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Bivalve mollusc production has been proposed as a method to reduce carbon emissions as (1) a low-emission protein source, and (2) via carbon stored in their shells. Numerous studies have examined the fate of carbon in bivalve production. estimated carbon sequestration rates, and their role in a carbon economy. To address the fate of shell carbon for the Northwest Atlantic, stored oceanic carbon equivalents (Eq), released C[O.sub.2] via calcification, and hypothetical carbon credit value ($24 tC[O.sub.2]), for both aquacultured and wild-captured bivalves for New England and Canadian Provinces on the Atlantic between 2016 and 2020 were estimated. Bivalve shells do not sequester atmospheric C[O.sub.2], instead storing oceanic C[O.sub.2] Eq and cannot be directly included in a carbon sequestration scheme. In the present study, total annual estimates of stored oceanic C[O.sub.2] Eq were approximately 202.253 and 363,243 tons, with concurrent releases of approximately 121,255 and 217,771 tons of C[O.sub.2] to the atmosphere. of which only 4% and 8% were from aquaculture production in Canada and the United States, respectively. Even if bivalve shells sequestered atmospheric C[O.sub.2], current shellfish production levels are inconsequential with regard to current anthropogenic greenhouse gas (GHG) emissions. Stored oceanic carbon Eq for bivalve aquaculture is equivalent to 0.001% and 0.0005% of Canadian and US annual anthropogenic C[O.sub.2] emissions, whereas wild-capture would store 0.028%. and 0.005% of Canadian and US emission, respectively. Bivalve shell will not solve climate change, but the expansion of bivalve production provides a protein source with the lowest GHG emissions, which provides a multitude of environmental services. KEY WORDS: bivalves, carbon credits, climate change, sustainability, DEFINITIONS AND TERMS Term Definition Aquaculture Harvest of bivalves that have been modified by humans [i.e., spawned and cultured and/or intensively grown (long lines, cages, nets)] Wild-capture Commercial harvest of [...]

The purple hinged rock scallop. Crassadoma gigantea (Gray 1825), is a species of interest for commercial-scale aquaculture in its native range, along the Pacific coast of North America from Baja California. Mexico to southeastern Alaska. One serious, unresolved issue, however, is the lack of information on uptake, retention, and depuration of algal biotoxins in this species. It is known that rock scallops can retain high levels of paralytic shellfish toxins (PST), including saxitoxin and derivatives, within its tissues including the adductor muscle. Paralytic shellfish toxins can pose serious public health risks, including paralytic shellfish poisoning (PSP). which can be lethal in humans. Diarrhetic shellfish toxins (DST) produced by algal species within the genus Dinophysis spp. is another suite of marine biotoxins monitored by public health agencies, known to cause diarrhetic shellfish poisoning (DSP) in humans. This is the first study to investigate dynamics of Dinophysis spp., and DST in the rock scallop. The present study examined uptake, retention, and depuration of two common toxic algal species and associated biotoxins in Puget Sound. WA: Alexandrium calenella (PST) and Dinophysis spp. (DST), through multiyear field exposures and controlled laboratory studies. Assessment of PST in rock scallop tissues by receptor binding assay from field and laboratory studies revealed very high and persistent levels of PST in visceral tissue and also PST in adductor muscle tissue beyond the FDA limit (80ug STX equivalents 100 [g.sup.-1] shellfish tissue) for safe shellfish consumption. An estimate of total depuration time of PST in rock scallop viscera was inconclusive, indicating potentially long depuration times for this species. Toxicity levels varied among individuals of the same cohort, size class, collection time, and location for both visceral and adductor muscle tissues. Laboratory results showed PST levels beyond the FDA limit within adductor muscle tissue during a 6-wk depuration period, indicating a shucked, adductor-only product for this species will require careful testing and management to ensure rock scallops are safe for consumption. More research is needed to decouple the complex interactions of Dinophysis spp., DST. water quality, and rock scallop physiology to inform shellfish managers and public health agencies reliably. KEY WORDS: Crassadoma gigantea, rock scallop, saxitoxin. biotoxin, paralytic shellfish toxins, diarrhetic shellfish toxins, Alexandrium catenella, Dinophysis, depuration, aquaculture, INTRODUCTION The purple hinged rock scallop, Crassadoma gigantea (Gray 1825), has long captured the interest of commercial shellfish farmers in its native range along the Pacific coast of North America [...]

