Heteromastus Filiformis Research Articles

인천연안 대형저서동물 군집 변동에 미치는 환경요인의 영향

In coastal area of Inchon, dredging and the disposal of dredged material for sea-wall construction and reclamation have increased in recent years. These activities may impact the benthic environment and result in changes in benthic communities, but little information is available on the extent and direction of these changes. We investigated whether there have been changes in the dominant macrobenthic species and benthic community over the last decade, and explored the relationship between environmental variables and spatial patterns of macrobenthic community structure. We sampled macrobenthos and recorded environmental variables in the coastal habitats of Inchon in March and June 2004. In total, 212 macrobenthic species were recorded during this study, predominately crustaceans , mollusks and polychaetes . The mean density of macrobenthos was .The most abundant species was Amphioplus japonicus , followed by Heteromastus filiformis , Theora fragilis and Ampharete sp. . Over the past decade the dominant macrobenthic species in this area shifted. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure among three regions: the middle part of the sampling area (B), site 8 (C) and other sites (A). Mean density varied significantly among the three regions, but no differences in the number of species and diversity (H`) were observed. The distribution of the macrobenthic community was affected by environmental variables such as percentage sand content and sediment kurtosis. Species that were important in different areas included A. japonicus in region A, Raeta puchella in region B and T. fragilis in region C. The important species in regions B and C were filter-feeding bivalves, and the abundance of these species may be related to the increase in percentage sand content. We suggest that the sediment composition (percentage sand content) may be an important factor in determining the dominant species and structure of the macrobenthic communities in coastal Inchon. Long-term monitoring programs are necessary to understand ongoing changes in the benthic communities of this area.

이원방조제 주변의 조간대 및 조하대 대형저서동물의 군집과 환경요인과의 관계

Spatial patterns in the macrobenthic community structure in the inter- and subtidal zones in front of the Iwon Dike and environmental variables were examined in August 2001, In total, 156 macrobenthic species(123 intertidal species and 90 subtidal species) were recorded during this study, predominately polychaetes , bivalves , and crustaceans . Polychaetes made up less than of the intertidal communitr, but more than of the subtidal community. The mean density during this study was Multivariate analysis (multidimensional scaling) revealed significant differences in community structure among four regions: near the Iwon dike (B1), the high and middle intertidal zone (B2), low intertidal zone (Al), and subtidal zone (A2). The number of species, total density, and diversity (H`) varied significantly among the four regions. The distribution of macrobenthic community was affected by environmental variables, such as silt/clay content, total sulfide, lose of ignition, and chemical oxygen demand. These environmental variables were negatively correlated with the dominant species (Nephtys polybranchia, Umbonium thomasi, and Scoloplos armiger) in the intertidal area, but positively correlated with the dominant species (Lumbrineris cruzensis, Notomastus latericeus, and Moerella sp.) in the subtidal area. Environmental variables were positively correlated with the dominant species (Heteromastus filiformis) in region Bl, but negatively correlated with the dominant species (Umbonium thomasi and Scoloplos koreanus) in region B2. Amphipods Urothoe spp. and Monoculodes koreanus were the dominant species in region Al. Umbonium thomasi, the dominant species in region B2, was not found in regions Bl or Al. We suggest that the inter-specific competition for territory and exposure to seawater may be important factors controlling the macrobenthic community structure in the inter- and subtidal zones in front of the Iwon Dike.

