Characterization of the major proteins in the crystalline styles of Perna canaliculus and Mytilus galloprovincialis was carried out to attempt to identify the molecular basis of differences in the physical structure of the styles and their biochemical significance. The bivalve P. canaliculus has a crystalline style that is typical of those with permanent hard-type styles, whereas the style of M. galloprovincialis is typical of bivalves with transient soft-type styles. The consistency of the styles is clearly related to their respective moisture content, and both style types contain a suite of high-molecular weight (>800 kDa and ∼95–170 kDa) glycolproteins and medium-molecular weight (40–50 kDa) protein duplexes. Total carbohydrates (as determined by the phenol-sulfuric acid method) make up a small proportion of the mass of the styles. It is suggested that these 40–50 kDa proteins play a role in the formation of the protein gel that establishes the structural integrity of the style. Their solubility is minimal at pH 4.5–5.5, which corresponds broadly to the pH of the gastric fluids. The proportion of low-solubility, putative gel-forming proteins (at∼pH 5.5) is greater in the hard styles of P. canaliculus than in the soft styles of M. galloprovincialis. One- and 2-dimensional sodium dodecylsulfate—polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization—time of flight/time of flight peptide analysis of style proteins shows that the major digestive enzymes (cellulases, amylases, laminarinases) make up only a minor proportion of total protein content of the styles. Amino acid de novo sequencing shows there is close similarity between the sequences of several peptide fragments of the prominent 40–50 kDa protein duplexes and myosinases I and II annotated within an M. galloprovincialis express sequence-tagged database (“Mytibase”). Myosinases belong to a large family of astacin-like metalloproteins that have numerous functions and are widely distributed in nature, although in many cases their role is unknown. It has yet to be determined whether these proteins have enzymatic activity; however, they are clearly important as part of the style matrix of these 2 mussels species and probably the crystalline styles of other bivalve molluscs as well.

Assays of chitinase, cellulase, and amylase activities in the crystalline styles of selected fast- and slow-growing families of the mussel Perna canaliculus were carried out on 2 occasions over 6 mo, during which time the shellfish grew in a normal mussel cultivation situation. The data did not support the hypothesis that differences in growth rate by these families could be related to differences in the expression of digestive enzymes in the styles, leading to improved nutritional efficiency by faster growing families. On the contrary, the styles of faster growing families in general exhibited lower rates of enzyme activity. Differences in enzyme activities between families appeared to be related to the size of the individuals rather than their genetic heritage. The crystalline styles of larger, more mature shellfish contained less moisture and less soluble protein, and the lower rates of enzyme activity in larger individuals may be indicative of a reallocation of style protein synthesis toward higher levels of insoluble structural proteins.

Public support of mussel farming in Greece is an important factor because of its financial viability. The profitability of the activity is seriously reduced in small farms (1–3 ha) as a result of their high production costs; however, small farms represent a major part of the industry. Mussel farming is an extensive activity, with space availability regulated by public administrators via licensing of marine cultivation area property rights. The available space, though, is limited and, consequently, impedes any future expansion, restricting the production capacity of small farms. Nevertheless, the cost of new establishments and the modernization of existing ones (suitable boats, grading equipment, and so on) is affordable only by the larger companies. For small farms, it seems harder to recruit the large labor teams needed to work on a seasonal basis because this is the optimum to effect least operational costs, as shown by sensitivity analyses. In conclusion, for financial sustainability this sector needs to be restructured and organized into larger schemes, such as with producer organizations or cooperatives, to achieve economies of scale.

