Search Results (12)

Intertidal reefs comprised of the eastern oyster (Crassostrea virginica) are an important habitat type within the estuarine landscape and provide many unique ecosystem services. Within West Galveston Bay (WGB), Texas, this type of reef plays an important ecological role; however, the system’s intertidal reef abundance, structure, and habitat provisions are relatively understudied, and the current spatial extent of these reefs has not been recently quantified. The primary objectives of the study were to identify intertidal oyster reefs utilizing GIS models and sample representative reefs for topographical characteristics, oyster demographics, and the associated benthic macrofauna (ABM) community composition in WGB from August 2019 to February 2020. Secondarily, GIS models and oyster population abundance were utilized to estimate the intertidal oyster abundance in WBG. The total area of intertidal oyster reefs in WGB was estimated to be 818,128 m², with 59,931 m² of reefs confirmed through GIS analysis and ground truthing, and the GIS model estimating an additional 758,197 m² of reef. Through ground truthing, reefs were found to be either shell rakes, consisting of piled shell with minimal three-dimensional structure and oysters, or true intertidal reefs with high reef structure and oyster abundance. High oyster abundance was spatially distributed within the northeastern and southwestern areas of WGB and the total intertidal oyster population, coupling the GIS models and reef sampling, was estimated to be 500 million individual oysters. The ABM community was sparse in terms of richness and diversity, further indicating a lack of structural complexity in most of the reefs within this system. This study demonstrates the importance of coupling field results with GIS modeling to estimate system level population sizes and furthers the understanding of the spatial distributions of intertidal oyster reef to promote management, conservation, and restoration efforts. Full article

The nomenclatural status and typification of the names Arthrocaulon macrostachyum, Salicornia fruticosa, S. fruticosa var. deflexa, S. fruticosa var. glaucescens, S. fruticosa var. intermedia, S. fruticosa var. humilis, S. fruticosa var. pachystachya, S. fruticulosa, S. glauca, S. lignosa, S. macrostachya var. virescens, S. macrostachya var. glaucescens, S. perennis, S. radicans, S. radicans var. caespitosa, S. sarmentosa, S. sempervirens, and S. virginica, as well as an unnamed β-variety of S. fruticosa proposed by A. Bertoloni, are investigated. Concerning A. macrostachyum, we document that the type indicated in literature (G00177362) is not a holotype, and that lectotypification is necessary. A specimen from G (G00687638) is here designated as a lectotype. On the level of variety, Arthrocnemum fruticosum var. macrostachyum is an earlier legitimate name for Salicornia fruticosa var. pachystachya. Furthermore, Piirainen et al. are incorrect when citing Forsskål’s “Salicornia” from Alexandria as “S. virginica Forssk.”; it is not a new name and should be cited as S. virginica auct. non L., as published in Forsskål’s Flora Aegyptiaco-Arabica. Like with numerous other parallel cases in Flora Aegyptiaco-Arabica, Forsskål’s designation of “Salicornia virginica” for an Arabian plant is to be considered a misapplication of the earlier Linnaean name for an American plant. Arthrocnemum glaucum (a nomen illegitimum of Ungern-Sternberg), was listed as type species of Arthrocnemum by the Names in Current Use project; the basionym, Salicornia glauca Delile, is here lectotypified and identified as Arthrocaulon meridionale, published by Ramirez et al. Updated synonymies of Arthrocaulon macrostachyum, A. meridionale, Salicornia fruticosa, and S. perennis are proposed. Salicornia sempervirens is an invalid name according to Art. 36.1a of ICN. No original material was found for S. radicans var. caespitosa. This paper also refer to lecto- or neotypifications on specimens deposited at BM, G, LINN-HS, LY, MPU, NAP, and PAL, and their current taxonomic positions are suggested in a taxonomic part of the paper. Full article

The marine peptide, American oyster defensin (AOD), is derived from Crassostrea virginica and exhibits a potent bactericidal effect. However, recombinant preparation has not been achieved due to the high charge and hydrophobicity. Although the traditional fusion tags such as Trx and SUMO shield the effects of target peptides on the host, their large molecular weight (12–20 kDa) leads to the yields lower than 20% of the fusion protein. In this study, a short and acidic fusion tag was employed with a compact structure of only 1 kDa. Following 72 h of induction in a 5 L fermenter, the supernatant exhibited a total protein concentration of 587 mg/L. The recombinant AOD was subsequently purified through affinity chromatography and enterokinase cleavage, resulting in the final yield of 216 mg/L and a purity exceeding 93%. The minimum inhibitory concentrations (MICs) of AOD against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus galactis ranged from 4 to 8 μg/mL. Moreover, time-killing curves indicated that AOD achieved a bactericidal rate of 99.9% against the clinical strain S. epidermidis G-81 within 0.5 h at concentrations of 2× and 4× MIC. Additionally, the activity of AOD was unchanged after treatment with artificial gastric fluid and intestinal fluid for 4 h. Biocompatibility testing demonstrated that AOD, at a concentration of 128 μg/mL, exhibited a hemolysis rate of less than 0.5% and a cell survival rate of over 83%. Furthermore, AOD’s in vivo therapeutic efficacy against mouse subcutaneous abscess revealed its capability to restrain bacterial proliferation and reduce bacterial load, surpassing that of antibiotic lincomycin. These findings indicate AOD’s potential for clinical usage. Full article

