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Truncated life cycles may emerge in digeneans if the second intermediate host is eliminated, and the first intermediate host, the mollusc, takes up its role. To understand the causes of this type of life cycle truncation, we analyzed closely related species of the genus Neophasis (Acanthocolpidae) with three-host and two-host life cycles. The life cycle of Neophasis anarrhichae involves two hosts: wolffishes of the genus Anarhichas as the definitive host and the common whelk Buccinum undatum as the intermediate host. Neophasis oculata, a closely related species with a three-host life cycle, would be a suitable candidate for the comparison, but some previous data on its life cycle seem to be erroneous. In this study, we aimed to redescribe the life cycle of N. oculata and to verify the life cycle of N. anarrhichae using molecular and morphological methods. Putative life cycle stages of these two species from intermediate hosts were linked with adult worms from definitive hosts using ribosomal molecular data: 18S, ITS1, 5.8S-ITS2, 28S. These markers did not differ within the species and were only slightly different between them. Intra- and interspecific variability was also estimated using mitochondrial COI gene. In the constructed phylogeny Neophasis spp. formed a common clade with two other genera of the Acanthocolpidae, Tormopsolus and Pleorchis. We demonstrated that the first intermediate hosts of N. oculata were gastropods Neptunea despecta and B. undatum (Buccinoidea). Shorthorn sculpins Myoxocephalus scorpius were shown to act as the second intermediate and definitive hosts of N. oculata. The previous reconstruction of the two-host life cycle of N. anarrhichae was reaffirmed. We suggest that life cycle truncation in N. anarrhichae was initiated by an acquisition of continuous morphogenesis in the hermaphroditic generation and supported by a strong prey-predator relationship between A. lupus and B. undatum., Graphical abstract Image 1, Highlights • Life cycles of digeneans Neophasis oculata and N. anarrhichae were redescribed. • Phylogenetic position of genus Neophasis within family Acanthocolpidae was established. • Causes of life cycle truncation within Neophasis are discussed.

Buccinum undatum is a subtidal gastropod that exhibits clear spatial variation in several phenotypic shell traits (color, shape, and thickness) across its North Atlantic distribution. Studies of spatial phenotypic variation exist for the species; however, population genetic studies have thus far relied on a limited set of mitochondrial and microsatellite markers. Here, we greatly expand on previous work by characterizing population genetic structure in B. undatum across the North Atlantic from SNP variation obtained by RAD sequencing. There was a high degree of genetic differentiation between Canadian and European populations (Iceland, Faroe Islands, and England) consistent with the divergence of populations in allopatry (FST > 0.57 for all pairwise comparisons). In addition, B. undatum populations within Iceland, the Faroe Islands, and England are typified by weak but significant genetic structuring following an isolation‐by‐distance model. Finally, we established a significant correlation between genetic structuring in Iceland and two phenotypic traits: shell shape and color frequency. The works detailed here enhance our understanding of genetic structuring in B. undatum and establish the species as an intriguing model for future genome‐wide association studies.

The whelk Buccinum undatum is commercially important in the North Atlantic. However, monitoring the ontogenetic age and growth of populations has been problematic for fisheries scientists owing to the lack of a robust age determination method. We confirmed the annual periodicity of growth rings present in calcified statoliths located in the foot of field-collected and laboratory reared whelks using microscale measurements of trace element geochemistry. Using Secondary Ion Mass Spectrometry (SIMS), annual trace element profiles were quantified at 2 μm resolution in statoliths removed from whelks collected alive from three locations spanning the length of the UK; the Shetland Isles (North), the Menai Strait, North Wales (Mid) and Jersey (South). Clear cycles in the Mg/Ca ratio were apparent with minimum values corresponding with the visible dark statolith rings and comparatively higher ratios displayed in the first year of growth. Statoliths from one and two-year-old laboratory reared whelks of known age and life history contained one and two Mg/Ca cycles respectively and demonstrated that the statolith growth ring is formed during winter (February and March). Cycles of Na/Ca were found to be anti-correlated to Mg/Ca cycles, whilst ratios of Sr/Ca were inconsistent and showed an apparent ontogenetic increase, suggesting strong physiological control. Variability in elemental data will likely limit the usefulness of these structures as environmental recorders. The results obtained using SIMS for trace element analysis of statoliths confirms the robustness of the statolith rings in estimating whelk age. μXRD at 2 μm spatial resolution demonstrated the statoliths were wholly aragonitic and thus trace element variation was not the result of possible differences in CaCO3 polymorph within the statolith. Changing XRD patterns along with SEM imaging also reveal an ‘hourglass’ microstructure within each statolith. The validation of the annual periodicity of statolith growth rings now provides a robust and novel age determination technique that will lead to improved management of B. undatum stocks.

Using growth rings observed in statoliths, the size-at-age relationship was modelled for waved whelk (Buccinum undatum) populations within the Mid-Atlantic Bight. A total of 45 sites in the Mid-Atlantic were sampled between 2016 and 2019 using a scallop dredge, and a subset of the whelk collected were aged (n = 318). Lab-reared individuals and back-calculation methods were used to fill missing juvenile observations. The Mid-Atlantic Bight population appears to differ in the fit of growth curves, compared to other assessed populations, due to a timing difference in hatching. Growth curves for whelk from the Mid-Atlantic Bight show that maturity is reached between 4 and 6 years of age. A statolith chronology spanning a 10-year period was developed using a mixed-effects modeling approach. The chronology was used to explore the influence of temperature variation on growth during ecologically relevant periods. Growth increased with higher annual temperatures however specific seasonal bottom temperature had varying effects on growth. Increasing bottom temperature during summer, the anticipated egg-development and hatching period in this region, resulted in an age-dependent decline in growth with a positive effect on younger whelk and a negative effect on older whelk growth. Higher summer temperatures provide larger time-windows for growth, facilitating increased growth in early life stages. It appears that whelk in this region possess sufficient growth plasticity to adapt to warmer conditions throughout the year, but increased warming during specific seasons may depress growth in older individuals, potentially affecting fitness and population persistence. Understanding these temperature-growth dynamics are critical for disentangling the effects of climate change on whelk growth, allowing for population predictions in the future.

The variation in shelled marine gastropod morphology across small spatial scales can reflect restricted population connectivity, resulting in evolution or plastic responses to environmental heterogeneity. The common whelk, Buccinum undatum, is a subtidal gastropod, ubiquitous in the North Atlantic, that exhibits considerable spatial variation in shell morphology and colour. Given that species delimitation in shelled marine gastropods is often based on shell characteristics, such morphological variation can lead to taxonomic confusion. Phylogeographical analysis based on mitochondrial DNA and microsatellites suggested cryptic species composed of Western and Eastern North Atlantic common whelk populations, the separation of which dates to the onset of the Pleistocene glaciation ~2.1 Mya. Divergence within the Eastern North Atlantic is more recent and characterized by isolation by distance. In the present study, phenotypic variation in shell morphology across the North Atlantic range is analysed and compared with molecular divergence. The morphological variation of B. undatum populations reflected the pattern observed for the molecular markers only for certain comparisons of populations and might, in other cases, reflect larger constraints on the morphological variation and, possibly, the impact of environmental influences.

