often more diverse and abundant community than surrounding sandflats. However, few studies have been carried out on tube aggregations of the polychaete Lanice conchilega, although its tube tops are conspicuous habitat features on European intertidal coasts with densities reaching several thousand per m².The aim of this study was to determine differences between benthic communities associated with tube aggregations and tube-free areas, and to investigate the longevity of community patterns around L. conchilega tubes. From 1995 to 2000, the L. conchilega population of an intertidal sandflat off the Eastern Friesian coast was sampled annually. Multivariate analysis showed significant differences between the L. conchilega and reference communities. Species diversity and abundance were higher among tube aggregations. This pattern developed rapidly after L. conchilega colonisation but was also readily destroyed, mainly due to dynamic changes of the L. conchilega population.Five species of benthic macrofauna were exclusively found among L. conchilega tubes, and four species were more abundant in tube aggregations than in reference areas. Only one species, the polychaete Aphelochaeta marioni, was found in lower numbers in dense L. conchilega aggregations.Hence, it is concluded that L. conchilega is a habitat engineer, which alters the composition of the benthic community and contributes to its patchy distribution pattern. However, this pattern is dynamic and ephemeral. Effects of tube aggregations depend on the population dynamic of L. conchilega itself and the species composition in the surrounding sands.     

Note on an invasion of intertidal zoanthid colonies by a chaetopterid polychaete at Park Rynie Beach,KwaZulu-Natal,South Africa

At Park Rynie Beach on the KwaZulu-Natal coast, South Africa, four species of zoanthids were invaded by a sand-tube building polychaete Mesochaetopterus minutus. It is a small polychaete about 15 mm long, which occurs gregariously in dense masses of sandy tubes. M. minutus is an opportunistic species that exploits zoanthid colonies mainly for support and protection from heavy wave action because of the inability of the fragile sandy tube to survive in exposed habitats. Population density studies of the polychaete were undertaken to quantify the degree of invasion of the different zoanthid species. Highest polychaete density was recorded for Zoanthus sansibaricus, the number of polychaetes exceeding 3 500 m^?2, followed by Palythoa nelliae, with a density of 2 200 m^?2. Polychaete densities were comparatively low in Z. durbanensis and Z. natalensis (<1 000 m^?2). No polychaete tubes, however, were seen among the polyps of Isaurus spongiosus.     

Spatial Overlap and Coexistence in a Mussel-Associated Polychaete Assemblage on a South American Rocky Shore

Abstract. Mussel beds in the intertidal of subtropical South America are known to harbour a large number of invertebrates, particularly polychaetes. This paper presents a quantitative analysis of the patterns of spatial overlap and coexistence in an assemblage of polychaetes associated with mussel beds in a rocky intertidal habitat on the Pacific coast of Peru. Mussel beds are made up of two zones in the intertidal: the lower, more extensive zone formed by Semimytilus algosus and the upper zone formed by Perumytilus purpuratus . Null models were employed to assess the magnitude of spatial overlap between pairs of taxa encompassing a total of seven taxonomic groups. Two taxa belonging to the same functional group tended to be spatially segregated in the Semimytilus bed: Pseudonereis vs. Halosydna (large free-ranging predators) and Scoloplos vs. Mediomastus (deposit feeders), with further segregating tendencies between Pseudonereis and Mediomastus , and between Halosydna and Scoloplos . Small-sized, free-ranging ' Typosyllis ' and the bottom-dwelling scavenging predator Lumbrineris were also spatially associated. Thus, this polychaete assemblage appears to be loosely organised around groupings of taxa which are somewhat different in ecological traits and form mosaic patterns of distribution with reduced overlap within the Semimytilus bed. These relationships were weak to non-existent in the upper, drier Perumytilus habitat where polychaete density was low.     

Impact of a combined sewer overflow on the abundance,distribution and community structure of subtidal benthos

A biological survey of the subtidal fauna near an intertidal combined sewer overflow (CSO) discharging into Puget Sound, Washington, USA, was conducted during April and May, 1977. The purpose of this study was to determine the effect of the CSO on the surrounding marine invertebrate communities.The shallowest subtidal sites studied (9 m below MLLW) appeared to be more affected by the CSO than deeper sites (13 and 24 m below MLLW). The subtidal area affected, as reflected in the levels of organic material, heavy metals and pesticides in the sediments, as well as the composition of the benthic macrofauna, appeared to be highly localised. The numerically dominant species at sites closest to the CSO was the polychaete Capitella capitata while the abundance of the bivalve Axinopsida serricata increased with distance from the CSO.Burrowing deposit feeders were the numerically dominant polychaete feeding type at sites nearest the CSO. Surface deposit feeders were more abundant at sites farther from the CSO, perhaps due to reduced sedimentation rates.Site-classification analyses indicated that sites adjacent to the CSO were more similar to one another than to sites which were farther away and apparently less affected.The positions of the sites along the first three principal component ordination axes were significantly correlated with depth and volatile organics (traceable to the CSO) in the sediments.     

