Growth Of Clams Research Articles

Habitat effects of macrophytes and shell on carbonate chemistry and juvenile clam recruitment, survival, and growth

Adverse habitat conditions associated with reduced seawater pH often, but not always, negatively affect bivalves in early life history phases. Improving our understanding of how habitat-specific parameters affect clam recruitment, survival, and growth could assist natural resource managers and researchers in developing appropriate adaptation strategies for increasingly acidified nearshore ecosystems. Two proposed adaptation strategies, the presence of macrophytes and addition of shell hash, have the potential to raise local seawater pH and aragonite saturation state and, therefore, to improve conditions for shell-forming organisms. This field study examined the effects of these two substrate treatments on biological and geochemical response variables. Specifically, we measured (1) recruitment, survival, and growth of juvenile clams (Ruditapes philippinarum) and (2) local water chemistry at Fidalgo Bay and Skokomish Delta, Washington, USA, in response to experimental manipulations. Results showed no effect of macrophyte or shell hash treatment on recruitment or survival of R. philippinarum. Contrary to expectations, clam growth was significantly greater in the absence of macrophytes, regardless of the presence or absence of shell hash. Water column pH was higher outside the macrophyte bed than inside at Skokomish Delta and higher during the day than at night at Fidalgo Bay. Additionally, pore-water pH and aragonite saturation state were higher in the absence of macrophytes and the presence of shell. Based on these results, we propose that with increasingly corrosive conditions shell hash may help provide chemical refugia under future ocean conditions. Thus, we suggest adaptation strategies target the use of shell hash and avoidance of macrophytes to improve carbonate chemistry conditions and promote clam recruitment, survival, and growth.

Ecosystem services of geoduck farming in South Puget Sound, USA: a modeling analysis

Provisioning and regulatory ecosystem services of Pacific geoduck clam (Panopea generosa) culture were simulated for an intertidal shellfish farm in Eld Inlet, South Puget Sound, Washington, USA. An individual geoduck clam growth model was developed, based on a well-established framework for modeling bivalve growth and environmental effects (AquaShell™). Geoduck growth performance was then validated and calibrated for the commercial farm. The individual model was incorporated into the Farm Aquaculture Resource Management (FARM) model to simulate the production cycle, economic performance, and environmental effects of intertidal geoduck culture. Both the individual and farm-scale models were implemented using object-oriented programming. The FARM model was then used to evaluate the test farm with respect to its role in reducing eutrophication symptoms, by applying the Assessment of Estuarine Trophic Status (ASSETS) model. Farm production of 17.3 t of clams per 5-year culture cycle is well reproduced by the model (14.4 t). At the current culture density of 21 ind m−2, geoduck farming at the Eld Inlet farm (area: 2684 m2) provides an annual ecosystem service corresponding to 45 Population-Equivalents (PEQ, i.e. loading from humans or equivalent loading from agriculture or industry) in top-down control of eutrophication symptoms. This represents a potential nutrient-credit trading value of over USD 1850 per year, which would add 1.48% to the annual profit (USD 124,900) from the clam sales (i.e. the provisioning service). A scaling exercise applied to the whole of Puget Sound estimated that cultured geoducks provide a significant ecosystem service, of the order of 11,462 PEQ per year (about USD 470,600) in removing primary symptoms of eutrophication, at the level of the whole water body. The modeling tools applied in this study can be used to address both the positive and negative externalities/impacts of shellfish aquaculture practices in the ecosystem and thus the trade-offs of the activity.

Growth of the Asian ClamCorbicula fluminea(Müller, 1774) Cultured in Çine Creek, Aydin, Turkey

Natural stocks of the Asian clam Corbicula fluminea (Muller, 1774) provide an important food source predominantly in Southern Asia. It is, therefore, important not only to assess the sustainability of natural stocks, but also to facilitate aquaculture efforts of this species. This study investigated the growth and survival rate of C. fluminea in bottom net culture over 13 mo in Cine Creek, Aydin, Turkey, in a temperate Mediterranean climate zone. Water temperature ranged between 10 and 24°C and food availability (measured by concentrations of chlorophyll-a (Chl-a) and suspended particulate organic matter) peaked during the autumn and spring. The final shell length (SL) and total body weight of C. fluminea (mean ± SE) were 29.02 ± 0.5 mm (initially 23.76 mm) and 12.17 ± 0.5 g (initially 6.65 g), respectively. Maximum growth rates were significantly higher during the autumn and spring months. A strong positive correlation was found between the availability of food (Chl-a) and total particulate matter concentrations and growth rates (in terms of SL and total weight). Survival was high (97%) by the end of the study and environmental conditions in Cine Creek supported good growth of clams. The species Corbicula fluminea, either as a native or introduced species, can be considered as a promising candidate species for the diversification of aquaculture in the region.

