Nassarius Reticulatus Research Articles

Sterol and Mineral Profiles of the Common Sea Snail Hinia Reticulata and the Long Sea Snail Nassarius Mutabilis (Gastropods) Collected from the Middle Adriatic Sea

Sea snails represent a common food in the world as a source of sterols, such as cholesterol and phytosterol, and minerals. Sterols play important roles in body functions and also minerals are important for human health, so the intake of these nutrients into human diets should be known. The aim of this study was to examine the sterol and mineral profiles of the long (Hinia reticulata) and the common (Nassarius mutabilis) sea snails. Samples of both species were collected at different catch times from November 2019 to March 2020 and transported to the University of Camerino (UNICAM) for the evaluation of their sterol and mineral profiles, including toxic elements (Cd, Cr, Pb). The results of the study showed that the average content of total lipid were 57 mg/100 g, 38 mg/100 g for cholesterol and 19 mg/100 g for phytosterol in the long sea snail, and the values were respectively 68, 48, and 20 mg/100 g in the common sea snail, without significant differences in the two examined sea snails. Additionally, the result of the mineral analysis showed that both species were significant sources of minerals, with negligible levels of toxic metals and metalloids. Therefore, the Long and the Common sea snail are suitable and safety sea products for human nutrition.

Evaluation of Long Sea Snail Hinia reticulata (Gastropod) from the Middle Adriatic Sea as a Possible Alternative for Human Consumption.

In mid Adriatic Sea the common sea snail is the habitual snail eaten, but over the years fishermen started to capture also the long sea snail, a possible alternative for human consumption. This study aims to compare the quality traits of the edible fraction in the common and long sea snails. In this study, common and long sea snail samples were provided by fishermen in November 2018 and March 2019. Total weight (meat and shell), fractions of meat and shell (after having extracted the edible part), fatty acid, elements in meat, and calcium content in shells were determined. Meat quality traits showed high nutritional value without significant differences between the two species. The fatty acid profile showed n3/n6 ratio significantly different both considering the season of sampling (November: 4.1; March: 2.38) and the species of sea snail (common: 4.98; long: 2.86). The long species showed a higher yield in the total body and calcium content concentrations. However, the long sea snail showed 50% lower meat yield compared with the common sea snail. In conclusion, the long sea snail can be used as an alternative to the common sea snail for human consumption.

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.

Liver Antioxidants in Relation to Beak Morphology, Gizzard Size and Diet in the Common Eider Somateria mollissima.

Antioxidants in the liver are particularly abundant in capital breeders that rely on stored resources for egg production. Capital breeders like eider (hereafter common eider) Somateria mollissima have disproportionately large livers with low levels of coenzyme Q10 when compared to other bird species. Concentrations of total carotenoids and vitamin E in the livers of eiders were smaller than predicted for similarly sized bird species. Eiders with high body condition estimated as body mass relative to skeletal body size had high levels of total carotenoids and low levels of coenzyme Q10. The concentration of total carotenoids per gram of liver increased with age, and vitamin E and total carotenoids accumulated during the winter onwards from February to peak at the start of incubation in April. Total vitamin E, total carotenoids, and coenzyme Q10 per gram of liver decreased with increasing beak volume. The size of the empty gizzard increased with increasing liver mass but decreased with total carotenoids and coenzyme Q10. The main components of the diet were blue mussels Mytilus edulis (40%), draft whelk Nassarius reticulatus (27%), and periwinkle Littorina littorea (10%). The concentration of vitamin E increased with the number of razor clams Ensis sp. and draft whelks in the gizzard and the concentration of total carotenoids increased with the number of beach crabs Carcinus maenas. These observations are consistent with the hypothesis that eiders are limited in their levels of antioxidants through food limitation. Furthermore, they imply that diet and morphological characters involved in food acquisition and processing are important determinants of the level of antioxidants in the liver.