Neophasis anarrhichae (Nicoll, 1909) Bray, 1987, unlike the majority of acanthocolpid digeneans, has an abbreviated two-host life cycle. The reproduction of rediae, development of cercariae, and their transformation into unencysted metacercariae occur within the only intermediate host, the whelk Buccinum undatum. Normally, the metacercariae develop into sexual adults (maritae) and egg production starts when the infected whelk is eaten by a wolffish Anarhichas lupus. In the White Sea, we have found three cases of infection of B. undatum by progenetic metacercariae of N. anarrichae. These metacercariae had a fully developed and functioning hermaphroditic reproductive system, and eggs were found in their uterus. Most eggs observed in the histological sections were abortive, but some contained embryos at early stages of development. The progenetic metacercariae were similar in their morphometric characteristics to the sexual adults from the wolffish, the main differences being the size of the ovary and eggs. In order to confirm progenesis, and thus a facultative one-host life cycle in N. anarrichae, we need to prove that the eggs from metacercariae are viable.

The purpose of this study was to revisit the mitochondrial genetic divergence of North Atlantic populations of the subtidal gastropod Buccinum undatum, because previous mitochondrial DNA (mtDNA) analysis by Pálsson et al. (2014) included 16S ribosomal RNA sequences that were incorrectly assigned to the species. In the present study, population mtDNA variation is now assessed using COI sequences obtained from previous research (Pálsson et al., 2014) and, to increase the geographical cover of the study, data from recently assembled transcriptomes of 96 Icelandic whelks (Jónsson et al., 2019) and GenBank are also used. To estimate the mtDNA divergence in B. undatum across the North Atlantic, two species screening indices were used: automatic barcode gap discovey (ABGD; Puillandre et al., 2012a) and species screening threshold index (SSTI; Witt et al., 2006). Phylogenetic reconstruction revealed monophyletic Eastern and Western North Atlantic whelk lineages, which diverged early in the Pleistocene glaciation (2.1 Mya), followed by a subsequent divergence event between Greenlandic and Canadian populations at 1.3 Mya. Species screening indices, ABGD and SSTI, indicated cryptic speciation or allopatric divergence. Genetic distances between populations from the two continents were similar to or greater than interspecific genetic distances across several North Pacific and North Atlantic Buccinum species.

The waved whelk (Buccinum undatum) is commercially fished in the North Atlantic Ocean; the fishery is growing in Atlantic Canada. The species’ oviparous reproduction limits dispersal, posing a challenge to fishery management at the meta-population level. The Minimum Landing Size (MLS) for B. undatum in Nova Scotia is set at 65 mm with intent to maintain an adequate spawning stock. The implicit assumption that the MLS approximates a size at which half the population has reached reproductive maturity (LM50) is unjustified. We measured the LM50 of the whelks sampled from commercial fishing catches during 2016 and 2017 at five sites on the Eastern Scotian Shelf located roughly 11–210 km apart. There were significant differences among all measured parameters including total shell length, LM50, sex ratio and parasitic prevalence. The latter was measured to investigate its effects on calculations of LM50 and fishery regulations. The LM50 was smaller than the MLS at all sites. The LM50 for males ranged 45–64 mm, and 53–65 mm for females. The age at LM50 was found to be consistent with other studies: 5–6 years for both sexes. The size-frequency distributions in most samples were approximately normally distributed. The sex ratio was within the range found in other studies but varied among sampling sites. The prevalence of castrating trematodes was found to be 2–26% in males and 5–25% in females. We suggest that the area-based, effort management model for the fishery should adopt locale-specific MLS values based on the LM50 determined for sub-populations being exploited within specific areas of fishing access.

The common whelk, Buccinum undatum, is a commercially important gastropod found throughout the North Atlantic. One method of age and life history analysis for gastropod species is the use of oxygen isotope ratio (δ18O) measurements from their shells, which is a well-established technique for the reconstruction of historical seawater temperatures at the time of shell biomineralization. Palaeotemperature calibrations have been developed for different types of calcium carbonate as well as species-specific equations to produce the most accurate seawater temperature reconstructions. Here we investigate the four-layer internal structure of B. undatum shells and confirm an aragonite composition using Micro-Raman Spectroscopy (MRS). We then calibrate a species-specific palaeotemperature equation for this gastropod species. This was achieved through the isotopic analysis of shells from laboratory reared specimens of known provenance reared at specific seawater temperatures to produce the following: t(°C) = 14.96 (± 0.15) – 4.94 (± 0.22) x (δ18Oshell – δ18Owater) The calibrated equation differs significantly from previously published data derived from both aragonite and calcite. An offset of 1.04‰ (± 0.41‰) was discovered between observed δ18OShell values and those expected under equilibrium, suggesting a species-specific vital effect. The calibrated equation was used to reconstruct accurate, high resolution historical seawater temperatures from three sites across the U.K. (Shetland, the Menai Strait and Jersey). With this new accurate calibration, both modern and fossil B. undatum shells now have the potential to be employed as high-resolution archives of recent and historical seawater temperature.

Few digeneans of the family Fellodistomidae are known from the Russian Arctic seas. The taxonomic status of these species, their life cycles and host range raised recurrent questions, some of which remain unanswered. To revise the species composition and life cycles of fellodistomids in the White Sea, we searched for them in several known and suspected hosts: wolffish, flatfishes (definitive), gastropods of the family Buccinidae (second intermediate) and protobranch bivalves (first intermediate). Species identification was based both on morphology and 28S ribosomal RNA gene sequences. We found Fellodistomum agnotum in the White Sea for the first time. Buccinum undatum was proved to be intermediate host of both F. agnotum and Fellodistomum fellis, and metacercariae of F. fellis were registered from two more buccinid species: Buccinum scalariforme and Neptunea despecta. We also found metacercariae of F. agnotum and F. fellis producing eggs in the second intermediate host. Two fellodistomids were found in protobranch bivalves: sporocysts and cercariae of Steringophorus furciger in Nuculana pernula, and sporocysts with large furcocercous cercariae in Ennucula tenuis. The latter were identified as F. agnotum by molecular analysis; thus, the entire life cycle of this species was reconstructed.

Development of the unmanaged waved whelk (Buccinum undatum) fishery on the Mid-Atlantic continental shelf of the United States has initiated investigation into fisheries-related biological and population attributes of the species in this region. Maturation and reproduction timing vary by location for this species and are likely linked to bottom water temperature. This study examined the seasonal fluctuations in relevant body metrics and gonadosomatic index in relation to bottom temperature to assess the timing of the reproductive cycle of the B. undatum population in the southern-most extent of this species’ range in the Atlantic. To characterize variation over the maturation schedule, nine locations in the Mid-Atlantic Bight (MAB) were sampled five times between January 2017 and September 2017. Maturity was assessed macroscopically, with morphological methods, and via gonadosomatic indices. Male behavioral maturity estimates, based on a penis length to shell length index (PL50), were compared to estimates made using other methods for assessing maturity to test the efficacy of this commonly used ratio. Mature whelk were found in all months and peak reproductive activity was observed in spring and early summer. This timing suggests that ideal sampling to visually identify maturity to estimate size of maturity would be late winter or early spring. Unique oceanographic dynamics in the MAB, such as strong seasonal stratification results in large changes in annual bottom temperature which appears to be closely linked to the reproductive cycle in this region. Our data suggest that B. undatum in the MAB experience spawning and development at ~ 7–8 °C; temperatures warmer than Canadian populations and cooler than some UK conspecifics. To our knowledge, this is the first study to document the annual reproductive cycle of waved whelk in the United States.

