Tharyx Marioni Research Articles

Macrofaunal community responses to marina-related pollution on the south coast of England and west coast of France

This study evaluates the influence of man-made activities on the benthic environment at two different marinas: Southsea Marina on the south coast of England, and Minimes Marina on the Atlantic coast of France. We assessed the differences in: (1) sediment percentage organic matter, particle size and heavy metal concentration, using copper (Cu), cadmium (Cd), zinc (Zn) and lead (Pb) as contamination indicators; (2) sediment elutriate toxicity (LC50) using algal (Fucus serratus) bioassay; and (3) benthic community characteristics (number of species, abundance, most contributing species (SIMPER) and biotic index (AMBI)). Canonical correspondence analysis (CCA) was performed to relate the abundance of species to the environmental variables. At both marinas, we observed an increasing gradient of contamination from outside to the innermost sites. At both marinas, the lowest macrofaunal abundance was recorded at the innermost sites and differences in benthic community structure were observed between sites. At Southsea Marina, the cirratulidsTharyx marioniandT. killariensisand the cossuridCossura pygodactylatadominated sites outside, while the opportunistic speciesCapitellides girardidominated the innermost sites. At Minimes Marina, the cirratulidStreblospio shrubsoliiwas abundant outside and at the middle sites but was almost absent at the innermost sites. The biotic index—AMBI—indicated that sediments in the innermost sites were heavily disturbed at Southsea Marina and slightly to moderately disturbed at Minimes Marina. In Southsea, the AMBI was positively correlated to the sediment metal concentrations (Cu, Zn and Cd) and elutriate toxicity (LC50), while in Minimes the AMBI was positively correlated to the % of sediment fine particle and elutriate toxicity (LC50).

Arsenic bioaccumulation and species in marine polychaeta

Published whole tissue arsenic concentrations in polychaete species tissues range from 1.5–2739 µg arsenic/g dry mass. Higher mean total arsenic concentrations are found in deposit-feeding polychaetes relative to non-deposit-feeding polychaete species collected from the same locations. However, mean arsenic concentrations at some of the locations are skewed by the high arsenic concentrations of Tharyx marioni. There appears to be no direct correlation between sediment arsenic concentrations and polychaete arsenic concentrations. Arsenic bioaccumulation by polychaetes appears to be more controlled by the physiology of the polychaetes rather than exposure to arsenic via ingested material or the prevailing physiochemical conditions. Arsenic concentrations in polychaete tissues can vary greatly. Most polychaete species contain the majority of their arsenic as arsenobetaine (57–98%), with trace concentrations of inorganic arsenic (<1%) and other simple methylated species (<7.5%). However, this is not always the case, with unusually high proportions of arsenite (57%), arsenate (23%) and dimethylarsinic acid (83–87%) in some polychaete species. Arsenobetaine is probably accumulated by polychaetes via organic food sources within the sediment. The presence of relatively high proportions of phosphate arsenoriboside (up to 12%) in some opportunistic omnivorous Nereididae polychaete species may be due to ingestion of macroalgae, benthic diatoms and/or phytoplankton. Consideration of the ecology of individual polychaete species in terms of their habitat type, food preferences, physiology and exposure to arsenic species is needed for the assessment of arsenic uptake pathways and bioaccumulation of arsenic. Future research should collect a range of polychaete species from a wide variety of uncontaminated marine habitats to determine the influence of these ecological factors on total arsenic concentrations and species proportions. Copyright © 2005 John Wiley & Sons, Ltd.

