The eastern oyster (Crassostrea virginica) is an ecologically and economically important species that provides invaluable services for coastal communities. The oyster industry has a long history and tradition in the U.S. Gulf Coast states, but this fishery has declined dramatically in recent years following Hurricane Katrina, the Deepwater Horizon oil spill, and freshwater flooding events. Mississippi was once known as the “seafood capital of the world,” but no commercial harvest from Mississippi oyster reefs has occurred since the 2018–2019 season. A review of the Mississippi oyster fishery was conducted to characterize historical conditions relative to a sustainable resource in this region, and how the oyster resource has changed over time due to environmental factors and nonbiological events. Since state management of the oyster fishery began in 1902, oyster landings have fluctuated dramatically over time due to complex interactions between man-made and natural disasters, variability in salinity regimes, and alterations in management authority and approaches. Prior to 2010, Mississippi oyster populations eventually recovered from mass mortality events due to improved environmental conditions coupled with large cultch planting efforts. Significant resources have been invested to restore wild oyster populations in the northern Gulf of Mexico, but these efforts have faced many obstacles, and the baseline to assess restoration progress is not well defined. Present-day challenges hindering oyster recovery efforts in Mississippi were also examined to improve understanding of key abiotic and biotic factors that influence oyster reef health and resilience. At present, adult populations are severely diminished and appear to be more recruitment-limited than during previous historical collapses. Climate change-related precipitation events in the past decade have altered water quality in the Mississippi Sound and have further hampered critical early life history recruitment processes, as well as overall reef resilience. Successful restoration and persistence of sustainable oyster reefs in Mississippi under current and future conditions will require substantial investment in management practices that provide suitable substrate for larval settlement, as well as enhancement of existing stock to promote increased larval supply.

Benthic habitat and macrobenthos recovery were measured over an 11-y period beginning in January 2002 following the closure of a green-lipped mussel farm in the Marlborough Sounds, New Zealand. Habitats and abundance of eight invertebrate species were compared under two types of farming structures (production backbones and warps) used to grow mussels and secure the farm to the seabed, adjacent areas unaffected by farming served as the control reference. The mean percent of the seabed covered by mussel shells under backbones declined from 38% to 0% after 11 y whereas deposition of shells beneath warps was low (<4%) and resembled that at reference sites after only 3 y. One month following farm closure, mean species densities beneath warps, where the upper confidence limit of mean percent shell cover was 7%, did not differ from reference sites. By contrast, the mean densities of two macrobenthic species beneath backbones exceeded that at reference sites whereas the densities of three species were less than that at reference sites. The mean densities of the remaining three species did not differ (P > 0.05) between backbones, warps, and reference sites. The mean abundance of invertebrates was significantly and positively (three species) or negatively (three species) related to the percent shell cover on the seabed. Recovery of four epibenthic species was rapid with mean densities beneath backbones similar to reference sites after 1- to 2-y following farm closure. Densities of the fifth species resembled that at reference sites after 10 y whereas the remaining three species did not differ from controls. Multivariate analyses showed that epibenthic invertebrate communities beneath warps were similar to reference sites throughout the entire 11-y study period. Communities beneath the two backbones differed initially from reference sites but were similar to reference sites 6- and 8-y postfarm closure. After establishing the importance of percent shell cover as an indicator of effects on epibenthic species, data from multiple mussel farms in the Marlborough Sounds were analyzed. These analyses showed that the mean percent of mussel shells beneath backbones (x̄ = 29.5%, range = 0%–100%), exceeded that beneath warps (x̄ = 2.3%), and at reference sites (x̄ = 0.08%). Analyses also showed that the mean maximum distance of mussel shell deposition was 13.5 m distance (range = 1.5–26.5 m) away from farms and was positively (P < 0.01) related to the depth of water where farms were located. Based on multiple mussel farms, mean mussel shell cover declined to below a possible impact threshold of 7% by 7.5 m distance for farms in <12 m depth and 18.5 m distance for farms located in deeper water (>20 m depth). Taken together, the effects of mussel farm on epibenthic species abundance as well as overall community structure showed relatively localized impacts, that recovery occurred within 1–10 y following farm removal and that percent shell cover appears to be a useful indicator of effects of mussel farming on the epibenthos.