Environmental quality status of the Portuguese coast regarding TBT pollution – Recommendations for considering imposex monitoring within the scope of the Marine Strategy Framework Directive

The recent years witnessed an increasing society consciousness on subjects concerning aquatic pollution. In Europe, several legislative pieces have been implemented to improve and protect the aquatic environment like the Water Framework Directive (WFD) and the Marine Strategy Framework Directive (MSFD), as well as the specific strategies adopted by Regional Sea Conventions. Here we assess the quality status of the Portuguese coastal and transitional waters regarding TBT pollution, using imposex as biomarker, aiming its integration as an indicator of environmental quality assessment under the MSFD. Imposex data available for two gastropod bioindicators, Nucella lapillus and Nassarius reticulatus, are used for that purpose, applying the classification previously proposed for the WFD (described elsewhere) and the OSPAR Assessment Criteria. A good quality status was achieved in most of the stations located in coastal waters while a worse ecological status was perceived in stations located in transitional water bodies, due to the proximity of TBT contamination sources. The comparison between the WFD classification proposal and the OSPAR Assessment Criteria shows a similar temporal trend in the study area however, slight differences can be perceived and are discussed. Both the WFD and OSPAR should be considered on the MSFD implementation but they differ in their objectives regarding TBT pollution. Therefore, this work allows the integration of imposex monitoring within the MSFD and recommends the use of the WFD assessment criteria also in this directive.

Critical analysis of the relationship between imposex and butyltin body burden in Nassarius reticulatus and Nucella lapillus

Imposex is a disorder caused by organotins, mainly tributyltin, which results in the appearance of male sexual characteristics in females of gastropod mollusks. The main objective of this work was to make a critical analysis of the relationship between imposex and butyltin body burdens in Nucella lapillus and Nassarius reticulatus. Specifically, this study evaluates possible additive effects among butyltins, proposes scales of effects based on robust statistical criteria as alternatives to existing ones and defines the body burdens of TBT in N. lapillus and N. reticulatus corresponding to the assessment classes (ACs) of the Vas Deferens Sequence Index (VDSI) established by OSPAR. Data of organotin body burdens and biological effects was retrieved from the ICES Dataset and from scientific literature. All responses, except the percentage of females displaying Imposex (IMPF) in Nucella lapillus, showed a sigmoidal profile regarding to the body burden of mono- (MBT), di- (DBT) and tributyltin and sum of butyltins (SumBTs). TBT and the SumBTs were better indicators of the VDSI or Relative Penis Size Index/Relative Penis Length Index (RPSI/RPLI) responses than MBT or DBT in most cases. From a statistical point of view, RPSI/RPLI and VDSI were better indicators of contamination by TBT than IMPF, although both RPSI and RPLI showed lower sensitivity than VDSI. The model used for describing the joint effect of butyltins provided a statistically significant fitting to the data assuming a null effect for both MBT and DBT for N. lapillus, and a lower toxic contribution of MBT and DBT with respect to TBT for N. reticulatus. RPSI or RPLI values, equivalent to the ACs for VDSI, were proposed as alternative criteria when measuring moderate to high levels of imposex. TBT concentrations in N. reticulatus and N. lapillus tissues, corresponding to the ACs were calculated and provided valuable information for cross-species comparisons.

Exposure of Nassarius reticulatus veligers in 24-well plates to assess effects of ocean acidification and warming projections on larval survival and behavior

Exposure of Nassarius reticulatus veligers in 24-well plates to assess effects of ocean acidification and warming projections on larval survival and behavior

Extended imposex monitoring in N Atlantic Spain confirms punctual attainment of European environmental objectives for TBT

Legislation in the European Union (EU) aimed at reaching by 2015 a Good Ecological Status in regard to tributyltin (TBT, the biocide used in traditional antifouling paints). With a view to check such an achievement in N Atlantic Spain, baseline monitoring of gastropod imposex (the recommended assessment tool) was extended up to that date. In Galicia (the Western part of the study area) the use of the rock snail Nucella lapillus since 1996 had shown this environmental objective to be met as soon as 2009, but new surveys reveal no further improvement thereafter. As for the Eastern Cantabrian coast, imposex levels in the mud snail Nassarius reticulatus progressively declined from 2006 to 2015, when records finally complied with expectations. Both data sets are confronted and discussed in relation to the diverse environmental factors that may be determining the distribution of gastropods in these regions.