A series of acute and sublethal experiments were conducted to examine the potential effects of exposure to wateraccommodated fractions (WAFs) of Macondo Canyon 252 crude oil and chemically enhanced (Corexit 9500A dispersant) wateraccommodated fractions (CEWAFs) on embryogenesis, larval development, growth, and survival of the eastern oyster, Crassostrea virginica. Nominal exposure concentrations for acute experiments were 0, 100, 200, 400, 800 and 1,200 mg/L for WAFs, and 0, 6.25, 12.5, 25, 50, 100, and 200 mg/L for CEWAFs. Calculated total polycyclic aromatic hydrocarbon (TPAH) values were 0, 22.5, 45, 90, 181, and 271 µg/L for WAFs, and 0, 4.5, 8.9, 17.8, 35.7, 71, and 142 µg/L for CEWAFs. The exposure concentration for sublethal experiments was 16 mg/L CEWAF. Total polycyclic aromatic hydrocarbon concentrations represent moderate to high levels of TPAH reported during the Deepwater Horizon (DWH) event. Exposure to acute concentrations of 1 or both of these contaminants was shown to decrease fertilization success (≥100 mg/L CEWAF), hinder trochophore (≥100 mg/L WAF, ≥12.5 mg/L CEWAF) and D-stage (≥200 mg/L WAF, ≥25 mg/L CEWAF) development, increase the risk of D-stage developmental abnormalities (≥100 mg/L WAF, ≥100 mg/L CEWAF), and decrease survival of D-stage (1,092 to 261.8 mg/L WAF, 24–96 h LC₅₀; 177.6 to 24.8 mg/L CEWAF, 24–96 h LC₅₀) and eyed (81.9 to 14.5 mg/L CEWAF; 24–96 h LC₅₀) larvae. Exposure to CEWAFs, in general, resulted in increased toxicity over WAFs, likely as a result of the increased bioavailability of hydrocarbons. In contrast to acute exposures, short-term (24-h) sublethal exposure of D-stage larvae to CEWAFs (16 mg/L) had no impact on survival or growth. Although concentrations used represent possible TPAH exposure levels based on maximum reported values, these findings do not imply that oyster larvae were exposed to similar concentrations during or after the DWH event.

Fluid and its associatedmucus from the pallial (mantle) cavity of eastern oysters Crassostrea virginica (Gmelin) from Black RockHarbor, Bridgeport, Connecticut, inhibited growth of both Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Serratia marcescens, and Vibrio parahaemolyticus) bacteria in antimicrobial assays. In the presence of oyster fluid, E. coli resulted in significant reduction in growth after 26 h. Soluble lysozyme activity in pallial cavity fluid of oysters collected in the fall was 3 times greater than that measured in combined winter—spring—summer samples (P = 0.0008). During the course of the study, copper concentrations in pallial cavity fluid ranged from 0.60–2.49 ppm and zinc concentrations ranged from 9.7–61.0 ppm. Copper concentrations remained relatively constant throughout the study; the highest zinc concentrations were recorded in the fall. Fall antimicrobial assays showed heightened antimicrobial activity compared with the spring, which may be the result of increased lysozyme activity and higher zinc concentrations present in the pallial cavity fluid at that time of year. Results of this study suggest that pallial cavity fluid and its associated mucus likely serve an important role in defense-related functions as the first line of defense against infections from environmental pathogens in Crassostrea virginica.

Subtidal oyster (Crassostrea virginica) reefs constructed during in the mid 1990s in Pamlico Sound, North Carolina, initially supported high densities of oysters; however, beginning around 2007, oyster density subsequently declined. Concurrent with the decline in oyster density was an increase in the prevalence of boring sponges (Cliona) on oysters and the underlying reef substrate material at these sites. The limestone marl substrate used to build these reefs became colonized by boring sponge to the degree that bioerosion by sponge potentially compromised the suitability of the reefs for oysters. Laboratory and field experiments were conducted to determine whether oyster demographic rates of settlement, recruitment, growth, and mortality were affected by the presence of Cliona on underlying shell substrate. Oyster settlement on shells with varying levels of sponge was measured in the laboratory, and oyster recruitment, growth, and mortality in the presence and absence of sponge were measured in 2 estuaries in coastal North Carolina from 2011 to 2012. Potential alternative substrates for future reef restoration were tested in the field to determine their susceptibility to bioerosion by sponges. Substrates included 2 composed of calcium carbonate (CaCO₃; oyster shells and limestone marl) and 2 non-CaCO₃ substrates (concrete and granite), because bioerosion by clionids target CaCO₃. Surprisingly, no differences in oyster settlement, recruitment, growth, or mortality in the presence versus absence of Cliona were observed, suggesting that effects of the presence of sponge on oysters are either chronic rather than acute or are indirect and must act in concert with other oyster enemies. Notable patterns of sponge growth on the alternate substrates emerged; oyster shells were most susceptible to sponge growth, followed by marl, whereas concrete and granite were not susceptible to colonization by Cliona. Results from this study demonstrate the importance of having a strong understanding of the specific restoration methodology to be implemented, because the susceptibility of a substrate to bioerosion could have serious implications for reef longevity. Evidence is presented that consideration of the broader estuarine environment, including both biotic and abiotic factors, is vital when planning restoration actions, because the presence of Cliona was less important than the estuarine salinity gradient in altering oyster demographic rates and may shift the trajectories of restored reefs.