Preliminary data on the composition and distribution of polychaetes in the deep-water areas of the north-western part of the Sea of Japan

During the SoJaBio expedition, the deep sea fauna of the north-western Sea of Japan was sampled in August–September 2010. From this study, 11 epibenthic sledge stations are analyzed, with a focus on species composition, diversity and distribution patterns of polychaetes. A total of 92 polychaete taxa belonging to 70 genera and 28 families and 3 indeterminate species were found. Twelve species and eight genera have not been reported from the Sea of Japan before, but were registered from other deep-sea basins. Calculation of diversity (Shannon–Wiener Index, Pielou's Evenness) showed that the upper bathyal of the Sea of Japan is an area of higher polychaete diversity than the abyssal plain. The increased richness and diversity here could possibly be explained by a zoogeographic overlapping with the shallower species' assemblages of the shelf. At a higher taxonomic level the polychaete fauna of the deep Sea of Japan does not seem to differ from that of other deep-sea regions world-wide. In depths below 2000 m about 30% polychaete species have wide distributional ranges.     

Difficulties in separating hurricane induced effects from natural benthic succession: Hurricane Isabel,a case study from Eastern Virginia,USA

Hurricane Isabel reached the Eastern seaboard of North America on 18 September 2003 causing estimated damage >3 billion US dollars and the death of ∼50 people. Isabel is considered to be one of the most significant tropical cyclones to affect Virginia, since the Chesapeake Potomac Hurricane of 1933 and Hurricane Hazel in 1954. A study of the temporal changes in the benthic fauna pre- and post-hurricane was conducted on an intertidal sandflat within the dynamic barrier island system near Wachapreague, Eastern Virginia. Replicate sediment cores were collected 3 weeks before Isabel made landfall and further samples were collected on 5 occasions over the following 20 months. An immediate effect of Isabel was a doubling in the number of species, a significant increase in invertebrate species diversity (H′) and a rise in opportunistic species and deposit feeders, but a non-significant increase in the total number of organisms. Changes in infauna occurred such that by the end of the study there were significantly increased numbers of species, faunal abundances and community diversity measures, as compared with pre-hurricane samples, suggesting a potentially positive medium-term effect of this hurricane perturbation. The most notable direct effects of the hurricane were on the relative abundances of feeding guilds with a reduction in interface feeders from 87% pre-hurricane to 64% post-hurricane, and an increase in surface deposit feeders from 7% pre-hurricane to 20% post-hurricane. The study highlights potential problems in interpreting post-perturbation data when insufficient pre-perturbation data exist.     

Distribution patterns of macrobenthic fauna communities in Deukryang Bay,one of the environment conservation areas of Korea

Macrobenthic fauna were collected seasonally at 44 sites in Deukryang Bay from February to November, 2012. The species number of macrobenthic fauna was in the range of 140 to 181, and polychaetes comprised 41.4% of them. The average density of the whole study area changed seasonally from 755 to 1,507 ind. m^?2, and the most abundant fauna group was crustaceans which accounted for 55.1% of total abundance. An amphipod species Nippopisella nagatai was the most dominant species and a decapod species Xenophthalmus pinnotheroides, an amphipod species Photis longicaudata, and a polychaete species Paralacydonia paradoxa were also dominant in all seasons. The mean seasonal values of Shannon’s diversity index (H′) were in the range of 2.2–2.4, and those values for the evenness index and richness index were 0.7–0.7 and 4.6–5.7, respectively. From the cluster analysis, Deukryang Bay could be divided into 3 or 4 station groups with its specific fauna composition. The cluster analysis and an nMDS ordination revealed that local environmental factors such as water depth were related to the spatial delineation of macrobenthic fauna communities in Deukryang Bay.     