Fifteen years of imposex and tributyltin pollution monitoring along the Portuguese coast

IMO’s Anti-Fouling Systems convention banned the use of organotin-based antifouling systems in 2008 as the ultimate effort to stop tributyltin (TBT) inputs into the marine environment. One of the hazardous effects of TBT is imposex (the superimposition of male sexual characters onto gastropod females), a phenomenon that may cause female sterility and the gastropod populations decline. Despite previous European Union legislation had already been shown effective in reducing the imposex levels along the Portuguese coast, this study intends to confirm these decreasing trends after 2008 and describe the global evolution in the last 15 years. Imposex levels were assessed in two bioindicators – the dog-whelk Nucella lapillus and the netted-whelk Nassarius reticulatus (Gastropoda, Prosobranchia) – in 2011 and 2014, and the results were compared with previous years. Both species showed progressive decreasing trends in imposex levels over the last 15 years; median values of the vas deferens sequence index (VDSI) fell from 3.96 to 0.78 in N. lapillus and from 3.39 to 0.29 in N. reticulatus. The temporal/spatial evolution of imposex suggests an apparent shift of TBT hotspots, being now restricted to fishing ports and marinas in detriment of large commercial harbours where TBT levels fell rapidly. Butyltins were measured in the whole tissues of N. lapillus females collected in 2014: monobutyltin (MBT) varied from < DL (detection limit: 1 ng Sn/g) to 13 ng Sn/g dw, dibutyltin (DBT) from 2.2 to 27 ng Sn/g dw and TBT from 1.5 to 55 ng Sn/g dw. Although TBT body burden has declined over time, the butyltin degradation index ([MBT]+[DBT])/[TBT] exhibited values < 1 in c. a. 90% of the sites assessed, suggesting that recent TBT inputs are still widespread in the Portuguese coast eventually due to illegal use of TBT antifouling systems and TBT desorption from sediments.

Gastropods As A Bioindicator and Biomonitoring Water Pollution

Water pollution effect on aquatic organisms and if consumed can affect people's health. These pollutants can be heavy metals such as Cd, Pb, Cr, Hg, and others. Heavy metals have high levels will cause disorders of the kidneys, brain, severe irritation to the skin, can cause diarrhea and even death. The purpose of this paper is to explain physiological mechanisms that occur in the body of gastropods are linked to pollutants in the water environment. Therefore, monitoring the level of pollution a body of water that is alleged to have suffered contamination is very important. Gastropods are one of the aquatic animals (Class) used as bioindicators and biomonitoring for this group of animals has a high ability to accumulate heavy metals in their bodies compared to other aquatic animals. Gastropods is one bioavailability against metal pollution so that it can be used for environmental monitoring. Littoraria scabra , Nassarius reticulatus , Nerita albicilla , Nucella lapillus , Gibberulus gibbosus , Terebralia palustris , and Telescopium telescopiun always use as biomonitoring metal pollution. The main indicator that can be shown by gastropods is declining abundance and body size. Other indicators are as bioavailability of heavy metals in the soft tissues and shells. The ability of the heavy metal deposits is influenced by environmental factors, body size, weight, and gender. Heavy metals can affect hard, thickness, volume, and color of the shell.

Bi-species imposex monitoring in Galicia (NW Spain) shows contrasting achievement of the OSPAR Ecological Quality Objective for TBT

Imposex is decreasing worldwide after the total ban on tributyltin (TBT) from antifouling paints. In order to assess improvement in the NE Atlantic, the OSPAR Convention designed an Ecological Quality Objective (EcoQO) based on the VDSI (vas deferens sequence index, an agreed measure of imposex) in the rock snail Nucella lapillus; wherever this is not available, the mud snail Nassarius reticulatus was proposed as a proxy. We determined VDSI in Galician populations of rock (n≥34) and mud (n≥18) snails at regular intervals from pre-ban times until 2009 and 2011, respectively. While imposex in the former started decreasing in 2006 and by 2009 the EcoQO had been met in the area, VDSI in the latter was not significantly reduced until 2011 and values contradict such an achievement. This suggests that the OSPAR imposex bi-species scheme may not be of direct application in the current post-ban scenario.

Imposex in Nassarius nitidus (Jeffreys, 1867) as a possible investigative tool to monitor butyltin contamination according to the Water Framework Directive: A case study in the Venice Lagoon (Italy)