Fecundity, condition index, and gametogenic development of the Manila clam Ruditapes philippinarum were quantified at 2 sites on the intertidal fishing grounds of the Akkeshi-ko estuary, Hokkaido, Japan. In this study, an enzyme-linked immunosorbent assay was used to quantify the number of eggs in the clams. Fecundity and condition index were greater at the site with more availability of higher chlorophyll a concentrations and current velocities. However, histological analysis revealed that gametogenic development in the clams was completed at the site with lower food supply. The fecundity and condition index were limited in a part of this site, with high juvenile recruitment (>8,200 individual/m²) and intense food competition between the clams. Moreover, fecundity increased with size. The Akkeshi-ko estuary is located in northern Japan, where low temperatures mean sexual maturation progresses slowly in these clams. These results suggest that Manila clam fecundity increased through weight gain and repeated spawning could not occur due to their slow maturation.

The nuclear factor-κ;B (NF-κ;B) signaling pathway has been studied extensively in mammalians and insects but has been less well investigated in marine molluscs. Inhibitor of κ;B (Iκ;B), an important component of the NF-κ;B signaling pathway, serves as a crucial mediator of the innate immune system. A homolog of Iκ;B was identified in a razor clam (Solen grandis), designated as SgIκ;B, and its messenger RNA expression was detected both in tissues and towards pathogen-associated molecular patterns. Full-length complementaryDNAof SgIκ;B is 2,232 bp, containing a 181-bp 5′ untranslated region (UTR) and a 970-bp 3# UTR with a poly (A) tail. The open reading frame is 1,080 bp, encoding a 359-amino acid polypeptide with a predicted molecular weight of 40.1 kDa and an isoelectric point of 4.88. A potential PEST motif (E₂SNDLEMDTCPLEMDS₁₇) and the Iκ;B degradation motif (ES₄₄GYKS₄₈) are located at the N-terminus, and 2 conserved casein kinase II phosphorylation sites (S₃₃7DEE₃₄₀ and S₃₄₆YDD₃₄₉) exist at the C terminus. The presence of 6 conserved ankyrin repeats in SgIκ;B and its close phylogenetic relationship with other IχBs strongly suggest that SgIκ;B belongs to the IχB superfamily. Messenger RNA of SgIκ;B is expressed constitutively in various tissues of healthy S. grandis, with the greatest expression in gill and hepatopancreas, followed by gonad, mantle, hemocyte, and muscle in descending order. Messenger RNA expression of SgIκ;B in hemocytes is upregulated significantly to varying degrees (P < 0.01) on stimulation with lipopolysaccharide, peptidoglycan, and β-1,3-glucan. The results indicate the existence of a NF-κ;B signaling pathway in S. grandis and provide evidence for possible regulatory mechanisms during an immune challenge.

Naticid gastropods provide a highly tractable system for exploring ontogenetic changes in diet because the telltale boreholes they leave behind in their hard-shell molluscan prey can be linked reliably to naticid size. In this study, ontogenetic changes in diet and size selectivity across 7 common prey species of Lunatia heros (Say, 1822) were explored using a forensic approach based on beach-collected shells from the eastern coast of Nova Scotia, Canada. Laboratory experiments were also undertaken to assess the relationship between predator size and outer borehole diameter (OBD) for 3 of these prey species. The results confirmed a strong relationship between OBD and shell length for L. heros and demonstrated that this relationship was consistent across prey species varying in shell thickness and composition. Analyses of drilled, beach-collected shells revealed that L. heros clearly differentiates among prey with respect to size and species, with ontogenetic changes in prey selection appearing to reflect shifting predator—prey size relationships. Among prey species, larger predators demonstrated the capacity to select larger prey species and avoid smaller prey taxa. Similarly, within prey species, larger predators preyed on larger individuals of a given species, but also exploited a wider selection of prey sizes than smaller moonsnails. The moonsnail L. heros also exhibited borehole site specificity for both bivalve and gastropod prey, but did not discriminate between left versus right valves when drilling bivalve taxa. The results of this study are important for understanding the changing role of L. heros across its life span within soft-sediment communities. This research should now be broadened to encompass the full suite of prey species targeted by this drilling predator.