Spatial pattern indicates an influence of barnacle and ascidian aggregations on the surrounding benthic assemblage

Joint clusters of solitary ascidians Styela spp., Bolthenia echinata (L.), Molgula spp. and barnacles Balanus crenatus Bruguiere in the White Sea subtidal often develop on shells or stones partially buried into muddy sediment. To assess the structuring role of these suspension-feeders' aggregations, we examined the spatial patterns of the surrounding infaunal assemblage. Pairs of cores obtained close to clusters (Close ones) and 20–25 cm away from them (Distant ones) were compared, the distance corresponding to the average distance observed between aggregations. These pairs were spatially grouped in replicas (blocks) tens of meters from each other. Out of 10 dominating invertebrate species found around the clusters (84 in total), 5 demonstrated significant difference in density ( N) close to aggregations and between them. All the five, including polychaets Scoloplos armiger (Muller, Orbiniidae), Aricidea nolani (Eliason, Paraonidae) , Heteromastus filiformis Zachs (Capitellidae), Chaetozone setosa Malmgren (Cirratulidae) and undetermined oligochaets, were associated with Close cores. Total abundance of polychaets, oligochaets, crustaceans and bivalves was also different in Close and Distant cores and indicated significant correlations (of either sign) with biomass estimates for barnacles and ascidians in each block. Individual mean body weight (IMW) in pairs of cores was different for 3 of 10 dominants, maldanid polychaets being larger close to clusters, and cirratulids being larger between them. For several taxa the difference, observed in both parameters ( N and IMW), significantly varied between the replicas. Filter-feeding activity and faeces production are regarded as the main possible factors explaining the effect of barnacles and ascidians presence, since the spatial pattern observed corresponds with feeding types of the infaunal taxa studied. Average distance between the clusters was short enough, which allows us to conclude that the spatial distribution pattern of benthic infaunal species within the research area strongly depends on barnacle and ascidian aggregations mosaic.

Soft-bottom macrobenthic faunal associations and factors affecting species distributions in an Arctic glacial fjord (Kongsfjord, Spitsbergen)

The Kongsfjord (west Spitsbergen) hosts the most active glacier on the island. Therefore the glacial impact on the marine ecosystem is very pronounced and easily recognisable. The study examines the influence of the steep glacier-derived environmental gradients on dominant macrofaunal species distributions and faunal associations in the fjord. The macrobenthic fauna was sampled by van Veen grab at 30 stations situated throughout the fjord (at depths 38–380 m). Two major communities were recognised. An inner basin receives the outflows from three glaciers and is occupied by a Glacial Bay Community dominated by small, surface detritus-feeders, with Chone paucibranchiata and a set of thyasirid and nuculanid bivalves (Thyasira dunbari, Yoldiella solidula, Y. lenticula) as characteristic species. An outer basin of the fjord is characterised by a common set of dominant species, including Heteromastus filiformis, Maldane sarsi, Levinsenia gracilis, Lumbrineris sp. and Leitoscoloplos sp. Three associations may be distinguished within the Outer Basin Community. Association TRANS is of transitional character, with Nuculoma tenuis and Terebellides stroemi. Association CENTR is the most typical for the community. It is dominated by tube-dwelling Prionospio sp., Clymenura polaris, Galathowenia oculata and Spiochaetopterus typicus. Association ENTR contains shelf benthos elements, e.g. Ophiura robusta and Lepeta caeca. An opportunistic eurytopic Chaetozone group is present throughout the fjord and its density and dominance increase with proximity to the glaciers. Dominant species distribution is discussed in relation to environmental factors, of which sediment stability, inorganic particle concentration, sedimentation rate and amount of organic matter in sediments are considered to be most important in structuring the communities.

Long-term changes in a Mediterranean benthic community: Relationships between the polychaete assemblages and hydrological variations of the Rhône River