Butyltin (TBT, DBT, and MBT) effects on molluscs, especially endocrine disruption in bivalves and gastropods, have been widely investigated. Imposex, the superimposition of male characters onto female gonochoristic Caenogastropods, is the most studied biological effect of TBT. TBT compounds are among the priority hazardous substances within Directives 2000/60/EC (WFD) and 2008/105/EC. The Environmental Quality Standards (EQSs) set by the WFD for TBT are quite difficult to quantify by means of chemical analysis, without the use of expensive and high performance methods. Assuming that EQSs set for TBT were derived from evidence of imposex development at very low concentrations, this specific biomarker could be used as an indirect measure of assessing levels of bioavailable BTs. Therefore, this study aims to validate the use of imposex development as an investigative tool to monitor the bioavailable fraction of BTs within the WFD, by comparing imposex levels and BT concentrations in Nassarius nitidus from the Venice Lagoon.BT concentrations and imposex levels in N. nitidus, collected in 2013, had decreased when compared to previous studies in the same area. Both VDSI and RPLI correlated positively with BT body burden in females, confirming that imposex is a valid tool to monitor bioavailable BTs. However, TBT is still a matter of concern in the Venice Lagoon, as TBT concentrations were still higher than its degradation products suggesting recent fresh TBT inputs in the studied area. To propose imposex levels as an indicator of the impact of BTs within the WFD, classification class boundaries and Ecological Quality Ratios were introduced.As a preliminary attempt, imposex levels were also compared to the OSPAR Commission EcoQOs which linked imposex levels in Nassarius reticulatus with TBT concentrations in water. Based on this comparison the degree of imposex development in the Venice Lagoon suggested that TBT concentrations in water should be over the EQS-AA concentration and, at one site, also over the EQS-MAC.From all the results obtained in this work, it appears that imposex evaluation in N. reticulatus could give information about the ecological status regarding BT compounds under the WFD and also be used to monitor their effects and support chemical analyses until more sensitive methods become available.

The usefulness of a sediment bioassay with the gastropod Nassarius reticulatus in tributyltin monitoring programs

Despite the use of tributyltin (TBT) had been banned worldwide in 2008 there is still evidence of its deleterious presence in environment. We evaluate the usefulness of a 28days sediment bioassay with Nassarius reticulatus females to monitor TBT pollution, using imposex as endpoint. In addition, butyltins were determined in sediments and tissues, and, whenever posible, imposex was assessed in native N. reticulatus at the same sites where sediments were sampled. In the bioassay, a significant increase in imposex parameters was obtained with three sediments (Vi2, Vi3, and Vi4). No correlation was found between this and TBT concentrations in sediment although good correlations were obtained for TBT in tissues, putting in evidence TBT bioavailability in sediment. A significant decrease in imposex from 2008 to 2013 in native snails was only observed at sites that did not cause any effect in the bioassay. In contrast, imposex levels in 2013 were kept as high as 2008 in one of the sites where a significant imposex increase in the bioassay was observed. The bioassay proves thus to be a practical and ecological relevant tool, as: (i) it can be conducted in sites with no native populations of snails, (ii) it provides early identification of polluted sites, anticipating future imposex levels or early identification of recovering, and (iii) it yields information on the bioavailable fraction of the TBT in the sediment. Therefore, this tool can be of extreme usefulness under the scope of recent European legislative frameworks.

Detection of periodic Sr Ca−1 cycles along gastropod statoliths allows the accurate estimation of age

Gastropods retain less obvious periodic growth marks on calcified structures than individuals in other groups (e.g. bivalves, cephalopods, fish), a fact that has hampered age estimation in this Class. Nevertheless, a model of age estimation for the gastropod Nassarius reticulatus is possible based on the annual growth rings deposited in statoliths during the winter. These spherical aragonitic carbonate structures are located inside the statocysts and contain a characteristic microstructural pattern of concentric rings. However, this pattern can be biased by the formation of nonperiodic disturbance rings (DRs). In Aveiro (NW Portugal), an increased frequency of DRs was reported in statoliths of specimens inhabiting the Ria de Aveiro lagoon (a highly dynamic environment), when compared with specimens collected from the relatively environmentally stable adjacent offshore area. One approach to resolve annual growth in organically precipitated carbonates is to find a chemical signature within the microstructure that faithfully records changes in seasonal environmental parameters. In this contribution, we have analysed the Sr Ca−1 variation along statolith sections by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) as a proxy to resolve seasonal cycles of temperature, allowing the identification of annual growth rings. Combining this information with size–frequency distributions of shell height, we found strong evidence that the rings chemically labelled with 88Sr 48Ca−1 peaks are formed annually during the cold season. Hence, LA-ICPMS allows not only the detection of visible rings but also the distinction between rings formed at low temperatures (i.e. a periodic seasonal signature) and those of disturbance (not characterised by increased 88Sr 48Ca−1). There is also clear evidence that the 88Sr 48Ca−1 peaks become less conspicuous from the nucleus to the statolith edge, leading to a loss of discriminatory power for the identification of older age rings. Nevertheless, this new method allows the accurate age estimation of N. reticulatus specimens and is liable to be applied in a wide range of gastropods after specific validation.