In the face of an increasing world population and a subsequent need for an increase in sustainable and healthy food production, low trophic species, such as oysters, emerge as a promising alternative. However, regional variations in oyster production techniques, market dynamics, and consumption patterns create challenges for both the global and local industry’s growth. In this study, a descriptive qualitative analysis of oyster markets across seven Atlantic regions was carried out. The Pacific oyster (Crassostrea gigas) was found to be farmed in most Atlantic regions except the US but is classified as invasive in Sweden and potentially invasive in South Africa. Other farmed and/or harvested species include native species (C. gasar and C. rhizophorae) in Brazil, the American cupped oyster (C. virginica) in the US, and the European flat oyster (Ostrea edulis) in France, Sweden, and the US. In Irish farms, Pacific oysters are primarily for export to European markets. The marine aquaculture sectors of Sweden, South Africa, and Namibia, as well as Brazil’s farming for C. gasar, were found to be underdeveloped. This study also observed a variation in licensing, property rights, and regulatory frameworks. Financial challenges for small businesses, ecological implications of seed production techniques, biosecurity risks, and public health considerations are emphasized as critical areas for attention. This study offers valuable insights into the selected markets and can serve as a useful resource for policymakers, aquaculture practitioners, and stakeholders in optimizing global shellfish industry strategies. Full article

Refrigerated raw oysters, including Pacific oysters (Magallana gigas), eastern oysters (Crassostrea virginica), and European flat oysters (Ostrea edulis), are popular seafood products. Pathogenic contamination and spoilage during storage and transport limit their shelf life. High hydrostatic pressure (HHP) and irradiation effectively reduce pathogens and spoilage microorganisms in raw oysters while preserving their taste and texture. This review article presents a comprehensive analysis of the use of HHP and irradiation as sanitation methods for raw oysters, incorporating findings from geographical distribution, mathematical modeling, and radiation quality’s impact on sterilization efficacy. The results demonstrate that untreated eastern oysters can maintain a total bacterial count below the recommended limit of 10⁷ CFU/g for only 2–3 weeks at 5 °C, and are at risk of harboring pathogens such as Vibrio spp. and norovirus. HHP treatment at 600 MPa and irradiation treatment at 2 kGy can effectively reduce the pathogen load in raw oysters. However, supplementary measures such as additional cleaning or lower temperatures are required to prolong the shelf life of treated raw oysters to 2–3 weeks. Taken together, the application of HHP and irradiation to raw oyster sanitation represents a promising approach for enhancing the safety and quality of this beloved seafood delicacy. Full article

This work explored the effects of salinity and temperature on the efficacy of purging V. parahaemolyticus from eastern oysters (Crassostrea virginica). Oysters were inoculated with a 5-strain cocktail of V. parahaemolyticus to levels of 10⁴ to 10⁵ MPN (most probable number)/g and depurated in a controlled re-circulating wet-storage system with artificial seawater (ASW). Both salinity and temperature remarkably affected the efficacy for the depuration of V. parahaemolyticus from oysters during wet-storage. The wet-storage process at salinity 20 ppt at 7.5 °C or 10 °C could achieve a larger than 3 log (MPN/g) reduction of Vibrio at Day 7, which meets the FDA’s requirement as a post-harvest process for V. parahaemolyticus control. At the conditions of 10 °C and 20 ppt, a pre-chilled system could achieve a 3.54 log (MPN/g) reduction of Vibrio in oysters on Day 7. There was no significant difference in the shelf life between inoculated and untreated oysters before the depuration, with a same survival rate (stored in a 4 °C cooler for 15 days) of 93%. Full article

