Dog Whelk Research Articles

A foundation for comparative genomics and evolutionary studies in Nucella lapillus based on complete mitogenome assembly

The Atlantic dog whelk, Nucella lapillus, is a marine snail that exhibits divergent evolution in response to habitat adaptation, resulting in distinct populations at the phenotypic, genotypic, and karyotypic levels. In this study, we utilized short- and long-read NGS data to perform a de novo assembly of the entire mitochondrial genome of N. lapillus and developed a multiplex PCR protocol to sequence most of its length using ONT sequencing. Our analysis revealed a typical circular configuration of 16,474 bp in length with 13 protein-coding genes, 22 different tRNA genes, 2 of them showing two copies, 2 rRNA genes, and a control region. Long-read sequencing enabled us to identify a 1826 bp perfect inverted repeat within the control region. Comparative analysis of the mitogenomes of related species in the Muricidae family revealed a conserved gene configuration for N. lapillus. We found a low genetic diversity, as well as a moderate genetic differentiation among the studied populations. Interestingly, there was no observed differentiation between the two chromosomal races, suggesting either introgression and permanent incorporation of the mitochondrial DNA haplotype from one of the chromosomal races into the other or a slower evolutionary rate of the mtDNAs with respect to that of the karyotypes. Our study serves as a foundation for comparative genomics and evolutionary investigations in this species.

Bacteriological assessment of crab (Pachycheles pubescens) and dog whelk (Nucella lapillus) shellfishes from mesotidal estuarine ecosystem

Background: Shellfishes are susceptible to a wide variety of bacterial pathogens, most of which are capable of causing disease in humans but are considered to be saprophytic in nature. Bacteriological diversity of shellfishes depends on the fishing grounds, habitats and environmental factors around them. This study assessed the bacteria associated with shellfishes, Pachycheles pubescens (crab) and Nucella lapillus (dog whelk) harvested from mesotidal estuarine ecosystem.
 Methodology: The bacteriological assessment of crab (Pachycheles pubescens) and dog whelk (Nucella lapillus) harvested from Okwano Obolo estuary in Eastern Obolo local government area (LGA), Akwa Ibom was evaluated. The density of heterotrophic and potential pathogens was determined using standard analytical procedures. The pure bacterial isolates were grouped into recognizable taxonomic units and characterized to their generic level.
 Results: The mean (and range) total heterotrophic bacterial count (THBC), total coliform count (TCC), faecal coliform count (FCC), Salmonella-Shigella count (SSC) and total Vibrio count (TVC) of the crab samples (log10 cfu/g) for the crab samples are; 4.281±0.085 (4.18-4.39); 4.187±0.078 (4.11-4.30); 4.115±0.081 (4.00-4.20); 4.076±0.058 (4.00-4.14); and 4.114±0.085 (4.00-4.23) respectively (p=0.003915). For the dog whelk samples, the mean (and range) THBC, TCC, FCC, SSC and TVC are 4.232±0.095 (4.11-4.36); 4.185±0.095 (4.04-4.28); 4.082±0.068 (4.00-4.18); 4.062±0.055 (4.00-4.15) and 5.155±0.062 (4.08-4.23) respectively (p=0.028856. Bacterial species isolated from the crab and dog whelk samples included Salmonella, Bacillus, Shigella, Corynebacterium, Pseudomonas aeruginosa and Vibrio (which was the most frequently isolated bacteria pathogen from both samples in 80%).
 Conclusion: Some of the bacteria species especially Vibrio, Salmonella and Shigella isolated from the crab and dog whelk samples are known human pathogens, that can pose serious health risk if these seafoods are not properly cooked before consumption.

130 years of heavy metal pollution archived in the shell of the intertidal dog whelk, Nucella lapillus (Gastropoda, Muricidae)

Heavy metals in coastal waters are a great environmental concern in the North Sea since the middle of the 20th century. Regulatory efforts have led to a significant reduction in atmospheric and water-transported heavy metals. Still, high concentrations of these in sediments remain a risk for ecosystems, requiring close monitoring. Here, we investigated the applicability of Nucella lapillus museum collections as a tool for targeted tracking of chronic anthropogenic heavy metal pollution. We analysed the concentration ratios of the common heavy metals Cu, Cd, Pb, and Zn in relation to Ca in N. lapillus shells collected from the Dutch and Belgian intertidal zone over the last 130 years. We found that shell Cu/Ca and Zn/Ca concentration ratios remained remarkably constant, whereas Pb/Ca concentration trends were closely aligned with emissions of leaded petrol in Europe. Our results suggest that N. lapillus provides a suitable Pb pollution archive of the intertidal zone.

