Studies that carefully monitor and attempt to explain causes of massive oyster mortalities are urgently needed. The objective of the present study was to assess the effects of seeding dates on the mortality and reproductive cycle of the oyster Crassostrea gigas. Seeds of two sizes (3.5–4 mm and 1.5–2 mm) were planted during three seasons: early summer, early autumn, and late autumn. The experimental period was 6 mo. Mortalities of C. gigas at culture phase nursery lantern-nets, intermediate lantern-nets, and final lantern-nets were recorded. The reproductive cycle of the oysters grown from 3.5 to 4 mm seeds planted in each season was closely monitored (bimonthly) during the experimental period. In addition, seawater parameters [temperature (daily) and salinity (weekly)] were monitored throughout the experimental period. Results of this study demonstrated that the planting season affected C. gigas mortality after the nursery phase. Lower cumulative mortality was observed for 3.5–4 mm seeds than for 1.5–2 mm seeds when the seeds were planted in early (MarL: 0.29 ± 0.02) and late (JunL: 0.22 ± 0.10) autumn, after 6 mo of culture. The reproductive cycle of seeds planted in the summer exhibited an early maturation process, and those planted in the autumn exhibited late reproductive development.

To examine the role of substratum concavity in determining oyster [Crassostrea virginica (Gmelin, 1791)] settlement success, laboratory settlement was examined on natural and artificial substrata of various concavities, defined by width-to-depth (W:D) ratio. Experiments were conducted in 204-l capacity laboratory flumes. Concavities tested include W:D ratios of 2, 5, and 16, plus a flat surface for control comparisons. Active settlement, passive settlement, and flow around these concavity treatments were examined. In addition, settlement on oyster shell cultch presented in different surface orientations, and either zip-tied to open mats, or packed in mesh bags, was examined. Results indicate that concavity can affect settlement success (W:D ratio of 5 resulted in the highest settlement success under this study's conditions). Examination of flow rates and patterns suggests that water movement over W:D 5 treatments delivers larvae to the settlement surface, but active attachment behavior is required to explain W:D 5's higher settlement densities relative to W:D 2. The highest settlement occurred with open mats on surfaces oriented horizontally and facing downward. Comparisons of mat, bag, and orientation results suggest that optimal current range for settlement is between 0.3 and 2.0 cm/sec. Too little flow results in supply failure, while flow exceeding 2 cm/sec inhibits searching and attachment behaviors.

To improve the accuracy and reproducibility of the previous near infrared reflectance spectroscopy (NIRS) model for glycogen in the oyster species Crassostrea virginica, a new model using freeze-dried samples was developed. The NIRS glycogen calibration model was developed using 380 individual oyster samples collected between 2014 and 2016 from several locations in the Chesapeake Bay. Homogenized freeze-dried samples were scanned in the near infrared region between 1,000 and 2,500 nm. In parallel, glycogen concentration (GC), measured as percent dry weight, was determined using laboratory-based methods. The two sets of data allowed us to build a NIRS model based on freeze-dried oyster meats, and the model gave a strong prediction of GC [coefficient of determination for validation (R²_val) = 0.96 and residual predictive deviation (RPD) = 5.2]. The second part of the study applied the model to determine GC among 39 diploid and 40 triploid C. virginica and determined the strength of the relationship between the GC of tissues excised for histological sampling to the remaining tissue (corpus) to verify assumptions made throughout the literature. There was an estimated R² = 0.99 between the GC in the corpus and the tissues of whole oyster meat. Among the samples, two factors, ploidy and size (shell height), had a significant effect on GC.

Mortality of two size classes (<35 and >35 mm) of eastern oysters Crassostrea virginica when exposed to combinations of low salinity (1, 2, 3, and 4) for extended periods (up to 30 days) at summer water temperatures typical of the Virginia Chesapeake Bay subestuaries was examined. A critical salinity-temperature combination of less than two at greater than 28°C for more than 1 wk exposure for oyster mortality is suggested. A review of limited historical salinity-temperature tolerance data suggest selection of local populations of oysters having differing salinity tolerances. Such selection may prove critical to persistence of low-salinity populations in the Chesapeake Bay subestuaries with projected climate change.