GROWTH OF JUVENILE HORSE'S HOOF CLAMS (Hippopus hippopus) REARED IN COASTAL WATERS, PARI ISLAND, KEPULAUAN SERIBU

The main purpose of this present study is to determine the growth and survival rate of juvenile horse's hoof clams {Hippopus hippopus) and to find out a suitable site for their rearing in nature. Juveniles used in this study were about 3 years old, produced in the hatchery of CV Dinar, Bali. They were reared in the cages, placed on the sea bed at several sites, namely: (1) on the reef flat, (2) on the bed of a lagoon, and (3) on the sea channel. After 360days of rearing, the highest daily growth was found for juveniles reared in site-2, i.e. 0.110 mm in length, 0.080 mm in width and 0.091 mm in height. These values were significantly different from other two sites. The survival rate after 360 days of rearing was 85.5% in site-1, 99.4% in site-2 and 96.8% in site-3. Based on these results the bed of a lagoon is the best and suitable site to grow horse's hoof clam juveniles in nature. Water condition at this site is relatively calm with sandy-muddy substrates and relatively dense seagrasses, mainly Thallasia spp.

Characteristics of α-Amylase gene and its association with growth traits in Meretrix meretrix

α-Amylase is a major digestive enzyme in phytophagous animals that catalyzes the hydrolysis of starch into sugars so that it affects the carbohydrate metabolism and growth of many species. In the present study, the full-length cDNA and intron sequences of α-amylase (MmAmy) were investigated by rapid amplification of cDNA ends (RACE) method. The genomic DNA sequence of MmAmy is 6689 bp, which contains 7 exons and 6 introns. The cDNA of MmAmy is 1783 bp, with a 1569 bp of open reading frame (ORF) encoding 522 amino acids. No expression was detected in the early stages of unfertilized mature eggs, fertilized eggs, 4-cell embryo, blastula, gastrulae, trochophore, whereas it was detected after D-shaped larva showing the highest expression in umbo larvae. The quantitative expression of six different tissues in adults showed that expression of MmAmy was enriched in visceral mass, while no expression was detected in other tissues. Furthermore, gene expression and enzyme activity of MmAmy in visceral mass were highly correlated with the growth rates of four shell color strains. The positive correlation between MmAmy and growth traits suggested that α-amylase gene could be used as a candidate gene in the molecular breeding programs to improve clam growth.

Characterization of two splice variants of EGFR and their effects on the growth of the razor clam

The epidermal growth factor receptor (EGFR) plays a vital role in cell growth, proliferation, and body growth. In this study, two EGFR isoforms (Sc-EGFR-1a and Sc-EGFR-1b) were obtained from Sinonovacula constricta. Sequence analysis of the coding region of Sc-EGFRs, revealed the 2 isoforms were generated from a common gene by alternative splicing and that one form possessed an extra 81 bp that corresponded to an insertion of 27 amino acids in the C-terminus. Expression of the Sc-EGFR isoforms were detectable in the early embryo stages and increased in the middle-late stages. Both isoforms were widely expressed in tissues, but the highest levels were detected in the siphon. Although both isoforms had a typical extracellular region, transmembrane region, and intracellular region, the insertion/deletion of 27 aa in the C-terminus changed the phosphorylation sites and may have influenced downstream kinase activities. In vitro, the proliferating cell nuclear antigen indicator and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that HEK293T cells transfected with Sc-EGFR-1a and Sc-EGFR-1b exhibited different proliferation patterns. Sc-EGFR-1a caused more rapid proliferation than Sc-EGFR-1b and the EGFP-N1 control. In vivo, Sc-EGFRs were successfully knocked-down for at least 15 days by injecting the clams with the dsRNA and was associated with a significant reduction in shell length. Our results reveal for the first time in mollusks the existence of alternative splicing of EGFR and provide the basis for further studies to establish the role of EGFR in growth and development of S. constricta.