Size composition of common whelk Buccinum undatum in its aggregations on sandy and stony grounds at the depth of 2–15 m is analyzed on the data of experimental fishing by scuba divers and traps in the Kislaya Guba and Ura Guba Bays in different seasons of 2004–2017. The size group with shell height > 60 mm was the most abundant (70 %) and formed 90 % of the total biomass. This group is recommended for fishery; the shell height of 60 mm is sug­gested as the minimal commercial size for common whelk in this area.

This study was conducted to assess the potential application of ultrasonic treatment to enhance the tenderness of whelk (Buccinum undatum) meat. The optimum ultrasonic conditions for the maximum tenderization effect were determined using response surface methodology by a three‐level factorial Box–Behnken design for the optimization of three variables. The optimum conditions for the three variables found were as follows: ultrasound power at 200 W, treatment time for 9.6 min, and temperature at 45°C. The resulted tenderization effect was comparable to traditional enzymatic methods. Furthermore, disruption of muscle microstructure was observed in the ultrasonic‐treated whelk meat by scanning electron microscopy, while evaluations on physicochemical properties indicated the ultrasonic treatment has no significant undesirable effects on the quality of whelk meat including pH, water‐holding capacity, and lipid oxidation. In conclusion, this study showed the feasibility of ultrasonic treatment as a promising tenderization method for whelk meat without detrimental effects on its quality.

The commercial fishery for common whelk (Buccinum undatum L.) has expanded significantly in the Irish Sea since 1990 and continues to grow, particularly in Welsh waters and the Isle of Man territorial sea, with landings throughout the region increasing by 227% between 2011 and 2016. Whilst whelk populations are known to be vulnerable to localised overexploitation due to inherent life-history parameters, fisheries remain relatively unrestricted by conservation measures in comparison to other fisheries operating in the area. With the exception of the northernmost fishing ground between the Isle of Man and Scotland (Point of Ayre), the size-at-maturity (L50) estimate for populations sampled during peak-aGSI (the months in which adjusted gonadosomatic index is highest) indicates that whelk are being fished before the time at first spawning throughout the study area. A correlation was detected between the size (total shell length) and depth, with smaller whelks found in deeper waters where there generally is greater fishing effort, although effort data is not available at a resolution to investigate this relationship quantitatively. No clear link between benthic infauna biomass and the average size (total shell length) or reproductive capacity (aGSI) of whelk sampled throughout ICES Area VIIa was found, indicating that the ecological energetics of whelk populations are more likely to be a function of scavenging opportunities than predation on benthic communities. A mixed cohort analysis utilized length-based data to infer a size-at-age relationship in the absence of direct age observations (e.g. statolith rings), with whelk recruiting into the Isle of Man fishery five years after hatching. The evidence presented in this study suggests that, prior to recommending a MLS that will adequately protect the spawning stock biomass, L50 values should be adjusted for pre-spawning growth between the ideal time of assessment (when aGSI values are at a peak) and the spawning season (when aGSI values decrease).

Calculating age and growth rate for the commercially important whelk, Buccinum undatum in the aid of fishery management has historically been undertaken using growth rings on the organic operculum. This is difficult due to their poor readability and confusion between two different sets of growth lines present. Recent work presented the calcium carbonate statolith as an alternative for age determination of B. undatum. Here we compare the use of statoliths and opercula, comparing their readability and creating growth curves for three distinct populations across the United Kingdom. Using these data, we also test the most appropriate growth equation to model this species. Lastly, we use oxygen isotope analysis of the shells to assign accurate ages to several individuals from each site. These data were used to test the accuracy of statolith and operculum ages. Statoliths, whilst more time consuming to process have improved clarity and accuracy compared with the opercula. This improved readability has highlighted that a Gompertz growth function should be used for populations of this species, when in past studies, von Bertalanffy is often used. Statoliths are a viable improvement to opercula when assessing B. undatum in the context of fishery monitoring and management.

Sustainability within the fisheries of the commercially important European whelk Buccinum undatum has become a major concern because of over-exploitation and increased landings in many European coastal shelf seas due to the expansion of export markets to East Asian countries. Current management of B. undatum populations is difficult to achieve as several life history traits are problematic to accurately monitor. The current method of age determination for stock assessment has a low success rate and focuses on the use of putative annual rings on the surface of the organic operculum. Here, we validate an annual periodicity of growth ring formation in B. undatum statoliths that provides an alternative, reliable and accurate method for determining a whelk’s age. Laboratory-reared juvenile B. undatum of known provenance and age deposited a hatching ring at the time of emergence from their egg capsule and a clearly defined growth ring during February of their first and second years. Stable oxygen isotope profiles from the shells of 2 adult whelks confirmed annual growth ring deposition by demonstrating seasonal cycles of δ18O in the shell that matched the relative position and number of visible growth rings in the statolith. Validation of annually resolved statolith growth rings will, for the first time, provide fisheries scientists with a tool to determine the age structure of B. undatum populations and allow analytical stock assessments that will enable informed decisions for future management practices of whelk fisheries.

Recent expansion of the unmanaged waved whelk (Buccinum undatum) fishery within the United States Mid-Atlantic continental shelf region has prompted investigation into local life history parameters. Limited adult dispersal and lack of a planktonic larval stage has the potential to create spatially distinct populations with respect to size of sexual maturity and size frequency. During the summer of 2015, a comprehensive survey was undertaken to evaluate population structure, sex ratio, relative abundance, and size of sexual maturity for whelk in the Mid-Atlantic. Samples (n = 228) were collected from Georges Bank through the DelMarVa region using a modified scallop dredge at depths ranging from 27.4 to 112 m, with most whelk caught between 40–75 m, and peak abundances at 51–60 m. All whelk collected (n = 3877) were sexed, weighed, measured, and assessed for maturity. Sex ratios were skewed in favor of females in the south and balanced through the rest of the regions. Size of maturity ranged from approximately 56–73 mm and varied among regions and sex. Estimates of size of sexual maturity for B. undatum from other regions of the world were compiled, demonstrating that the size of maturity for this species is highly variable, and current minimum landing size regulations tend to fall below the estimated size of sexual maturity, potentially increasing the risk of recruitment overfishing. Overall, spatial variation in whelk phenotype suggests local adaptation in this species, indicating that regional management would be most appropriate.

A comparative immunological survey of cytotoxic properties of whole and cell-free haemolymph (plasma) was performed on four species of marine molluscs. Diverse target cells were used: auto- and heterologous mollusc haemocytes, starfish Asterias rubens coelomocytes, trematode Himasthla elongata rediae, and human erythrocytes. While all the four mollusc species were found to contain cytotoxic factors in their plasma, functional features of these molecules in bivalve and gastropod species are essentially different. Cell-free haemolymph of two clams, Mya arenaria and Mytilus edulis, contains pre-synthetized cytolytic complexes capable of immediate and generalized activation, leading to destruction of a broad range of target cells. On the contrary, two gastropod species, Buccinum undatum and Littorina littorea, possess haemolytic factors which display high specificity of recognition of receptor molecules on the target cells and slow cytolytic reaction. Overall, molecular strategies of cytolytic cascade activation in Bivalvia and Gastropoda can be described as low- and highly selective, respectively.