Long-term changes in a macrobenthic, muddy community of the French Mediterranean coast, near the mouth of the Rhone River, were studied using 14 samples collected between 1963 and 1996 at 70-m depth. No drastic change in the community was observed over this time period. A factor correspondence analysis (FCA) performed with the most frequent polychaete species revealed that 3 sample groups were related to trends in the Rhone River discharge. Between 1965 and 1976, the effects of dumping events close to the study site acted in synergy with river drought leading to a drop in the abundance of the most common species of the community (e.g.,Sternaspis scutata). Floods were observed to be the main factor structuring the polychaete assemblages. These floods were subsequently followed, over a period of several years, by peaks of opportunistic species (Heteromastus filiformis, Prionospio cirrifera) and, with a time lag of 1 or 2 yr, by peaks ofS. scutata. Autumn and early winter floods were mainly the result of heavy rainfalls on the Mediterranean part of the drainage basin. They transported large amounts of mineral and particulate organic matter that increased the surface and subsurface deposit feeders assemblages. Late winter and spring floods originated from the north of the basin. They proportionally brought more dissolved material and were followed by developments of suspension and surface deposit feeders. Eutrophication of the area due to increased nitrate concentrations in the river is suggested to be responsible for the abundance, since the 1980s, of small-sized deposit feeders. There is a good parallel between the cumulative mean deviations of the river discharge and the quantity of soles caught in the area with a time lag of 4 yr between these two curves. These results may be of value to the management of the regional resources.

Population structure and secondary production of Heteromastus filiformis (Polychaeta: Capitellidae) in the Loire estuary, France

A survey was carried out from April 1998 to June 2000 to study the structure and the secondary production of the population of Heteromastus filiformis in the Loire estuary. Each month, samples were collected in the intertidal zone of Mindin harbour. The length of the thorax (L12) was correlated with the fresh weight (FW) with the relation FW=1·49848 L12–3·62804 (r=0·92). In 1999, the mean density was 2184 ind m−2 with a minimum of 1104 ind m−2 in December and a maximum of 3328 ind m−2 in March. The mean annual biomass was 15·4 g m−2 with a minimum of 2·6 g m−2 in December and a maximum of 28·2 g m−2 in March. Most of the histograms of size–frequency are unimodal and could be considered a single cohort except in May and November/December 1999. The abundance and biomass of the population of H. filiformis decreased during summer and winter which are mortality periods and increase during spring and autumn which are recruitment periods for the population. The life time for a cohort was from six to nine months depending on the recruitment period and on the inter-annual variations. The secondary production was estimated by the method of Crisp (1971). The annual secondary production in 1999 was P=104·3 g m−2 with B¯=15·4 g m−2 and P:B¯=6·8. The quantity of sediment reworked by H. filiformis is about 116 l m−2 y−1 or 65 kg m−2 y−1 which is approximately a deep-sediment layer of 12 cm transported to the surface annually.

외나로도 주변해역 퇴적물의 지화학적 특성과 저서 생물상

In order to evaluate the relationship between geochemical characteristics and benthic facies of the sediments from the Oenaro Island where red tide proliferation is first observed every year including this year, surface and short multiple core sediment samples were analyzed in terms of geochemical and benthic facies variation. The contents of organic carbon, carbonate, and sulfide gas were relatively low. The variation in C/N ratios, which indicate nature of organic carbon, suggested that the organic carbon recorded in the study area is composed of mixtures of marine and terrigenous organic matters. The concentration of minor elements found at the surface and multiple core sediment samples were also low as well as the enrichment factors(Ef) for the seven heavy metals indicated that the sediment of this area is not polluted significantly. The macrobenthic faunal community comprised 61 species, and their mean density was 708 ind./m2. Polychaete worms were major taxa of this benthic community. A crustacean amphipod, Melita sp. was the most abundant species accounted for 20.7% of total abundance, and the small polychaetes such as Heteromastus filiformis, Paralacydonia poradoxa, Magelona japonica and Sigambra tentaculata were the next dominant species. The macrobenthos around the Oenaro Island were more diverse and abundant than that in Gamak Bay. The benthic communities in the study area sustained somewhat different species composition based on the cluster analysis and the MDS ordination. The benthic community health condition at three stations seemed to be unbalanced, and slightly polluted based on the biological index such as BPI and BC. There was no clear relationship between the geochemistry characteristic and the benthic faunal facies attributed by the micro-algal blooms in this coastal area.