Recognition of the global loss of subtidal oyster reefs has led to a rise in reef restoration efforts, including in the Gulf of Mexico. Created reef success depends entirely on selecting a location that supports long-term oyster growth and survival, including the recruitment and survival of on-reef oysters. Significant changes in estuarine salinity through management of freshwater inflows and through changed precipitation patterns may significantly impact the locations of optimal oyster restoration sites. These rapid shifts in conditions necessitate a need to better understand both impacts to on-reef oyster growth and population development, and variation in oyster stock performance. Oyster growth, mortality, condition, and disease prevalence were examined in three different stocks of oysters located in protected cages, as well as oyster recruitment and mortality on experimental reef units in three different locations representing a salinity gradient, along the Louisiana Gulf coast in 2011 and 2012. Over a 2-y period, the high-salinity site had highest oyster growth rate in protected cages but demonstrated the least likelihood for reef development based on on-reef oyster population failure, likely because of predation-related mortality (high recruitment and 100% mortality). In contrast, the midsalinity site with moderate oyster growth and on-reef recruitment and low mortality demonstrated a higher likelihood for reef development. The lowest salinity site exhibited extreme variability in all oyster responses between years because of extreme variation in environmental conditions during the study, indicating a low likelihood of long-term reef development. Whereas limited differences in stock performance between sites were found, the range of site environmental conditions tested was ultimately much lower than expected and may not have provided a wide enough range of conditions. In areas with limited, low recruitment, or rapidly changing environmental conditions, seeding with stocks selected for best growth and survival under expected future environmental conditions could better ensure reef development by using oyster populations best suited to the predicted conditions. With rapidly changing estuarine conditions from anthropogenic activities and climate change, siting of oyster reef restoration incorporating both oyster population dynamics and in situ biotic and abiotic interactions is critical in better directing site selection for reef restoration efforts.

An effective method of anesthesia for Olympia oysters (Ostrea lurida) would allow for nonlethal sampling of tissues for genetic analysis, biopsy for diseases, assessing reproductive status, and collection of brooding larvae. The use of magnesium sulfate (MgSO₄) as an anesthetization method for Olympia oysters was assessed in laboratory trials and field use. Three replicate groups of 10 oysters were exposed to MgSO₄ at three concentrations (0, 75, 85, and 100 g/L) in the laboratory to investigate the optimal concentration for anesthetization. Laboratory trials determined that 45 min of treatment with 100 g/L MgSO₄ was the most effective. In the field, more than 14,000 oysters were exposed to MgSO₄ as an anesthetic to assess reproductive status and validate the procedure. In field trials, the anesthetization method of 45 min air exposure followed by 45 min submersion in 100 g/L MgSO₄ was found to have a success rate >80%. No influence of sampling date, location, or reproductive status on anesthetization was detected. Shell height was negatively correlated with anaesthetization success rate, with small oysters more likely to open their shell in response to MgSO₄.

Oyster classification is problematic because of variations in shell morphology, and the use of molecular data may help to confirm species identity and clarify taxonomic confusion. Two ostreid oysters were collected from Peru and identified as Undulostrea megodon (Hanley, 1846) and Talonostrea talonata (Li & Qi, 1994), based on shell morphology. To confirm their taxonomic status, fragments of mitochondrial cytochrome oxidase I and 16S rRNA genes were sequenced. Phylogenetic analyses of both sequences do not support the validity of the two genera that were solely founded on these two species. Oyster U. megodon is clearly a member of Ostrea and T. talonata a member of Crassostrea. Thus, U. megodon should retake its original name of Ostrea megodon (Hanley, 1846), and T. talonata should be renamed as Crassostrea talonata (Li & Qi, 1994). Oyster C. talonata is a described species of China, and its occurrence in western Pacific is unusual and probably because of human facilitated introductions.

