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Aim: The Antarctic Circumpolar Current imparts significant structure to the Southern Ocean biota. The Antarctic Polar Front is a major barrier to dispersal, with separate species (or sometimes intraspecific clades) normally occurring either side of this feature. We examined the biogeographic structure of an apparent exception to this rule in a widespread genus of the Southern Ocean, the periwinkle snail, Laevilitorina. Location: Southern Ocean. Taxon: Littorinidae, Laevilitorininae, Laevilitorina. Methods: Using 750 specimens from 16 Southern Ocean Laevilitorina populations across >8000 km, we analysed mitochondrial COI and nuclear 28S sequences to uncover the evolutionary history of these marine near‐shore snails. We utilized multi‐locus phylogenetic reconstructions, species‐delimitation analyses, divergence‐time estimations and geometric morphometrics. Results: Molecular data revealed that the widespread nominal species L. caliginosa comprises seven species‐level clades, all supported by morphological data, whereas the Antarctic nominal species L. antarctica, L. claviformis and L. umbilicata are conspecific. Six "caliginosa" clades are restricted to southern South America, but one lineage extends from Antarctica to distant sub‐Antarctic islands on both sides of the APF. Geometric morphometrics also identified significant differences among these clades, but uncoupled from genetic differentiation. Main conclusions: The apparent trans‐APF distribution of the poorly dispersing Laevilitorina caliginosa is largely illusory: this taxon consists of at least seven discrete species, only one of which has a trans‐APF distribution. Similar to most Laevilitorina species, the remaining six "caliginosa" clades are narrow endemics. Biogeographical patterns in Laevilitorina reflect the role of vicariance associated with geological processes together with recent long‐distance dispersal events. Laevilitorina originated near the Eocene/Oligocene boundary and diversified during the Miocene and the Pliocene. Laevilitorina is not a cryptic‐species complex: speciation was accompanied by hitherto unrecognized morphological differentiation. This study represents the most detailed molecular work on Southern‐Ocean littorinids and reveals unforeseen diversity across this globally important region. [ABSTRACT FROM AUTHOR]

Parasites can play a critical role in mediating inter-species interactions. Potential effects induced by parasites can range from species-wide traits to functional alterations in host community structure. One of the most intriguing host–parasite interactions pertains to adaptative host manipulation, an evolutionary occurrence where parasites alter the phenotype of their host to increase their own fitness. This study aims to address this phenomenon in a marine setting by investigating the effect of a philophthalmid trematode, Parorchis sp., on the vertical upward movement and phototactic behaviour of their intermediate hosts whilst simultaneously addressing the host specificity of these effects. These behaviours could impact the odds of trematodes successfully transmitting from their intermediate snail host to their definitive shorebird host, a crucial step in the life cycle of these parasites. Most trematode species exhibit strong specificity for snail hosts, typically infecting only a single snail species. In this rare system, however, the trematode infects a pair of sympatric and congeneric littorinid sea snails found in the intertidal zone of New Zealand's rocky shores: Austrolittorina cincta and A. antipodum. Precisely, experiments were conducted in a controlled, laboratory-based setting, extending over a period of six weeks, during which vertical displacement and response to light were measured. Our results demonstrate that vertical upward movement amongst infected snails increased for A. cincta, but not for A. antipodum. No difference in response to light between infected and uninfected groups was evident across either species. Our findings highlight the complex nature of parasitic infections, where trait-specific behavioural effects are dissimilar across even congeneric host taxa. [ABSTRACT FROM AUTHOR]

We demonstrated the genetic variation and population structure of a direct developing marine gastropod, Littorina horikawai which is endemic species distributed in the western coast of Kyushu, Japan and is found mainly on the adjacent islands. We conducted the field survey and sampling covering most of the distribution area of L. horikawai. In total, we collected 173 individuals from 13 localities (between Tsushima Island and Yakushima Island) and determined the sequences of mitochondrial DNA, the cytochrome b (CYTB) gene. We detected a significant genetic population differentiation in L. horikawai despite the limited distribution area of the western coast of Kyushu. Also, its haplotype distribution is mainly consistent with the geographical structure: the northern part of Kyushu, the central islands, and the southern islands. However, some haplotypes obtained from the Goto Islands which is located in the border between the northern part of Kyushu and the central islands do not correspond to the above geographic distribution. The high level of genetic differentiation of L. horikawai compared to other low dispersal Littorina species despite its narrow distribution range may be due to its predominantly fragmented island habitats. Although it is necessary for understanding the detailed evolutionary history of L. horikawai to perform the high-resolution genetic analysis, our present findings indicated that a high level of genetic differentiation of L. horikawai occurred even in a narrow distribution range because of not only the ecological traits linking to dispersal ability but also its discontinuous pattern such as the island inhabitation. [ABSTRACT FROM AUTHOR]

Periwinkle Littoraria sinensis is a widely distributed gastropod in rocky intertidal zone of the northwestern Pacific. To examine genetic diversity and genetic connectivity among coastal populations of L. sinensis in China, 1 636 pairs of primers were successfully designed using whole-genome shotgun sequencing, de novo assembly, and a bioinformatics pipeline QDD. Twelve highly variable polymorphic markers were selected to genotype 351 individuals from 15 populations. Data of nine microsatellite loci were retained for population genetic analysis, and weak genetic differentiation among populations were detected, suggesting high gene flow among populations. The long planktonic larval duration of L. sinensis might have played an important role in the high gene flow among populations. A tendency of genetic differentiation between north and south populations of L. sinensis was detected, which might be resulted from isolation due to lowered sea level in the last glacial maximum. Furthermore, the newly founded populations along the coast of Jiangsu Province were closely related to populations to the south of the Changjiang (Yangtze) River estuary, suggesting that the main source of the newly founded populations is from natural rocky populations south of the estuary. [ABSTRACT FROM AUTHOR]

The digenetic trematode family Gorgocephalidae comprises just a few species, and the literature devoted to the lineage consists of only a handful of reports. With one exception, all reports have been based on material collected in the Indo-West Pacific, an expansive marine ecoregion stretching from the east coast of Africa to Easter Island, Hawaii and French Polynesia. We collected adult and intramolluscan gorgocephalids from kyphosid fishes and littorinid gastropods from several Australian localities, and from South Africa and French Polynesia. Specimens of Gorgocephalus kyphosi and G. yaaji were collected from, or near, their type-localities, providing new morphological and molecular (COI , ITS2 and 28S) data needed for a revised understanding of species boundaries in the family. Two new species are recognized: Gorgocephalus euryaleae sp. nov. and Gorgocephalus graboides sp. nov. New definitive host records are provided for described species and three new intermediate hosts are identified. These new records are all associated with Kyphosus fishes and littorinid gastropods, reaffirming the restriction of gorgocephalids to these hosts. Most significantly, we provide evidence that G. yaaji is distributed from South Africa to French Polynesia, spanning the breadth of the Indo-West Pacific. Our findings have significant relevance regarding digenean species delineation over geographic range. [ABSTRACT FROM AUTHOR]