Benthic video landers reveal impacts of dredged sediment deposition events on mobile epifauna are acute but transitory

The “beneficial uses” of dredged sediment are increasingly being explored for habitat restoration and beach nourishment, but beneficial uses must be tempered by evaluating impacts to organisms. We studied a subtidal nearshore deposition site intended to aid beach nourishment where a “thin-layer” sediment deployment method was employed to minimize mounding and disperse sediment within a proscribed area. Baited benthic video landers (BVLs) in a Before-After Control-Impact (BACI) experimental design were used to test the acute effects (within one hour of deposition) of sediment deposition on dominant epifaunal Dungeness crab (Cancer magister) and dog whelk (Nucella spp). The effects of sediment deposition depths and the lateral surge (the turbidity front transiting the seafloor) were both considered. Observations revealed sedimentation levels were limited to <4 cm and burial likely posed no direct threat to epifauna. However, video and instrument measurements showed the lateral surge to impact the BVLs as a 1 to 3 m/s sediment-laden front. Crabs were significantly impacted, while gastropods were more resistant to dislodgment. However, the high velocity impact was relatively brief (2 to 7 min). Further, crabs returned to forage at BVLs after a mean lag of about 20 min post-impact. These results indicate an acute but ephemeral impact effect on crab, and support use of the thin-layer deposition method to minimize burial. Our novel use of BVLs in a BACI experimental design were an effective means of evaluating sediment impacts to targeted mobile epifaunal species, and video observations were informative for understanding lateral surge dynamics and the behavioral interactions of organisms.

‘Tuesday Morning’, the schoolboy and Mann

The rediscovery of human remains, correspondence and other unpublished excavation archival material in the Glasgow Museums collection of Ludovic McLellan Mann prompted the reappraisal of a short archaeological investigation undertaken in April 1931 at Holm Park, near Ballantrae, Ayrshire, by a schoolboy, Eric French and his biology teacher, William Hoyland. This article offers a re-evaluation of their fieldwork which exposed two inhumation burials, named ‘Tuesday Morning’ and ‘Tuesday Afternoon’. Eight dog whelk shells remain from an overlying diffuse shell midden spread that may reflect the remnants of a dye-processing site. The skeletons and marine shells went on temporary display at Bryanston School, Dorset. The area south of Ballantrae is well known for prehistoric flint scatter sites and the finds presented the intriguing possibility that the burials might be Mesolithic in age, the excavators believing they might even be Palaeolithic. A collection of flint cores, initially associated with the archive, now appears unrelated to this excavation for it was found with a note written by a local lithic collector, William Edgar. New osteological analysis confirmed the presence of at least two adult individuals, and one bone sample returned an early medieval radiocarbon date. This evidence contributes to national understandings of early historic burial practices in unenclosed cemeteries during the transition from Iron Age pagan to Christian burial rites, important given the paucity of 1st millennium evidence in south-west Scotland. It also offers insight into an earlier account of multiple inhumation burials, found in the general vicinity in 1879, although aspects of the precise location and relationship between the two discoveries is currently unresolved. Mann’s correspondence with French’s father, a prominent Glasgow industrialist, and with Hoyland reveals the character of archaeological social networks in western Scotland during the 1930s which have been a neglected aspect of research to date.&#x0D; Canmore ID 60957&#x0D; Canmore ID 60935&#x0D; Canmore ID 275902

Determining the risk of calcium oxide (CaO) particle exposure to marine organisms

