Distribution Patterns Of Polychaetes Research Articles

Description of the new species Sigambra nkossa (Annelida, Pilargidae), with an analysis of the distribution patterns of polychaetes associated with artificially hydrocarbon-enriched bottoms.

The monitoring of the N’Kossa offshore oil and gas fields in the Republic of Congo allowed us to assess the ecological traits of two polychaete species belonging to Sigambra (Annelida, Pilargidae). Sigambra parva occur in very low densities in all bottoms, except the most impacted, where it is totally absent; it is an undescribed species that reached >4,000 ind/m2 in hydrocarbon-enriched sediments. Their distribution patterns are compared with those of other polychaetes, showing a range of affinities for hydrocarbon-enriched sediments in the N’Kossa region. Our results suggest that S. parva would be a representative of the original local fauna, while the species associated with artificial hydrocarbon-enriched sediments, including the other Sigambra, six more polychaetes and a bivalve, could be natively associated with natural hydrocarbon-enriched sediments, using the former as alternative habitats and as dispersal stepping stones. This ecological segregation, together with a careful morphological and morphometric analyses led us to describe the latter as a new species, namely Sigambra nkossa sp. nov. Moreover, morphometric analysis allowed us to discuss on the taxonomic robustness of the key morphological characters of S. nkossa sp. nov., as well as to emend the generic diagnosis of Sigambra to accommodate the new species.

Correlation between rocky reefs and surrounding benthic habitats: Distribution and diversity patterns of polychaetes in the macrobenthic community in the East Sea of South Korea

The movement of animals and materials among habitats can affect community structure. Subtidal rocky reefs are important in the productivity, food web, recruitment, and behavior of benthic animal communities and fish. We investigated how rocky reefs influence the composition and abundance of benthic species in the East Sea of Korea. In total, 157 species of macrobenthic fauna were collected, of which 56 were polychaetes, 49 were crustaceans, and 33 were mollusks. Polychaetes constituted the dominant taxon and accounted for 55% of the average density of the macrobenthos. The sediment around the rocky reef comprised mainly coarse-grained particles, and was dominated by suspension-feeding polychaetes. Cluster analysis divided the macrobenthic community into three groups, which were correlated with the distribution of polychaete species. The canonical correspondence analysis showed that sediment composition is an important variable in polychaete distribution patterns. This study suggests that polychaetes are a representative taxon around subtidal rocky reefs, and changes in sediment type is a key factor influencing the characteristics of polychaete communities.

Biogeography of polychaete worms (Annelida) of the world

The global biogeography of polychaete worms has never been assessed previously. In the present study, we studied the world distribution patterns of polychaetes based on datasets obtained from the Global Biodiversity Information Facility, the Ocean Biogeographic Information System and our recently published checklist of Indonesian polychaete species. Polychaete biogeographic regions were visualized using ‘Infomap Bioregions’, and the latitudinal species richness gradient of the animals was examined using 3 metrics, i.e. alpha, gamma and estimated species richness (the last metric was adjusted for sampling bias). We identified 11 major polychaete biogeographic regions. The North Atlantic, Australia and Indonesia were the top 3 species-rich biogeographic regions in the world. The total number of polychaete species was higher in the southern hemisphere (~2100 species, 67 families) than in the northern hemisphere (~1800 species, 75 families) despite significantly more data in the latter (>500000 records compared to >26000 records). Contrary to the classical idea of a unimodal distribution pattern, the latitudinal gradient of polychaetes was generally bimodal with a pronounced dip north of the Equator (15°N). We suggest that the slightly higher peak of species richness in the southern (30°S) than in the northern (60°N) hemisphere reflects higher southern endemicities. These patterns are unlikely to be due to sampling bias but rather represent a natural phenomenon, and we found them most significantly correlated with sea temperature.

Macrobenthos at marine hotspots along the northwest Indian inner shelf: Patterns and drivers

Marine hotspots are areas prioritized for conservation and monitoring, based on their sensitivity or vulnerability. Understanding the natural variability of resident organisms in such critical areas is integral for deciphering human-induced perturbations to formulate appropriate management strategies. Five marine hotspots along northwest India, comprising three active harbours and two marine protected areas, were surveyed seasonally to understand the macrofaunal distribution patterns and functional traits. Among the 33 macrobenthic taxa, Polychaeta constituted the dominant taxon. Spatial variability was prominent due to differences in terms of polychaete species types, relative abundances and functional trait matrices. Monsoonal hypoxia altered the macrobenthic species and functional composition. CCA revealed a combination of natural (texture, DO, salinity) and anthropogenic (PHc, SS, ammonia) hydro-sedimentological variables as key drivers for the polychaete distribution patterns. The results are expected to improve the understanding of the variability and functioning of polychaete taxocommunity within the ecologically and economically significant “marine hotspots”.