Lethal and non-lethal effects of an invasive naticid gastropod on the production of a native clam

Predators often affect prey production not only by lethal predation but also by unintentional inhibition of feeding and growth. The present study examined the lethal and non-lethal effects of the invasive naticid Laguncula pulchella on the survival and growth of the prey clam Ruditapes philippinarum in a sandy tidal flat. Cages accommodating 30 clams (10 individuals × 3 size classes of ≤ 20 mm, 20–30 mm, and > 30 mm shell length) and one L. pulchella (approximately 37 mm shell height) per cage were buried in the tidal flat for 10 weeks. Medium sized clams were consumed by predators much more (80.5%) than small (12.2%) and large clams (7.3%). Clams were consumed by L. pulchella at a frequency of 0–2.5 individuals per predator per week. The growth of clams caged with L. pulchella was lower (23, 27, 33, 41, and 57% for clam of 10, 20, 30, 40, and 50 mm, respectively) than that in control cages (clams without L. pulchella). The clam burial depths did not increase by the presence of predators in a laboratory experiment, indicating that growth suppression was caused by the reduced feeding activity following physical disturbance and/or chemical signals. The results of this study demonstrate that the introduction of L. pulchella reduced the productivity of the commercially important clams not only by lethal predation but also by mere presence.

Comparison of the ecotoxicological effects of biochar and activated carbon on a marine clam (Meretrix meretrix)

Abstract Biochar (BC) and activated carbon (AC) amendments have been applied to remediate contaminated sediments because of their benefits in reducing toxicity and/or the bioavailability of contaminants. However, their ecotoxicity to benthic organisms, which are not well understood, should be carefully considered before their practical application. Therefore, a wood-derived BC (WBC) or a coconut shell-derived AC (CAC) was incorporated into a marine sediment at 5% (dw%) to investigate their effects on the growth and nutritional quality of a marine clam (Meretrix meretrix). CAC and WBC had no effect on the pH and calcium content of the sediment, but significantly increased the electrical conductivity (EC) and total organic carbon (TOC), and decreased the dissolved organic carbon (DOC). After 28 days of cultivation, WBC reduced the shell growth of the clam by 36.4%, and CAC reduced the soft tissues of the clam by 9.05%. This was probably because WBC and CAC adsorb organic matters and the feeding algae may colonize within their pores, thus, reducing food bioavailability for the clams. Water extracts of CAC and WBC had negligible effects on soft tissue growth, whereas the CAC extract inhibited the growth of clam shells by 57.9%. WBC and CAC had little influence on the nutritional quality of clams, including moisture, crude protein, and crude lipid contents. These findings are helpful to understand the ecotoxicological risks of BC and AC amendments to benthic organisms when used for the remediation of contaminated marine sediments.

Assessment of household risk management strategies for coastal aquaculture: the case of clam farming in Thaibinh Province, Vietnam

Clam farmers have experienced different types of risks that have been further exacerbated by the rapid expansion of clam farming areas, increased growing densities, and increased market difficulties in recent years in the Thaibinh Province of Vietnam. Most farmers have been seriously affected by production risk, market risk, and financial risk, while a number of others have met with success in almost all of their clam-raising cycles. This study applied a differentiating comparative analysis method and multiple discriminant analysis method to discuss the differences in risk management strategies between and among clam farming households and the impacts of those differences on their success/failure rates. In general, the tactics are related to increase in farm size, the application of technical innovations, diversifying livelihood activities, and accessing secure financial sources all provided better conditions for clam growth, diminished losses, and led to speedier recovery from shocks. To support farmers in managing risks, several government interventions are needed: (1) better re-zoning of clam farming areas in parallel with an increase in the farm size of each household, (2) promoting sustainable linkages between the farmers and the formal financial market and output market, and (3) investing more funding into research and extension related to sustainable clam farming practices and to the improvement of farmers’ skills in cooperative works and management.