Calcium oxide (CaO) is being considered as a possible treatment for both the control of echinoderm populations and the treatment against sea lice infestation in Norwegian salmon farms. CaO particles produce an exothermal reaction when in contact with water, which can cause epidermal burns and lesions to certain target organisms leading to death. The aim of the present study was to determine the effects of fine (<0.8 mm) and coarse (<2.5 mm) CaO particles to a range of marine species from different taxonomic groups: two echinoderms (Asterias ruben and Strongylocentrotus droebachiensis); two crustaceans (Carcinus maenas and Tisbe battagliai); two molluscs (Mytilus edulis and Hinia reticulata); a polychaete (Nereis pelagica); a fish (Cyclopterus sp.); and seaweed germlings (Fucus vesiculosus). Overall, the fine CaO particles were more toxic to the selected marine species than the coarse particles. Coarse CaO particle effects were only observed in four of the nine species tested (A. rubens, S. droebachiensis, N. pelagica, T. battagliai) with similar LC50 values between 207 and 268 g/m2. For the fine CaO particles, the lowest LC50 was for the epibenthic copepod (T. battagliai) at 3.14 g/m2, followed by the sea urchin (20.1 g/m2), starfish (22.2 g/m2), ragworm (29.6 g/m2), and netted dog whelk (41.9 g/m2). Lump sucker fish exhibited significant mortalities only at the highest fine CaO concentration tested (320 g/m2) and recorded an LC50 of 226 g/m2. The toxicity data were used to generate species sensitivity distributions (SSDs) for both fine and coarse CaO particles. The hazard concentrations for 5% of the species (HC5) calculated from the SSDs, based on NOEC values, for the coarse and fine particles were 35.5 and 1.5 g/m2 respectively. Using a recommended assessment factor of 5, the Predicted No Effect Concentration (PNEC) was calculated as 7.1 and 0.3 g/m2 for coarse and fine CaO particles respectively.

Exploring Biotic Impacts fromCarcinus maenasPredation andDidemnum vexillumEpibiosis onMytilus edulisin the Gulf of Maine

Mytilus edulis (Blue Mussel) is an ecologically important species in the Gulf of Maine. However, many introduced species that have a direct negative impact on the Blue Mussel have entered this system, some as predators (e.g., Carcinus maenas [Green Crab]) and others as aggressive epibionts (e.g., Didemnum vexillum [Carpet Sea Squirt]). Didemnum vexillum has been increasing in abundance throughout the Gulf for the past 10 years and form large mat-like growths on mussel beds, covering individual mussels completely. The first part of our study used a predator-exclusion experiment to determine the impact of predators on the plantigrade stage of the Blue Mussel life cycle. During this stage, no epibiosis occurs due to a protective periostracum layer on the mussel shell. The second part of our study used laboratory trials to assess how overgrowth by D.vexillum impacts predator choice, handling time, and consumption of mussels. There were a significantly greater number of Blue Mussel plantigrades on exclusion panels than on the exposed-cage control panels. Green Crab and Nucella lapillus (Dog Whelk) predators were present on our non-exclusion panels. In laboratory trials, Green Crab handling time of Blue Mussels was not significantly different between mussels that were clean and mussels that were overgrown, but crab behavior and overall consumption showed a greater selection for clean mussels. This selection indicates an associational predator-resistance effect of D.vexillumt epibiont on Blue Mussels. The results of our study, while focused on one specific predator species, suggest that while young Blue Mussels with no epibionts are preyed upon heavily, D.vexillum likely deters predators from older mussels. Because D.vexillum form large mat-like colonies that can cover a large area, their presence may have a significant impact on community structure in the Gulf of Maine.

Contaminants and impoSEX: transcriptomics of contaminant‐induced sex change

Reproduction is the goal of living organisms, and environmental conditions that influence sexual development are therefore critical to understanding adaptation in natural populations. It is not surprising that so much attention has been devoted to the impacts of the physical and chemical environment on this process (Vandenberg et al.2012). Chemicals of concern include a variety of endocrine disruptors (EDs) including oestrogen and oestrogen mimics that directly lead to malformation of the gonad. On the molecular side, the impact that EDs have on genes directly involved in the feminization or masculinization of the gonad such as Cyp 19A (or aromatase), foxl2,Sox9, Dmrt1 and NrOb1, has received considerable attention due to their direct involvement in the regulation of oestrogen and testosterone. In this issue of Molecular Ecology, Pascoal et al. (2013) examine the impact of a known endocrine disruptor (tributyltin or TBT) on the transcriptome of the dog whelk, Nucella lapillus (Fig. 1),in relation to the formation of imposex individuals (masculinized females). They conclude that TBT mimics the endogenous ligand of the nuclear retinoid X receptor (RXR) and/or peroxisome profilerator-activated receptor (PPAR) disrupting pathways.