Succession patterns of polychaetes on algal‐dominated rocky cliffs (Aegean Sea,Eastern Mediterranean)

Ecological succession has been scarcely investigated on sublittoral rocky cliffs. The few relevant studies deal with the structure of the developing community and are limited to higher taxa or sessile forms. The objective of the present study was to examine succession patterns on algal‐dominated rocky cliffs both at the structural (species composition) and functional (feeding guild composition) level, using Polychaeta, a dominant taxon in this marine habitat, as a reference group. Cement panels were seasonally installed on the rocky substratum (25–30 m depth) and sampled every 3 months over a 1‐year period. Twenty‐nine polychaete species were recorded, previously reported from the surrounding benthic community, and classified into eight feeding guilds. Most species were assigned as sessile filter‐feeders; this guild dominated in abundance and biomass. A strong effect of the length of immersion and of the seasonal onset of succession on the developed communities was assessed: species composition analyses suggested convergence into a similar organization as succession proceeds, whereas the impact of starting season on succession was stronger when analysing feeding guilds. In both cases succession was faster on panels installed in winter. The main emerging patterns were in agreement with relevant surveys of the entire benthic fauna, thus supporting the efficacy of polychaetes as a surrogate group for studying ecological succession in the benthic marine environment.     

Impact of Biodeposition on Macrofaunal Communities in Intertidal Sandflats

Abstract. This investigation deals with the changes in macrofaunal communities in intertidal sandflats caused by the input of organic material via biodeposition produced by mussel beds. The area of investigation was the back barrier tidal flat system behind the East Frisian Island of Spiekeroog. Due to erosion by the ebb current a plume of biodeposits extended from an area of mussel beds ( Mytilus edulis ) towards the adjacent sandy sediments. This plume represented a gradient of decreasing contents of organic material. Five stations were installed along this gradient to analyse the effects of this organic input on the macrofaunal communities; a control station was placed on sandy sediments.
The macrofaunal communities differed along the transect. In the mussel patches oligochaetes dominated, whereas deposit-feeding polychaetes increased along the transect. These polychaetes were different from the communities of the sand flats. The changes in the macrofaunal communities discussed in the framework of the organic carbon contents of sediments and interspecific relationships.
After a cover of green algae during summer and after a cold winter, the mussels were almost completely eliminated from the area of investigation and reaggregated in another area of the flat. The layer of biodeposits eroded as well. After the decrease in contents of organic matter, the macrofaunal communities no longer followed the transitional distribution but showed a diffuse and seasonally influenced distribution.
The results indicate that biodeposits changed the quality of the sediment structure of the sand flats and that the amount of organic matter (TOC) is a main structuring factor for the macrofaunal communities.     

厦门地区软相潮间带多毛类的生态

根据厦门地区１９９０年２月至１９９２年１月调查软相潮间带所获资料，研究了该区多毛类的种类组成，数量与分布，结果表明，该区多毛类种类丰富，共鉴定出１１８种，隶属于３７科８３属。其中，高潮区４０种，中潮区９０种，低潮区８３种。多毛类平均栖息密度８７个／ｍ＾３，平均生物量３．３３ｇ／ｍ＾２。     

Structure of subtidal and intertidal communities of psammophilous ciliates of the Pechora Sea

A rich and diverse bottom ciliate fauna (168 species) was observed in the course of the studies of the subtidal and intertidal zones of the Pechora Sea; 81 of them were encountered for the first time in the Barents Sea region. As compared to the intertidal fauna, the sublittoral ciliofauna featured a higher species diversity but a lower total abundance (32.6 and 20.7 species per station and 10–100 and 2.4–443 ind./cm² in the subtidal and intertidal zones, respectively). With respect to trophic strategies, raptorial feeders were most abundant in the sublittoral zone (up to 77% of the total biomass), while both raptorial feeders (45%) and upstream filter feeders (36%) dominated in the littoral sediments. In the subtidal zone, two different types of ciliate communities were distinguished according to their total abundance and species composition. The first type is represented by abundant and species-rich communities mainly dominated by large specific interstitial ciliates developed over fine-grained well-sorted sands. The second type of communities joins mainly nonspecific eurybiotic ciliates dwelling over heterogeneous silty sediments; they feature lower abundance and species richness values. The high species diversity, the low abundance or absolute absence of meso-and polysaprobic groups indicating organic pollution, and the high values of the ABC size structure index suggested a good condition of the sediments and biota in the region studied.     