Shallow-water polychaete assemblages in the northwestern Mediterranean Sea and its possible use in the evaluation of good environmental state

Sarda, R., Serrano, L., Labrune, C., Gil, J., March, D., Amouroux, J.M., Taboada, S., Bonifacio, P. and Gremare, A. 2014. Shallow-water polychaete assemblages in the northwestern Mediterranean Sea and its possible use in the evaluation of good environmental state. Memoirs of Museum Victoria 71: 289–301. Forty-four shore-normal transects along the Northwestern Mediterranean coast between the mouth of the Rhone River (France) and Valencia City (Spain) were sampled during the REDIT-I (September 1998, [R1]) and REDIT-II (December 1999, [R2]) campaigns. Polychaete distribution patterns on shallow littoral fine sands (10 to 50 m water depths) were analyzed at a regional scale. A total of 359 species of polychaetes were identified which represents 38% of all polychaete species recorded in the western Mediterranean. Four main soft-bottom communities were identified from the samples in the area: Littoral Fine Sands, Littoral Sandy Mud, Terrigenous Coastal Mud and Detritic Sand. Predominantly sandy environments were characterized by Ditrupa arietina and Owenia fusiformis while Lumbrineris latreilli, Hilbigneris gracilis and Sternaspis scutata were numerically dominant in muddy environments. Biological diversity assessments at different temporal and spatial scales are required by the European Marine Strategy Framework Directive (2008/56/EC) in accordance with criteria and methodological standards of Good Environmental Status (GEnS). Selected indicators for descriptors are explored based on this mesoscale assessment.

A meta-analysis approach to the effects of fish farming on soft bottom polychaeta assemblages in temperate regions

Marine fish farms could cause environmental disturbances on the sediment due to uneaten food and fish faeces that impact the marine benthos. Polychaete assemblages are considered good indicators of environmental perturbations. The present study aimed to establish groups of polychaetes as potential indicators of fish farm pollution. This study was carried out in ten fish farms along the Spanish coast. Changes in polychaete assemblage were analyzed with meta-analysis and multivariate techniques. Abundance, richness and diversity showed significant decreases under fish farm conditions. Distribution patterns of polychaetes responded to combinations of physicochemical variables. The main ones are sulfide concentration, silt and clays percentage, and stable nitrogen isotope ratio. The results showed that some families are tolerant, Capitellidae, Dorvilleidae, Glyceridae, Nereididae, Oweniidae and Spionidae; while others are sensitive to fish farm pollution, Magelonidae, Maldanidae, Nephtyidae, Onuphidae, Paralacydoniidae, Paraonide, Sabellidae and also Cirratulidae in spite of being reported as a tolerant family.

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 2000m about 30% polychaete species have wide distributional ranges.

Community structure and diversity of polychaetes (Annelida) in the deep Weddell Sea (Southern Ocean) and adjacent basins

During the austral summer of 2005, the Weddell deep sea and adjacent basins were sampled in the course of the ANDEEP III project. In this study, 19 epibenthic-sledge stations are analyzed, with a focus on species diversity and distribution patterns of polychaetes. The polychaete fauna of the deep Southern Ocean has been found to be similarly speciose and diverse compared with deep-sea basins worldwide. Also, in depths below 2,000 m many polychaete species do not seem to be endemic for certain areas but are rather far spread within the Southern Ocean and beyond. Therefore, ongoing faunal exchanges between adjacent basins, even beyond the Antarctic convergence, are strongly suggested, ruling out a general isolation of the Southern Ocean deep-sea benthos. Driving forces behind species distribution patterns were investigated. The findings indicate that polychaete species’ distribution in the Southern Ocean deep sea is rather dependent on local environment than depths.

Impact of the changing ecology on intertidal polychaetes in an anthropogenically stressed tropical creek, India

Polychaete assemblages and associated environment of 12 strategically selected intertidal stations along the extremely polluted Thane creek on the west coast of India were studied monthly for a year and compared with past available data to investigate changes in the creek ecology due to various anthropogenic activities like industrial, domestic, and solid waste disposal along with land reclamation. Shannon’s index (H′) varied spatially from 0.4 to 1.5, Margalef richness index (d) from 0.4 to 1.1, and evenness index (J) from 0.3 to 0.7 indicating poor polychaete diversity. Ceratonereis burmensis and Lycastis indica were the most abundant and omnipresent polychaetes in the creek indicating their tolerance and adaptability to various degrees of pollution. Hydro-sedimentological investigations revealed enhancement of total nitrogen (TN) and organic carbon (Corg) load and hypoxic levels of dissolved oxygen (DO) over the years. Silt component of sediment was increasing, with proportionate decrease in clay due to various anthropogenic disturbances. Species richness was correlated positively with clay and negatively with silt. The BIO-ENV analyses indicated the strong influence of NO3−-N, clay and TN on the distribution patterns of polychaetes. Pollution-tolerant polychaetes like Lycastis ounaryensis and Polydora tentaculata were getting replaced by more pollution-resistant species like C. burmensis in the creek due to changing sediment texture, reduced oxygen levels, and increased Corg and TN.