Chaperonin-containing T-complex polypeptide 1 (CCT) is a molecular chaperone in the cytoplasm of eukaryotic cells involved in the correct folding and assembly of proteins, which plays an important role in cold-stress response. This study cloned two transcripts of Pinctada maxima CCT-beta composed of 1,829 bp (CCT-beta1) and 2,289 bp (CCTbeta2), respectively, using rapid amplification of cDNA ends. Both transcripts possess 105 bp of 5′ noncoding region and the same coding region, but contain different 3′ noncoding regions of 591 bp (CCT-beta1) and 131 bp (CCT-beta2), respectively. The open reading framework (ORF) consisted of 1,593 bp that encodes 530 amino acids. The CCT-beta protein has three conserved functional domains (equatorial, apical, and intermediate domains), three CCT-family signature sequences, nine conserved ATP-binding sites, one DEAD box motif, and three protein-binding sites. The CCT-beta is highly conserved, with the cDNA homologies between P. maxima and Crassostrea gigas, Danio rerio, and Homo sapiens being 90.4%, 76.8%, and 75.8%, respectively. Real-time quantitative PCR showed that CCT-beta was differentially expressed in different organs of P. maxima, with mRNA contents declining from the gill, adductor muscle, foot, labial palps, mantle, and heart to hepatopancreas. Under cold stress, CCT-beta mRNA expression in various organs increased, but the patterns of increase varied among organs. The transcriptional level of CCT-beta peaked at 6 h in the heart and hepatopancreas, and decreased significantly at 12 h. In the adductor muscle, gill, and mantle, CCT-beta mRNA increased significantly at 12 h and declined markedly at 24 h in cold stress-exposed animals. These results indicate that CCT-beta is a cold-stress response gene, but the response pattern varies among organs. Organs with low CCT-beta basal expression may be more sensitive to cold stress than the organs with relatively high basal expression content.

Trends in Atlantic surfclam (Spisula solidissima) population demographic parameters were analyzed using age and length observations obtained from NOAA stock surveys conducted from the 1980s to 2010s in six regions distributed along the Middle Atlantic Bight (MAB) continental shelf. Atlantic surfclam asymptotic length and specific growth rate were estimated for each survey region and decade using the von Bertalanffy growth function. Specific mortality rates were estimated using a linearized negative exponential relationship and the maximum Atlantic surfclam age observed in each survey region for each decade. The estimated Atlantic surfclam mean length in the southern regions of the MAB decreased from 127 to 103 mm, about a 19% decrease, over the four decades. The mean length remained stable at about 130–135 mm in the central survey regions in contrast to the mean length of the Georges Bank Atlantic surfclam population which showed an increase from 101 to 135 mm over the four decades. The asymptotic length estimated for the southernmost survey region declined by 20% and remained relatively constant for the other survey regions over the four decades. Estimated specific growth rates remained unchanged for most of the survey regions, with the overall regional mean decreasing from about 0.25 y^–1 in the 1980s to 0.20 y^–1 by the 2010s. Specific mortality rates were not significantly different across the survey regions, although the maximum age estimated for the population in the southern survey region decreased by about 36%. This study provides a quantitative assessment of past and ongoing changes in MAB Atlantic surfclam population demographics that can be used to develop projections of responses to stresses imposed by climate change and commercial fishing.

Pacific razor clam shell growth was examined using data provided by the Alaska Department of Fish and Game containing 235,606 length-at-age records based on visible annuli on the shell from 57,534 individual clams measured from 1966 to 2021 at nine locations in Cook Inlet, AK. Shell growth was modeled via the von Bertalanffy Growth Function treating each individual clam as a random effect. Asymptotic mean length at time infinity (L_∞) varied considerably between sites, from 121.35 to 186.58 mm, as did the growth coefficient k which ranged from 0.28 to 0.54 y^–1. When both L_∞ and k were examined collectively via a growth performance index (∅′), all Cook Inlet sites were similar (∅′ range: 3.80–4.02). The growth performance of Pacific razor clams in Cook Inlet was also compared with summary statistics from previously published mean length-at-age estimates for Pacific razor clams across their distribution. Growth performance estimates from Alaska and British Columbia sites were largely similar, whereas sites in Washington, Oregon, and California were generally characterized by faster growth and smaller maximal lengths. Although this study did not attempt to quantitatively identify predictors of variation in growth parameters and performance within and outside of Cook Inlet, AK, this manuscript concludes with speculations on possible correlates to growth and recommendations for future work.

A new invasive snapping shrimp from the Alpheus lobidens De Haan, 1849 species complex has become one of the most frequently observed crustaceans in certain saltmarshes along the southwestern Spanish coast. The first place in Europe where this invasion has occurred is reported in this study; however, little is known about this species, even within its undetermined native range. Here, the population structure, density, sex ratio, sexual dimorphism, reproductive period, and relative growth of this nonnative shrimp are reported for an intertidal saltmarsh in SW Spain based on monthly data collection over a year. Ovigerous females were collected during all months of the year. This population trait is not found in any native crustacean in the temperate zone of Europe. The sex ratio showed a similar proportion of male and female individuals, 0.88:1 (F:M), throughout the year. Sexual dimorphism was evident in the growth characteristics of body structures and implications are discussed. These results highlight the successful establishment of this shrimp in the Mediterranean climate area of Spain and have implications on marine fauna conservation and management. These findings also provide a basis for future comparative research in the shrimp native regions and enhance understanding of the species population dynamics.