Length—weight measurements of 1,480 specimens of the Humboldt or jumbo squid Dosidicus gigas were analyzed. Spatial coverage of databases included the Gulf of California and the Pacific Ocean off Baja California peninsula. This study presents a historical review of length—weight relationships for D. gigas over its entire distribution and provides baseline data on length—weight relationships with associated condition factors (relative weight and Fulton's coefficient). Results show that the jumbo squid has a predominantly positive allometric growth pattern (coefficient b, >3), and the condition factor most effective for this species was Fulton’s coefficient (K). The Humboldt squid also showed strong variability in length'weight parameters and condition factors depending on the geographic region, the year or the season, the range size of the population, and/or the environmental conditions. Further research is needed to understand the mechanisms involved in this variability as part of the phenotypic plasticity reported for Dosidicus gigas.

The interplay of competition and predation often affects prey habitat use, which may concentrate prey in safer areas with indirect consequences on their foraging efficiency and the effects of their foraging on the community. Predation is intense on coral reefs where competition for limited space and food is severe. The sea urchin Diadema antillarum, an inhabitant of Caribbean coral reefs, uses crevice shelters and often aggregates with conspecifics for protection against predators, which appears to reflect a conflicting balance between group defense versus competition for limited shelter. A series of laboratory experiments was used to determine how the availability of shelter, conspecifics, and chemical odors from conspecifics and a predator—the spotted spiny lobster (Panulirus guttatus)—affect D. antillarum shelter use. The long-spined sea urchin D. antillarum responded strongly to the odor of conspecifics and the lobster predator. Absent the threat of predation, D. antillarum compete for shelter and avoid shelters bearing the scent of other urchins. But, D. antillarum readily shared shelters and preferred the scent of conspecifics when exposed to lobster odors. Thus, efforts to enhance the recovery of D. antillarum populations on degraded reefs must strike a balance between minimizing their mortality from predation and increasing habitat complexity, which not only increases shelter for D. antillarum, but also their predators.

The rock crab Grapsus adscensionis (Osbeck, 1765) is a common intertidal species in the eastern Atlantic. Little is known, however, about the status of its population because of its relatively recent taxonomic separation from Grapsus grapsus. Adult abundance of G. adscensionis was sampled throughout the Canary Islands (24 sites in total) in March and October 2003 and 2004. Abundance varied significantly at intermediate scales (sites spaced by tens of kilometers) but not at larger scales (islands separated by tens to hundreds of kilometers). Habitat complexity (measured as difficulty in walking and terrain variance) was the main source of spatial variability in abundance. In general, G. adscensionis was more abundant in sites of high complexity, mainly in cliffs. Abundance was greater in October (spring/summer) than in March in both sampling years. The frequency of black and red adults varied in time. Red individuals, which were larger than black ones, were very scarce.

The stone crab, Menippe spp. (Say, 1918), fishery is a large fishery in the southeastern United States. One of the primary regulations for this fishery requires that fisherman only harvest crab claws and return the living crab to the ocean. This regulation was put in place in an effort to reduce the overall mortality of harvested organisms and to promote fishery sustainability; however, fishery-related claw loss is likely to influence the population through multiple pathways. How fishery-related claw loss influenced stone crab diet choice, prey size selection, and consumption over time was examined, in addition to how these factors may influence the reproduction of harvested individuals. The consumption of soft-bodied prey, such as polychaete worms, was not influenced by claw loss. In contrast, claw loss has strong negative impacts on the consumption of more common hard-bodied prey, such as bivalves. Specifically, 1-clawed stone crabs consumed bivalves that were approximately 15% smaller after claw removal and consumed, on average, approximately 50% fewer bivalve prey than 2-clawed stone crabs. These decreases in consumption persisted over time. As a result of these dietary changes, stone crabs are likely to experience energetic constraints after claw removal that may limit the growth, reproduction, and survival of harvested stone crabs.