Weathervane scallop, Patinopecten caurinus, the largest scallop species in the world, is distributed from northern California, U.S.A., to the Bering Sea, and is only commercially harvested in Alaska. The fishery is considered well managed by the State of Alaska (U.S.A) Department of Fish and Game (ADF&G) and federal government, with many precautionary measures in place to avoid overharvest. There have been episodic declines in some management areas due to unknown causes. Fishermen also encounter scallops with abnormal adductor muscles, a condition colloquially termed “weak meat”, characterized by the retention of muscle when shucked, an obvious darkened discoloration, and/or an abnormal texture making the product unacceptable for marketing. A similar syndrome in Atlantic sea scallops, Placopecten magellanicus, described as “gray meat”, occurs in the eastern U.S. and Canada, and proposed causes include senescence, loss of bioenergetics due to chronic infestations, or a synergism of these factors. Recently a severe apicomplexan infection was found to cause a gray meat condition in Iceland scallops, Chlamys islandica, and the collapse of that stock. This parasite was subsequently detected in Atlantic sea scallops with the gray meat condition off the U.S. East Coast. Studies that followed identified the parasite as Merocystis kathae, previously described from the common whelk, Buccinum undatum, more than 100 years ago. In 2015 Bering Sea fishermen reported weak meat in their catch, so samples were submitted to ADF&G for diagnosis. Adductor muscles from all affected scallops had many large foci of an apicomplexan associated with necrosis, fibrosis, and muscular atrophy. Given the reduced quality, marketability, and possibly fitness of affected scallops, we performed a survey to estimate prevalence, intensity, and geographic distribution of this apicomplexan in Alaskan weathervane scallops. We sampled 180 scallops, from individual beds within each of the three major geographically broad scallop areas in Alaska. Overall prevalence was about 82%, ranging from 69 to 100% by district. Overall mean infection intensity, based on the number of parasite foci/section, was about 9 (range of 5–29, by location), with scallops from the Bering Sea and Southwest Kodiak being most severely infected. Molecular analyses confirmed that the Alaskan parasite is M. kathae, i.e., the same apicomplexan that caused the collapse of Icelandic scallops and a suspected cause for gray meat and mass mortality of Atlantic sea scallops in northeast North America.

Whelk fisheries globally suffer a from a lack of data and dearth of stock assessments, even though they are growing and can contribute important income locally in some regions. Hierarchical Bayesian methods are especially suitable for estimating biological parameters and reference points for data-poor stocks, as they can borrow strength from stocks with more information. Here we analyze the common whelk (Buccinum undatum) fishery in Iceland, which was initiated in late 1996 and is restricted to Breiðafjorður in Western Iceland. Whelk may be vulnerable to overexploitation due to low dispersal, differences in growth and maturation on small spatial scales, and limited regulation. A population dynamics model for whelk was used to test whether inclusion of spatial variation improved model fit, and demonstrates where more data are needed to improve stock assessment. We used CPUE data as an index of biomass and catches to fit a Bayesian hierarchical Schaefer surplus production model that included six sub-regions, and compared this model with all models that included successively less hierarchical structure. We also consolidated environmental and whelk demographic data from Iceland, including growth, maturity, and mortality rates, to form prior probability distributions for population growth and carrying capacity parameters. To determine whether spatial catch distribution would aid sustainability, we compared results when catches were evenly distributed over sub-regions to those based on status-quo catch distributions. The best model chosen included spatial variation in population dynamics, but more contrast in the data or additional abundance data are needed to be useful for stock assessment. As whelk is traditionally a data-poor fishery, our results yield hyperparameter distributions that can be used as prior information for assessments of whelk elsewhere, as well as sensitivity analyses that show how influential prior distributions can be on model selection and results.

Many studies have the aim of increasing our knowledge on settlement and colonization of epifauna. Despite broad interest these important processes have proved to be very complex and there are still issues which need more attention. Experiments presented here, performed in the Arctic, aim to explore colonization of epifauna on hard substrates in relation to: (1) site, (2) depth, and (3) substrate characteristics (i.e. heterogeneity and biotic/abiotic origin). Three different substrate types (pebbles, empty Buccinum undatum shells and artificial shells made of granite) were prepared and deployed on the seabed in four Arctic sites (two at Spitsbergen 78°N, two in Northern Norway 69°N) for one year. After recovery, epifaunal assemblage structure, species richness, abundance, and Shannon-Wiener diversity of each substrate was estimated, subjected to a three-factor fixed experimental design and analysed using permutational multivariate analysis of variance (PERMANOVA). As hypothesized, site (i.e. colonizer species pool, local environmental conditions) explained most of the variation, and proved to be most influential factor in determining epifaunal assemblage structure. However, where the spatial scale of investigation was lower, as at Spitsbergen where study sites were in close vicinity (2 nm apart), factors that varied with depth (e.g. macrofaunal cover) predominated. The study indicated that epifaunal assemblages are influenced to a different degree at various sites. Depending on the region (Spitsbergen or Northern Norway), the substrate surface area or substrate type were the least important factors, but still made some contribution. Results suggest also that among substrate features surface heterogeneity is of high importance, higher than its biotic/abiotic character. In most of the cases rough surfaces of artificial shells supported the highest species richness, abundance and diversity.

Currently ground limestone and oyster shell are the common sources of calcium for laying hens. Processed whelk (Buccinum undatum) shell contains approximately 34.8% calcium, very similar to the 38% value for commercial oyster shell and ground limestone. The objective of this study was to evaluate the effect of feeding whelk shells to laying hens on performance, egg and bone quality, and calcium balance. White Leghorn hens were fed a basal diet and either one-third large particle oyster shell (>1.4-4 mm) + two-thirds ground limestone (OS/GL), one-third large particle whelk shells (>1.4-4 mm) + two-thirds ground whelk (W/GW), 100% ground limestone (GL), or 100% ground whelk shells (GW) starting at 20 wk of age for 14 28 d periods. Production data were comparable among calcium sources for the first 8 periods of production. During periods 9 to 14, feed consumption for hens fed GW was lower (P

Analysis of simultaneously occurring live molluscs and empty shells of the whelk Buccinum undatum indicated similar abundance on the seabed making possible the estimation of recent natural mortality. Nearly all empty shells were occupied by hermit crabs Pagurus bernhardus and most of the remainder by Pagurus prideaux. P. bernhardus is highly selective for robust whelk shells, whereas anemone-protected P. prideaux use a range of smaller and thin-walled shells. Application of age size keys based on age reading of opercula surfaces permitted a tentative estimate of natural mortality of M = 1.34 on trap fishing grounds for brown crab in the southwest North Sea (whelks aged 4–7 years) and M = 0.85 and M = 0.63 for the fishing grounds on the Western Waters (whelks aged 4-7 years and 4-9 years respectively). Estimates of total mortality (Z), based on size-frequencies of live whelks, were Z = 1.35 (North Sea) and Z = 1.46 and 1.23 (Western Waters, aged 4-7 years and 4-9 years). Estimates of M for the North Sea might be biased by differences in trap selectivity between hermit crabs and live whelks. This is a novel approach that might be developed for whelk fisheries assessment and management, particularly using better age determination techniques.