Biological mixing responses to sublethal concentrations of DDT in sediments by Heteromastus filiformis using a 137Cs marker layer technique

Sediment mixing by benthic macroinvertebrates is an important process affecting the fate of sediment-bound and dissolved contaminants in marine environments. A non-invasive, state- of-the-art radiotracer technique was used to study sediment mixing by Heteromastus filiformis (Capitellidae), a common marine head-down deposit feeder, exposed to several sub-lethal concen- trations of DDT (0, 5, 10 and 20 µg g -1 ; control, Treatments 1, 2 and 3). Several horizontal sub- millimeter layers of 137 Cs-labeled clay were deposited approximately every 2 cm in each of 3 repli- cate sediment columns per treatment; 4 polychaetes were then introduced to each column and the γ activity of each column was measured vertically using an automated scan detector. Nonlinear least- square fits were applied to obtain parameterized values that were used to determine the mixing rates of each 137 Cs layer over time. A simple diffusion model was used to calculate biological diffusion coef- ficients (Db) for H. filiformis. Overall mixing rates increased towards the surface. Control and Treat- ment 1 had higher Db values at the surface compared to Treatments 2 and 3. The Db depth profiles were similar in the control and Treatments 1 and 2, with mixing occurring at the sediment water interface and a subsurface maximum at 10 to 12 cm below this interface. This pattern was not clear in Treatment 3, where Db had the lowest values and decreased with depth. Bioturbation besides mix- ing of solids also changed the water content throughout the sediment column. Porosity profiles at the end of the experiments increased by 10 to 20% at 10 to 12 cm depths compared to above and below this horizon. The DDT depth concentration profiles decreased towards the surface as a result of the mixing by the benthic macroinvertebrates, clearly indicating removal/uptake by the organism. The feeding rate constant (γb, % h -1 ) in the control showed a maximum at 7 to 12 cm. However, the γb in the treatments was essentially constant with depth. For all treatments and the control, the burial rate (Wb) (downward movement of radiolabeled layers) decreased with depth. The surface layers were buried faster (ANOVA, p < 0.05) in the control than in sediments containing DDT. A sensitivity ana- lysis comparing burial rate, Db, γb (surface only) and worm weights showed that worm weights and burial rate have the highest fractional rate changes per µg g -1 DDT.

Macrobenthic polychaete assemblages of the continental shelf and upper slope off the west coast of the South Island, New Zealand

Polychaete assemblages are described from replicate box‐core samples collected in summer 1983 at 18 stations on the continental shelf and upper slope (28–943 m) off the west coast of the South Island, New Zealand, south‐eastern Tasman Sea (c. 41–43°S, 169–172°E). Three main station groupings were identified by multivariate analysis: (1) inner shelf sandy stations characterised by Prionospio australiensis, Aricidea (Acesta) sp., Magelona cf. dakini, Paraprionospio aff. pinnata, Aglaophamus sp., Heteromastus filiformis, and Magelona sp.; (2) middle to outer shelf muddy stations characterised by Levinsenia cf. gracilis, Prionospio australiensis, Paraprionospio coora, Aglaophamus verrilli, and Auchenoplax mesos; and (3) upper slope sandy mud or mud stations characterised by Prionospio ehlersi. A combination of water depth and sediment clay content provided the best correlation with the biotic pattern. Spionidae was the most abundant family (49% of polychaete individuals), which may reflect the scope for opportunistic species in a shelf environment characterised by a high input of terrigenous sediment and episodic upwelling.

Temporal variation of annelids in the intertidal zone of beaches of the São Sebastião Channel, southern Brazil