An important goal of marine population genetics is to understand how spatial connectivity patterns are influenced by historical and evolutionary factors. In this study, we evaluate the demographic history and population structure of Littoraria flava , a highly dispersive marine gastropod in the Brazilian intertidal zone. To test the hypotheses that the species has (1) historically high levels of gene flow on a macrogeographical spatial scale and (2) a distribution in rocky shores that consists of subpopulations, we collected specimens along the Brazilian coastline and combined different sets of genetic markers (mitochondrial DNA, ITS-2 and single nucleotide polymorphisms) with niche-based modelling to predict its palaeodistribution. Low genetic structure was observed, as well as high gene flow over long distances. The demographic analyses suggest that L. flava has had periods of population bottlenecks followed by expansion. According to both palaeodistribution and coalescent simulations, these expansion events occurred during the Pleistocene interglacial cycles (21 kya) and the associated climatic changes were the probable drivers of the distribution of the species. This is the first phylogeographical study of a marine gastropod on the South American coast based on genomic markers associated with niche modelling. [ABSTRACT FROM AUTHOR]

Littorina Férussac, 1822 is an abundant genus of small gastropods found in the upper littoral zone of rocky seashores worldwide. Although ecologically important, shell-based species identification in this genus is challenging due to phenotypic variation in shell morphology and lack of diagnostic characters among morphologically similar species. In this study, we revised the taxonomy of Korean Littorina species using morphological characters (shell and radula) and cox1 mitochondrial DNA sequences for three Korean species: L. brevicula, L. sitkana, and L. horikawai. Results suggest that L. sitkana was erroneously reported as L. kasatka in a previous study. A new record for Littorina horikawai (Matsubayashi & Habe in Habe, 1979), previously unknown from Korea, is described, which can be distinguished from L. sitkana by the presence of alternating white and brown spiral ribs on each whorl. Comparison of the mtDNA cox1 gene sequences shows very low intraspecific variation even between geographically distant populations. A phylogenetic tree supports a close relationship between L. horikawai and L. sitkana, consistent with earlier phylogenetic studies.

Recovery following salt marsh restoration in the northern Gulf of Mexico is investigated using meta-analysis for two salt marsh indicator invertebrates, the periwinkle snail (Littoraria irrorata) and amphipod crustaceans (Amphipoda). These invertebrates serve key marsh ecosystem functions including facilitating nutrient cycling and serving as prey for larger ecologically and economically important species. Recovery of periwinkles in restored marshes compared to reference sites is quantified by progression in population density and, because the species is long-lived (~ 10 years), in terms of biomass added per unit area each year following restoration. Amphipods are shorter-lived with high annual turnover; thus, recovery through time is estimated by the density of individuals rather than by biomass. The results of the analyses indicate progressive periwinkle recovery to equivalence with reference systems by year 4 in terms of density and year 6 with respect to annual biomass addition, while amphipod densities do not fully recover in the first 20 years following restoration. Although periwinkle recovery in terms of annual biomass addition reaches equivalence by year 6, the development of an age class structure characteristic of reference marshes would likely take longer because of the relatively long lifespan for this species. In addition to providing insight into the benefits of salt marsh restoration in the northern Gulf of Mexico, the approach described can be applied more generally to restoration scaling in a natural resource damage assessment context. [ABSTRACT FROM AUTHOR]

Background The introduction of DNA-based molecular markers made a revolution in biological systematics. However, in cases of very recent divergence events, the neutral divergence may be too slow, and the analysis of adaptive part of the genome is more informative to reconstruct the recent evolutionary history of young species. The advantage of proteomics is its ability to reflect the biochemical machinery of life. It may help both to identify rapidly evolving genes and to interpret their functions. Methods Here we applied a comparative gel-based proteomic analysis to several species from the gastropod family Littorinidae. Proteomes were clustered to assess differences related to species, geographic location, sex and body part, using data on presence/absence of proteins in samples and data on protein occurrence frequency in samples of different species. Cluster support was assessed using multiscale bootstrap resampling and the stability of clustering—using cluster-wise index of cluster stability. Taxon-specific protein markers were derived using IndVal method. Proteomic trees were compared to consensus phylogenetic tree (based on neutral genetic markers) using estimates of the Robinson–Foulds distance, the Fowlkes–Mallows index and cophenetic correlation. Results Overall, the DNA-based phylogenetic tree and the proteomic similarity tree had consistent topologies. Further, we observed some interesting deviations of the proteomic littorinid tree from the neutral expectations. (1) There were signs of molecular parallelism in two Littoraria species that phylogenetically are quite distant, but live in similar habitats. (2) Proteome divergence was unexpectedly high between very closely related Littorina fabalis and L. obtusata, possibly reflecting their ecology-driven divergence. (3) Conservative house-keeping proteins were usually identified as markers for cryptic species groups (“saxatilis” and “obtusata” groups in the Littorina genus) and for genera (Littoraria and Echinolittorina species pairs), while metabolic enzymes and stress-related proteins (both potentially adaptively important) were often identified as markers supporting species branches. (4) In all five Littorina species British populations were separated from the European mainland populations, possibly reflecting their recent phylogeographic history. Altogether our study shows that proteomic data, when interpreted in the context of DNA-based phylogeny, can bring additional information on the evolutionary history of species.