The structure and composition of mantle tissue from red abalone Haliotis rufescens were studied in relation to pearl farming. Histological (hematoxylin-eosin) and histochemical (PAS Alcian Blue, Sudan Black, Dahl's) tools were used to determine variations in the glycogen index, lipid index, and calcium coverage index of mantle tissue as a function of seasonality (cold and warm period) and body region (dorsal, central, ventral). Anatomically, only two well-developed and functional mantle folds (inner and outer) were observed across the marginal zone, together with a poorly developed, and presumably, rudimentary fold with the same cellular morphology as the inner fold. The inner mantle epithelium stored significantly higher concentrations of glycogen and mucins, triglycerides, and calcium than the outer epithelium. This pattern occurred significantly more during the cold season than during the warm season. Mucins from mantle tissue not only regulate crystal nucleation and orientation during biomineralization, but also give the inner nacreous layer its luster and color. High concentrations of lipids in mantle tissue could help compensate for the energy loss caused by the wound-healing processes associated with mantle tissue removal and seeding, which are stressful and energetically costly. The absorption of calcium ions from the environment to integrate a microlaminate of calcareous compounds gives the shell its structural properties of hardness and strength. An approach with molecular-ultrastructural tools is recommended to broaden the understanding of mantle tissue regionalization and its relationship to pearl sac formation, which may help increase pearl yield and quality in H. rufescens.

The supply of macroalgal feed materials for abalone aquaculture is threatened by increasing costs, limited availability, and the allocation of seaweed resources for other purposes. The use of biofouling Sargassum horneri (SH) as additional macroalgal biomass for abalone has been studied, albeit full inclusion is discouraged due to low utilization. This study applied heat treatment and fermentation to increase the nutritive value of SH meals for the aquaculture feed industry. Untreated (UN) as control, heat treated (HT, 121°C for 20 min), and fermented (FE, 10⁷ CFU/mL each of Bacillus sp. SJ-10 and Bacillus sp. KRF-7) SH meal was fed to the abalone (11.60 ± 0.02 g body weight and 42.98 ± 0.53 mm shell length) for 8-wk growth trial. The results showed that there is no apparent difference in the growth performance (body weight and shell length morphometrics) and survival of abalone given experimental diets (P > 0.05). The crude protein, lipid, and ash composition of edible abalone flesh were similarly unaffected (P > 0.05). The gut microbiota profile of abalone was analyzed through next-generation sequencing. The α-diversity indicators (microbial richness and abundance) were statistically similar (P > 0.05), and the β-diversity of operational taxonomic units revealed short distances within samples and clustering among diet groups. The core phyla (Fusobacteria, Proteobacteria, Tenericutes) and genera (Psychrilyobacter, Vibrio, Mycoplasma) known to inhabit the gut of abalone predominantly were likewise identified irrespective of diets; however, there is a difference in their relative abundance. Genus Psychrilyobacter was relatively abundant in UN and FE compared with HT, whereas Vibrio and Mycoplasma had higher abundance in FE and HT-fed abalone, respectively. Taste sensory attributes were discriminated in the abalone meat using an electronic tongue. Principal component analysis of sensor scores revealed several overlapping points, resulting in a negative discrimination index (–184), which means no apparent difference in the general taste profile was detected. Furthermore, the taste screening matrix through radar mapping revealed slight intensity differences in the umami, saltiness, and sourness flavor. Overall, the methods used for heat treatment and fermentation procedures herein were ineffective in improving the nutritive value of seaweed meal for abalone.

Tetramine [tetramethylammonium ion, (CH₃)₄N⁺] is a toxic substance found in marine predatory gastropods causing food poisoning when consumed. Despite a considerably high consumption of carnivorous marine gastropods in Korea, studies in tetramine are limited in Korea. This study analyzed tetramine content in eight carnivorous and four herbivorous marine gastropod species obtained from the east coast of Korea using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Method validation showed good linearity (r² over 0.999) with a wide linear range (0.1–50 mg/kg), low method detection limit (0.008–0.011 mg/kg), and low method quantitation limit (0.025–0.033 mg/kg) in low-fat/high-fat matrices. The intraday (n = 5) and interday (3 days, n = 15) accuracy and precision results met the CODEX guidelines. The salivary glands of Neptunea showed higher tetramine levels than the other species, and the average tetramine content of the salivary glands was higher in the order of Neptunea cumingii (7,610 mg/kg), Neptunea arthritica (4,950 mg/kg), and Neptunea eulimata (2,710 mg/kg). Tetramine content was higher in the salivary gland (up to 16,700 mg/kg) than in other tissues. Tetramine was detected only in the predatory species in the genus Neptunea, not in herbivorous gastropod species. To prevent tetramine food poisoning, the salivary glands of the predatory gastropods should be removed when they are cooked and served.