Tributyltin pollution biomonitoring under the Water Framework Directive: Proposal of a multi-species tool to assess the ecological quality status of EU water bodies

The Water Framework Directive (WFD) is a key legislative action developed by the European Union in order to protect aquatic ecosystems. One of the concerning pollutants, listed in this directive as a priority hazardous substance, is tributyltin (TBT), a biocide largely used in antifouling paints and identified as a causative agent of imposex/intersex in gastropods. In order to integrate TBT pollution monitoring within this legislative framework, a practical exercise is here proposed to assess the evolution of surface water ecological status in Ria de Aveiro (NW Portugal). Three bioindicators – the caenogastropods Nucella lapillus, Nassarius reticulatus and Littorina littorea – were used under the general WFD benthic invertebrate quality element, and the vas deferens sequence index (VDSI) and the intersex index (ISI) were selected as biomarkers for the purpose of assessing the condition of this quality element regarding the impact of TBT pollution. Levels of VDSI in N. lapillus and N. reticulatus, and ISI in L. littorea, were surveyed in 2013 and compared with previous data available for the same species and study area in 1998 and 2005, providing a time lapse for a period of 15 years. VDSI and ISI values were converted into Ecological Quality Ratios (EQR) and EQR boundaries were set for each species in order to define the five ecological status classes (High, Good, Moderate, Poor and Bad). We propose N. lapillus as key bioindicator, however the combined use of further species is very useful to cover a wider study area. Based on the proposed method, it is concluded that the ecological status of the surface waters surveyed in Ria de Aveiro, concerning the impact of TBT pollution on the above benthic invertebrate taxa, improved considerably since 1998 and achieved a Good Ecological Status in 2013, thus meeting the WFD environmental objectives for this priority hazardous substance even before 2015.

Cockle infection by Himasthla quissetensis – I. From cercariae emergence to metacercariae infection

The European cockle (Cerastoderma edule) is an exploited bivalve along the North-Eastern Atlantic semi-sheltered ecosystems. Its population dynamics are driven by numerous environmental factors, including parasitism, particularly by trematodes. The complex life cycle of trematodes includes a free living stage (cercaria) between the first (a mollusk) and the second (an invertebrate or a vertebrate) intermediate hosts. Taking the example of Himasthla quissetensis, a dominant trematode in Arcachon Bay (France) utilizing Nassarius reticulatus as first intermediate host and the cockle as second intermediate host, we investigated the correlation between cockle infection and cercariae emergence by N. reticulatus, including the role of water temperature and light. Experimental and field data provided evidence that cercariae emergence from N. reticulatus took place during the night and for water temperature comprised between 15°C and 22°C (optimum at 20°C). The lifespan of cercariae did not exceed 48h and 50% of them were no more infectious after 7h. A model was designed (emergence=f(water temperature)) in order to calculate an average monthly cercarial emergence rate according to water temperature that was daily recorded for 5years (1998–2002). Concomitantly, non-infected cockles were transplanted each of these years in order to assess the infection rate by H. quissetensis. Infection occurred strictly for the same water temperatures (and dates) as those expected for cercariae emergence. Within each year, there was often (but not always) a good correlation between the predicted number of emerging cercariae and the observed number of cercariae transformed into metacercariae in cockles. However, the among-years variability of cockle infection (×4.4 range) was not explained by the predicted annual number of emerging cercariae. This study highlights the importance of water temperature and light in stimulating cercariae emergence which is closely related to the occurrence of cockle infection. Accordingly, climate change would be expected to alter certain parasite transmission traits. Conversely, the lack of correlation between the total number of metacercariae in cockles and the expected number of cercariae suggests that other factors contribute to infestation variability.

A combined whelk watch suggests repeated TBT desorption pulses

Environmental quality in coastal Europe has improved since the complete 2003 ban on the use of tributyltin (TBT) in antifouling paints. However, there is evidence that TBT is entering the water column, presumably from illegal practices. We determined the concentration of butyltins (BTs: TBT and derivatives) in populations of two gastropods, the rock snail Nucella lapillus (n=17) and the mud snail Nassarius reticulatus (n=18) at regular intervals from pre-ban times until 2009 and 2011, respectively, in NW Spain. Although a substantial decline in TBT occurred shortly after the ban, no significant changes were observed in either species over the last 3-year period of study. In addition, the proportion of TBT relative to the sum of BTs (a marker of recent pollution) in the most recent rock snail samples unexpectedly increased; this proportion therefore showed a generally decreasing but oscillatory trend over time. The results are consistent with the theoretical expectation of BT desorption from sediments; however, this natural phenomenon is now interpreted as a recurrent episode rather than a unique, transient event. Evidence of this subtle input improves our understanding of TBT persistence in the environment in Europe and worldwide.