Enhancement of dietary effect of Nannochloropsis sp. on juvenile Ruditapes philippinarum clams by alginate hydrolysates

The eustigmatophyte Nannochloropsis sp. can be produced on a large scale at low cost. However, its dietary usefulness for juvenile bivalves is less than that of other algae. Recently, we reported that growth of juveniles of the clam Ruditapes philippinarum was dramatically promoted by supplementing a diet of the diatom Chaetoceros neogracile with alginate hydrolysates (AHs) at the concentration of 4mgL−1. In this study, we examined the effect of AHs on Nannochloropsis sp. as a clam diet. Ten-day rearing experiments in 500-mL beakers showed that AHs have a beneficial effect on clam culture regardless of water temperature. Shell growth in clams given AHs at the concentration of 4mgL−1 along with Nannochloropsis sp. at the concentration of 20×104 cells mL−1 was higher than in any other test groups at 15 or 25°C. In 20-day rearing experiments in 30-L tanks, the average shell length in the groups given AHs at the concentration of 4mgL−1 along with Nannochloropsis sp. at the concentration of 30×104 cells mL−1 was significantly greater than that in the groups given C. neogracile and Nannochloropsis sp. alone (P≪0.05). Furthermore, the total weight of clams given AHs at the concentration of 4mgL−1 along with Nannochloropsis sp. at the concentration of 30×104 cells mL−1 was greater than that in the group given only Nannochloropsis sp. (P≪0.05). Hence, the enhanced dietary effect of a combination of Nannochloropsis sp. and AHs will help to shorten the rearing time of R. philippinarum and to provide a stable supply of algal diet.

Association of α-amylase gene with growth traits in the razor clam Sinonovacula constricta

The razor clam Sinonovacula constricta is a commercially and ecologically important benthic mollusk. In the present study, we investigated the full-length cDNA sequence of the S. constricta α-amylase gene (Scamy) using expressed sequence tags and rapid amplification of cDNA ends. The genomic DNA sequence of Scamy is 5086 bp, which contains 6 exons and 5 introns. The full-length Scamy cDNA was 2196 bp, with a 2085 bp open reading frame encoding 694 amino acids. Scamy expression was very low before the D-shaped larvae stage, with the highest expression levels in juvenile clams. Expression levels of Scamy were significantly higher in the digestive gland compared with other tissues in adults (p < 0.01). Analysis of the Scamy gene in the digestive gland in starved clams indicated that both gene expression and enzyme activity increased before decreasing, reaching its highest expression on the second day. Gene expression and amylase activity both increased gradually after refeeding. These results demonstrated that starvation and refeeding increased amylase activity in razor clams. Association analysis identified one shared single nucleotide polymorphism, C1503T, for which individuals with genotypes TT and CT had significantly higher growth traits than those with genotype CC (p < 0.05). This study suggests the potential value of amylase markers in selective breeding to improve clam growth.

Expression and characterization of insulin-like growth factor II mRNA binding protein in the razor clam Sinonovacula constricta

Insulin-like growth factor-II mRNA binding protein (igf2bp) is an mRNA binding protein that regulates the post-transcriptional fate of multiple transcripts. In this study, a novel igf2bp gene was identified in the razor clam Sinonovacula constricta. The complete 2254 bp Sc-igf2bp cDNA consists of an open reading frame (ORF) encoding 610 amino acid (aa) residues. The deduced protein includes a single RNA recognition motif (RRM) and four K homology (KH) domains. Sc-igf2bp transcripts were expressed widely during different developmental stages and in adult tissues, and a 95 kDa recombinant pEGX-4T-1-Sc-igf2bp protein was expressed in Escherichia coli Rosetta (DE3) pLysS cells and purified using Glutathione Sepharose 4B resin. Activity was evaluated by GST pull-down assays, and mass spectrometry results indicated that Sc-igf2bp may participate in RNA-related processes. The findings provide a basis for further research on the role of igf2bp in regulating the growth and development of the razor clam.

Effects of environmental factors on growth, survival, and metamorphosis of geoduck clam (Panopea japonica A. Adams, 1850) larvae

A series of experiments were conducted to evaluate the effects of temperature, salinity, diet, and stocking density on the growth, survival, and metamorphosis of geoduck clam Panopea japonica larvae. The larvae all died at a temperature of 22°C after day 12, suggesting that the larvae of P. japonica could not survive when the temperature was higher than 22°C. P. japonica could be incubated at 19°C for the fast growth, high survival and metamorphosis of larvae. The embryos all died when the salinity was below 25 ppt. The larvae showed poor survival when the salinity was below 25 ppt, with all larvae dying before day 12, suggesting that larvae are sensitive to low salinity. The optimum salinity for the growth, survival and metamorphosis of larvae was 32 ppt. The use of a mixture of Isochrysis galbana and Nitzschia closterium (1:1) as a food source for the P. japonica larvae improved their growth, survival, and metamorphosis. A density of 20 individuals/ml appeared to be optimal for normal D-larvae of Panopea japonica, and 3–9 larvae/ml was optimal for the growth and survival of the P. japonica larvae raised in the hatchery.