Although oysters are important aquaculture and fishery species as well as keystone species in coastal and estuarine ecology, their global species diversity is not fully understood due to problems of oyster classification. Molecular taxonomy has contributed to oyster classification but not been applied to oysters from many regions including Myanmar. In this study, oysters from Myanmar were collected and subjected to taxonomic analysis with mitochondrial cytochrome oxidase I and 16S rRNA sequences. Sequence analysis reveals that the Myanmar oysters collected in this study belong to three species: Saccostrea malabonensis (Faustino, 1932), a distinct member of the superspecies Saccostrea cucullata (Born, 1778) group; Crassostrea belcheri (Sowerby, 1871), a common species found in Indo-Pacific; and Crassostrea gryphoides tanintharyiensis, a sister subspecies of Crassostrea gryphoides dwarkaensis from Arabian Sea that is different from the fossil species Crassostrea gryphoides (von Schlotheim, 1813). Results of this study highlight the need for molecular taxonomy of oysters from all world oceans to understand and protect the species diversity of this important species group.

Nacre, also known as mother of pearl, contains factors that can promote osteogenesis. In this study, pearlin, a protein from the mantle tissue of the pearl oyster Pinctada fucata, was expressed and purified, and its functional activity analyzed using two mineralogenic cell lines, MRC-5 (fibroblasts) and MC3T3-E1 (preosteoblasts). The open reading frame of pearlin was subcloned into the expression vector pET32a( ) and used to transform Escherichia coli BL21 (DE3) strain. The expression of the recombinant protein (molecular weight: 34.19 kDa) was induced by isopropyl-β-D-thiogalactopyranoside in the form of inclusion bodies which were solubilized in 8 M urea. The recombinant protein was renatured by stepwise dialysis, purified by Ni-NTA affinity chromatography, and analyzed for the effects on cell proliferation by the MTT assay and osteoblastic differentiation by alkaline phosphatase (ALP) activity. The recombinant pearlin promoted proliferation ofMRC-5 andMC3T3-E1 cells at 10 µg/mL and increased their ALP activity at 2.5 µg/mL and 5 µg/mL, respectively. The present study showed that the recombinant pearlin exerted functional effects similar to those of the natural protein, laying a foundation for large-scale production of pearlin in a prokaryotic system.

A 2007 study of Suminoe (Crassostrea ariakensis) and eastern (Crassostrea virginica) oysters exposed to Indian River Lagoon (IRL), Florida waters revealed the presence of Bonamia spp. in exposed oysters. In 2010, a survey of oysters and other bivalves (n = 721, 18 species) was conducted in the southern IRL (10 sites) and in the more southerly Lake Worth Lagoon (LWL, 3 sites). Polymerase chain reaction (PCR) was used to assess the prevalence of three oyster parasites, Bonamia spp., Perkinsus marinus, and Haplosporidium nelsoni, in collected samples. Histology, fluorescent in situ hybridization (FISH) and standard H&E staining, was used to confirm PCR-positive Bonamia results. Bonamia spp. was detected in eight species (Brachidontes exustus, Crassostrea virginica, Geukensia demissa, Ischadium recurvum, Isognomon alatus, Isognomon bicolor, Mercenaria campechiensis, and Ostrea stentina). The prevalence was 17.3% in the IRL and 9.9% in LWL with 66% of PCR-positive samples subsequently identified as either Bonamia exitiosa or Bonamia perspora. The presence of Bonamia spp. was confirmed by FISH in C. virginica, O. stentina, I. alatus, I. bicolor, and G. demissa, although only C. virginica and O. stentina showed evidence of infection. The presence of P. marinus was detected in eight species (Atrina rigida, B. exustus, C. virginica, G. demissa, I. recurvum, I. alatus, I. bicolor, and O. stentina). The prevalence was 12.4% in the IRL and 7.7% in LWL. The presence of MSX was not detected in any of the collected bivalves. This study confirms the presence of Bonamia spp. and P. marinus in Florida east coast waters and widens the described geographic range for Bonamia spp., and provides further evidence that MSX is unlikely to be found in Florida waters