Morphometric analysis is one of the tools widely used to quantify, analyse and describe the variations in the biological forms of animals. In this study, we examined the linear morphometric variations of the shell of the small intertidal gastropod Echinolittorina lineolata and compared the patterns to identify variations among populations and between sexes. The individuals were collected from latitudes 3°S, 14°S, 21°S and 23°S along the Brazilian coast. Traditional morphometric analysis was performed, and the morphometric variables of the shells, namely, the length and width of the shell and the length and width of the shell opening were obtained. The observed size pattern was influenced by latitude, as well as by local spatial responses to factors such as the substrate changing the morphometric variables of the snail. Of the morphometric variables, the length and the width of the shell were the most representative variables that influenced the gastropods in the different latitudes. These variables were also different in males and females, with females having larger shell lengths and widths across all latitudes. [ABSTRACT FROM AUTHOR]

The rust fungus Puccinia vincae was found for the first time in Australia on blue periwinkle (Vinca major). Puccinia vincae was confirmed by comparison of the ITS2-LSU region to reference sequences from Europe as well as by morphology. [ABSTRACT FROM AUTHOR]

Background: The introduction of DNA-based molecular markers made a revolution in biological systematics. However, in cases of very recent divergence events, the neutral divergence may be too slow, and the analysis of adaptive part of the genome is more informative to reconstruct the recent evolutionary history of young species. The advantage of proteomics is its ability to reflect the biochemical machinery of life. It may help both to identify rapidly evolving genes and to interpret their functions. Methods: Here we applied a comparative gel-based proteomic analysis to several species from the gastropod family Littorinidae. Proteomes were clustered to assess differences related to species, geographic location, sex and body part, using data on presence/absence of proteins in samples and data on protein occurrence frequency in samples of different species. Cluster support was assessed using multiscale bootstrap resampling and the stability of clustering--using cluster-wise index of cluster stability. Taxon-specific protein markers were derived using IndVal method. Proteomic trees were compared to consensus phylogenetic tree (based on neutral genetic markers) using estimates of the Robinson-Foulds distance, the Fowlkes-Mallows index and cophenetic correlation. Results: Overall, the DNA-based phylogenetic tree and the proteomic similarity tree had consistent topologies. Further, we observed some interesting deviations of the proteomic littorinid tree from the neutral expectations. (1) There were signs of molecular parallelism in two Littoraria species that phylogenetically are quite distant, but live in similar habitats. (2) Proteome divergence was unexpectedly high between very closely related Littorina fabalis and L. obtusata, possibly reflecting their ecology-driven divergence. (3) Conservative house-keeping proteins were usually identified as markers for cryptic species groups ("saxatilis" and "obtusata" groups in the Littorina genus) and for genera (Littoraria and Echinolittorina species pairs), while metabolic enzymes and stress-related proteins (both potentially adaptively important) were often identified as markers supporting species branches. (4) In all five Littorina species British populations were separated from the European mainland populations, possibly reflecting their recent phylogeographic history. Altogether our study shows that proteomic data, when interpreted in the context of DNA-based phylogeny, can bring additional information on the evolutionary history of species. [ABSTRACT FROM AUTHOR]

Abstract The impact of salt farming on the habitats and food sources of Austruca occidentalis and Littoraria subvittata was studied in mangroves along the coast of Tanzania using stable isotopes (13C and 15N) and sediment particle size analysis. The 13C and 15N stable isotope composition in mangrove leaves, sediments and invertebrate tissues, were used to evaluate whether there are differences in feeding ecology of the crab Austruca occidentalis and the snail Littoraria subvittata collected from natural mangroves and mangroves around the salt ponds. Organic C, total N content and particle size distribution in sediments were used to assess if there are differences in habitat characteristics of mangroves around the salt ponds. Mangrove leaves and sediments were found to be 13C enriched around salt ponds compared to those from natural mangroves. Likewise the macroinvertebrates collected from mangroves around salt ponds were found be enriched in 13C relative to undisturbed mangroves. In addition, mangrove sediments around salt ponds were poorer in organic carbon and nitrogen and had more sand content compared to sediments from natural mangroves. These results indicate that salt pond activities have contributed to the modification of the habitats of macroinvertebrates by causing δ13C stable isotopes enrichment and alteration of sediment characteristics in the ecosystem. Highlights • Salt farming contribute to low amount of organic C and N content in sediments. • Salt farming promotes higher 13C isotopic composition in mangrove ecosystem. • The δ13C values recorded from invertebrates were higher compared to mangrove leaves. • The diet of invertebrates from natural mangroves is diluted with mangroves materials. • The effect of salt farming on 15N isotopic composition had no clear pattern. [ABSTRACT FROM AUTHOR]

Abstract The rapid dissemination of microplastics in many habitats of the oceans has raised concerns about the consequences for marine biota and ecosystems. Many adverse effects of microplastics on marine invertebrates are consequences of ingestion. Accordingly, the identification of mechanisms that facilitate the uptake of microplastics is essential for the evaluation of possible implications for marine organisms and food webs. Gastropods produce mucus for locomotion. Gastropod pedal mucus naturally retains formerly suspended micro-organisms, such as bacteria, microalgae, and seaweed spores. The retained organisms are consumed by gastropods that forage on pedal mucus. Here, we investigated the potential of gastropod pedal mucus to retain suspended microplastic particles and make them available for ingestion by periwinkles that forage on the contaminated mucus. In laboratory experiments, mucus of the periwinkles Littorina littorea and Littorina obtusata efficiently retained microplastics. Retention of microplastics varied between mucus from conspecifics of different size but not between mucus from either species. The density of microplastics in mucus trails increased concomitantly with the experimental particle concentration but was independent of incubation time. Aging of mucus and, particularly, desiccation affected the retention of microplastics. Periwinkles ingested microplastics when foraging on the contaminated mucus. Our results reveal a functional link between biogenic accumulation of microplastics and their trophic transfer by marine benthic herbivores into marine food webs. Graphical abstract Image 1 Highlights • Gastropod pedal mucus promotes uptake of microplastics by benthic consumers. • Pedal mucus from different periwinkles retains suspended microplastics. • Retention of microplastics varies with characteristics of the mucus. • Periwinkles readily ingest microplastics when foraging on contaminated pedal mucus. • Substantial amounts of ingested microplastics are released with fecal material. [ABSTRACT FROM AUTHOR]

Some marine species show homogeneous populations across most of their distributional range, but also population genetic structure at a smaller geographic scale. This intriguing scenario can be caused by different spatial and temporal factors, such as local oceanographic features, larval aggregation during dispersal, variable reproductive success and even natural selection. In this study, we evaluated small-scale population genetic structure in Echinolittorina lineolata, a gastropod with homogeneous populations at a large geographic scale in Brazil. Three concatenated mitochondrial DNA markers were used to infer genetic diversity and assess population-genetic differentiation between two locations. Repeated sampling of juveniles over time allowed us to test for constancy of genetic differentiation across four generations. Our diversity analysis revealed 103 haplotypes with low nucleotide diversity. The majority of the haplotypes were unique, but four were in high frequency and commonly found in individuals from both locations. There was only one location-specific haplotype with high frequency. When considering all samples, we detected spatial population differentiation within the dispersal range of E. lineolata. However, spatial differentiation was present in the first two generations sampled, while the following two showed genetic homogeneity between locations. In addition, there was genetic differentiation among individuals sampled from distinct rocks inside each location. When comparing generations within locations, different results were observed: in one location the first two generations were genetically similar, but differed from the following two generations; in the other location there was no genetic differentiation among all four generations. We hypothesize that E. lineolata is influenced by variance in reproductive success and resulting kinship among recruits. However, other factors could also cause transient genetic structure. We suggest that these curious genetic patterns can be better understood by combining the genetic information with in-depth knowledge of the species' biology and local oceanographic features. [ABSTRACT FROM AUTHOR]