The Dog Whelk Nucella lapillus and Dye Extraction Activities From the Iron Age to the Middle Ages Along the Atlantic Coast of France

ABSTRACT In Europe, the extraction of dyes from marine shells found in archaeological contexts is little known outside the Mediterranean area. Although smaller than the Mediterranean species with dyeing properties, the dog whelk Nucella lapillus and the oyster drill Ocenebra erinaceus can be indicative of dyeing activities. They are regularly found broken in archaeological contexts in France and Ireland, where their presence can indicate an important economic activity of the coastal inhabitants. In this article, I summarize the archaeological data for this activity along the Channel and Atlantic coasts of France, including localization of these deposits and their chronology, composition of the shell middens, typology of fragments of shell, and presence of other activities. The application of biometrics to dog whelks from one site, ZA du Pladreau, yields information on the way in which the shells were selected first on the seashore, and second at the place of pigment extraction.

Nucella lapillus L. imposex levels after legislation prohibiting TBT antifoulants: temporal trends from 2003 to 2008 along the Portuguese coast

Nucella lapillus (dog whelk) imposex levels were assessed along the mainland Portuguese coast in 2006 and 2008 and were compared with available data from 2003 for the same area. Given that specimen size has been described as a factor inducing variation in some of the imposex assessment indices, and thus resulting in less reliable results, new monitoring and data analysis procedures are described and applied to study change of imposex levels from 2003 to 2008. A significant decline in imposex intensity was observed in the study area during the study period, and the Portuguese coast ecological status (under the terms defined by the OSPAR Commission) notably improved after 2003, confirming the effectiveness of the Regulation (EC) No. 782/2003 in reducing TBT pollution. Nevertheless, N. lapillus populations are still extensively affected by imposex, and fresh TBT inputs were detected in seawater throughout the coast in 2006. These recent inputs are attributed to vessels still carrying TBT antifoulants applied before 2003, as their presence in vessels was only forbidden in 2008. Considering that Regulation (EC) No. 782/2003 is an anticipation of the IMO global ban entered into force in September 2008, a worldwide-scale decrease in TBT pollution can be expected in the near future.

First records of the Australian dog whelk, Nassarius (Plicarcularia) burchardi (Dunker in Philippi, 1849) (Mollusca: Gastropoda) from New Zealand

Nassarius (Plicarcularia) burchardi (Dunker in Philippi, 1849) is a common dog whelk in subtropical and temperate regions of Australia. In April 2009, two shells of this species were found in the central Waitemata Harbour, Auckland. On the 22 June 2009, a live specimen was found at an intertidal site near Henderson Creek on the western central section of the harbour. Between August 2009 and February 2010, a further 21 living specimens in a range of sizes were found across multiple sites in the central Waitemata Harbour. This species is currently adventive and its presence in the Waitemata Harbour suggests accidental introduction from Australia and subsequent survival. If this species becomes firmly established in New Zealand, there may be significant interactions with native species such as Cominella glandiformis (Reeve, 1847), with which it may directly compete for food, and the invasive mussel Musculista senhousia (Benson in Cantor, 1842), which it is known to eat.

Divergence genetics analysis reveals historical population genetic processes leading to contrasting phylogeographic patterns in co‐distributed species

Coalescent samplers are computational time machines for inferring the historical demographic genetic processes that have given rise to observable patterns of spatial genetic variation among contemporary populations. We have used traditional characterizations of population structure and coalescent-based inferences about demographic processes to reconstruct the population histories of two co-distributed marine species, the frilled dog whelk, Nucella lamellosa, and the bat star, Patiria miniata. Analyses of population structure were consistent with previous work in both species except that additional samples of N.lamellosa showed a larger regional genetic break on Vancouver Island (VI) rather than between the southern Alexander Archipelago as in P.miniata. Our understanding of the causes, rather than just the patterns, of spatial genetic variation was dramatically improved by coalescent analyses that emphasized variation in population divergence times. Overall, gene flow was greater in bat stars (planktonic development) than snails (benthic development) but spatially homogeneous within species. In both species, these large phylogeographic breaks corresponded to relatively ancient divergence times between populations rather than regionally restricted gene flow. Although only N.lamellosa shows a large break on VI, population separation times on VI are congruent between species, suggesting a similar response to late Pleistocene ice sheet expansion. The absence of a phylogeographic break in P.miniata on VI can be attributed to greater gene flow and larger effective population size in this species. Such insights put the relative significance of gene flow into a more comprehensive historical biogeographic context and have important implications for conservation and landscape genetic studies that emphasize the role of contemporary gene flow and connectivity in shaping patterns of population differentiation.