Blue mussels Mytilus edulis (Linnaeus, 1758) from southern Barnegat Bay, NJ, were examined to determine the make-up of the normal blue mussel microbiome. Sequencing of 16S ribosomal DNA amplicons from gill and intestinal content microbiomes using the Illumina MiSeq platform yielded 1,276,161 paired-end sequence reads from the gill libraries and 1,092,333 paired-end sequence reads from the intestinal content libraries. General bioinformatic analyses were conducted with the opensource packages Qiime and Mothur. Phylotype assignments to the genus level were made using the commercial One Codex platform. This resulted in 1,697,852 gill and 988,436 intestinal content sequences being classified to genus. A majority of these (67.6% and 37.2%, respectively) were assigned to a single operational taxonomic unit (M. edulis Symbiont, MeS) that has homologies with other recently described Endozoicomonas pathogens and symbionts of marine invertebrates. This newly discovered symbiont shares 98% identity with an uncultured bacterium from the gill tissue of an invasive Indo-Pacific oyster and with HQE1 and HQE2 isolated from the sea squirt Styela clava. Other than MeS, most of the detected bacterial species are known from marine sediments and seawater.

The sunray venus clam has been advanced as an alternative species to hard clams for aquaculture in Florida. Although interest and market potential are high, hatchery operators continue to experience problems with consistent year-round spawns. Gametogenesis in other species has been linked to changes in fatty acid (FA) profiles, which are in turn affected by temperature and diet. Knowledge of specific FAs that are important for the development of high-quality gametes has implications in determining optimal conditions for maturation systems. This study compared the FA profile of sunray venus clams (wild, cultured) collected from two locations during the natural fall spawning cycle to (1) determine which FAs are associated with gametogenesis and (2) assess the impact of exogenous influences. The FA profile of developing clam larvae was likewise examined to offer additional insight into endogenous and exogenous influences. Males and wild females exhibited fall spawning peaks, with the majority in gametogenesis in the spring. Males had a second spawning peak in February, and cultured females spawned continuously throughout the 6-mo study period. The FA profile appeared to be less associated with gametogenesis than with sex or exogenous influences. Decreases in n-6 PUFAs (inverse relationship) and increases in n-3 PUFAs (positive relationship) were associated with gametogenesis in males and wild females, but not cultured females, perhaps because of the protracted spawning period. Differences were noted between the sexes, regardless of month or location, with females having a higher amount of total FAs, MUFAs(16:1 n-7), and SFAs (16:0 and 14:0), but lower n-3 PUFAs (22:6 n-3). There was little difference in the FA profile of clams collected at the two locations, although the wild population tended towards higher total FAs and n-3 PUFAs. Diet (chlorophyll a concentration and turbidity) appeared to have a stronger link with changes in FA profile and gametogenesis than temperature. Discernable differences were observed in the FA composition (n-3 and n-6 PUFAs) of larvae and 5-day postset that reflected the impact of both endogenous and exogenous (diet) influences. These results indicate that algal species with select FA profiles may increase maturation, particularly in females, leading to more consistent spawns.