Comparative study on the fauna composition of intertidal invertebrates between natural and artificial substrata in the northeastern coast of Jeju Island

This study was carried out to learn about differences in the sessile macrobenthic fauna communities between the artificial and natural habitats. There were some differences in terms of species composition and dominant species and community structure between two habitat types. The dominant species include Pollicipes mitella and Granuilittorina exigua in natural rocky intertidal zones; Monodonta labio confusa, Ligia exotica, Tetraclita japonica in the artificial rocky intertidal zones. Among all the species, L. exotica and T. japonica occurred only in the artificial rocky intertidal zone. The results of cluster analysis and nMDS analysis showed a distinct difference in community structure between artificial and natural rocky intertidal zones. The fauna in the natural rocky intertidal zones were similar to each other and the fauna in the artificial rocky intertidal zones were divided depending on the slope of the substratum. In the case of a sloping tetrapod, M. labio confusa and P. mitella were dominant, but at the vertical artificial seawall, Cellana nigrolineata, L. exotica T. japonica were dominant. The analysis of the species presented in natural and artificial rocky intertidal areas showed the exclusive presence of 10 species on natural rocks and 12 species on artificial rocks. The species in the natural rocky intertidal area included mobile gastropods and cnidarians (i.e. rock anemones), and the species in the artificial rocky intertidal area mostly included non-mobile attached animals. The artificial novel structure seems to contribute to increasing the heterogeneity of habitats for marine invertebrate species and an increase the species diversity in rocky coastal areas.     

Distribution patterns of interstitial polychaetes in sandy beaches of southern Brazil

This study describes the distribution patterns of interstitial polychaetes along morphodynamic gradients on six exposed sandy beaches in Santa Catarina and Paraná (South Brazil). Three random transects were sampled at two points on each beach, one at the swash and another at the surf zone, in winter and summer conditions. Six sediment replicates were collected at each sampling point using a corer of 4.6 cm internal diameter that removed 10 cm into the sediment. Abundance and composition of interstitial polychaete were correlated to wave height, slope, grain size, CaCO₃, chlorophyll a , omega indexes, temperature and relative tide range using a canonical correspondence analysis (CCA). A factorial ANOVA showed that taxa richness, mean density and Shannon's diversity were significantly higher at the reflective beaches, but average values differ significantly between transects and these differences change according to the beach zones on both sampling dates. PERMANOVA showed that polychaete associations differ among transects according to the beach zones. The composition of interstitial polychaete associations was significantly correlated to beach morphodynamics and features (P < 0.01). Polychaete associations of reflective beaches were more diverse than in other morphodynamic states. Intermediate beaches may also sustain diverse associations due to temporal variability of the morphodynamic patterns. Beaches presenting extreme dissipative morphodynamics and compacted sediments appear to be unfavourable for the occurrence of interstitial polychaetes.     

Polychaete taxocenes variability associated with sediment pollution loading in the peter the great bay (the East Sea/Japan Sea)

Variations in species diversity and abundance of polychaete taxocenes that occurred in 1980–1989 under different contamination levels of bottom sediments were studied in three areas of Peter the Great Bay. The most polluted area was shown to be the Golden Horn Inlet where contaminant contents in the bottom sediments exceed the threshold values of negative biota alterations. Amursky Bay is characterized by a moderate level of contamination, while Ussuriysky Bay has the lowest level of contamination. Pollutant contents vary considerably within the same areas and their separate patches are polluted differently. An integral index characterizing the contamination of bottom sediments is proposed. This index is an average grade of the rank value of contaminant contents in sediments. The index was used to compare the contamination level and data on polychaete species diversity and abundance. The highest species diversity of polychaetes is found in the least affected zones. Monotonous decrease of the species number, as well as decrease in the indices of diversity and evenness, is correlated with pollution level increases. Significant growth of the average polychaete biomass and polychaete density is observed in the case of an increase of contamination from low to moderate levels. Conversely, the biomass and abundance of polychaetes decline following an increase in contamination.     

Experimental evidence of habitat provision by aggregations of Riftia pachyptila at hydrothermal vents on the East Pacific Rise

Habitat created or modified by the physical architecture of large or spatially dominant species plays an important role in structuring communities in a variety of terrestrial, aquatic, and marine habitats. At hydrothermal vents, the giant tubeworm Riftia pachyptila forms large and dense aggregations in a spatially and temporally variable environment. The density and diversity of smaller invertebrates is higher in association with aggregations of R. pachyptila than on the surrounding basalt rock seafloor. Artificial substrata designed to mimic R. pachyptila aggregations were deployed along a gradient of productivity to test the hypothesis that high local species diversity is maintained by the provision of complex physical structure in areas of diffuse hydrothermal flow. After 1 year, species assemblages were compared among artificial aggregations in low‐, intermediate‐, and high‐productivity zones and compared to natural aggregations of R. pachyptila from the same site. Hydrothermal vent fauna colonized every artificial aggregation, and both epifaunal density and species richness were highest in areas of high chemosynthetic primary production. The species richness was also similar between natural aggregations of R. pachyptila and artificial aggregations in intermediate‐ and high‐productivity zones, suggesting that complex physical structure alone can support local species diversity in areas of chemosynthetic primary production. Differences in the community composition between natural and artificial aggregations reflect the variability in microhabitat conditions and biological interactions associated with hydrothermal fluid flux at low‐temperature hydrothermal vents. Moreover, these local ecological factors may further contribute to the maintenance of regional species diversity in hydrothermal vent communities on the East Pacific Rise.     