The global demand for crabs, coupled with increasing threats to natural populations, creates the need to investigate captive breeding programs. To achieve this, it is crucial to acquire a comprehensive understanding of key aspects of their life cycle. This study represents the early comprehensive characterization of the red mangrove crab, Ucides occidentalis. Furthermore, leveraging epifluorescent microscopy, we examined the effect of six distinct microalgae diets on the progression of larval stages and their subsequent survival. Embryonic development in U. occidentalis unfolded over a period of 14 days, systematically detailed across eight distinct phases, each marked by the progressive emergence of the embryo and its associated appendages. Notably, an increase in the heart rate was registered just prior to spawning. Following spawning, a brief period of 10–15 min elapsed before the embryos successfully ruptured the chorion. Larval development underwent segmentation into five zoeal stages (zI–zV), spanning a 15-day duration, with an equivalent temporal period encompassing the megalopal stage until the attainment of the first juvenile crablet. Each transition between stages was heralded by a molting event. Despite our observations confirming the ingestion and digestion of the assessed microalgae, it became evident that diet supplementation with rotifers and brine shrimp is essential to optimize molting periods and, consequently, enhance survival rates. Specifically, diatoms Chaetoceros gracilis and Chaetoceros muelleri were ingested and digested up to the zoea V stage. In contrast, the microalgae Tetraselmis maculata and Rhodomonas salina, while undergoing ingestion and digestion, were only able to sustain larvae until the zoea III stage. The outcomes of our research affirm the viability of U. occidentalis crablet production within a laboratory setting, thereby offering the potential inclusion of this species as a valuable aquaculture product. This endeavor holds the promise of contributing to the conservation and enhancement of wild U. occidentalis populations.

The northern quahog, Mercenaria mercenaria (= hard clam) is an important aquaculture species on the U.S. east coast and shares a partially sympatric distribution with a sister species Mercenaria campechiensis which is endemic to the mid-Atlantic coast from the Chesapeake Bay to Florida and the Gulf of Mexico. These two species are morphologically similar, and their identification is laborious and challenging. To support aquaculture breeding and restoration activities, it is essential to develop an accurate and easy method to identify the two Mercenaria species. In the present study, high-melting resolution analysis was applied to identify these two Mercenaria species and their hybrids using three genes of cytochrome oxidase subunit 1 (CO1), mitochondrial large ribosomal subunit (16S rRNA), and internal transcribed spacer 1 (ITS1). The temperature melting points (T_m) of CO1, 16S rRNA, and ITS1 were significantly different between the two Mercenaria species and could be used to distinguish M. mercenaria and M. campechiensis. By use of the melting T_m of CO1, 16S rRNA, and ITS1, a discriminant function equation was established to effectively eliminate the impacts of intraspecific sequence variations on species identification. Compared with their true species classification, the accuracy of the predicted classification of each sample was 100% based on the discriminant function equation. Furthermore, a linear discriminant analysis model was used for cross-validation and the mean classification success was 100% with no observed erroneous classification. Moreover, the interspecific hybrids of M. mercenaria and M. campechiensis were verified by the melting curve of nuclear DNA marker ITS1, and their maternity was further clarified by mitochondrial DNA markers CO1 and 16S rRNA. The methodology developed in this study would be useful as a rapid and accurate tool to support Mercenaria aquaculture, breeding, and restoration.

The natural mortality rate (M) is a crucial population parameter, particularly for managing exploited stocks. Empirical methods developed to estimate M generally depend on individual growth and habitat temperature. The gnomonic-stage method, in contrast, allows estimates of M for all life-history stages considered of a species; the challenge is how to derive a single M value for use in further fisheries analyses. In this study, a single M value was derived using the gnomonic method for the blue lobster (Panulirus inflatus) fished off the southern Gulf of California. The estimated M value relied on existing biological data for the exploited phase of the species for which there is only scarce information. Because in the gnomonic method, M relates to fecundity, a sensitivity analysis of yield-per-recruit to different fecundity values was performed. The results have practical implications for ecology and stock assessment of the blue spiny lobster and other fished resources.