Conrad's false mussel (Mytilopsis leucophaeata) is an invasive alien bivalve species causing severe biofouling problems in cooling water systems of power and industrial plants. Settlement, seasonal shell size distribution, and growth of this bivalve species were analyzed in relation to relevant environmental factors, using monitoring data from a brackish canal over a period of 4 y. Salinity at the sampling site ranged from3.2 to 9.2,water temperature from 4.5°C to 23.9°C, and chlorophyll a content from 2 to 56 µg l^-1. Once a month one short-term exposed panel (1mo exposed) and one long-term exposed panel (exposed from February 1989 to the month of sampling) were collected. Settled spat and attached mussels were collected monthly from these polyvinylchloride panels and from stones in the littoral zone. The short-term exposed panels were used to determine the period of spat fall. The long-term panels were used to study growth, shell length-frequency distribution, and densities of the mussel population after settlement. To study maximum age, M. leucophaeata were kept in cages in the canal. The highest recorded settlement was 204,000 individuals/m2. The largest mussel had a shell length of 24.0 mm. Three cohorts of shell length (1–5 mm, 5–15 mm and 15–24 mm) could be distinguished. Data on survival of individual mussel size groups in cages indicated a maximum age of 4.5 y. Shell growth was very low in winter time (average growth less than 1 µm/day in the period of November to April). The average growth rate on the stones during the summer periods (3–4 mo) was 89 µm/day. On the panels, a rapid shell growth to an average shell length of 4mm was recorded in the period of July until November in their first year, followed by a period of hardly any shell growth from December until May, and a subsequently rapid shell growth to an average shell length of 13mmduring the period of May until August in the second year. Individual mussels grew up to 20.9 mm during a 13-mo period. Growth of shells was significantly correlated with water temperature. The minimum threshold temperature for shell growth stops was 9.1°C (9.1°C–10.1°C) based on monthly measurements. Growth started at a minimum temperature of 9.1°C (9.1°C–14.2°C).

Channeled whelks, Busycotypus canaliculatus, support commercial fisheries throughout their range along the US Atlantic seaboard. Given the modest amounts of published information available on channeled whelk, this study focuses on understanding the temporal and spatial variations in growth and reproductive biology in the Mid-Atlantic region. Channeled whelks were sampled from three inshore commercially harvested resource areas in the US Mid-Atlantic: Ocean City, MD (OC); Eastern Shore of Virginia (ES); and Virginia Beach, VA (VB). The largest whelk measured 230-mm shell length (SL) and was recorded from OC. Mean SL was largest in OC site (158.1 mm), followed by ES (137.6 mm) and then VB (132.4 mm). Both VB and ES populations showed a unimodal length-frequency distribution with the single peak at SL less than minimum landing size (MLS) for those regions, whereas OC population showed a bimodal (two peaks) distribution with the smaller peak at SL less than the MLS for that region and larger peak at SL greater than the MLS. Brody growth rate coefficient (k) was higher in males than females from all areas and highest for both sexes in VB (Male 0.245, Female 0.155), followed by ES (Male 0.220, Female 0.151) and then OC (Male 0.112, Female 0.100). The median size (SL) at 50% mature varied between resource area and sex. Males from ES and VB reached maturity at a smaller mean size (123 and 121 mm, respectively) than OC (134 mm). Females from VB reached maturity at a smaller size (148.9 mm) than ES (157.6 mm) and OC (158.6 mm). Recruitment to the fishery was estimated to occur at ∼6 y for VB and ∼7–8 y for ES and OC and was calculated from length at age estimates from von Bertalanffy growth model. Under current MLS for each area, whelk harvested from VB were recruited into the fishery at a much younger age compared with those from OC. The probability of females reaching MLS before sexual maturity in all three commercially targeted resource areas is quite low given current MLS.