Shell shape affects movement patterns and microhabitat distribution in the hermit crabs Calcinus elegans, C. laevimanus and C. latens

This study examined the influence of shell shape on the distribution and movement patterns of three species of Hawaiian hermit crabs: Calcinus elegans, C. laevimanus, and C. latens. Field surveys showed strong differences in shell use depending on habitat. Individuals of C . elegans and C. latens were more frequently in unusual shapes of shells (the cowrie Cypraea caputserpentis and the variable worm shell Serpulorbis variabilis) when in tide pools and in more standard gastropod shells, such as the dog whelk Nassarius papillosus, when found in the subtidal. In addition, for both C . elegans and C. latens in tide pools, most crabs in unusual shaped shells were out on top of rocks, whereas most crabs in shells that were standard shapes were under rocks. In the laboratory, individuals of C . elegans and C. laevimanus in unusual shells initiated more shell exchanges and when given empty shells crabs readily occupied the standard shaped shells, but crabs did not move into the unusual shaped shells. Mark-recapture experiments in the field showed that C. elegans in standard shaped shells moved out of tide pools and stayed longer when placed on subtidal coral heads, whereas crabs in unusual shaped shells stayed in tide pools and did not stay on subtidal coral heads (in part due to predation). Laboratory tests showed that C. elegans in unusual shaped shells were more readily dislodged by surge than crabs in standard shaped shells. Thus, the difference in movement patterns in preferred vs. unpreferred shell shapes is an important factor influencing the microhabitat distribution of these hermit crabs.

Use of Caged Nucella Lapillus and Crassostrea Gigas to Monitor Tributyltin‐Induced Bioeffects in Irish Coastal Waters

Caging studies have been previously reported to be useful for providing valuable information on biological effects of mollusks over short periods of time where resident species are absent. The degree of imposex in caged dog whelk (Nucella lapillus), was measured using the vas deferens sequence index (VSDI) and the Relative Penis Size Index (RPSI) and the extent of shell thickening in caged Pacific oyster (Crassostrea gigas) was investigated at t = 0 and t = 18 weeks. Nucella lapillus, when provided with mussels as a food source at the control site at Omey Island on the west Irish coast, did not demonstrate imposex features, whereas those transplanted to port areas did. Dunmore East exhibited the highest level of imposex (3.25 VDSI and 2.37 RPSI). Shell thickening was evident in C. gigas transplanted to Dunmore East, with low effects evident at the control location, Omey Island, and Dublin Bay at t = 18 weeks. Dry weight whole-body concentrations of organotins were most elevated in all species held at Dunmore East compared with other locations. Greatest delta15N and delta13C enrichment was observed within the tissues of the predatory N. lapillus in all three test sites. Increased assimilation in the Dublin Bay oysters might have been influenced by the presence of more nutrients at this location. Surficial sediment organotin levels were most elevated in the Dunmore East <2-mm fraction (22,707 microg tributyltin/kg dry weight), whereas low organotin levels were determined from Dublin and Omey Island sediments. The valuable application of cost-effective caging techniques to deliver integrated biological effects and chemical measurements in the absence of resident gastropod populations in potential organotin/tributyltin hotspot locations is discussed.

Genetic Isolation by Distance among Populations of the Netted Dog Whelk Nassarius reticulatus (L.) along the European Atlantic Coastline

Estimates of the average distances by which marine larvae disperse are generally poorly described, despite the central role that larval dispersal plays in the demographic connectivity of populations across geographic space. Here, we describe the population genetic structure and average dispersal distance of the netted dog whelk Nassarius reticulatus (L.) (Mollusca, Gastropoda, Prosobranchia), a widespread member of European intertidal communities, using DNA sequence variation in a fragment of the mitochondrial gene cytochrome c oxidase subunit I (COI). An analysis of 156 individuals from 6 locations spread across approximately 1700 km of the European Atlantic coastline revealed weak and nonsignificant population structure (overall Phi(ST) = 0.00013). However, pairwise Phi(ST) values revealed a slight but significant increase in genetic isolation with geographic distance (IBD), suggesting that populations are not panmictic across the sampled geographic range. If we assume that the isolation by distance is maintained by a stable, stepping stone model of gene flow, then the slope of the IBD is consistent with an average larval dispersal distance of approximately 70 km per generation. The spatial scale of larval dispersal in N. reticulatus is consistent with the life cycle of the species (planktotrophic veliger lasting 30-60 days before competent to settle). A mismatch analysis of the COI sequences revealed a signature of an ancient demographic expansion that began 61 500-160,000 years ago, well before the most recent Pleistocene glaciation event. The greatest levels of genetic diversity occur within the middle latitudes of the whelk's geographic range, consistent with the notion that historic populations of N. reticulatus might have expanded northward and southward from the centrally located Bay of Biscay.