Sewage impact on the composition and distribution of Polychaeta associated to intertidal mussel beds of the Mar del Plata rocky shore, Argentina

The polychaete composition and distribution within mussel beds were studied in order to assess organic pollution due to domestic sewage in a rocky shore of Mar del Plata (Argentina) during 1997. Four stations and a control site were randomly sampled around the local effluent. Quantitative data on polychaetes, as well as sediment accumulated among mussels and its organic carbon content were measured. Polychaete distribution patterns are related to the organic matter gradient, being Capitella cf. capitata, Neanthes succinea (Frey & Leuckart, 1847) and Boccardia polybranchia (Haswell, 1885) the dominant indicator species close to the effluent. At medial distances, the cirratulids Caulleriella alata (Southern, 1914) and Cirratulus cirratus (Müller, 1776) are very important in abundance. The syllids Syllis prolixa Ehlers, 1901 and S. gracilis Grube, 1840 are distributed along the study area, but dominate at the medial stations and at the control site. The orbiniid Protoariciella uncinata Hartmann-Schröder, 1962 is subdominant at the control station.

Distribution patterns and biogeographic analysis of Austral Polychaeta (Annelida)

Summary Aim We investigate the biogeography of Austral Polychaeta (Annelida) using members of the families Eunicidae, Lumbrineridae, Oenonidae, Onuphidae, Serpulidae and Spionidae and Parsimony Analysis of Endemicity (PAE). We determine whether observed polychaete distribution patterns correspond to traditional shallow‐water marine areas of endemism, estimate patterns of endemism and relationships between areas of endemism, and infer the biological processes that have caused these patterns. Location The study is concerned with extant polychaete taxa occupying shallow‐water areas derived from the breakup of the Gondwana landmass (i.e. Austral areas). Methods Similarity was assessed using a significance test with Jaccard's indices. Areas not significantly different at 0.99 were combined prior to the PAE. Widespread species and genera (155 taxa) were scored for presence/absence for each area of endemism. PAE was used to derive hypotheses of area relationships. Hierarchical patterns in the PAE trees were identified by testing for congruence with patterns derived from cladistic biogeographic studies of other Gondwanan taxa and with geological evidence. Results The polychaete faunas of four area‐pairs were not significantly different and the areas amalgamated: South‐west Africa and South Africa, New Zealand South Island and Chatham Islands, Macquarie Island and Antipodean Islands, and West Antarctica and South Georgia. Areas with the highest levels of species endemism were southern Australia (67.0%), South‐east South America (53.2%) and South Africa (40.4%). About 60% of species and 7.5% of genera occupied a single area of endemism. The remainder were informative in the PAE. Under a no long‐distance dispersal assumption a single minimal‐length PAE tree resulted (l=367; ci=0.42); under dispersal allowed, three minimal‐length trees resulted (l=278; ci=0.56). In relation to the sister grouping of the New Zealand areas and Australia we find congruence between our minimal‐length trees and those derived from a biogeographic study of land plants, and with area relationships predicted by the Expanding Earth Model. Main conclusions The polychaete distribution patterns in this study differ slightly from the classical areas of endemism, most notably in being broader, thereby bringing into question the value of using single provincial system for marine biogeographic studies. The Greater New Zealand region is found to be ‘monophyletic’ with respect to polychaetes, that is comprising a genuine biogeographical entity, and most closely related to the polychaete fauna of southern Australia. This finding is consistent with studies of land plants and with the Expanding Earth model, but disagrees with conventional geology and biogeographic hypothesis involving a ‘polyphyletic’ New Zealand. Both vicariance and concerted range expansion (=biotic dispersion) appear to have played important roles in shaping present‐day distribution patterns of Austral polychaetes. Shallow‐water ridge systems between the Australian and Greater New Zealand continental landmasses during the Tertiary are thought to have facilitated biotic dispersion.

Distribution of western beaufort sea polychaetous annelids

Depth and depth-related processes appear to exert primary control over the distributional patterns of species of polychaetous annelids in the western Beaufort Sea (Cape Halkett to Barter Island, Alaska). Species richness and total polychaete abundance are maximal along the outer continental shelf and upper continental slope. Stations exhibiting the most similar polychaete assemblages are located at similar depths. However, some species distributions appear to correlate better with sediment type than with depth. Maximum abundance occurs deeper on the continental slope to the west, and station clusters generated by non-hierarchical clustering (using the dominant polychaete species data) are not sorted strictly by depth. In a canonical analysis of discriminance, the station clusters were projected onto a two-dimensional plane in “species space”. The first and second canonical variables of the station clusters correlate with sediment grain-size distributions, suggesting a relationship between polychaete distribution patterns and the sedimentary environment. This relationship is further substantiated when sediment grain-size distributions for each station are plotted on a tertiary diagram: the stations are grouped and ordered in a pattern similar to that generated by the canonical analysis of discriminance.