Mud crab (MC) aquaculture is rapidly developing fast worldwide, and there is a high consumer demand for Scylla paramamosain. Demand for MCs is especially high in China, where such crabs, especially the gravid females, are regarded a delicacy. In Hainan Island, pond-rearing wild MC juveniles in the presence of local trash fish and shrimps in brackish water has been shown to be successful. The nutritional value of cultured MC, however, has not been evaluated. In this paper, the biochemical composition of pond-cultured and wild gravid female MCs was studied. The cultured MCs had a higher ratio of total edible yield than the wild ones. The contents of crude protein and crude lipid in the cultured MCs were significantly lower than in the wild MCs (P < 0.05). Furthermore, the total amino acid (TAA) and essential amino acid (EAA) contents of gonads in the wild MCs were both significantly higher than those in the cultured MCs (P < 0.05). The TAAs and EAAs of claw and body muscles in cultured MCs, however, were significantly higher (P < 0.05). There were no significant differences in the contents of polyunsaturated fatty acids (PUFAs), n-3 fatty acids, and n-6 fatty acids in the gonad of bothMCgroups, whereas the contents of total saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were significantly different between the wild and the cultured MCs (P < 0.05). Furthermore, there were no significant differences in the contents of SFAs, MUFAs, and PUFAs in both claw and body muscle between the wild and cultured MCs.

Limited approaches exist for studying population connectivity in widely dispersing marine benthic invertebrates. Genetic techniques can provide important insights toward identifying recruitment trajectories. Here, 10 microsatellite loci were used to examine connectivity among Oregon Dungeness crabs (Cancer magister, Dana, 1852) in the California Current System (CCS) (n = 801) as well as between Oregon and two British Columbia populations, Alison Sound (n = 54) and Boundary Bay (n = 48). Using population-based methods (F-statistics), evidence for weak genetic differentiation was found among 12 sites in Oregon that did not conform to a pattern of isolation by distance.Whereas individual-based methods (kinship analyses) indicated higher than expected relatedness in two Oregon sites, this finding did not help interpret the pattern of genetic differentiation observed among sites in the CCS. Extending our analyses to British Columbia, it was determined that genetic diversity within the Boundary Bay population was comparable to that observed for Oregon, whereas genetic diversity within Alison Sound was considerably lower. Furthermore, genetic connectivity between Oregon and British Columbia was reduced as Alison Sound was genetically distinct from all Oregon sites, whereas Boundary Bay was genetically differentiated from several Oregon sites. In accordance, a Bayesian clustering approach provided support for two genetic groups: (1) Oregon and Boundary Bay and (2) Alison Sound. Kinship analysis revealed a high degree of relatedness within Alison Sound which helps explain the observed pattern of population differentiation. By combining population-based and individual-based approaches, these results demonstrate that connectivity between ocean and fjord-like areas is reduced and may lead to elevated kinship in isolated populations.

The physiology of ion regulation in the highly invasive European green crab Carcinus maenas has been widely studied, but mostly in constant salinity conditions, and not in context of their molt cycle-dependent sternite coloration. The ventral sternites are typically green after molting, and turn red through prolonged intermolt, with a concurrent decrease in stress tolerance. In this study, whole animal and molecular physiology was evaluated at constant low salinity (12), and oscillating salinity (12–32 every 6 h). Performance in three whole animal measures revealed that the green phase is more tolerant than the red phase, and that females are more tolerant than the respective males under both salinity conditions. These differences result from larger increases in expression of the drivers behind ion transport (Na /K -ATPase, cytoplasmic carbonic anhydrase) in green phase and female crabs. Low salinity exposure resulted in increased expression of these markers compared with oscillating salinity, demonstrating that low salinity is more strenuous, as more cellular regulation is required. This agrees with the crabs' natural environmental conditions where prolonged low salinity is rarely experienced. These findings are presented in context of a crab population survey conducted from May 2012 through November 2016 in southern Maine, USA. Female and red phase crabs were found at higher proportions in the intertidal than previously reported. In addition, gravid females were found year round, which is indicative of continuous reproduction. The data demonstrate the necessity to evaluate C. maenas in an ecologically relevant context with respect to color phase within each invasive population to truly understand the invasive capabilities of this species and to better inform management strategies.