Global temperatures are rapidly changing, causing shifts in both biotic and abiotic environments. In the short term, physiological plasticity is likely to play an important role in the survival of species. We studied the association between temperature and reproductive investment in the common whelk Buccinum undatum, a North Atlantic gastropod exhibiting non-pelagic development. We calculated the number of eggs per capsule volume and egg energetic status (Carbon: Nitrogen (C: N) ratio) for egg masses from a temperate population of whelks from the Solent, UK over a four-year period (2009–2013). Data were compared with egg masses from a sub-Arctic population from Iceland collected in 2011. Results were compared to local seasonal water temperatures to examine the association between temperature and reproductive investment. In the Solent, average winter temperatures increased significantly between 2009 and 2013, the winter increase being significant. Both the number of eggs per capsule volume and the C:N ratio of eggs increased significantly between the initial and final spawning years. The number of eggs per capsule volume was significantly lower in eggs collected in Iceland, but C:N ratio was significantly higher. The results indicate that shifts in reproductive investment in B. undatum are associated with environmental temperature. B. undatum appears to show a high level of physiological plasticity in reproduction which may, in the short term, facilitate species survival as annual temperature shifts become more variable.

Publisher's version (útgefin grein), The complete mitogenome of Buccinum undatum obtained from transcriptome analysis is presented here. The mitogenome is 15,265 bp in length and comprises 13 protein-coding genes, 2 ribosomal subunit genes, and 22 transfer RNAs. The complete genome was used to perform a phylogenetic analysis together with other Buccinoidea representatives with mitogenome data from GenBank., This work is supported by the Icelandic Research Council, under grant number 141302051.

Prey size selection in some bird species is determined by the size of the beak. However, we assumed for bird species swallowing whole prey that a cognitive process may be involved. As cognitive feature, brain mass was used. We hypothesized that the mass of the brain was more strongly positively correlated with prey size than morphological features such as beak volume, gizzard mass and body mass. We tested this hypothesis on eiders Somateria mollissima that swallow the prey whole, by using mean and maximum size of nine prey categories. Eiders were collected at the main wintering grounds in Denmark. As index of brain mass we used head volume, which is positively correlated with brain mass (r2 = 0.73). Head volume of eiders was significantly, positive correlated with mean and maximum size of blue mussels Mytilus edulis, razor clams Ensis directus and all prey sizes combined and the maximum size of draft whelk Hinia reticulata and conch Buccinum undatum. Gizzard mass was also significantly positively correlated with maximum size of draft whelk and conch. Beak volume and body mass was not significantly correlated with the size of any of the nine food items. Analyses of effect size for organs showed that head volume was positively related to prey size, whereas beak volume, gizzard mass and body mass did not show a significant positive relationship. These results indicate that cognitive processes connected to brain mass may be involved in prey size selection by eiders.

The impacts of bottom trawling in coastal ecosystems are significant, not only for targeted species but also for non-commercial ones. However, the critical gaps in scientific knowledge associated with these impacts on untargeted but functionally important species remain to be filled. This is notably the case for a great proportion of discarded invertebrates, for which only a handful of studies have investigated their survival. In this study, 600 individuals from six different benthic invertebrate species were collected in commercial conditions in the Bay of Biscay for short-term survival experiments. Overall, the observed survival after 100–130 h and the predicted survival via mixture models were very high (>93%) for Asterias rubens, Aphrodita aculeata, Buccinum undatum and Pagurus sp. Survival of Maja brachydactyla was lower though still high (>80% overall) and Atelecyclus undecimdentatus was more vulnerable to trawling and handling, with ∼ 50% of survival. Both showed 100% mortality when presenting carapace cracks and survival of M. brachydactyla was lower when missing appendages. No biotic nor abiotic parameters were correlated to survival, except injury class for M. brachydactyla and A. undecimdentatus. This study shows an overall high survival but highlights the fact that otter trawl fisheries may differentially affect discarded benthic invertebrates, therefore bringing light for future studies on longer-term impacts on benthic communities and coastal ecosystems. Furthermore, we recommend incorporating survival rates of discarded invertebrates in ecosystem-level modelling studies and encourage the use of detailed information and biomass reports of benthic invertebrates for a better management of natural populations and fisheries resources.

To ensure the sustainability of waved whelk, Buccinum undatum, stocks in a context of high environmental variability, it is increasingly needed to assess spatio-temporal variation in size-at-maturity. Validation of more rapid methods, visual assessment, penis length index (PLI) and a surface-based gonadal index (SGI), compared to conventional and more laborious mass-based gonadal index (MGI) and the ‘gold standard’ histological method is needed. These five methods were applied to the same samples of whelks stratified by size (Total shell height: TSH = 50−95 mm) and sex, captured at three sites of the St. Lawrence Estuary in July 2013, during the spawning season. Parasitized and imposex-affected individuals, detected by visual inspection, were excluded from the samples used for maturity assessment. Each whelk was classified as mature or immature using the different methods. The percentages of overall agreement between each method and histological assessment were calculated for each sex and site. In females (N = 140), compared to the MGI and SGI, the visual assessment, the simplest and less costly method, provided the outcome most concordant with histology. The strength of visual grading was that it could classify post-spawning females as mature more accurately than the two biometric indices, more influenced by the timing of sampling in relation to the stage of the reproductive cycle. The TSH at which 50 % of the females were mature was not significantly affected by the method selected for maturity assessment. In males (N = 45) which did not exhibit gonad resorption contrarily to the females, all methods were highly concordant. The PLI combined with visual examination, is recommended for a rapid, low-cost and quantitative male maturity assessment. Overall, this study validates the use of PLI and visual assessment for maturity assessment of whelks, enabling more frequent verification of the pertinence of the current minimum legal size for the protection of whelk stocks in different fishing areas.

Publisher's version (útgefin grein), Geographical patterns in morphology can be the result of divergence among populations due to neutral or selective changes and/or phenotypic plasticity in response to different environments. Marine gastropods are ideal subjects on which to explore these patterns, by virtue of the remarkable intraspecific variation in life‐history traits and morphology often observed across relatively small spatial scales. The ubiquitous N‐Atlantic common whelk (Buccinum undatum) is well known for spatial variation in life‐history traits and morphology. Previous studies on genetic population structure have revealed that it exhibits significant differentiation across geographic distances. Within Breiðafjörður Bay, a large and shallow bay in W‐Iceland, genetic differentiation was demonstrated between whelks from sites separated by just 20 km. Here, we extended our previous studies on the common whelk in Breiðafjörður Bay by quantifying phenotypic variation in shell morphology and color throughout the Bay. We sought to test whether trait differentiation is dependent on geographic distance and/or environmental variability. Whelk in Breiðafjörður Bay displayed fine‐scale patterns of spatial variation in shape, thickness, and color diversity. Differentiation increased with increasing distance between populations, indicating that population connectivity is limited. Both shape and color varied along a gradient from the inner part of the bay in the east to the outer part in the west. Whelk shells in the innermost part of Breiðafjörður Bay were thick with an elongate shell, round aperture, and low color diversity, whereas in the outer part of the bay the shells were thinner, rounder, with a more elongate aperture and richer color diversity. Significant site‐specific difference in shell traits of the common whelk in correlation with environmental variables indicates the presence of local ecotypes and limited demographic connectivity., The project was funded by a research grant no. 141302051 from the Icelandic Centre for Research and a PhD grant from the University of Iceland Research Fund to Hildur Magnúsdóttir.