Monthly collections were made for one year (August 1995 to July 1996) in the intertidal zone of two beaches (Engenho d'Água and São Francisco) located in the São Sebastião Channel, State of São Paulo, Brazil, in order to establish the seasonal fluctuations of the species and the factors determining these fluctuations. On each beach, a 10 m wide sector of varying width was established, from which 15 samples/month were collected with a cylindrical corer (0·01 m2). The salinity of the interstitial water and the temperature of the sediment were measured monthly, while the granulometric parameters and calcium carbonate and organic matter concentrations were recorded seasonally. The temporal distribution of the species was more homogeneous at Engenho d'Água, where the highest diversity and evenness values were also found, although the number of individuals was lower. At São Francisco, the monthly abundance was higher, but the richness, diversity, and evenness values were lower, showing some heterogeneity in the temporal distribution patterns of the species. Most species at Engenho d'Água reached their peak of abundance in summer and autumn. The most abundant and frequent species at Engenho d'Água were Nematonereis hebes, Cirriformia filigera (summer), Scyphoproctus djiboutiensis (spring), Owenia fusiformis and Isolda pulchella (winter). At São Francisco, the capitellids Capitella capitata, Heteromastus filiformis, and Capitomastus minimus, and the tubificid oligochaetes dominated in the summer, and Laeonereis acuta and Scolelepis squamata in the winter. The log-normal distribution of the species was used to group those species that are sensitive to and those that are tolerant of organic enrichment, over the four seasons of the year.

Distribution patterns and trophic structure of soft-bottom polychaete assemblages in a North-Western Mediterranean shallow-water bay

Abstract This study describes the spatial distribution and trophic structure of the polychaetes inhabiting the soft-bottoms of Alfacs Bay, a semi-enclosed, shallow-water area (Ebro Delta, north-western Mediterranean). The hydrographic regime is basically marine, with a combination of sea-water renewal and continental runoff causing permanent stratification. The Bay was affected by anthropogenic activities (viz. influx of irrigation waters, large-scale aquaculture, and periodical dredging at the mouth). 41 samples were taken during summer (July 1987 and September 101 polychaete species were identified, with an average density and biomass of 6370(650-23700) ind.m-2 and 7.52(0.87-66) DWgm-2, respectively. Nine assemblages were identified: shelf (stressed, confined, typical), boundary, deep central basin (inner, typical, seaward) and marine (typical, navigation channel). The trophic structure was dominated by deposit-feeding polychaetes (mainly Pseudomastus deltaicus, Heteromastus filiformis, Notomastus later...

Influence of Acid Volatile Sulfide and Metal Concentrations on Metal Bioavailability to Marine Invertebrates in Contaminated Sediments

An 18-day microcosm study was conducted to evaluate the influence of acid volatile sulfides (AVS) and metal additions on bioaccumulation from sediments of Cd, Ni, and Zn in two clams (Macoma balthica and Potamocorbula amurensis) and three marine polychaetes (Neanthes arenaceodentata, Heteromastus filiformis, and Spiophanes missionensis). Manipulation of AVS by oxidation of naturally anoxic sediments allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A vertical sediment column similar to that often found in nature was used to facilitate realistic biological behavior. Results showed that AVS or porewater (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal combinations. Bioaccumulation of all three metals by the bivalves was related significantly to metal concentrations extracted from sediments (SEM) but not to [SEM − AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata, but Cd bioaccumulation followed PW Cd concentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis, with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results from toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode and depth of feeding.

The subtidal macrobenthos in the mesohaline part of the Schelde Estuary (Belgium): influenced by man?

The macrobenthos of the subtidal, mesohaline zone of the Schelde Estuary (Belgium) was sampled in October 1996 and 1997 at 54 and 73 sampling locations respectively. Sediments ranged from silty to very coarse, with the dominant sediment type being silt (33% of all locations). Of the 35 macrobenthic species observed, only seven species occurred in more than 20% of the samples. The polychaete Heteromastus filiformis and Oligochaeta were most common. Multivariate techniques revealed three distinct communities, linked mainly with sedimentological factors: (1) a species-poor (nine species) community with a dominance of the amphipod Bathyporeia pilosa, a low mean abundance and biomass (86 ind m−2, 0.0189 g ash-free dry weight (AFDW) m−2), and a mean median grain size of 215±19 μm (fine sand); (2) a species-rich (22) community, with the small polychaete Polydora ligerica as indicator species, a relatively high mean abundance and biomass (2298 ind m−2, 1.395 g AFDW m−2, oysters excluded), a mean median grain size of 133±41 μm, and also the occurrence of sediments with hard substrates being characteristic for this community; (3) a community with an intermediate species richness (12), abundance and biomass (248 ind m−2, 0.249 g AFDW m−2), with H. filiformis and Oligochaeta as indicator species, and a median grain size of 76±9 μm. In the study area several typical brackish water species were observed (e.g. Polydora ligerica, Corophium lacustre, Gammarus salinus).Mean total abundance and biomass were very low, and the benthic communities appeared to be under stress, with a dominance of mainly small, subsurface deposit and surface deposit feeding opportunistic species. This is probably a combined effect of both natural physical and human-induced disturbance. Only sediments with hard substrates (e.g. rocks) seems to favour species richness, providing a shelter against physical disturbance.