The Muddy Fine Sand Abra alba– Melinna palmata Community of the Bay of Morlaix Twenty Years After the Amoco Cadiz Oil Spill

The muddy fine sand Abra alba–Melinna palmata community from the Bay of Morlaix (western English Channel) was strongly polluted by hydrocarbons from the Amoco Cadiz oil spill in April 1978. Long-term changes of this community (1977–1996) showed that it was weakly affected by the spill. This was due to the low number and low abundance of sensitive species present on the community in normal conditions. Polychaetes, such as Chaetozone setosa dominated the community, supporting high levels of organic matter. Only two opportunistic polychaetes Mediomastus fragilis and Tharyx marioni increased in abundance just after the spill. Temporal changes showed two successive periods: (i) 1978–1984 with an establishment of the polychaete Lanice conchilega, and its associate fauna, then (ii) from 1985 to the end of the survey in 1996 with the disappearance of L. conchilega and the establishment of the polychaete Clymenura clypeata and the bivalve Thyasira flexuosa. The soft-bottom Abra alba–Melinna palmata community of the Bay of Morlaix may support a maximal carrying capacity of approximately 20 g m −2 during the establishment of Lanice, and only 8.0 g m −2 during the last 12 years of the survey (mean annual biomass in decalcified dry weight). During the 20 year survey, the overall mean P/ B was 1.71. The results were compared with these obtained on the nearby A. alba Pierre Noire community where the spill affected strongly and durably the community.

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.

Development of Small Mytllus Beds and its Effects on Resident Intertidal Macro fauna

Abstract. The development of temporary Mytilus edulis beds and their associated macro fauna was studied on an intertidal sand flat in the German Wadden sea during 1986 by comparing mussel beds with bare sandy areas of the same tidal elevation. Macro fauna samples We taken with a 100 cm2 corer (penetration depth 27 cm, mesh size 0.5 mm, 5 parallel samples).Numbers of taxa and diversity were higher in the mussel beds compared to the sandy areas. The abundance of macro fauna organisms decreased with the age of the mussel bed, whereas the relative abundance of species was not strongly affected. Hydrobia ulvae, oligochaetes, and Heteromastus filiformis dominated the macro fauna inside as well as outside the mussel beds. Among the lower ranks of dominance changes in species composition were observed due to increasing densities of opportunistic polychaetes.About six weeks after the establishment of the mussel beds a higher abundance of Capitella spp., Polydora ligni, Tharyx marioni, and nemerteans occurred within the mussel beds while other species such as Hydrobia ulvae and Pygospio elegans showed a significantly lower abundance compared to the adjacent flat. Macoma balthica as well as Mya arenaria were not affected by the alteration of a bare sand flat to a mussel bed. O‐group Carcinus maenas reached their highest abundance in the mussel beds (over 1000 indiv. m‐2). In contrast juvenile Crangon crangon preferred the bare sand flat. After destruction of the mussel beds by an early autumn storm, species abundance and composition was similar to the situation before the mussel beds had become established.

The Influence of the Cockle, Cerastoderma edule, on the Macrozoobenthic Community of Tidal Flats in the Wadden Sea

Abstract. The cockle Cerastoderma edule is one of the large and important species of the tidal flats of the Wadden Sea. C. edule disturbs the upper sediment layer due to its crawling and “shaking” behaviour. About 7% of a cockle population move within one week. The mean distance of movement is ‐4 cm per week, which, in the case of a 2‐year‐old cockle with a length of ˜3 cm, means that ˜20 cm2 of sediment is disturbed to a depth of ˜3 cm. Besides these measurable movements, cockles also regularly “shake” themselves, thereby disturbing the sediment around them to at least ˜0.5 cm. At a density of 500 cockles per m2 of a mean length of 3 cm, ˜16% of the sediment surface is occupied by cockles and another ˜29% is disturbed by cockles within one week.To study the effects of cockles on recruitment of other benthic species, densities of 0, 125, 250, 375 and 500 cockles (mean length 3 or 3.5 cm) were added to 1‐m2 plots within large depopulated squares in April. Subsequently, sediment samples were sieved once a month (from June to September) and the densities of all macrozoobenthic species were estimated. The presence of cockles significantly reduced the densities of juveniles of the bivalve species C. edule, Macoma balthica, Mya arenaria, Tellina (Angulus) tenuis, and Ensis directus and of the worm species Pygospio elegans, Lanice conchilega, Eteone longa, Anaitides spec., Nephtys hombergii, Heteromastus filiformis, Scoloplos armiger, and Tharyx marioni and of the amphipods Corophium volutator and C. arenarium. Non‐significant effects were found only in Capitella capitata and Nereis diversicolor. For all species mentioned above a negative effect was already observed at the lower cockle densities of 125 ‐ 250 per m2. Reductions of about 50% or more were found at densities of 500 per m2, which was more than could be expected based on the area occupied by the cockles (˜16%), but close to the area occupied plus disturbed (˜45%). It is concluded that (dense) assemblages of adult cockles can have a strong influence on the macrozoobenthic community.