The osphradium is a putative chemosensory organ of aquatic molluscs. Previously, we identified two distinct types of primary sensory neurons in the osphradial ganglion of freshwater pulmonates, one immunoreactive to leucine-enkephalin (LEnk-ir) and another to FMRFamide (FMRFa-ir). In addition, NADPH diaphorase (NADPHd)-positive elements apparently producing nitric oxide (NO) were demonstrated in the organ. In the present study, prosobranch molluscs, which have retained the osphradial sensory neurons within the epithelium, were studied. Both types of peptidergic neurons, as well as NADPHd-positive cells, were found within the epithelium or in a basiepithelial position in the relatively simple osphradium of the mesogastropod Littorina littorea and in the complex, bipectinate osphradium of the neogastropod Buccinum undatum. Similar evidence was also obtained for another mesogastropod, Ampullarius sp. Transmitter-specific sensory cell types like those discovered in the osphradium are also present as single neuroepithelial cells in other organs of the mantle complex in prosobranchs and in the pelecypod Anodonta cygnea. We suggest that evolutionarily conservative, transmitter-specific types of epithelial and neuroepithelial sensory cells predated the osphradium, which developed as the site of their concentration, while retaining characteristic subsets of sensory neurons.

There is little common rationale for the 45 to 75 mm total shell length (TSL) minimum landing sizes (MLS) for Buccinum undatum among countries in the Northeast Atlantic. Size at maturity and length frequency of B. undatum populations vary over small spatial scales; however, the driving mechanism for this is unknown. Size at maturity research for B. undatum dates back to the late 1980s; since then, there has been little consensus on laboratory methods or in which season to undertake the research. Here, we assess small-scale spatial variation in size at maturity over a year to identify the seasons that increase error in visual maturity estimates. We compare and contrast results from methods used in the literature to estimate maturity for B. undatum. Monthly, B. undatum samples were obtained from Welsh fishers between May 2013 and May 2014 from eight sites at four locations (n = 5080). All whelks were sexed, weighed, and measured, and up to 60 whelks from each location were assessed for maturity (n = 1659). Mature whelks were found in all months, with a peak in reproductive activity through summer and early autumn, followed by the onset of spawning in November. Size at maturity varied between sexes and sites, and ranged from 51 to 76 mm TSL. Whelks caught in shallow waters (0–10 m) matured at a smaller size than those from deeper waters (up to 60 m). Length frequency varied at each site suggesting that a single increase in MLS would impact fishers disproportionately. No methodology trialled was found without inherent errors when used in isolation, though a combination of methods proved ideal. The seasonal variation in maturity estimates suggested that assigning maturity is increasingly difficult outside annual reproductive periods and that prespawning is the ideal time to undertake visual gonad assessments for whelks.

The exploitation of the common whelk ( Buccinum undatum L.) has become an integral part of commercial fisheries in both Jersey and French waters. Since 2004 declining catches have been reported, and it has been suggested that existing management measures may not be effective. This study reports a further 8 years of annual monitoring of whelk catches from 2003 to 2011, using identical methodology and analysis as previous work. Jersey commercial whelk fishermen's logbook returns from 2007 to 2011, were also analysed for changes in effort and catch. Average catch per unit effort (CPUE) dropped by 36.7% from 3.3 kg per pot to 2.09 kg per pot. Since 2007, Fishermen's reported landings per unit effort for whelks, also dropped from 2.12 kg per pot to 1.75 kg per pot. Whilst a decline in catch rates of whelks greater than 44 mm shell length was reported earlier, this study also found catch rates for smaller whelks (

Hydrostatic pressure is the most constant physical parameter on Earth. It increases linearly with water depth and is stable over evolutionary timescales. Despite this, bathymetric shifts in physiological adaptations that are observed in marine invertebrates (eg in metabolic rate and egg size) are currently interpreted to result predominantly from decreases in temperature. However, analysis of invertebrate egg size data presented here indicates an increase in egg volume with depth in the absence of a thermal gradient. This suggests hydrostatic pressure may also be important in determining resource allocation to offspring. In order to test the hypothesis that an increase in energy expenditure during development occurs with increasing depth, we examined the effect of sustained exposure to pressure (1, 100, 200 and 300 atm) on development of a shallow-water marine gastropod, Buccinum undatum. Embryos developed successfully at 1, 100 and 200 atm, but the rate of development slowed with increasing pressure (by 3 days at 100 atm and 6 days at 200 atm). No development was observed at 300 atm. In embryos reared at 200 atm, veliger dry weight and carbon and nitrogen biomass were significantly reduced. These results indicate that high pressure significantly increases the metabolic cost associated with development, demonstrating a negative and ultimately critical effect. We hypothesise that pressure imposes increased metabolic cost on all physiological processes. This offers an additional explanation for physiological adaptations observed with increasing depth, indicating that hydrostatic pressure is an important and previously underestimated factor contributing to metabolic theory for approximately 99% of our biosphere. This may represent a critical physiological bottleneck for the maximum depth distribution of shallow-water fauna.

The common whelk Buccinum undatum is widely distributed around the coast of the United Kingdom, and supports valuable fisheries in many areas around the English coast. A minimum landing size (MLS) of 45 mm currently applies in England and is generally viewed as a useful management measure to help support a sustainable whelk fishery. However, there is limited knowledge about regional variation in the size of sexual maturity (SOM) in English whelk populations. Whelks were collected at 12 different sites around the English coast and SOM estimates were compared to the current MLS. The national SOM was above MLS, and the proportion of mature whelks at the MLS was extremely low or zero at most sites. Significant differences were found in SOM between sites and between sexes within some sites. The current MLS may therefore provide little or no protection to the English spawning stock, and whelk populations may thus be vulnerable to recruitment overfishing. Site-specific values of SOM suggest that discrete populations may occur at each sampled location, despite some being geographically close to one another. We recommend that regional rather than national management measures are necessary to protect English whelk fisheries, and further research is needed to determine the appropriate MLS for each region.

The dispersal and history of species affects their genetic population structure at both small and large geographical scales. The common whelk, Buccinum undatum, is a widespread subtidal gastropod in the North Atlantic that has no planktonic larvae and has thus limited dispersal capacity. The snail, which has been harvested by humans for centuries, is highly variable in morphology. To evaluate the population structure in the rich fishing grounds in western Iceland and its divergence from samples across the Atlantic, genetic patterns based on sequence variation in two mitochondrial (mt)DNA genes (COI and 16S) and five microsatellites were studied and compared with variation in populations from both sides of the Atlantic. Significant differences in allele and haplotype frequencies were found among samples separated by short distances along the coast of Iceland. Partition of the variation showed larger variance among samples obtained from distant regions than from neighbouring sites and genetic distances were correlated with geographical distance among populations in Europe. Phylogeographic patterns in mtDNA reveal different monophyletic lineages on both sides of the Atlantic, which predate the onset of the Ice Age and which may constitute cryptic species. Similar micro- and macrogeographical patterns were observed for the mtDNA and microsatellite markers, despite high frequencies of null alleles. Bayesian skyline reconstructions of the demographic history and mismatch distributions suggest that, although sizes of some populations were unaffected by Ice Age glaciations, others show signs of expansion after the Last Glacial Maximum. These phylogeographical patterns are consistent with patterns expected for low dispersal species that have survived in allopatric glacial refugial populations on both sides of the Atlantic and in deep-sea refugia within each continent. The observed genetic structure has implications for conservation and sustainable management of the harvested populations. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 145–159.