Re-occurrence and bioindication status of the netted dog whelk Nassarius reticulatus (Linnaeus, 1758) in the Western Baltic Sea (Mecklenburg Bight, Germany)

The netted dog whelk Nassarius reticulatus (Linnaeus, 1758), considered as an extinct benthic species in German Baltic waters, was found again alive in the Mecklenburg Bight during several macrozoobenthic surveys since 1997. All data indicate that the establishment of this marine prosobranch species is connected with the more frequent intrusions of highly saline water from the North Sea into the Baltic that have been observed over the past few years. It is proposed that N. reticulatus is a good bioindicator for the hydrographic status in the western Baltic rather than for other existing potential conditions. Since 1998 a second extinct marine species, the polychaete Scalibregma inflatum Rathke, 1843 was found alive here, too.

Behavioural responses of the netted dogwhelk Nassarius reticulatus to olfactory signals derived from conspecific and nonconspecific carrion

Netted dogwhelks Nassarius reticulatus were offered standardized olfactory signals derived from flesh of: cod (Gadus morhua), starfish (Asterias rubens), shore crabs (Carcinus maenas), mussels (Mytilus edulis), periwinkles (Littorina littorea), dog whelks (Nucella lapillus) and netted dogwhelks. Nassarius reticulatus responded positively to all signals except the conspecific one. Positive responses to extracts were in the order (strongest to weakest): Gadus, Carcinus, Nucella, Mytilus, Asterias, Littorina. Starved Nassarius reticulatus buried in sand emerged rapidly to feed on crushed C. maenas, but remained buried when offered crushed conspecifics. These data confirmed the hypothesis that N. reticulatus would not respond positively to the smell of conspecific carrion, to avoid emerging from the substratum while neighbours were being predated. However, a second hypothesis, that strength of response to olfactory signal was proportional to taxonomic distance between N. reticulatus and the source of carrion was not supported by the data.

Östrogenartige wirkungen von bisphenol a auf vorderkiemenschnecken (Mollusca: Gastropoda: Prosobranchia)