Mussel beds — amensalism or amelioration for intertidal fauna?

The faunal assemblages of a mussel bed (Mytilus edulis L.) and ambient sandflat were compared to study how a bioherm of suspension feeding organisms affects benthic communities in a tidal flat. During a survey of mussel beds in the Wadden Sea at the island of Sylt (North Sea), a total of 52 macrofaunal species and 44 meiobenthic plathelminth species were detected. They occupied different microhabitats in the mussel bed. 56% of the macrofauna species were dwelling in the sediment beneath the mussels and 42% were epibenthic or epiphytic. The latter were restricted in their occurrence to the mussel bed. Along a transect from the sandflat to the mussel bed the mean species densities of macrofauna did not differ significantly, while abundances were significantly lower in the mussel bed than in the sandflat. The composition of the assemblages shifted from a dominance of Polychaeta in the sandflat to Oligochaeta in the mussel bed. Surface filter-feeding polychaetes of the sandflat (Tharyx marioni) were displaced by deposit feeding polychaetes under the mussel cover (Capitella capitata, Heteromastus filiformis). The total meiobenthic density was lower and single taxa (Ostracoda, Plathelminthes, Nematoda) were significantly less abundant in the mud of the mussel bed. The plathelminth assemblage was dominated by grazing species (Archaphanostoma agile), and differed in community structure from a sandflat aseemblage. An amensalistic relationship was found between the suspension-feeding mussels and suspension-feeding infauna, while deposit-feeders were enhanced. The presence of epibenthic microhabitats results in a variety of trophic groups co-occurring in a mussel bed. This is hypothesized as trophic group amelioration and described as an attribute of heterotrophic reefs.

Impact of amoco cadiz oil spill on the muddy fine sand Abra alba and Melinna palmata community from the Bay of Morlaix

Thirteen quantitative quarterly samples of the Abra alba-Melinna palmata community from the Bay of Morlaix (France) were taken from August 1977 to August 1980. The quantitative and qualitative changes in the community subsequent to the Amoco Cadiz oil pollution (March 1978) could thus be studied. Hydrocarbons were present in the sediments in exceptionally high quantities for more than a year after the oil spill, and then they decreased sharply. The numbers of species in the community increased as a whole during the 3 years' observation; in fact, a regular increase in the species numbers in polychaetes was observed, compensating for a reduction in the species numbers in amphipods after the oil pollution. Some species that disappeared after April 1978 have not yet re-appeared. Density and biomass showed important seasonal variations, with summer maxima and winter minima and with a net dominance by the polychaete populations, particularly of Chaetozone setosa . During the first annual cycle after the pollution, there was a sharp increase in the density of some species which were present in very low ( Mediomastus fragilis, Tharyx marioni ) or very high ( Chaetozone setosa ) numbers before the pollution. Neither Shannon diversity and Pielou evenness indices nor Gray's log-normal diagram were useful in describing the effects of the pollution on the community structure. The present study shows that, under such conditions, it is often difficult to employ highly synthetic methods to expose a perturbation in the structure of a benthic community.