Managerial decisions as experiments: an opportunity to determine the ecological impact of boat-generated waves on macrobenthic infauna

A previous correlative study showed that assemblages of macrobenthic infauna and abundances of common taxa on intertidal mudflats differed between a no-wash zone, where ferries had to minimize production of wash, and places where the production of wash was unrestricted (wash zone). This suggested that boat-generated waves (wash) are important in determining the structure of these assemblages. Causality between wash and the observed patterns could not, however, be unambiguously established, due to the absence of ‘before’ data. Here, a managerial decision to stop ferry services on the upper Parramatta River, Sydney, Australia during the 2000 Olympics was used as the basis for a manipulative experiment to examine the effects of changes in the amount of wash on these fauna. It was hypothesized that if wash is important in structuring infaunal assemblages, assemblages in the wash zone would become more similar to those of the no-wash zone following removal of the disturbing force, i.e. the ferry service. Similarly, if the smaller abundances of capitellids, nereids and spionids in the wash zone are caused by this disturbance, abundances should increase in the wash zone during the stoppage and decrease following the return of services. As hypothesized, assemblages within the wash zone became more similar to those of the no-wash zone following the temporary removal of the ferry services. Following the return of ferries, assemblages changed back towards (although not reaching) their previous state. Abundances of the polychaete families Nereididae, Capitellidae and Spionidae also increased at some sites during the cessation, although this pattern was not found in all sites and there was no general response to the cessation of wash as had been predicted. These results indicate that wash is important in structuring assemblages of macrobenthic infauna, although responses of individual taxa are more idiosyncratic. More importantly, they show that manipulations, resulting from managerial decisions, can be treated as testable hypotheses and utilized by scientists as experiments to test for causal relationships.     

Meiobenthic communities of seagrass beds (Zostera capricorni) and unvegetated sediments along the coast of New South Wales,Australia

Seagrass beds have higher biomass, abundance, diversity and productivity of benthic organisms than unvegetated sediments. However, to date most studies have analysed only the macrofaunal component and ignored the abundant meiofauna present in seagrass meadows. This study was designed to test if meiobenthic communities, especially the free-living nematodes, differed between seagrass beds and unvegetated sediments. Sediment samples from beds of the eelgrass Zostera capricorni and nearby unvegetated sediments were collected in three estuaries along the coast of New South Wales, Australia. Results showed that sediments below the seagrass were finer, with a higher content of organic material and were less oxygenated than sediments without seagrass. Univariate measures of the fauna (i.e. abundance, diversity and taxa richness of total meiofauna and nematode assemblages) did not differ between vegetated and unvegetated sediments. However multivariate analysis of meiofaunal higher taxa showed significant differences between the two habitats, largely due to the presence and absence of certain taxa. Amphipods, tanaidacea, ostracods, hydrozoans and isopods occurred mainly in unvegetated sediments, while kinorhyncs, polychaetes, gastrotrichs and turbellarians were more abundant in vegetated sediments. Regarding the nematode assemblages, 32.4% of the species were restricted to Z. capricorni and 25% only occurred in unvegetated sediments, this suggests that each habitat is characterized by a particular suite of species. Epistrate feeding nematodes were more abundant in seagrass beds, and it is suggested that they graze on the microphytobenthos which accumulates underneath the seagrass. Most of the genera that characterized these estuarine unvegetated sediments are also commonly found on exposed sandy beaches. This may be explained by the fact that Australian estuaries have very little input of freshwater and experience marine conditions for most of the year. This study demonstrates that the seagrass and unvegetated sediments have discrete meiofaunal communities, with little overlap in species composition.     

泉州湾及其附近海域底栖多毛类生态的初步研究

本文用2001-2002年泉州湾及其附近海域综合调查中获得的底栖多毛类资料,探讨该海域多毛类的组成、数量分布及与环境因子的关系.共鉴定出该海域多毛类68种,多数属亚热带海区常见种,其中双鳃内卷齿蚕为主要的优势种.多毛类年平均栖息密度和生物量分别为56个/m^2和1.11 g/m^2,数量分布不均匀,下洋附近海域为主要的高栖息密度和高生物量区.沉积物类型显著影响多毛类的数量分布,而底层海水的温度和盐度对其也有一定的影响.