Depth Correlated Benthic Faunal Quantity and Infaunal Burrow Structures on the Slopes of a Marine Depression

In the northern part of the Kattegat, western Sweden, a series of marine depressions remain since the last glaciation. One of these, the well-oxygenated Alkor Deep, is about 3km long and 800m wide and with a depth of 138m. Random depth-stratified sampling was made along four transects on the slopes including benthic macrofauna (0·1m2grab samples) and sediment profile imaging. A significant positive correlation was found between depth and the faunal variables abundance and biomass. Deposit feeders such as Maldane sarsi, Heteromastus filiformis andAbra alba were among the dominants and may have been supported by down-slope advected organic material. In many images, pockets and extensive burrows were seen in the sediment that appeared to be constructed by the crustaceans Calocaris macandreae and Maera loveni. The ecological significance of their irrigation of the sediment is discussed. Due to the faunal activity deep down in the sediments of the slopes, the mean apparent redox potential discontinuity (RPD) was found as deep as between 8·0 and 11·3cm depth, and RPD was significantly positively correlated with water depth. On the slopes there appears to be a balance between the input of organic material and the capacity of the benthic organisms to assimilate that carbon.

Long‐term observations on the dynamics of three species of polychaetes living on tidal flats of the Wadden Sea: the role of weather and predator–prey interactions

Summary 1. On the tidal flats of the Wadden Sea, the predatory polychaete Nephtys hombergii (Sav.) is sensitive to low winter temperatures, whereas its main prey, the smaller polychaetes Scoloplos armiger (O.F.M.) and Heteromastus filiformis (Clap.) are not. 2. Monitoring macrofauna dynamics during the last three decades (1970–97) in two distant Wadden Sea areas revealed that Nephtys abundance was severely reduced in all eight coldest winters (generally to an average of &lt; 0·1 g ash‐free dry weight m–2), whereas its biomass reached mean values around 1 g AFDW m–2 during periods with mild winters (≤ 5 days with an air temperature remaining below 0°C all day). Over‐winter changes in Nephtys abundance were strongly related to temperature and 70% of the variability in late winter abundance of this species could be explained by temperature characteristics of the foregoing winter. 3. Biomass values of Nephtys observed in late winter predicted to a high degree (90%) the generally somewhat higher values in the subsequent summer. This seasonal change of predator abundance was generally not related to prey density. Only locally (in an exposed low‐biomass area) and rarely (one‐tenth of the years of observation) did low prey supply (if it was lower than simultaneous predator biomass) coincide with a decline, rather than the usual seasonal increase in Nephtys biomass. 4. A negative influence of predator abundance on prey biomass was observed in both prey species over the entire range of observed predator biomass values. The usual seasonal (winter to summer) increase of prey biomass was significantly smaller at high than at low Nephtys biomass and was even reduced to nil at the highest predator density observed. Scoloplos biomass was about four times higher after years with low (&lt; 0·1 g m–2) than after years with high (&gt; 1·0 g m–2) Nephtys biomass. Similar differences were observed in biomass of Heteromastus. 5. It is concluded that winter temperatures act as an important structuring factor in the Wadden Sea zoobenthic community by directly governing the densities of an important infaunal predator and indirectly affecting the abundance of at least two important prey species. Cold winters intervene by starting a new cycle of predator–prey interaction on average once per 3 or 4 years. 6. Predator abundance was more frequently determined by weather conditions than by food supply. Prey abundance was primarily governed by predator abundance and food supply and was only indirectly (via predator abundance) affected by the incidence of cold winters.