Im Rahmen eines vom Umweltbundesamt geforderten Forschungsprojektes zur Entwicklung eines biologischen Tests mit der Suswasserschnecke Marisa cornuarietis fur geschlechtshormonahnlich wirkende Substanzen wurden unter anderem die Effekte des als Xenoostrogen verdachtigten Bisphenols A (BPA) untersucht. Zusatzlich zu den Laborversuchsreihen mit der Apfelschnecke M. cornuarietis wurden Versuche mit der Zwergdeckelschnecke Potamopyrgus antipodarum als Suswasserspezies sowie zwei marinen Arten, der Netzreusenschnecke Nassarius reticulatus und der Nordischen Purpurschnecke Nucella lapillus, durchgefuhrt. Wahrend N. reticulatus als sediment-bewohnende Art uber Kunstsedimente exponiert wurde, erfolgte fur die drei anderen Spezies die Exposition aquatisch. Die Tests mit der Apfelschnecke deckten einen nominalen Konzentrationsbereich von 1 bis 100 μg BPA/l in einem 5-monatigen Versuch mit adulten Tieren und einem kompletten Lebenszyklustest uber 12 Monate sowie einen Bereich von nominal 0,05–1 μg BPA/l (analytisch ermittelt: 0,0079–0,404 μg/l) in einem 6-monatigen Experiment mit adulten Exemplaren ab. In den drei Versuchsreihen loste die Testsubstanz ein komplexes Syndrom physiologischer und morphologischer Veranderungen bei M. cornuarietis aus, das als Ausbildung von ‘Superweibchen’ bezeichnet wird. Betroffene Exemplare sind durch zusatzliche weibliche Geschlechtsorgane, eine Vergroserung der akzessorischen Geschlechtsdrusen im Genitaltrakt, Missbildungen des pallialen Eileiterabschnitts mit einer daraus resultierenden erhohten Mortalitat der Weibchen und eine massive Stimulation der Ei- und Gelegeproduktion charakterisiert. Bei den Experimenten ergab sich eine LOEC von 48,3 ng/l, eine NOEC von 7,9 ng/l und eine EC10 von 13,9 ng/l. Superweibchen traten auch bei den drei anderen untersuchten Schneckenarten auf, doch wurden bei diesen wahrscheinlich aufgrund artspezifischer Unterschiede in der Anatomie der Genitaltrakte keine Eileitermissbildungen gefunden. Bei Potamopyrgus antipodarum loste BPA in einem 9-wochigen Experiment (nominaler Konzentrationsbereich: 1 bis 100 μg/l) eine vermehrte Bildung von Embryonen wahrend der sexuellen Ruhephase aus. Fur den Versuch ergab sich eine invertiert Uformige Konzentrations-Wirkungsbeziehung. Die 3-monatige Exposition von Nassarius reticulatus erfolgte uber kunstliche Sedimente (nominaler Konzentrationsbereich: 10–1000 μg/kg TG). BPA zeigte bei dieser Art konzentrationsabhangig eine uterotrophe Wirkung, die sich in einer signifikanten Vergroserung und Gewichtszunahme der akzessorischen Eileiterdrusen auserte. Adulte Nucella lapillus wurden uber einen Zeitraum von 3 Monaten aquatischen Nominalkonzentrationen von 1–100 μg BPA/l ausgesetzt. Die Superweibchen waren bei dieser Art ebenfalls durch vergroserte akzessorische Geschlechtsdrusen und eine verstarkte Eibildung gekennzeichnet. Zusatzlich loste die Testsubstanz aber auch bei den Mannchen charakteristische Veranderungen aus: Der Anteil fortpflanzungsfahiger Tiere mit reifen Spermien in der Vesicula seminalis ging ebenso zuruck wie die Ausdehnung von Penis und Prostata. Auch bei dieser Spezies wurden bereits bei der niedrigsten Testkonzentration statistisch signifikante Effekte im Vergleich zur Kontrolle ermittelt (LOEC ≤ 1 μg BPA/l; NOEC < 1 μg BPA/l). Die Ergebnisse zeigen, dass Vorderkiemerschnecken bereits bei erheblich niedrigeren BPA-Konzentrationen als andere systematische Gruppen des Tierreichs negative Effekte zeigen. Daher ist zum Schutz der aquatischen Lebensgemeinschaften und vor dem Hintergrund der derzeit auf EU-Ebene stattfindenden Risikobewertung fur BPA eine Berucksichtigung der vorgestellten Resultate zu fordern.

Toxicity of cadmium and zinc to encystment and in vitro excystment of Parorchis acanthus (Digenea: Philophthalmidae).

The toxicity of cadmium, zinc and cadmium/zinc mixtures at concentrations ranging from 1000 to 50000 microg/l were investigated against cercariae and metacercariae of Parorchis acanthus obtained from the dog whelk Nucella lapillus. Cercarial encystment at concentrations of 25000 microg/l or higher was significantly impaired by all test metals; however, at lower concentrations only zinc demonstrated toxicity. Mixtures of cadmium and zinc had a synergistic effect compared with single metal toxicity but only at 50000 microg/l. Excystment in vitro was only significantly affected by cercariae exposed to cadmium/zinc mixtures whilst encysting. Twenty-four h exposures of fully formed cysts had no effect on excystment in vitro. Effects on in vitro excystment rates over a 2 h period demonstrated widespread effects for cercariae-exposed P. acanthus. No effects were evident on excystment rates of cyst-exposed parasites.

Nucella lapillus as a paratenic host for Maritrema arenaria

Metacercariae of the microphallid trematode Maritrema arenaria are found in the shore barnacle Semibalanoides balanoides which is heavily predated by the dog whelk, Nucella lapillus. This study demonstrated that, under experimental and natural conditions, M. arenaria metacercarial cysts were ingested by N. lapillus and the metacercariae retained their viability while passing through the molluscs' digestive systems. Dog whelks are a known food source for numerous bird species, leading to the conclusion that they may act as paratenic hosts of M. arenaria. The strategic importance of the adoption by M. arenaria of N. lapillus as a paratenic host is discussed.