Decapod crustaceans are a valuable seafood product and although their price is typically gauged by their overall size, the quality of the product (organ/muscle mass and moisture content) is also important. The current study investigated the use of the serum protein concentration (determined from the refractive index) as an indicator of the quality and physiological condition of the adult lobster Homarus americanus (Milne-Edwards, 1837). Lobsters were maintained in a variety of feeding regimes and environmental conditions for 6 mo in both the laboratory and in the field. A hand-held refractometer was used to determine serum protein concentrations indirectly. At the end of the experimental period, the lobsters were killed and the hepatopancreas and heart mass, edible meat content, and moisture content of the hepatopancreas and muscle tissue were measured. In each case, there was a significant correlation with serum protein concentration. Serum protein concentration increased linearly with hepatopancreas mass, heart mass, and edible meat content. There was a concomitant decrease in serum protein concentration with increasing moisture content of the hepatopancreas and muscle tissue. Food intake had a significant effect, with higher serum protein concentrations and thus larger organs, in animals that were maintained on a high-feeding frequency regime. The serum protein concentration also changed during the molt cycle, reaching its highest levels during the premolt stage followed by a sharp decrease after the lobsters had molted. The serum protein concentration increased slowly thereafter and, 12 wk after molting, had reached levels that were similar to those measured at the start of the experiment. This rapid and noninvasive method has the potential to be a valuable tool for determining quality and physiological status of commercially important decapod crustaceans.

The freshness of Pacific white shrimp (Litopenaeus vannamei) stored for 0, 2, 4, 6, 8, and 10 days under vacuumpacking at 4°C was assessed by physicochemical, sensory, and microbiological methods. Thiobarbituric acid, total volatile basic nitrogen, pH, total viable counts, and K values increased significantly (P < 0.05) with the storage time, whereas the texture profile indexes decreased significantly (P < 0.05). Furthermore, a proteomic approach of 2-dimensional gel electrophoresis coupled with MALDI-TOF/TOF identification was used to analyze the differentially expressed muscle proteins at the different storage times. All of the 3 identified proteins (arginine kinase, phosphopyruvate hydratase, and actin T², which were involved in muscle energy metabolism, glycolytic pathway in adenosine triphosphate generation, and organization of myofibril, respectively) were downregulated with the increase of storage time. Quantitative reverse transcription—polymerase chain reaction showed that messenger RNA levels of these proteins also decreased during storage time. Downregulation of the identified proteins may contribute to changes of flesh texture and color. This study has important implications for understanding the molecular mechanism of postmortem changes and for developing predictive models suitable for determining the freshness and shelf life of shrimp.

Juvenile white shrimp Litopenaeus vannamei (1.98 ± 0.28 g) were fed a commercial diet for 8 wk in triplicate to investigate growth and lipid metabolism at 3 salinities (3, 17, and 30). Shrimp weight gain and survival at 3 were significantly less than that at 17 and 30. No differences were found in whole-body proximate composition. Linolenic acid (18:3[n-3]) and (n-3) long-chain unsaturated fatty acid levels in the hepatopancreas, and n-3 long-chain polyunsaturated fatty acid level, especially eicosapentaenoic acid (EPA; C20:5[n-3]) and docosahexaenoic acid (DHA; C22:6[n-3]) in muscle at 3 were significantly greater than at other salinities. Fatty acid synthase, hormone sensitive lipase, lipoprotein lipase, adipose triacylglycerol lipase, acyl-CoA, diacylglycerol acyltransferase 2, elongase of very long-chain fatty acid 6, and Δ5 and Δ6 fatty acid desaturase activity was detected and showed a negative trend with an increase of salinity, and no significant differences were found among salinity groups (P > 0.05). The results indicate that the low salinity of 3 decreases the growth of L. vannamei. Although L. vannamei could not synthesize either DHA or EPA de novo, it possibly has the potential ability to convert linolenic acid to DHA and EPA regardless of salinity. However, the factors influencing this ability remain unknown and need further study.