The decreasing average pH of the world's oceans, called ocean acidification, can be detrimental to marine organisms. Decreased pH causes dissolution of calcium carbonate shells, as well as changes to metabolism, behavior, growth, survival, and early development of many species; however, the impacts of lower pH on crustaceans have not been widely researched. This study investigated the effects of lower pH on the growth and survival of larval blue crabs Callinectes sapidus through laboratory experiments. Blue crab larvae live at the surface of the open ocean where the pH is decreasing with ocean acidification. A pH of 7.8 was used to mimic the average surface ocean pH predicted to be attained by 2,100 by the Intergovernmental Panel on Climate Change and was compared with a control pH of 8.2, the current average surface ocean pH. Larvae raised at the lower pH were 10% smaller and there was a 23% reduction in survival. Larval populations within an aquarium with a lower pH were more likely to exhibit sudden die-offs than larvae raised at the control pH.

Penaeid shrimp including Litopenaeus setiferus (white shrimp), Farfantepenaeus aztecus (brown shrimp), and Farfantepenaeus duorarum (pink shrimp) support one of the most valuable commercial fisheries in the U.S. Southeast Atlantic. Since the late 1990s, the fishery, especially in coastal Georgia and South Carolina, has experienced a significant decline. A contributing factor to this decline has been hypothesized to be a severe outbreak of shrimp black gill caused by a ciliate parasite. DNAsequence-based analysis of the gill parasite small subunit rRNA gene identifies the proposed causative agent as being closely related to the apostome ciliate Hyalophysa chattoni; however, morphological characteristics of the ciliate observed by electron microscopy are inconsistent with this identification. Although studies are ongoing to identify this ciliate, it was possible to develop a diagnostic polymerase chain reaction-based assay targeting the small subunit rRNA gene and use it to investigate the seasonal and geographic distribution of the parasite in wild shrimp populations. Next-generation sequencing of the gill microbiome confirmed that when black gill is at its peak, microeukaryotic communities were dominated by apostome-related ciliates, but over the year highly diverse communities of gill associates, including other potential ciliate, fungal, euglenozoid, and amoeboid parasites are commonly detected. Improved molecular diagnostics and the ability to explore the diversity of potential parasites in shrimp provide important new insights into the relationship between the shrimp fishery and black gill.

The synthesis of highly unsaturated fatty acids (HUFAs) from C18 fatty acids in the Pacific white shrimp, Litopenaeus vannamei, has long been debated in terms of the limited capacity or even the existence of fatty acid desaturase and elongase. In the present study, a Δ6 fatty acyl desaturase (Fad)-like gene was identified and characterized with a full length of 1,491 bp, including a 39-bp 5′-UTR (untranslated region), a 108-bp 3′-UTR, and a 1,344 bp open reading frame encoding a 448 amino acid protein. The protein contained a cytochrome b5-like heme/steroid binding domain and a Fad domain. The Δ6 Fad-like protein of L. vannamei shared 70%–77% sequence homology with those of Macrobrachium nipponense, Scylla paramamosain, Portunus trituberculatus and Eriocheir sinensis. When salinity was reduced from 30 to 3, Δ6 Fad-like gene expression significantly increased in the gills, muscles, eyestalk, and hepatopancreas (P < 0.05). The highest expression was observed in the hepatopancreas under salinity 3 in the linseed oil group, followed by the fish oil group. The results suggest that L. vannamei has a gene encoding a Δ6 Fad-like protein whose expression increases with decreased salinity and depends on the level of C18 fatty acids, such as α-linolenic acid and linoleic acid, in the diet. The present study improves the current understanding of Δ6 Fad-like genes in euryhaline shrimp species, particularly their mRNA expression under different conditions.