Annual macrofauna production in a Venus community

A station representative of the Venus community in Carmarthen Bay, S. Wales, has been sampled regularly between February 1974 and March 1975 with a Knudsen sampler, Day grab and naturalist's dredge. Estimates of annual production of the 15 most important macrofauna species in the community have been made using the techniques of cohort growth analysis. Annual production, mean annual biomass (g ash-free dry wt./m 2) and the P B ratio for each species were as follows: Pharus legumen; P = 16.119, B = 28.816, P B = 0.56 . Spiophanes bombyx; P = 3.345, B = 0.688, P B = 4.86 . Ensis siliqua; P = 1.372, B = 5.100, P B = 0.27 . Nephtys hombergi; P = 0.935, B = 0.492, P B = 1.90 . Donax vittatus; P = 0.721, B = 0.344, P B = 2.10 . Magelona papillicornis; P = 0.685, B = 0.625, P B = 1.10 . Venus striatula; P = 0.616, B = 1.496, P B = 0.41 . Ophiura texturata; P = 0.458, B = 0.672, P B = 0.68 . Tellina fabula; P = 0.292, B = 0.325, P B = 0.90 . Glycera alba; P = 0.281, B = 0.291, P B = 0.97 . Sigalion mathildae; P = 0.165, B = 0.376, P B = 0.44 . Lumbrineris latreilli; P = 0.120, B = 0.092, P B = 1.30 . Tharyx marioni; P = 0.015, B = 0.018, P B = 0.79 . Astropecten irregularis; P = 0.0004, B = 0.073, P B = 0.005 . Echinocardium cordatum; P = −0.012, B = 5.138, P B = −0.02 . The total annual production was 25.815 gm −2 year −1 and the mean biomass 45.793 gm −2, giving an overall P B for the community of 0.56. These values are discussed in relation to other communities for which comparable data are available.

A Comparative study of Reproductive Cycles in Four polychaete Species belonging to the Family Cirratulidae

Gametogenesis has been studied in four cirratulid polychaetes: Caulleriella caput-esocis, Tharyx marioni, Cirriformia tentaculata and Cirratulus cirratus.In all four species, sperm development follows a similar course of events, with the sperm cells being grouped in spheres and then platelets before developing tails to give rosettes which finally disintegrate to release the active spermatozoa. Except in Cirratulus, there is a well-defined annual cycle in the development of sperm.Oogenesis in Caulleriella and Cirriformia is similar in that the growth curve of the oocytes is roughly sigmoid. In Tharyx the release of the oocytes to the coelom is delayed and discrete ovaries are formed, only the later stages of oocyte growth taking place within the coelom. In contrast to the above three species, oogenesis in Cirratulus does not show an annual cycle.Maturation of the oocytes within the coelom prior to shedding has been established in Tharyx, Cirratulus and Cirriformia. In the former two species meiosis proceeds as far as the metaphase I stage and in the latter to the anaphase I stage, before the oocytes are released. Fertilizations were achieved only with oocytes which had matured in all three species. In the fourth species, Caulleriella, no fertile oocytes were discovered.The diameters of the mature oocytes and the main spawning seasons of the four species at Plymouth are as follows: Caulleriella, about 110 μ (August to October); Tharyx, 200– 220 μ (late October to early November); Cirriformia, about 117 μ (late June to early July); Cirratulus, 135–150 μ (throughout the year).

A NEW SPECIES AND TWO NEW RECORDS OF POLYCHAETA FROM EASTERN CANADA

Two of the three species recorded in this paper (Ceratonereis scotiae sp. n. and Nereis diversicolor O. F. Müller) were collected some years ago, but hitherto their occurrence has not been noted. The third (Tharyx marioni (Saint-Joseph)) was collected recently for the first time in Canadian waters.

Notes on the reproduction and early development of the cirratulid Tharyx marioni (St Joseph)

The larval development of the Cirratulidae is not well known, although an account of the development of Raphidrilus nemasoma Mont, was published by Sokolow in 1911 (under the name of Ctenodrilus branchiata), and of Audouinia tentaculata (Montagu) by Wilson in 1936. Apart from these two publications, only scattered observations may be found in the literature, and these are listed by Wilson (1936). Unfortunately, attempts to rear the larvae of Tharyx marioni (St Joseph) beyond the hatching stage have failed, and as it seems unlikely that further data may be gathered for some time, such results as have been obtained are presented here.The main points of interest in the development and reproductive habits of T. marioni are: (i) the adults are atoquous; (ii) the eggs are comparatively large and yolky, and unlike Audouinia tentaculata, the pelagic stage is omitted; and (iii the larva on hatching is achaetous, as in other cirratulid larvae.