The objective of this study was to develop a means to reduce the capture of undersize waved whelk (Buccinum undatum) in small mesh (51–64 mm) conical traps. To achieve this, egress windows were incorporated above the bottom ring of a trap to produce openings of sufficient width to allow undersize whelk to be released as a string of traps is being hauled to the surface. Analysis of the passage of undersize whelk through three egress window sizes revealed that a 30 mm wide window was most suitable. Simulations of two vertical surge distances and two trap angles were carried out in a controlled environment to provide a better understanding of trap performance. Experiments revealed that when a trap is oriented at an angle of 40–45o a substantial percentage (29–36%) of undersize whelk can be removed at vertical surge distances of 0.3–1 m. Few (3–4%) legal size whelk were emitted at a trap angle of 40–45o and all whelk emitted from a trap were observed to pass through an egress window. Increasing the angle of the trap to 70–75o resulted in loss of legal size whelk through the entrance located on top of the trap. The results of these simple experiments are promising but require verification through fishery trials before they can serve management decisions. Trap modifications and a trap line configuration that will maximize the egress of undersize whelk during fishing trials are discussed.

Temperature is arguably the primary factor affecting development in ectotherms and, as a result, may be the driving force behind setting species' geographic limits. The shallow-water gastropod Buccinum undatum is distributed widely throughout the North Atlantic, with an overall annual thermal range of below zero to above 22 °C. In UK waters this species is a winter spawner. Egg masses are laid and develop when sea temperatures are at their coolest (4 to 10 °C) indicating future climate warming may have the potential to cause range shifts in this species. In order to examine the potential impacts of ocean warming, we investigate the effects of temperature on the early ontogeny of B. undatum across a thermal range of 0 to 22 °C. Each egg mass consists of approximately 100 capsules, in which embryos undergo direct development. Successful development was observed at temperatures ranging from 6 to 18 °C. Rates of development increased with temperature, but the proportion of each egg mass developing successfully decreased at the same time. With increasing temperature, the mean early veliger weight increased, but the number of early veligers developing per capsule decreased, suggesting a negative impact on the number of crawl-away juveniles produced per capsule. Elemental analysis showed both carbon (C) and nitrogen (N) to increase with temperature in early veligers but not in hatching juveniles, indicating greater energy reserves are accumulated during early ontogeny to compensate for the higher energetic demands of development at higher temperature. The developmental plasticity observed in B. undatum suggests this species to be capable of adapting to temperatures above those it currently experiences in nature. B. undatum may possess a thermal resilience to ocean warming at its current upper temperature distribution limit. This thermal resilience, however, may come at the cost of a reduced offspring number.

Demonstrating the benefits that marine ecosystems provide to society can support marine spatial planning and enhance the protection of fragile, biodiverse habitats. However, the importance of ecosystem services provided by such habitats is rarely accounted for in spatial management due to a lack of detailed information. The present study investigated the ‘habitat provision’ ecosystem service delivered by horse mussel (Modiolus modiolus (L.)) reefs, a ‘Priority Marine Habitat’ in the NE Atlantic. By working with local fishers, the abundance and demographics of commercially important whelks (Buccinum undatum) were examined. B. undatum catches were three times higher on reef sites and a greater number of smaller individuals were caught on the reefs compared to off-reef habitats. We therefore show that these productive and physically complex mussel reefs are important feeding and nursery areas for whelks, demonstrating the ‘essential fish habitat’ value of the now rare M. modiolus reefs. The results are discussed in the context of marine spatial planning and the potential for historically more widespread shellfish habitats to have been capable of providing substantial ecosystem services.

Intracapsular development is common in marine gastropods. In many species, embryos develop alongside nurse eggs, which provide nutrition during ontogeny. The common whelk Buccinum undatum is a commercially important North Atlantic shallow-water gastropod. Development is intracapsular in this species, with individuals hatching as crawling juveniles. While its reproductive cycle has been well documented, further work is necessary to provide a complete description of encapsulated development. Here, using B. undatum egg masses from the south coast of England intracapsular development at 6 °C is described. Number of eggs, veligers and juveniles per capsule are compared, and nurse egg partitioning, timing of nurse egg consumption and intracapsular size differences through development are discussed. Total development took between 133 and 140 days, over which 7 ontogenetic stages were identified. The number of both eggs and veligers were significantly related to capsule volume, with approximately 1 % of eggs developing per capsule. Each early veliger consumed nurse eggs rapidly over just 3–7 days. Within each capsule, initial development was asynchronous, but it became synchronous during the veliger stage. No evidence for cannibalism was found during development, but large size differences between embryos developing within each capsule were observed, and occasionally ‘empty’ veligers were seen, which had not successfully consumed any nurse eggs. These results indicate a high level of competition for nurse eggs within each capsule during development in the common whelk. The initial differences observed in nurse egg uptake may affect individual predisposition in later life.

The common whelk Buccinum undatum (Neogastropoda, Buccinidae) is widespread along the north Atlan- tic coasts of France. In west Cotentin (Normandy), an important local fishery exists that depends exclusively on this marine resource and represents about 90% of French whelk production. Despite successive restrictive measures, fishing yields have decreased since 2000. Shell length frequency distributions of Buccinum undatum caught in west Cotentin were studied in 2005 (N = 2910), in 2007 (N = 2032) and in 2009 (N = 4145) ranging from 7 to 85 mm. In order to pre- serve this fishery and to characterise the whelk stock at this site, the reproductive biology of this species was studied in relation to age, sex and size, for whelks of commercial size (45 to 61 mm) over the complete annual cycle in 2008. Age was determined by reading the number of operculum striae: animals between 45 and 59 mm had 2 to 4 striae. Four reproductive stages were defined for males and females on the basis of histological analysis. The time course of repro- ductive events was described according to size and sex: the highest percentages of ripe stages were found in October for both sexes. Spawning events occurred between October and December. The shell length that corresponded to 50% of animals having mature gonads (49 mm and 52 mm for males and females, respectively, corresponding to 3 and 4 years old animals) exceeded the minimal landing size (45 mm). Fifty percent maturity was reached for males in their third year and for females in their fourth year. Reproductive investment was evaluated by quantitative analysis of the gonadal thickness or surface and was found to be proportional to shell size. We found that less than 20% of females under 49 mm in length were sexually mature and that these produced only a few eggs. This information, collected in a major fishing area, should assist fishery management decisions.