Littorina Férussac, 1822 is an abundant genus of small gastropods found in the upper littoral zone of rocky seashores worldwide. Although ecologically important, shell-based species identification in this genus is challenging due to phenotypic variation in shell morphology and lack of diagnostic characters among morphologically similar species. In this study, we revised the taxonomy of Korean Littorina species using morphological characters (shell and radula) and cox1 mitochondrial DNA sequences for three Korean species: L. brevicula, L. sitkana, and L. horikawai. Results suggest that L. sitkana was erroneously reported as L. kasatka in a previous study. A new record for Littorina horikawai (Matsubayashi & Habe in Habe, 1979), previously unknown from Korea, is described, which can be distinguished from L. sitkana by the presence of alternating white and brown spiral ribs on each whorl. Comparison of the mtDNA cox1 gene sequences shows very low intraspecific variation even between geographically distant populations. A phylogenetic tree supports a close relationship between L. horikawai and L. sitkana, consistent with earlier phylogenetic studies. [ABSTRACT FROM AUTHOR]

The nearly complete sequence of the mitochondrial genome of the periwinkle Littoraria sinensis is presented. This is the first mitochondrial genome of the genus Littoraria and the fifth sequenced Littorinidae. The mitogenome of L. sinensis is 16,320 bp in size, with 37 genes and one partial control region. The genes order is identical to those observed in other Littorinidae mitogenomes. The overall base composition shows that AT content (64.76%) is higher than GC content (35.24%). This study should provide new information for the further phylogenetic studies of this species.

Some Antarctic littorinoideans have a remarkable convergence with Naticoidea in shell and operculum features. Two naticid-like species of that group are studied in their phenotypic features in order to improve their taxonomy and to discuss the meaning of that convergence, as the former are herbivore-detritivore and the latter active predatory organisms. One of the studied species is the littorinid Laevilacunaria antarctica (Martens, 1885). The other belongs to a new genus – Pseudonatica , with the type species also newly described: P. antarctica , the genus is tentatively placed in Zerotulidae. Another Pseudonatica is also described, P. ampullarica , based only on shells collected by Marion-Dufresne French expedition off Brazilian coast, this finding expands the occurrence of zerotulids northwards. Besides the similarities of shell and operculum, other structures of these Antarctic species also show singular similarities with naticoideans, such as the wide foot, the complexity of opercular attachment in pedal opercular pad, the wide oesophageal gland, and the coiled arrangement of the pallial oviduct. The phenotypic characters were coded and inserted in a previous large phylogenetic analysis on Caenogastropoda (Simone, 2011), furnishing a wide basis for discussion on the characters, taxonomic position, evolution and adaptations of these organisms. [ABSTRACT FROM AUTHOR]

Abstract: The most successful study systems are built on a foundation of decades of research on the basic biology, ecology and life history of the organisms in question. Combined with new technologies, this can provide a formidable means to address important issues in evolutionary biology and molecular ecology. Littorinid marine snails are a good example of this, with a rich literature on their taxonomy, speciation, thermal tolerance and behavioural adaptations. In August 2017, an international meeting on Littorinid evolution was held at the Tjärnö Marine Research Laboratory in Western Sweden. In this meeting review, I provide a summary of some of the exciting work on parallel evolution, sexual selection and adaptation to environmental stress presented there. I argue that newly available genomic resources present an opportunity for integrating the traditionally divergent fields of speciation and environmental adaptation in Littorinid research. [ABSTRACT FROM AUTHOR]

Freshly harvested rough and smooth periwinkle species were processed, treated with 5% brine, 5% brine + 3% citric acid and 3% citric acid, and stored for three weeks. The proximate composition, total volatile nitrogen and microbial quality of the boiled and treated periwinkle were determined. Moisture content ranged from 81.35%-80.73%, ash 1.30%- 2.49%, fat 0.46%-0.47%, protein 16.00%-14.00% and carbohydrate 1.19%-2.3% for unpreserved rough periwinkle (sample A0) and smooth specie (sample B0), respectively. Application of preservatives increased the moisture content of the periwinkles from 81.35-86.62% (samples A2-3) and 80.73-86.71% (samples B1-3), fat 1.82-0.50% (samples A3-1) and 0.94-1.25% for samples B3-1,2, respectively. Protein decreased from 12.88% (sample A2) to 10.62% (sample A1). TVN values ranged from 10.5-20.3mg/100g (sample A1), 20.3-30.1mg/100g (A2 ), 15.4-25.8mg/100g (A3 ), 12.6-22.4mg/100g (B1), 25.2-33.2mg/100g (B2) and 20.2-30.5mg/100g (sample B3) from week 1 to 3, respectively. Microbial analysis showed that untreated periwinkle samples at zero week of storage had coliform count of 7.5x106 cfu/ml and 8.8x108 cfu/ml for samples A0 and B0, respectively. Total bacteria count of 2.0x107 cfu/ml and 2.5x107 cfu/ml for samples A0 and B0, respectively and salmonella/shigella count of 6.4x106 cfu/ ml and 7.5 x 105 cfu/ml for A0 and B0 samples, respectively. Preservative measures employed in this study successfully decreased the microbial counts of the periwinkle samples to the extent of no growth recorded in some weeks. [ABSTRACT FROM AUTHOR]

This study characterizes chitin extracted from bio-sources of snail and periwinkle using varied combinations of acid and alkali concentrations. A three level factorial design of experiment with alkali and acid concentrations was used. FTIR, XRD and SEM were used to investigate the structural changes after treatments. Results reveal that both alkali and acid concentrations significantly affect the development of the functional groups and their intensities in the extracted chitin. A certain combination of concentration of acid and alkali can be used to obtain chitin with high degree of order (Crystallinity Index (CrI) > 0.9) and a degree of de-acetylation (DD > 50%). This results in combined high crystallinity and degree of de-acetylation. The study also established that certain combination of acid and alkali concentrations could lead to alpha to beta transformation in chitin structure. [ABSTRACT FROM AUTHOR]

Se analizaron taxonómicamente por medio de caracteres de la concha 233 especímenes del género Echinolittorina (familia Littorinidae) recolectados en ecosistemas rocosos del Pacífico colombiano. Los especímenes revisados se encuentran depositados en la Colección de Referencia de Biología Marina de la Universidad del Valle (CRBMUV) y provienen de localidades en los departamentos de Valle del Cauca (Bahía Málaga, Bahía de Buenaventura), Cauca (Isla Gorgona, Guapi) y Nariño (Mulatos, Parque Nacional Natural Sanquianga). Hasta este trabajo, se pensaba que esta familia estaba representada solamente por tres especies en el Pacifico colombiano y en este estudio se registran seis especies: Echinolittorina apicina, E. atrata, E. conspersa, E. dubiosa, E. paytensis, y E. tenuistriata. Se incluye una descripción morfológica de cada una de ellas para facilitar su identificación.