The Eastern oyster Crassostrea virginica (Family Ostreidae) is one of the most important fishery and aquaculture species in the U.S. and is a keystone species for coastal reefs. A breeding program was initiated in 2019 to support the fast-growing aquaculture industry culturing this species in the Gulf of Mexico. Oysters from 17 wild populations in embayment along the U.S. Gulf of Mexico coast from southwest Florida to the Matagorda Bay, Texas were used as broodstock for the program to maximize genetic diversity in the base population. A sperm repository of the broodstock was established to support the breeding project. The goal of this study was to demonstrate the sperm sample collection, processing, cryopreservation, and the data management plan involved in the establishment of a sperm germplasm repository of base populations. The supporting objectives were to: (1) develop a data management plan for the sperm repository; (2) streamline the procedure for sample collection, processing, and cryopreservation; (3) incorporate sperm quality analysis into the procedure, and (4) archive the cryopreserved samples as a repository for future use in the breeding program. This sperm repository included a total of 102 male oysters from the 17 collection sites (six oysters per site). A data management plan was developed with six categories, including sample collection, phenotype, fresh sperm, genotype, cryopreservation, and post-thaw sperm, as guide for data collection. Sperm collection was accomplished by strip spawn, and fresh sperm production, motility, and fertility were recorded for quality analysis. Cryopreserved sperm samples were sorted, labelled, archived, and stored in liquid nitrogen for future use. Post-thaw motility (1–30%) and plasm membrane integrity (15.34–70.36%) were recorded as post-thaw quality parameters. Overall, this study demonstrated a streamlined procedure of oyster sperm collection, processing, and cryopreservation for establishing a sperm repository that can serve as a template for construction of oyster germplasm repositories for breeding programs. Full article

Several Vibrio spp. cause acute and severe mortality events in hatcheries where larvae of bivalve mollusks are reared, potentially leading to subsequent shortage of bivalve seed for the grow-out industry. In particular, strains of Vibrio coralliilyticus have been identified as a major cause of disease in Pacific, Crassostrea gigas, and eastern, C. virginica, oyster hatcheries in the USA of America. Probiotic bacteria are an inexpensive, practical, and natural method of disease control. Previous research shows that pretreatment of larval oysters with probiotic bacteria Bacillus pumilus RI06–95 (RI) and Phaeobacter inhibens S4 (S4) significantly decreases mortality caused by experimental challenge with the bacterial pathogen V. coralliilyticus RE22 (RE22). This study aims to characterize the immune response of 6–10-day-old eastern oyster larvae to experimental challenge with pathogen V. coralliilyticus RE22 and probionts RI and S4. Treatments included (a) pathogen and probiont exposure at a concentration of 5 × 10⁴ CFU per mL (~2500 bacterial cells per larva) for a duration of 6 h, (b) probiont exposure at the same concentration for a duration of 24 h, and (c) probiont RI daily treatment of larvae in the hatchery for 4, 11, and 15 days. Differential gene expression analysis compared pathogen or probiotic-treated transcriptomes to unexposed controls. Probiotic and pathogen treatment led to upregulation of transcripts coding for several immune pattern recognition receptors (PRRs) involved in environmental sensing and detection of microbes in oyster larvae. Larval oyster responses to pathogen RE22 suggested suppression of expression of genes in immune signaling pathways (myd88, tak1, nkap), failure in upregulation of immune effector genes, high metabolic demand, and oxidative stress that potentially contributed to mortality. On the other hand, the transcriptomic response to probiotic bacteria RI and S4 suggested activation of immune signaling pathways and expression of immune effectors (e.g., Cv-spi2, mucins and perforin-2). These key features of the host immune response to probiotic bacteria were shared despite the length of probiotic exposure, probiotic species, and the type of environment in which exposures were conducted. This study suggests that pre-exposure of eastern oyster larvae to probiotics for 6–24 h prior to pathogenic challenge leads to a robust and effective immune response that may contribute to protecting larvae from subsequent challenge with V. coralliilyticus RE22. This research provides new insights into host-microbe interactions in larval oysters that could be applied in the management of vibriosis in bivalve hatcheries. Full article

Eastern oyster (Crassostrea virginica) aquaculture is increasingly playing a significant role in the state of Maine’s (USA) coastal economy. Here, we conducted a qPCR-based survey for Haplosporidium nelsoni, Perkinsus marinus, and Perkinsus chesapeaki in C. virginica (n = 1440) from six Maine sites during the summer–fall of 2016 and 2017. In the absence of reported die-offs, our results indicated the continued presence of the three protozoan parasites in the six sites. The highest H. nelsoni qPCR-prevalence corresponded to Jack’s Point and Prentiss Island ( $\overline{x}=$ 40 and 48% respectively), both located in the Damariscotta River Estuary. Jack’s Point, Prentiss Island, New Meadows River, and Weskeag River recorded the highest qPCR-prevalence for P. marinus (32–39%). While the P. marinus qPCR-prevalence differed slightly for the years 2016 and 2017, P. chesapeaki qPCR-prevalence in 2016 was markedly lower than 2017 (<20% at all sites versus >60% at all sites for each of the years, respectively). Mean qPCR-prevalence values for P. chesapeaki over the two-year study were ≥40% for samples from Jack’s Point (49%), Prentiss Island (44%), and New Meadows River (40%). This study highlights that large and sustained surveys for parasitic diseases are fundamental for decision making toward the management of the shellfish aquaculture industry, especially for having a baseline in the case that die-offs occur. Full article