Polychaete zonation on sandy beaches of São Sebastião Island, São Paulo State, Brazil

This study was performed in the intertidal zone of Barra Velha, Pereque, and Engenho d'Agua beaches, located on Sao Sebastiao Island (Sao Paulo State, Brazil), to assess the composition, abundance, and zonation of the polychaete community in the intertidal zone. Four structurally different sectors were established, two on Barra Velha (I and lI), one on Pereque, and one on Engenho d'Agua. Each sector was divided into 3 tidal levels (lower, middle, and upper), in which 5 or 6 random samples were taken seasonally using a corer of 0.01 m2 in area. Laeonereis acuta, Capitella capitata, and Heteromastus filiformis dominated in the upper tidal levels, and Scoloplos (Leodamas) sp. and Cirriformia tentaculata in the lower levels. The structural complexity of Engenho d'Agua, caused by rocky fTagments mixed with sand, supported the richest and most diverse polychaete fauna of ali the sectors. The salinity of the interstitial water and the organic matter content were the principal factors related to the zonation patterns at these sites.

Polychaete zonation on sandy beaches of São Sebastião Island, São Paulo State, Brazil

This study was performed in the intertidal zone of Barra Velha, Perequê, and Engenho d'Água beaches, located on São Sebastião Island (São Paulo State, Brazil), to assess the composition, abundance, and zonation of the polychaete community in the intertidal zone. Four structurally different sectors were established, two on Barra Velha (I and lI), one on Perequê, and one on Engenho d'Água. Each sector was divided into 3 tidal levels (lower, middle, and upper), in which 5 or 6 random samples were taken seasonally using a corer of 0.01 m2 in area. Laeonereis acuta, Capitella capitata, and Heteromastus filiformis dominated in the upper tidal levels, and Scoloplos (Leodamas) sp. and Cirriformia tentaculata in the lower levels. The structural complexity of Engenho d'Água, caused by rocky fTagments mixed with sand, supported the richest and most diverse polychaete fauna of ali the sectors. The salinity of the interstitial water and the organic matter content were the principal factors related to the zonation patterns at these sites.

Annelid fauna of a Mediterranean lagoon (Gialova Lagoon, south-west Greece): community structure in a severely fluctuating environment

The annelid community of a shallow Mediterranean lagoon (Gialova Lagoon, Ionian Sea) was studied on a seasonal basis. Out of the 39 species identified eight are reported for the first time from the central Mediterranean. The dominant species were the polychaetes Capitella capitata, Neodexiospira pseudocorrugata, Malacoceros fuliginosus, Perinereis cultrifera, Hediste diversicolor, Heteromastus filiformis and the oligochaete Limnodriloides maslinicensis. Uni- and multivariate methods were employed to study the community structure. The coenocline observed is strongly related to the degree of isolation; its main features (i.e. number of species, density, geometric abundance and size-classes) in space and time are presented and discussed in detail. The distribution pattern of the annelid community has been found to be governed by a different set of environmental factors in each season. Although this narrow lagoonal habitat suffers severe dystrophic episodes it manages to recover, demonstrating a seasonal community pattern.