This article reports a successful removal of CaCO from snail and periwinkle shells for the purpose of producing high quality chitin for possible application as bio-fillers in bone fixation materials. Experiment was designed with varying concentrations of acid and alkali for demineralization, deproteinization and deacetylation of the samples. Thermal characteristics, morphology, degree of de-acetylation, crystalline structure and hydrogen bonding characteristics of the extracted chitin were examined. Infra-red spectra, thermogravimetric analysis and X-ray diffraction patterns show that demineralization with 1.7 M HCl led to a successful removal of CaCO. Subsequent deproteinization and deacetylation with 1.2 M NaOH led to a development of chitosan having a degree of deacetylation of 77 and 60% for periwinkle and snail shells, respectively. Generally, all results show that different treatments led to different chitin structure and consequently different properties. [ABSTRACT FROM AUTHOR]

A key element missing from many predictive models of the impacts of climate change on intertidal ectotherms is the role of individual behaviour. In this synthesis, using littorinid snails as a case study, we show how thermoregulatory behaviours may buffer changes in environmental temperatures. These behaviours include either a flight response, to escape the most extreme conditions and utilize warmer or cooler environments; or a fight response, where individuals modify their own environments to minimize thermal extremes. A conceptual model, generated from studies of littorinid snails, shows that various flight and fight thermoregulatory behaviours may allow an individual to widen its thermal safety margin (TSM) under warming or cooling environmental conditions and hence increase species' resilience to climate change. Thermoregulatory behaviours may also buffer sublethal fitness impacts associated with thermal stresses. Through this synthesis, we emphasize that future studies need to consider not only animals' physiological limits but also their capacities to buffer the impact of climate change through behavioural responses. Current generalizations, made largely on physiological limits of species, often neglect the buffering effects of behaviour and may, therefore, provide an over-estimation of vulnerability, and consequently poor prediction of the potential impacts of climate change on intertidal ectotherms. [ABSTRACT FROM AUTHOR]

Members of the genus Ulva are widespread and abundant in intertidal and shallow subtidal areas but there are conflicting data regarding susceptibility to herbivory. While some studies have documented that Ulva spp. were favored by a diversity of marine herbivores, other work has revealed herbivore deterrence. We investigated grazing and growth rates of the littorinid species, Littorina littorea and L. obtusata, when offered Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, and Chondrus crispus, highlighting distinctive vulnerabilities to toxic effects of U. lactuca. Ulva lactuca was the preferred food of L. littorea, while L. obtusata showed no grazing on this ephemeral algal species. In contrast, F. vesiculosus was highly preferred by L. obtusata. Although L. littorea demonstrated a grazing preference for U. lactuca, growth rate of this gastropod species was nearly 3× greater when fed F. vesiculosus, suggesting a non-lethal, negative effect of U. lactuca on L. littorea with long-term exposure. Mortality of L. obtusata ranged from 0% to 100% when held in the presence of various Ulva densities for 1 week, and Ulva exudate depressed herbivory of this gastropod. We conclude that the water-soluble, toxic exudate produced by U. lactuca in response to herbivory had allelochemical properties, and may contain a cleavage product (acrylic acid) of dimethylsulfoniopropionate or reactive oxygen species (i.e., H2O2). Observed differences in susceptibility to Ulva toxicity by the littorinid species may be related to generalist versus specialist feeding and habitat strategies. [ABSTRACT FROM AUTHOR]

The periwinkle, Littorina sitkana, is found throughout the intertidal zone, often in isolated subpopulations. The majority of trematode parasites use snails as intermediate hosts, and decreased survivorship is often observed in snails infected with trematodes. Sampling L. sitkana from four sites in Barkley Sound, British Columbia, Canada, we test the effects of parasitic infection on snail survival using maximum likelihood and Bayesian approaches using the software MARK and Win BUGS. We found that survival of periwinkles and trematode community composition differed among sites, but survival and trematode prevalence were uncorrelated. Win BUGS performed better than MARK in two ways: (1) by allowing the use of information on known mortality, thus preventing survival overestimation; and (2) by giving more stable estimates while testing the effect of body size on snail survival. Our results suggest that snail survival depends heavily on local environmental factors that may vary greatly within a small geographical region. These findings are important because the majority of experimental studies on survival are done on snails from a single location. [ABSTRACT FROM AUTHOR]

Distribution shifts of intertidal species have been thoroughly described for several organisms on the Atlantic coasts of Europe, but comparatively less work has been conducted in the Mediterranean Sea. However, such semi-enclosed basins react faster to global change. The periwinkle Echinolittorina punctata is a littorinid gastropod which has shown a remarkable range expansion during the last few decades. Moreover, its unambiguous taxonomy, accessible habitat and ease of identification qualify it as an ideal descriptor of biotic changes in the Mediterranean Sea. We investigated genetic differentiation among 17 Mediterranean and Atlantic populations covering its current distributional range, using the mitochondrial cox1 marker to test the hypothesis that it experienced a significant range expansion triggered by sea warming after the Last Glacial Maximum (LGM). This would confirm its suitability as descriptor of climatic fluctuations. E. punctata has a weak population structure along its distributional range, with greater haplotype diversity in the western African populations than in the Mediterranean Sea, suggesting a recent population expansion following a bottleneck event. Such range expansion is dated ca. 15,000 years BP, and is, thus, related to the end of LGM. E. punctata planktotrophic development lasts 3-4 weeks, likely triggering the weak population structure and enhanced ability to track environmental change. [ABSTRACT FROM AUTHOR]