A winter fishery closure has existed in the northern zone rock lobster fishery of South Australia since 1966. This study describes the process undertaken to review and ultimately change temporal management policy with the aim of providing greater fishing flexibility to the commercial fishing sector. The work was driven by a research subcommittee (RSC) project team consisting of various stakeholder groups that included commercial fishers, fishery research scientists, resource managers, and conservation representatives. The RSC ultimately reported to the South Australian Rock Lobster Fisheries Management Advisory Committee (RLFMAC), an expertise-based, advisory body to the South Australian Government. To inform management discussions and possible policy change, the RSC proposed monthly sampling surveys during the winter fishery closure to examine key aspects of the catch composition. Sampling was underpinned by strong industry support in terms of survey logistics. Results were reviewed by the RSC and indicated that compared with the regular fishing season, closed season surveys identified (1) low catch rates of undersized lobsters; (2) reduced levels of predation mortality; (3) low contribution of female lobsters to the catch; and (4) negligible impacts on key bycatch species. Based on these findings, the RLFMAC recommended that policy changes in relation to the winter fishing closure could be considered. In June 2016, the Department of Primary Industries and Regions South Australia implemented the removal of the winter closure in an offshore region (>80 m depth) of the fishery resulting in a 12-mo fishing season for this area. The winter closure in the remainder of the fishery can be reconsidered after a 3 y period. This work is an example of industry, science, and Government collaboration to deliver management outcomes from industry-supported research.

Commercially viable aquaculture of noble crayfish Astacus astacus (Linnaeus, 1758), a once plentiful food species in Europe, requires production of suitable artificial diets for optimal growth in recirculating aquaculture systems (RAS). This technique provides the opportunity to culture this species in an enclosed ecosystem which minimizes the risk of infection— resulting in high-value food products as well as high-quality juveniles for restocking purposes. In the current study, noble crayfish were fed in RAS with a commercial diet and relied on natural forage in an open pond system (OPS) for two months. Energy, lipid, and fatty acid (FA) content of available and alternative diets [Cyprinin K2 (CK2), Mytilus edulis Rafinesque, 1815, Elodea spp. Michx.) and crayfish tissue were determined. Crayfish from the pond system had significantly (P < 0.01 OPS versus all RAS treatments; Pairwise Wilcoxon) higher lipid content (8.51%) and more diverse FA composition than RAS crayfish. At least 15 partly combined FAs were present in crayfish whereas seven were provided by the diet CK2 and 10 by M. edulis and Elodea spp. In addition to the recommended lipid (<10%) and protein (>30%) proportions for commercial dietary formulation, analyses indicate that FA composition and amount play a key role in A. astacus growth, particularly in RAS. At least 15 measured FAs are required in an appropriate crayfish diet in sufficient amounts to achieve high growth rates while not losing energy and growth potential for FA synthesis. The FA profile of Elodea spp. and M. edulis indicate suitability as a feed or at least as a viable supplementary dietary component.

Red and purple sea urchins (Mesocentrotus francisanus and Strongylocentrotus purpuratus) cohabit the west coast of North America and exhibit behavioral switching between sheltering, when food is abundant, and emergence and overgrazing, when food is scarce. To better understand individual urchin foraging behavior, we conducted a series of time-lapse behavioral studies within and at the edge of a resilient sea urchin barren. Photographs were taken at 15-min intervals for weeklong periods to observe behavior (1) in different microtopographic settings, (2) in response to food additions, and (3) along a spatial gradient from the leading edge of a sea urchin grazing front to ∼100 m behind it. Movement was limited for both species when crowded or in complex microtopography. Consistent differences in sheltering behaviors and diel movement patterns were observed between species in the presence and absence of food indicating behavioral niche differentiation. Red sea urchins responded to food falls at distances of at least 3m and exhibit an ability to return to shelters at similar distances. Both species exhibit (1) local movement for up to weeklong periods indicating constraints on bulk movement and grazing front formation, (2) decreased movement rates owing to crowding and microtopography analogous to traffic jams, and (3) consistent instraspecific differences in individual movement behaviors (i.e., personality). We propose how small-scale behavioral modes may scale to larger-scale local population movements and affect the dynamics of sea urchin overgrazing.