Crystallinity and microchemistry of Nassarius reticulatus (Caenogastropoda) statoliths: Towards their structure stability and homogeneity

Gastropod statoliths are spherical biocarbonates formed during their lifespan. The stability and homogeneity of these structures' mineral matrix was characterised along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline polymorphs occurring in biocarbonates - aragonite and calcite - coexist along statolith radiuses, aragonite being unequivocally the most abundant phase. The presence of a diffuse organic matrix was also perceived by the detection of a weak Raman band between 2800 and 3000 cm(-1) consistently observed along radiuses. Beyond the apparent stability and homogeneity, different crystalline orientations were disclosed by Raman spectroscopy. A change in the intensity pattern of the features related to the lattice and bending modes of aragonite between different radiuses give new insights for a possible spherulitic-like growth of these structures. As expected from the relative homogeneity of both mineral and organic signals, there was no pattern on the distribution of Ca, O, Na and S along radiuses. However, a higher concentration of Sr occurs in growth rings (known as winter tags), corroborating the already described negative correlation between the concentration of this element in statoliths and temperature. Despite the apparent stability and homogeneity of the matrix during its lifespan, the periodic distribution of Sr potentially influences a dissimilar incorporation of trace elements in increments and growth rings. Since gastropod statolith elemental fingerprinting was recently suggested as a new tool to monitor marine environmental changes, the pressing need for further studies on the incorporation of traces in these structures is highlighted.

Monitoring the effectiveness of the European tributyltin regulation on the Basque coast (northern Spain) by assessing imposex in two gastropod species (Nassarius reticulatus and Nassarius nitidus)

Imposex and butyltin body burden were assessed in 2011 along the Basque coast (northern Spain) in two gastropod species (Nassarius reticulatus and Nassarius nitidus) four years after an initial survey in 2007. The aim of this re-survey was to monitor the effectiveness of the European ban on the use of tributyltin (TBT) based antifouling paints on ships’ hulls (EC 782/2003). Imposex levels in 2011 were lower than those determined in 2007 at most of the sampling sites. Accordingly, TBT concentrations in the female body burden of Nassarius reticulatus varied from 43 to 250 ng Sn/g in dry weight in 2011, which was a lower maximum than in 2007. Nevertheless, the results for the butyltin degradation index suggest that there have been recent inputs of TBT within the two main Basque harbours. Overall, the legislative measure is contributing to the reduction of TBT effects on the Basque coast although its presence is still evident.

Studies on the morphology and growth of statoliths in Caenogastropoda

Gravireception in gastropods occurs by the displacement of statoparticles (multiple statoconia or a single statolith) inside statocysts, resulting from changes in the animal's position. An easy method for extraction and processing of statoliths is given and their morphology and microstructure described in 12 species of caenogastropods collected on the NW Portuguese coast, belonging to eight different families. In addition, statolith growth was studied in two species, Nucella lapillus and Nassarius reticulatus. The relation between statolith diameter (StD) and shell height (SH) follows logistic curves [in N. lapillus SH = 34.98/(1 + 190.817−49.082 StD), P < 0.001; and in N. reticulatus SH = 31.03/(1 + 116.709−36.577 StD), P < 0.001]. All statoliths observed are hard and translucent, with several concentric layers delimited by well-marked growth rings. Recently, some studies have shown that these rings are annual and can be used to determine the age of some gastropods and we show that this applies in a wider range of caenogastropods. Statolith rings were clearer in species collected offshore (Aporrhais pespelecani, Ranella olearium, Charonia lampas and N. reticulatus), because additional disturbance rings were more often present in statoliths from inshore species (Crepidula fornicata, Littorina littorea, Peringia ulvae, Trivia monacha, N. reticulatus, Nassarius incrassatus, N. lapillus, Ocenebra erinaceus and Ocinebrina aciculata). Statoliths thus have potential for sclerochronology and may provide an important record of the physical and chemical characteristics of the marine environment throughout ontogeny.