Assortative mating in the wild is commonly estimated by correlating between traits in mating pairs (e.g. the size of males and females). Unfortunately, such an approach may suffer from considerable sampling bias when the distribution of different expressions of a trait in the wild is nonrandom (e.g. when segregation of different size classes of individuals occurs in different microhabitats or areas). Consequently, any observed trait correlation in the wild can be an artefact of pooling heterogeneous samples of mating pairs from different microhabitats or areas rather than true nonrandom matings. This bias in estimating trait correlations as a result of sampling scale is termed the scale-of-choice effect ( SCE). In the present study, we use two intertidal littorinid species from Hong Kong to show how the SCE can bias size-assortative mating estimates from mating pairs captured in the wild, empirically demonstrating the influence of this effect on measures of positive assortative mating. This finding cautions that studies overlooking the SCE may have misinterpreted the magnitude and the cause of assortative mating, and we provide a new analytical approach for protecting against this potential bias in future studies. [ABSTRACT FROM AUTHOR]

The hypothesis on monogenic inheritance of white longitudinal shell bands in the snail Littorina obtusata was tested. The data showed that a single gene with two alleles was responsible for the presence of the bands on the snail shell. The presence of bands was the dominant character. [ABSTRACT FROM AUTHOR]

Temperature is a fundamental element determining the distribution patterns of ectotherms, and it is generally recognized that physiological tolerances of ectotherms change according to thermal gradients in their habitats. However, little is known about the variation in cold tolerance of marine invertebrates among local populations of the same species. In this study, three experiments were conducted to demonstrate inter-population variation in the cold tolerance of the intertidal gastropod Littorina brevicula , and to explore factors driving the variation. First, seasonal changes in the freezing temperature (the supercooling point, SCP) and the median lower lethal temperature (LLT50) of snails collected from a single population were examined to identify the cold tolerance strategies of this species. Seasonal fluctuation was clear in only the LLT50 which was lower than the SCP in winter, indicating that cold tolerance strategy of this species was freeze tolerant. Second, the cold tolerance of snails from four populations was compared. These populations were distributed at latitudinally different locations, and the comparisons were performed before winter when their cold tolerance was not required and in winter when their cold tolerance increased. In this experiment, while the cold tolerance of snails collected in winter was higher than that of snails collected before winter in all four populations, there were differences in tolerance among the populations. Furthermore, to estimate their ability of acclimation to cold environments, snails that were collected from the northernmost and southernmost populations in the four populations before winter were acclimated to a constant low temperature in the laboratory for a long period (120–130 days). This long period of acclimation led to an increase in the cold tolerance of both populations, but the latitudinal difference was maintained. Additionally, after imposing the long period of acclimation to snails that were collected at 12 locations before winter, factors that might cause local variation in their cold tolerance were explored. This experiment clearly showed that local variation in cold tolerance was explained by the lowest local air temperature. Our study demonstrated inter-population variation in the cold tolerance of an intertidal mollusc, and that the variation is explained by thermal gradients in winter. [ABSTRACT FROM AUTHOR]

The influence of habitat modification by Mytilus edulis L. on the settlement and development of Fucus serratus populations was investigated on rocky shores of the Isle of Anglesey, North Wales. Settlement of fucoids was higher inside mussel habitat than outside on one of two shores studied. The effect of microhabitat on survival of fucoid germlings was examined by transplanting the germlings into and outside mussel habitats, each with and without the exclusion of grazers. Observation showed that periwinkles and top shells were abundant in mussel habitat, while limpets dominated bare rock. Exclusion of grazers greatly enhanced the survival of fucoid germlings in both habitats, indicating that while mussel habitat supports a different grazer assemblage to bare rock, both assemblages are important in limiting fucoid recruitment. The risk of dislodgement was assessed and compared between fucoids growing on mussel shells and bare rock. In situ pull-tests showed that less force was required to detach large fertile thalli growing on mussel shells than those growing on the rock. Adhesion was generally broken between the mussel and the rock rather than between the holdfast and the mussel. These observations indicate that mussels provide an unstable substrate for mature fucoids. Overall results suggest that a negative effect of mussel-modified habitat on fucoids is profound in adults; but the effect is context-dependent in juveniles and can be positive at settlement. Results from a survey on population structure of fucoids across two shores showed that there were greater numbers of large fertile fucoids growing directly attached to rock than on mussel shells, while there was no difference for juvenile fucoids confirming the experimental results. Moreover thalli larger than 60 cm were found only on the rock but not on shells. This finding suggests that a mussel dominated habitat may have a significant impact on reproductive output in fucoid populations. [ABSTRACT FROM AUTHOR]

The presence of Echinolittorina punctata (Gmelin, 1791) in the Adriatic Sea has been confirmed for the first time. In total, six specimens of this species were found near the city of Split. This species is considered as a tropicalization indicator in the Mediterranean Sea. The status of this species in the Adriatic Sea should be evaluated through future research. [ABSTRACT FROM AUTHOR]

Deepwater Horizon was the largest marine oil spill in U.S. waters, oiling large expanses of coastal wetland shorelines. We compared marsh periwinkle (Littoraria irrorata) density and shell length at salt marsh sites with heavy oiling to reference conditions ~16 months after oiling. We also compared periwinkle density and size among oiled sites with and without shoreline cleanup treatments. Densities of periwinkles were reduced by 80--90% at the oiled marsh edge and by 50% in the oiled marsh interior (~9 m inland) compared to reference, with greatest numerical losses of periwinkles in the marsh interior, where densities were naturally higher. Shoreline cleanup further reduced adult snail density as well as snail size. Based on the size of adult periwinkles observed coupled with age and growth information, population recovery is projected to take several years once oiling and habitat conditions in affected areas are suitable to support normal periwinkle life-history functions. Where heavily oiled marshes have experienced accelerated erosion as a result of the spill, these habitat impacts would represent additional losses of periwinkles. Losses of marsh periwinkles would likely affect other ecosystem processes and attributes, including organic matter and nutrient cycling, marsh-estuarine food chains, and multiple species that prey on periwinkles. [ABSTRACT FROM AUTHOR]