Expression of the regulatory stress rpoS gene controls the transcription of cspA genes, which are involved in survival and adaptation to low temperatures. The purpose of this study was to assess the growth kinetics of naturally occurring V. parahaemolyticus in shellstock oysters and in vitro and the cold-shock-induced expression of the rpoS and cspA gene response in vitro during postharvest refrigeration. Naturally contaminated eastern oysters (Crassostrea virginica) and pathogenic (Vp-tdh) and nonpathogenic (Vp-tlh) isolates were stored at 7 ± 1 °C for 168 h and 216 h, respectively. The regulatory stress (rpos) and cold-shock (cspA) gene expressions were determined by reverse transcription PCR. At 24 h, the (Vp-tdh) strain grew faster (p < 0.05) than the (Vp-tlh) strain in oysters (λ = 0.33, 0.39, respectively) and in vitro (λ = 0.89, 37.65, respectively), indicating a better adaptation to cold shock for the (Vp-tdh) strain in live oysters and in vitro. At 24 h, the (Vp-tdh) strain rpoS and cspA gene expressions were upregulated by 1.9 and 2.3-fold, respectively, but the (Vp-tlh) strain rpoS and cspA gene expressions were repressed and upregulated by −0.024 and 1.9-fold, respectively. The V. parahaemolyticus strains that were isolated from tropical oysters have adaptive expression changes to survive and grow at 7 °C, according to their virulence. Full article

Shellfish are known as a potential source of Toxoplasma gondii (responsible for toxoplasmosis), and Cryptosporidium parvum, which is one of the major causes of gastroenteritis in the world. Here we performed a comprehensive qPCR-based monthly survey for T. gondii and C. parvum during 2016 and 2017 in oysters (Crassostrea virginica) (n = 1440) from all six sites along the coast of Maine (USA). Pooled samples (mantle, gills, and rectum) from individual oysters were used for DNA extraction and qPCR. Our study resulted in detections of qPCR positives oysters for T. gondii and C. parvum at each of the six sites sampled (in 31% and 10% of total oysters, respectively). The prevalence of T. gondii was low in 2016, and in September 2017 several sites peaked in prevalence with 100% of the samples testing positive. The prevalence of C. parvum was very low except in one estuarine location (Jack’s Point) in June 2016 (58%), and in October of 2016, when both prevalence and density of C. parvum at most of the sampling sites were among the highest values detected. Statistical analysis of environmental data did not identify clear drivers of retention, but there were some notable statistically significant patterns including current direction and nitrate along with the T. gondii prevalence. The major C. parvum retention event (in October 2016) corresponded with the month of highest dissolved oxygen measurements as well as a shift in the current direction revealed by nearby instrumentation. This study may guide future research to locate any contributing parasite reservoirs and evaluate the potential risk to human consumption. Full article

The work aimed to study the structural variables of zooplankton to assess the water quality of the Caspian Sea. Studies of zooplankton were conducted in the spring and summer of 2008 and 2010. Abundance, biomass, an average individual mass of a specimen, Shannon Bi, Shannon Ab, Δ-Shannon indices, and Clarke’s W-statistic were calculated for zooplankton. Quantitative variables of zooplankton were the highest in the Northeastern and Northern Caspian, decreasing towards the Middle Caspian. In the Northeastern and Northern Caspian from spring to summer, the number of zooplankton, and the values of Shannon Bi and Shannon Ab indices decreased; the values of Δ-Shannon and Clarke’s W-statistic increased. In the Middle Caspian, the biomass of the community increased; the values of Δ-Shannon and Clarke’s W-statistic decreased. From spring to summer, the value of an average individual mass of a specimen decreased over the entire surveyed area. The jellyfish Blackfordia virginica and Moerisia pallasi significantly influenced the size structure of the holoplankton. Seasonal dynamics of structural variables of zooplankton as well as changes in water transparency showed that water quality improved from spring to summer in the shallow northern and northeastern areas of the sea, and decreased in the deep-water Middle Caspian. Full article