Predation of waders and gulls on Lanice conchilega tidal flats in the Wadden Sea

Evaluation of the importance of different benthos communities as feeding sites for waders and waterfowl is not only fundamental for understanding feeding ecology, it also enables the prediction of the effects of habitat loss. However, detailed analyses of the importance of different benthos communities for waterbirds are scarce, particularly for the German Wadden Sea. In the early 1990s, backbarrier tidal flats of the East Frisian Wadden Sea were dominated by Lanice conchilega. To estimate the relevance of those flats for waterbirds during autumn migration 1994, number, distribution and food consumption of the 7 most abundant bird species on these flats (oystercatcher, curlew, dunlin, redshank, common gull, black-headed gull, herring gull) were investigated on 2 different types of L. conchilega dominated flats (Lanice flat, Undulating flat). Spring tide counts throughout 1994 showed maximum bird numbers during spring (maximum: 56000 birds) and autumn migration (maximum 111 000 birds). Of the 7 species examined, 4 species (oystercatcher, curlew, redshank, common gull) used both flat types in higher densities than expected. Whereas common gulls preferred the Undulating flats, oystercatchers preferred the Lanice flats. The overall number of macrozoobenthos organisms varied between 3360 and 5520 m -2 on the Undulating flat, and between 8520 and 15100 m -2 on the Lanice flat. Correspondingly, the estimated biomass ranged from 67.6 to 142.3 g AFDW m -2 and 128.4 to 337.2 g AFDW m -2 (AFDW: ash free dry weight), respectively. Therefore, biomass was higher than in most other Wadden Sea areas. The most abundant species were Heteromastus filiformis, L. conchilega, Macoma balthica and Mytilus edulis. The overall consumption of the 7 bird species studied (70% of all waterbirds present) decreased from 16.6 g AFDW m -2 in August to 12.3 g AFDW m -2 in October. Assuming a similar consumption for the remaining 30% of the birds, overall consumption would have ranged between 17.6 and 23.7 g AFDW m -2 . Due to the high biomass of the standing stock, relative consumption (5.2 to 13.7 %) was similar to other regions of the Wadden Sea. Only 3 species (oystercatcher, curlew, common gull) consumed between 78 and 93% of the overall consumption of the 7 species examined. Whereas waders mainly foraged on the accompanying fauna of the L. conchilega community, the bulk of the diet of gulls was L. conchilega itself. In general, food supply on L. conchilega dominated flats can be judged as favourable. However, the possibility that food consumption could have been a limiting factor, at least for some species (e.g. oystercatcher), cannot be ruled out.

Widespread occurrence of natural halogenated organics among temperate marine infauna

Despite the global prevalence of marine sedimentary habitats, the potential for chemically mediated ecological interactions within these assemblages remains poorly known. Using GC/MS, we examined methanol extracts of worm, mollusc, and crustacean macroinfauna from 2 local intertidal sandflat communities for volatile organohalogens, a common, often bioactive class of secondary metabolites from marine organisms. Halogenated compounds were newly identified from 11 common polychaete species in the families Capitellidae, Chaetopteridae, Cirratulidae, Glyceridae, Pectinariidae and Spionidae. Tentative structures of these halometabolites are proposed based on GC/MS data. The represented chemical classes included aromatic mono- and dibrominated hydroxyphenylpropanoids, nitrogen-containing bromoalkylpyrroles, as well as brominated and chlorinated hydrocarbons and sulfides. Among the molluscs, only Terebra dislocata (Prosobranchia) contained an organohalogen compound (2,6-dibromophenol), which is likely derived from its diet of hemichordate worms. Volatile haloorganics were not found in amphipod and nemertean taxa. Possession of these compounds was not a function of any particular phylum, size categorization, or trophic mode, although hemichordates and all Capitellid and Spionid polychaetes collected at these sites invariably contained halocompounds. Most (40 of ca 54 taxa) of the numerically dominant macroinfaunal taxa at these 2 sites were examined in this survey; of these, 43% contained halometabolites, including the broadly distributed species Mediomastus ambiseta, Heteromastus filiformis, Streblospio benedicti, Tharyx marioni, and Saccoglossus kowalevskii, Thus, the potential for widespread occurrence of halogenated compounds among infauna is great. The presence of organohalogens in many common and abundant polychaete species suggests a general hiological significance for these metabolites, a result of potential interest to marine ecologists, toxicologists and environmental chemists.