佐伯湾番匠川河口域におけるアサリRuditapes philippinarumの漁場環境と成熟・加入・成長

佐伯湾番匠川河口域におけるアサリRuditapes philippinarumの漁場環境と成熟・加入・成長

A Comparative Study on the Growth of Black Clam (Villorita Cyprinoides) In Cochin Estuary with Special Emphasis on Impact Of A Salinity Barrier At Thannemukkom

A Comparative Study on the Growth of Black Clam (Villorita Cyprinoides) In Cochin Estuary with Special Emphasis on Impact Of A Salinity Barrier At Thannemukkom

Enhanced trace element concentrations in tissues of the clam &lt;em&gt;Ruditapes decussatus&lt;/em&gt; transplanted to areas influenced by human activities (Ria Formosa, Portugal)

To examine the extent to which human activities near the Ria Formosa coastal lagoon influence the accumulation of trace elements (TE) in Ruditapes decussatus, individuals were transplanted from a natural bank located in the lower lagoon to three sites located in clam growth grounds under the influence of a small city (Faro), a fish farming centre (Olhão) and a site near the lagoon inlet (Lavajo). Concentrations were determined in substrate of the clam grounds and in the digestive gland, gills, mantle plus siphons, and remaining tissues of clams in four periods of the year. These measurements were accomplished with the monthly survey of the gametogenic stages, condition index, proteins, glycogen, total lipids, pH and osmolarity of hemolymph. Arsenic, Cu, Mn, V, Cr and Pb were preferentially linked to the digestive gland, while Cd was linked to the gills. TE concentrations in the digestive gland and remaining tissues were higher in winter, most likely reflecting additional inputs associated with rain. The lack of disruptions in biological parameters and the prolonged period of spawning and gonad recovery in clams suggest that the current TE availability in the lagoon has a minor influence on the reproductive cycle and hence on clam production.

Impact of temperature and nutrient dynamics on growth and survival ofCorbicula fluminea: A field study in oligotrophic Lake Constance

The invasive clam Corbicula fluminea was first recorded in Lake Constance (Germany) in 2003 and subsequently established high population densities at various locations in the lake. In 2010, four standardized field experiments were conducted in Lake Constance, one in each season, to investigate seasonal changes in somatic growth and survival of C. fluminea at different water depths. Somatic growth and survival of the clams were related to seasonal variations in water temperature and seston characteristics, that is, phytoplankton species composition and essential nutrient concentrations, and to the elemental and biochemical composition of clam tissues using principal component analyses and regression models. The field experiments revealed that somatic growth and survival of C. fluminea in Lake Constance were primarily determined by water temperature. In winter, low temperatures (<5°C) and low food supply resulted in high mortality and zero growth. Positive somatic growth rates were recorded in the lake throughout the growing season, when the water temperatures exceeded 10°C. Other seston variables, that is, particulate organic carbon content, phytoplankton species composition, and the elemental (nitrogen, phosphorus) and biochemical (fatty acids, sterols) nutrient composition were of minor importance for growth and survival of C. fluminea in oligotrophic Lake Constance. In parallel to the field experiments, standardized laboratory growth experiments were conducted to assess the effects of temperature on clam growth and survival at high food quantity and quality. The results from the laboratory experiments confirmed the conclusion that somatic growth and survival of C. fluminea in Lake Constance were primarily determined by water temperature. Our data suggest that further spread of C. fluminea may be supported by climate change, because milder winter temperatures and an earlier onset of thermal stratification in spring may reduce winter mortality and thereby extend the growing season for C. fluminea.