In habitats where competition for space is a shaping force of animal distribution such as in the intertidal rocky ecosystem, new habitats are readily taken by colonising species. We examined the importance of empty Chthamalus spp. tests as a habitat for the intertidal common periwinkle Melaraphe neritoides on Portuguese rocky shores. The role played by the space between neighbouring barnacles as a habitat for other species has been largely studied with regard to how an ecosystem functions, whereas the equivalent role of empty barnacle tests remains largely unknown. The small periwinkle is one of the most abundant snails in European rocky shores and is an important prey for key mobile predators. Biological facilitation is common in the rocky intertidal zone, where biological structures often potentiate the abundance of other species. The role played by barnacles as biological facilitators through habitat provision is not fully understood. In this study, the abundance and morphometric features of empty barnacle tests and their occupants were examined across shore levels and shores with differing exposures, as these are important gradients explaining barnacle distribution. The availability of empty barnacle tests was also experimentally manipulated to examine the percentage, time and length of occupation. Empty barnacles were more abundant on the midshore of sheltered shores and barnacle tests were wider on the upper shore but taller on the midshore. The minimum barnacle test occupation rate by the periwinkle was 70%. Barnacle shell height was an important factor determining snail occupation, where taller barnacles harboured significantly more, but not necessarily larger, snails. Snails outside the barnacle tests were significantly larger than those found within, suggesting that this crustacean group has an increased importance as a habitat for juvenile snails, thus potentially influencing the population dynamics of M. neritoides. We found that occupation of experimentally created empty barnacles was extremely high (70%) on the day after, and remained at 100% after 3 months of monitoring. Our study is the first of its kind to focus on the features of barnacle tests that snails occupy and their occupying snail traits. According to our results, it is clear that barnacles have an important role in providing additional habitat for young gastropods. The small periwinkle is an important grazer and prey for intertidal and subtidal foraging predators; hence, the potential refuge role of barnacle tests for juvenile M. neritoides may be important in the dynamics of intertidal communities. [ABSTRACT FROM AUTHOR]

The littorinid gastropod Littoraria flammea has been widely quoted as one of only three or four marine molluscs believed to have become extinct in historic times. It is easily recognized by its delicate, elongate, striped shell. We review the literature and available museum material to show that its only recorded locality was Shanghai and that it has not been collected since about 1855. We report the rediscovery of this species in salt marshes near Shanghai, where the habitat is under threat from invasive Spartina. For the first time we describe the penis, pallial oviduct and radula. These are the same as those of L. melanostoma, previously recorded only from Fujian province and southwards, where its shell is different from that of L. flammea. We now report a population of L. aff. melanostoma from between Fujian and Shanghai, with shells of intermediate form and colour. Analyses of sequences of COI, 12S and 28S genes do not support separation of these two Littoraria species, in terms of either reciprocal monophyly or genetic distance. Present evidence suggests that L. flammea could be only a distinctive morphological form or extreme of a cline, at the northern limit of the range of L. melanostoma. [ABSTRACT FROM AUTHOR]

Species of the dinoflagellate genus Alexandrium produce phycotoxins responsible for paralytic shellfish poisoning. Blooms of Alexandrium minutum reach very high concentrations of vegetative cells in the water column; and when these blooms occur, large numbers of toxic cysts can be produced and deposited on sediments becoming available to benthic species. The present study investigated the potential effect of exposure to toxic cysts of A. minutum on the periwinkle Littorina littorea . Snails were exposed for nine days to pellicle cysts of toxic and non-toxic dinoflagellates, A. minutum and Heterocapsa triquetra , respectively, followed by six days of depuration while they were fed only H. triquetra . Toxin accumulation, condition index, immune and histopathological responses were analyzed. Histological alterations were also monitored in snails exposed to a harmful A. minutum bloom, which naturally occurred in the Bay of Brest. Snails exposed to toxic cysts showed abnormal behavior that seems to be toxin-induced and possibly related to muscle paralysis. Periwinkles accumulated toxins by preying on toxic cysts and accumulation appeared dependent on the time of exposure, increasing during intoxication period but tending to stabilize during depuration period. Toxic exposure also seemed to negatively affect hemocyte viability and functions, as ROS production and phagocytosis. Histological analyses revealed that toxic exposure induced damages on digestive organs of snails, both in laboratory and natural systems. This study demonstrates that an exposure to the toxic dinoflagellate A . minutum leads to sublethal effects on L. littorea, which may alter individual fitness and increase the susceptibility of snails to pathogens and diseases. [ABSTRACT FROM AUTHOR]

Along wave-protected shores of the northeastern Pacific, the demography and life history of Littorina sitkana vary with intertidal zone, producing spatially close, but separate, “populations” (high- and low-shore). Field sampling (at multiple sites in the wave-sheltered Bamfield Inlet, B.C., Canada), a common garden experiment, and genetic analysis were used to determine if these two “populations” should be considered a panmictic population or different locally adapted populations (ecotypes). In the field, shell mass and incidence of white shells were greater for low-shore than high-shore snails, complementing other previously documented phenotypic differences (growth rate, size at sexual maturity). The common garden experiment revealed patterns of genetically-based phenotypic variation between the populations. Genetic analysis using a mitochondrial marker ( COI ) and a nuclear maker ( APN54 ) did not resolve any spatial population genetic structure, but did confirm the absence of cryptic species. In the context of work on another littorinid ( Littorina saxatilis ), our study points to L . sitkana being an interesting species for further investigation of genetic differentiation between different populations depending on their position in the intertidal shore ecotone. [ABSTRACT FROM AUTHOR]

Echinolittorina snails inhabit the upper intertidal rocky shore and face strong selection pressures from thermal extremes and fluctuations. Revealing the molecular processes of adaptive significance is greatly obstructed by the scarcity of genomic resource for these taxa. Here, we reported the first comprehensive transcriptome dataset for the genus Echinolittorina. Using Illumina HiSeq 2000 platform, about 52 M and 54 M paired-end clean reads were, respectively, generated for the control and heat-stressed libraries. Totally, 115,211 unique transcript fragments (unigenes) were assembled, with an average length of 453 bp and a N50 size of 492 bp. Approximately one third of the unigenes could be annotated according to their homology matches against the Nr, Swiss-Prot, COG, or KEGG databases, and they were found to represent 23,098 non-redundant genes. Gene expression comparison revealed that 1,267 and 6,663 annotated genes were, respectively, up- and downregulated with at least twofold changes upon heat stress. Gene Ontology and KEGG pathway analyses indicated that there were overrepresented amount of genes enriched in a broad spectrum of biological processes and pathways, including those associated with cytoskeleton organization, developmental regulation, signaling transduction, infection, and cardiac function. In addition, a transcriptome-wide search for polymorphic loci yielded a total of 11,228 simple sequence repeats (SSRs) from 9,938 unigenes and 138,631 single nucleotide polymorphism (SNP) and insertion/deletion (INDEL) sites among 22,770 unigenes. The large number of transcript sequences acquired, the biological pathways identified, and the candidate microsatellite and SNP/INDEL loci discovered in the study will serve as valuable resources for further investigations of genetic differentiation and thermal adaptation among populations. [ABSTRACT FROM AUTHOR]