In this study the occurrence of sensory structures on the antennules and antennae of the giant river prawn Macrobrachium rosenbergii (De Man) during postembryonic ontogenetic development were examined. Larvae and postlarvae were obtained from hatchery recirculating tanks, juveniles from indoor nursery tanks, and adults from earthen grow-out ponds. The animals were fixed with Karnovsky fixative and dissected. Antennules and antennae were removed, metal-coated, and photodocumented using a scanning electron microscope. The antennules have aesthetascs and simple plumose and pappose setae; the antennae have simple, plumose and pappose setae. These structures increase in density, covered surface, and distribution during ontogeny and should be related to chemoreception and mechanoreception. The antennular statocyst that appears during larval stage VII of the giant river prawn has an array of sensory structures that enable the perception of chemical and tactile stimuli beginning with its early life stages. The ontogenetic changes observed allow an inference that initial-stage larvae, advance-stage larvae, juveniles, and adults have different capacities to exploit the environment.

Understanding spatial dynamics and creating spatial boundaries of marine food webs is an important topic that resource managers are beginning to understand. Food web structure, mediated by spatial and habitat differences, was examined in a subtropical estuary using stomach content and stable isotope analyses. The goal of this study was to characterize the trophic structure in subtidal oyster reef, intertidal marsh edge, and nonvegetated bottom habitats. Fish and macroinvertebrates were sampled seasonally from July 2006 to April 2007. Spatially, the lower region of the bay supported a more robust food web, with more species and links (72 and 130, respectively) than the upper bay (63 and 87, respectively). Trophic levels (determined by ¹⁵N) and carbon sources (determined by ¹³C) were combined with dietary links (determined by stomach contents), relative population levels, and linkage strength (determined by food volume) to construct 5 dimensional food web diagrams for the 2 regions and 3 habitats studied. The ¹⁵N isotope indicated differences in trophic levels and probable nitrogen sources among regions whereas the ¹³C isotope inferred differences in carbon sources among regions in the Lavaca Bay ecosystem. This evidence suggests that lower Lavaca Bay is providing an environment conducive to robust food webs, and that locations in relatively close proximities within the same estuary can have very different food web interactions. Our data suggest there are significant differences in food web structure at the spatial scales examined in Lavaca Bay, which supports the idea that food webs are compartmentalized. As resource managers move toward ecosystem-based management, they must consider the distinct communities and accompanying food webs associated with the varying habitat types and spatial scales observed in this coastal ecosystem.

Understanding how seafood will be influenced by coming environmental changes such as ocean acidification is a research priority. One major gap in knowledge relates to the fact that many experiments are not considering relevant end points related directly to production (e.g., size, survival) and product quality (e.g., sensory quality) that can have important repercussions for consumers and the seafood market. The aim of this experiment was to compare the survival and sensory quality of the adult northern shrimp (Pandalus borealis) exposed for 3 wk to a temperature at the extreme of its thermal tolerance (11°C) and 2 pH treatments: pH 8.0 (the current average pH at the sampling site) and pH 7.5 (which is out of the current natural variability and relevant to near-future ocean acidification). Results show that decreased pH increased mortality significantly, by 63%. Sensory quality was assessed through semiqualitative scoring by a panel of 30 local connoisseurs. They were asked to rate 4 shrimp (2 from each pH treatment) for 3 parameters: appearance, texture and taste. Decreased pH reduced the score significantly for appearance and taste, but not texture. As a consequence, shrimp maintained in pH8.0 had a 3.4 times increased probability to be scored as the best shrimp on the plate, whereas shrimp from the pH 7.5 treatment had a 2.6 times more chance to be scored as the least desirable shrimp on the plate. These results help to prove the concept that ocean acidification can modulate sensory quality of the northern shrimp P. borealis. More research is now needed to evaluate impacts on other seafood species, socioeconomic consequences, and potential options.