Distribution pattern, density and growth of the stout razor clam Tagelus plebeius in a South-west Atlantic estuarine system

The population biology of the stout razor clam Tagelus plebeius is poorly understood, despite the species' current wide distribution, and the potential use of its Holocene shell deposits to infer past environmental and ecological conditions. This study investigates distribution and growth pattern of T. plebeius in the south-western Atlantic Mar Chiquita Coastal lagoon (37°32′S 57°19′W), Argentina. The population includes the oldest individuals (up to 27 years) reported so far with shell length up to 77.9 mm. A von Bertalanffy model with L∞ = 67.60 mm (95% CI = 64.55; 70.64), k = 0.181 year−1 (CI = 0.142; 0.218), and t0 = −0.77 (CI = −1.46; −0.08) best described their individual growth for the whole population. The higher density, growth rate k, t0 and maximum age and lower L∞ were in the low intertidal rather than in the medium intertidal, but there were no differences in density and age between medium and high intertidal. Given the results and the current knowledge on the effects of different factors influencing this species, we conclude that the distribution pattern and shell growth observed in our study reflect a response to metabolic necessities in combination with a strong influence of biological interactions.

Acidification alters predator-prey interactions of blue crab Callinectes sapidus and soft-shell clam Mya arenaria

Acidification due to anthropogenic CO2 pollution, along with episodic or persistent acidification that occurs in coastal environments, will likely result in severe seasonal acidification in estuarine environments. Acidification decreases the fitness of individual species, but the degree to which predator-prey interactions will be impacted is largely unknown. This mesocosm study examined the effect of CO2 acidification on crab-bivalve predator-prey interactions involving two commercially important Chesapeake Bay species, the blue crab Callinectes sapidus and the soft-shell clam Mya arenaria. In particular, the direct effects of CO2 acidification on clam growth and behavior, and the indirect effects of CO2 acidification on interactions between crabs and clams were examined. Mya arenaria were grown in CO2-acidified water (pH7.2) or ambient conditions (pH7.8) for 30days. To determine the effect of acidification on clam responsiveness to mechanical disturbance, a probe was slowly moved towards clams until they ceased pumping (a behavior to avoid detection by predators), and the distance between the probe and the clam's siphon was noted. Clams were exposed to predation by C. sapidus, which were held under acidified or ambient conditions for 48h. Callinectes sapidus handling time, search time, and encounter rate were measured from video. Acidified clams had lighter shells than ambient clams, indicating that shell dissolution occurred. Acidification reduced the responsiveness of M. arenaria to a mechanical disturbance that simulated an approaching predator. As compared to ambient trials, crabs in acidified trials had higher encounter rates; however, this was offset by crabs taking longer to find the first clam in trials, and by increased occurrence of crabs eating only a portion of the prey available. As a result, there was no net change in predation-related clam mortality in acidified trials as compared to ambient conditions. Understanding how acidification will impact food webs in productive estuarine environments requires an examination of the direct impacts of acidification on organism behavior and physiology, as well as indirect effects of acidification mediated through predator-prey interactions.

Variability of Mya arenaria growth along an environmental gradient in the Plum Island Sound estuary, Massachusetts, USA

An understanding of the environmental factors that determine how clam growth varies in space and time improves effective mariculture and shellfish management. We examined the importance of temperature, salinity and chlorophyll-a in controlling the spatial pattern of Mya arenaria growth, the commercially important soft-shell clam, in the Plum Island Sound estuary in northeastern Massachusetts, USA. We collected clams (>5.08 cm) monthly during the April to November growing season from which we determined growth rate, maximum size (L-infinity), and time to reach a harvestable size. We also surveyed selected sites along the estuary to estimate the relationship between clam size and weight. We collected environmental data along the estuary, and our data were complemented with data collected and maintained by the Plum Island ecosystems long-term ecological research project. Clams reached harvestable size fastest and had the greatest L-infinity at the most oceanic site (Yacht Club) in the estuary. Clams had the smallest L-infinity and were slowest to reach the harvestable size at the least oceanic site (Railroad Meander). The spatial patterns of clam growth were best explained by a positive distribution of salinity. Salinity significantly accounted for 95 % of the spatial variation of clam growth in the estuary. Snow melt in spring increases freshwater input to the estuary and results in the lowest spring salinity during a year, and this explained the upper estuary limit of clam distribution. IPCC-projected climate change will cause sea-level rise and increasing precipitation in the northeastern USA, which will modify the spatial pattern of salinity in the region’s estuaries. Our research therefore suggests that future management of M. arenaria, an important economic resource for the local economy, should be concerned with the changes of salinity distribution under climate and land-use change.