Abstract: For rocky shore gastropods, attachment strength is a key determinant of survival, as getting dislodged by wave action or predators has negative consequences. Yet little is known of the factors that cause inter-individual variation in attachment strength among conspecifics. Here, we test the influence of trematode infection on the suction-mediated attachment strength of periwinkles from two New Zealand species, Austrolittorina cincta and A. antipodum. Using a standardised experimental protocol, we measured both the strength of attachment of individual snails to the substrate, and its repeatability, i.e. the consistency of measurements taken on different occasions on the same individuals. We then compared the attachment of snails infected with a philophthalmid trematode with that of their uninfected conspecifics. First, we found that for a given snail mass, infected snails were easier to detach from the substrate than the uninfected ones, although this pattern was only significant for A. cincta, the larger of the two snail species. Second, the repeatability of attachment strength measurements per individual snail did not differ between infected and uninfected conspecifics, for either of the two periwinkle species. Our findings show that parasitism can weaken snail attachment, and indirectly increase snail mortality, on exposed rocky shores, suggesting a new way in which parasites can affect host population dynamics. [Copyright &y& Elsevier]

This study investigates the potential usefulness of periwinkle shell as an alternative replacement of coarse aggregate in concrete work. The mechanical properties of concrete with fine and coarse aggregates components fully and partly replaced with lateritic sand and periwinkle shell was investigated. A working sample of one hundred and thirty five concrete cubes of 100mm dimensions were produced and cured in water for 7, 14 and 28 days. The fine aggregates and coarse aggregates were replaced with lateritic sand and periwinkle shells respectively at 10%, 20%, 30%, 40% and 100%. The mix proportions adopted for this work was 1:1½:3, 1:2:4 and 1:3:7 with water/cement ratio of 0.65. the results indicates that through partial replacement the concrete composed of up to 20% of lateritic sand and periwinkle shell developed a higher compressive strength for the curing ages of 7, 14, and 28days independent of the mix ratios than concrete containing lateritic sand and periwinkle shell at 100% full replacement. The study therefore recommends that 20% lateritic sand and periwinkle shell replacement for fine and coarse aggregate in concrete is suitable for use as low strength lightweight concrete. [ABSTRACT FROM AUTHOR]

Herbivory is a key factor for controlling seaweed biomass and community structure. To cope with grazers, constitutive and inducible defenses have evolved in macroalgae. Inducible chemical defenses show grazer-specificity and, at the same time, have the potential to mediate interactions among different herbivores. Furthermore, temporal variations in defense patterns, which may adjust antiherbivory responses to grazing pressure, were reported in two brown seaweeds. However, underlying cellular processes are only rudimentarily characterized. To investigate the response of Fucus vesiculosus (L.) to periwinkle ( Littorina obtusata) grazing, feeding assays were conducted at several times during a 33 d induction experiment. Underlying cellular processes were analyzed through gene expression profiling. Furthermore, direct processes driving the antiherbivory response to periwinkle grazing and indirect effects on another herbivore, the isopod Idotea baltica, were elucidated. F. vesiculosus showed multiple defense pulses in response to periwinkle grazing, suggesting a high level of temporal variability in antiherbivory traits. Defense induction was accompanied by extensive transcriptome changes. Approximately 400 genes were significantly up-/down-regulated relative to controls, including genes relevant for translation and the cytoskeleton. Genes involved in photosynthesis were mostly down-regulated, while genes related to the respiratory chain were up-regulated, indicating alterations in resource allocation. The comparison of genes regulated in response to isopod (previous study) and periwinkle grazing suggests specific induction of several genes by each herbivore. However, grazing by both herbivores induced similar metabolic processes in F. vesiculosus. These common defense-related processes reflected in strong indirect effects as isopods were also repelled after previous grazing by L. obtusata. [ABSTRACT FROM AUTHOR]

The distribution of organisms at small spatial scales and their use of microhabitats are important determinants of species-level interactions. In many ubiquitous rocky shore invertebrates, use of intertidal microhabitats has previously been studied with relation to thermal and desiccation stress, ontogenetic changes and predation. Here, the effects of parasitism on the microhabitat use and movement of two New Zealand littorinid hosts, Austrolittorina antipodum and A. cincta, were investigated by examining the effect of infection by a philophthalmid trematode parasite. Alterations in microhabitat use and movement of infected versus uninfected individuals were found during both field mark-recapture and laboratory experiments, carried out from August 2012 to March 2013 in Otago Harbour, New Zealand (45.83°S, 170.64°E). Specifically, a trend towards increased use of rock surface habitats and a reduction in the distance moved by infected snails was observed. In addition, decreased downward movement was observed for some infected individuals. This alteration in individual distribution is likely to increase the availability of infected individuals to predators, hence aiding the successful transmission of the trematode parasite. These results highlight the importance of including parasitism as a biotic factor in studies of gastropod movement and spatial distribution. [ABSTRACT FROM AUTHOR]

Abstract: Phenotypic plasticity may be critical to the maintenance of viable populations under future environmental change. Here we examined the role of behavioural avoidance of sub-optimal conditions in enabling the intertidal gastropod, Bembicium auratum, to persist in mangrove forests affected by the low pH runoff from acid sulphate soils (ASS). Behaviourally, the gastropod may be able to avoid periods of particularly high acidity by using pneumatophores and/or mangrove trunks to vertically migrate above the water line or by retreating into its shell. We hypothesised that (1) B. auratum would display greater and more rapid vertical migration out of acidified than reference estuarine waters, and (2) responses would be more pronounced in gastropods collected from acidified than reference sites. Gastropods from acidified sites showed significantly higher activity in and more rapid migration out of acidified waters of pH 6.2–7.0, than reference waters or waters of pH < 5.0. Gastropods from reference locations showed a significantly weaker response to acidified water than those from acidified waters, and which did not significantly differ from their response to reference water. At extremely low pHs, <5.0, a higher proportion of both acidified and reference gastropods retreated into their shell than at higher pHs. Both the migration of gastropods out of acidified waters and retraction into their shells serves to reduce exposure time to acidified waters and may reduce the impact of this stressor on their populations. The stronger response to acidification of gastropods from populations previously exposed to this stressor suggests that the response may be learned, inherited or induced over multiple exposures. Our study adds to growing evidence that estuarine organisms may exhibit considerable physiological and behaviour adaptive capacity to acidification. The potential for such adaptive capacity should be incorporated into studies seeking to forecast impacts to marine organisms of environmental change. [Copyright &y& Elsevier]