Life-history theory predicts an optimal offspring size, irrespective of reproductive effort; however, in some species offspring size correlates positively with maternal size. We examine hypotheses for why this latter situation should occur in the whelk Buccinum undatum. The trade-offs between aspects of reproduction in whelks are complicated due to the provision of protective egg capsules. Many eggs are placed within each capsule but c. 99% of these eggs are consumed by the remaining developing young. Large maternal size results in more eggs, larger eggs, more eggs consumed per hatchling, more capsules, larger capsules, more eggs per capsule, a larger number of hatchlings per capsule and larger hatchlings. Increased intra-capsule and post-hatch sibling competition may decrease the marginal value for additional young and select for larger young, however, our data do not support this explanation. Instead, packaging constraints within each capsule limit the size of hatchlings but this constraint is relaxed for medium to large females because they produce large capsules. Small females appear to produce young below optimum size because of the space constraint thus explaining the correlation between maternal size and offspring size.

The fine structure and function of the excretory system and associated veins of the muricid Nucella lapillus have been studied and compared with those of the buccinid Buccinum undatum. It is argued that in both species the nephridial gland vein is a functional unit with the auricle as it is in Littorina, and that its sinuses provide a compensation sac for blood displaced from the mantle skirt on retraction of the snail into the mantle cavity. This may be typical of marine caenogastropods. The epithelium lining the tubules of the gland recaptures organic solutes from the urine at the start of the systemic circulation, and phagocytes in its sinuses (the blood gland) abstract macromolecules and toxins from the blood. The development of two different types of folds on the dorsal wall of the kidney in neogastropods and other carnivorous neotaenioglossans is correlated with adaptations of the foregut to diet and with feeding mechanisms in which a retractile proboscis is accommodated in the cephalic haemocoel. It does not necessarily reflect phylogenetic relationship. On the basis of the observations reported here it is concluded that the dorsal afferent renal vein and secondary folds of the kidney act primarily as a compensation sac for blood displaced from the cephalopedal haemocoel during retraction of the proboscis, or when the snail withdraws into its shell. Aggregates of haemocyanin form in these blood spaces at such times. The relationship between the two sets of folds, which interdigitate in pycnonephridians or are largely separate in meronephridians, is related to shell shape, proboscis type and foregut structure in different families. Loss of the anal gland in the buccinoideans is correlated with changes in the efferent renal veins, a reduction in the size of the rectal sinus and the reduction or loss of the gland of Leiblein. Extracellular bacteria occur in the anal gland of the muricid Ocenebra erinacea similar to those previously reported in Nucella, suggesting that their presence may be typically associated with the gland in the Ocenebrinae and possibly other muricids.

The fates of a phenolic contaminant and its hydrocarbon precursor have rarely been compared, especially in an invertebrate species. Two groups of Buccinum undatum were exposed to equimolar amounts of pyrene and 1-hydroxypyrene over 15 d through their diets. Tissue extracts from the muscle and visceral mass were analyzed by liquid chromatography with fluorescence and mass spectrometry detection. Nine biotransformation products were detected in animals from both exposures. These included 1-hydroxy- pyrene, pyrene-1-sulfate, pyrene-1-glucuronide, pyrene glucose sulfate, two isomers each of pyrenediol sulfate and pyrenediol disulfate, and one isomer of pyrenediol glucuronide sulfate. These compounds represent a more complex metabolic pathway for pyrene than is typically reported. Diconjugated metabolites were as important in animals exposed to pyrene as in those exposed to 1-hydroxypyrene. Biotransformation products represented >90% of the material detected in the animals and highlight the importance of analyzing metabolites when assessing exposure. A mean of only 2 to 3% of the body burden was present in muscle compared with the visceral mass of both groups. The analytical methods were sufficiently sensitive to detect biotransformation products both in laboratory control whelks and in those sampled offshore. The tissue distribution of ( 14 C)pyrene was also studied by autoradiography. Radioactivity was present primarily in the digestive and excretory system of the whelks and not in the gonads or muscle tissue. Environ. Toxicol. Chem. 2010;29:779-788. # 2009 SETAC Keywords—Dietary uptake Polycyclic aromatic hydrocarbons Metabolite Phenolic Invertebrate

Data in the fatty acid composition of muscle tissue phospholipids of some representatives of gastropod molluscs (Gastropoda) have been presented for the first time. In the lake phytophagues Lymnaea stagnalis and Lymnaea ovata the long-chained C22-acid was not detected, where-as in the predator common whelk Buccinum undatum, C22:6ω3 was present. Comparison of absorption spectra (240–720 nm) of lipid extracts of the studied invertebrates and of rat has been performed. The obtained data are discussed from the point of view of participation of π-electrons of phospholipid fatty acid molecules in adaptation of membranes to the habitat temperatures, which arises owing to interelectron attraction and to the process of formation of Cooper’s pairs.

The aim of this study was to identify the presence of antimicrobial activities in the hemolymph of commercially important mollusc species. Acidic extracts were prepared from whole Cerastoderma edule ( Cardiidae ), Ruditapes philippinarum ( Veneridae ), Ostrea edulis ( Ostreidae ), Crepidula fornicata ( Calyptraeidae ) and Buccinum undatum ( Buccinidae ) and fractionated by Solid Phase Extraction. Fractions were first assayed for antibacterial activity against two indicator strains by an antagonism well diffusion method. Minimal Inhibitory Concentrations (MICs) were then determined against a panel of target bacteria including three Gram-positive and seven Gram-negative bacteria, some of which are aquaculture-pathogenic marine strains. In parallel, antiviral activities were assayed in vitro against Herpes simplex virus type 1 and Vero cells by cell viability. The broadest antibacterial activity was found in fractions from C. edule , but the highest activity was found in O. edulis (gills + mantle). At the antiviral level, the most active fraction was also attributed to C. edule acidic extract. Furthermore, SPE-fractions from other molluscs (40% SPE-fraction from O. edulis (gills + mantle), and 80% SPE-fractions from B. undatum , C. edule and R. philippinarum extracts) displayed lower EC 50 values than the 40% SPE from C. edule but at in vitro concentrations causing more cytotoxicity. These promising results have led us to consider purification of the active compound(s) which may be related to mollusc defense mechanisms.

A comparative analysis of fatty acids (FA) in neutral and phospholipids of digestive gland and pedal muscle has been performed in molluscs from various ecological groups differing by belonging to sea or fresh water, trophic types or the associated motor activity. In freshwater pulmonary gastropods Lymnaea stagnalis and Limnaea ovalis and marine prosobranchial molluscs Buccinum undatum and Littorina littorea the total content of omega3-acids in phospholipids of the studied tissues differed more than twice, predominantly due to the combined effect of temperature and salinity of the habitat. The lower viscosity of cell membranes in marine species (omega3/omega6 < 1) is determined to the greatest degree by the presence of eicosapentaenoic acid that accounts for 22-25 % of the FA sum in marine species. Comparison of the molluscs by their trophic belonging has revealed the presence of linoleic acid in triglycerides in digestive glands of phytophages (8-12 %), but the practically complete absence of this acid in the predator B. undulatum (

The principal inshore fishery in the southwest Irish Sea is currently for whelk Buccinum undatum, which expanded in the 1990s and yielded almost 10,000 t in 2003. The fleet exploiting it consisted largely of old boats many of which previously used a variety of gears but which cannot any longer compete with more modern towing craft. Whelk is the only target species for the majority. The fishery is in open access and is not regulated and the paper examines the consequences of this for the fishers, particularly the problems associated with maintaining a way of life traditionally associated with remuneration by share rather than wage. Lack of regulation, it is argued, encourages a short term, opportunistic harvesting regime, which is not conducive to maintain a biologically sustainable fishery.