This commentary reviews total aquatic food supply from aquaculture and capture fisheries from 2010 to 2020 at global, regional, and national levels within main producing countries; aquatic animal foods include fish, crustaceans, molluscs, and other invertebrate animals destined for direct human consumption or as fish and seafood by the FAO. Whilst total combined aquatic animal food supply from aquaculture and capture fisheries has increased on a global basis from 18.59 to 20.49 kg/capita over the past decade, the global supply has not kept up with population growth over the same period. Of particular concern was the decrease in fish and seafood food supply within the African region, decreasing from 10.40 to 9.58 kg/capita, whilst population growth increased by 3.12%/year over the same period. Moreover, the Asian region was the only region where per capita fish and seafood food supply exceeded population growth; the bulk of fish and seafood supply being sourced from increased aquaculture production of primarily freshwater fish species, compared with other regions where marine wild fisheries still dominated fish and seafood supply. Fish and seafood supply in leading aquaculture and capture fisheries producing countries between 2010 and 2020, including China, Indonesia, India, Viet Nam, Bangladesh, South Korea, Japan, and USA are presented and demonstrate growth in per capita fish and seafood supply being lower than human population growth in Ecuador, Philippines, Turkey, Chile, Norway, Brazil, Myanmar, the South Korea, and Japan. If aquatic food supplies from aquaculture and inland/marine capture fisheries are to make an increasing global contribution to healthy diets, then the increased production and market availability of these products needs to be promoted by governments and actively encouraged and stimulated, particularly within the African continent. [ABSTRACT FROM AUTHOR]

Suspension-feeding bivalve molluscs have evolved a highly effective mechanism for particle discrimination, which allows them to process efficiently the material to which they are exposed. The mechanisms controlling this preingestive sorting process have been described as either passive or active. Evidence of a passive selection mechanism has been demonstrated in several species of suspension-feeding bivalves. In contrast, to date there has been no evidence that active selection mechanisms underlay particle selection in bivalves, although the possibility of such mechanisms has been hypothesized numerous times. The present study was designed to examine active selection on the gill of the eastern oyster Crassostrea virginica. The gill was chosen for study because in oysters this organ is involved in particle selection. Two in vivo assays were designed in which the gill was exposed to dissolved cell exudate or extracts from the microalga Tetraselmis chuii, and the transport of polystyrene microspheres (25 um) by the frontal cilia of the ordinary filament quantified by means of video endoscopy. Results demonstrated that the addition of exudates or extracts of T. chuii cells had no significant effect on the percentage of particles being transported dorsally (likely ingested) or ventrally (more likely rejected), and no differences in the number of particles in the ventral groove between control and experimental treatments. Results of follow-up experiments using covalently bound neoglycoproteins commonly found on cell surfaces of microalgal species demonstrated differences in transport of captured microspheres (10 um, carboxylated) depending on the sugar type. Although chemoreception cannot be completely ruled out, these findings further indicate that physicochemical properties of particles, and not an active behavioral or physiological response (i.e.. chemoreception of dissolved metabolites) by the animal, mediate particle selection in oysters. KEY WORDS: Crassostrea virginicia, oyster, suspension feeding, metabolites, selection, INTRODUCTION Suspension-feeding bivalve molluscs are some of the most important near-shore organisms, often dominating the macrobenthos and contributing significantly to benthic-pelagic coupling, nutrient cycling, and the structure of benthic food [...]

Molluscan mariculture has become increasingly common in coastal areas of China with production accounting for ∼69% of Chinese total mariculture production. In other international locations, however, a possible underutilization of molluscan mariculture may result from hesitancy based on initial environmental impacts. This study investigated the dynamic relationship between the molluscan mariculture industry (MMI) development and environmental quality (solid waste production, total wastewater emissions, and sulfur dioxide emissions) at the meso level. Their relationship trend followed that described by the environmental Kuznets curve theory in ∼78% of the areas, and ∼89% of the areas were in a coupled coordination state in most periods. This implied that the healthy development of the MMI can reduce environmental stress. These results should help to alleviate the negative perceptions of some researchers and the public regarding mariculture operation. The findings suggest that China, given its substantial contribution to global blue growth, should further support sustainable molluscan production by developing new strategies and policies and reducing potential negative impacts of mariculture on the environment. [ABSTRACT FROM AUTHOR]

Direct measurements of ventilation rates in the marine gastropods Busycon carica, Busycotypus canaliculatus, Sinistrofulgur sinistrum, and Melongena corona were made. Ventilation in B. carica ranged between 3 and 186 mL [min.sup.-1]; the rate in B. canaliculatus was 12-174 mL [min.sup.-1], and 0.6-42 mL [min.sup.-1] in S. sinistrum. There was no consistent relationship between the size of the animals and the ventilation rate. Ventilation rates for any individual were variable, and rates varied among individuals. The rates reported here are relatively low in comparison with those of cephalopods and bivalves, but not surprising as in nearly all gastropods, ventilation is tied only to gas exchange. In cephalopods, ventilation is also involved in locomotion, and in bivalves, a primary role of ventilation is feeding. KEY WORDS: ventilation, gastropods, whelks, INTRODUCTION The respiratory systems found in the phylum Mollusca represent a wide variety of types (see Ponder et al. 2020 for detailed descriptions). Terrestrial eupulmonate gastropods breathe air with a [...]

Abstract Microplastics (MP) are a contaminant of emerging concern and, as such, there has been a rush to action and publication. Over the past two decades, this haste has resulted in a chaotic and cluttered literature rife with inappropriate methodologies, poor experimental protocols, misinterpreted results, overstated significance, and subsequent damaging media stories. This review provides a critical assessment of the current scientific literature on interactions between particle-feeding molluscs and MP and their purported impacts (>750 publications), and recommendations for future efforts. Experimental studies were critically assessed and assigned scores ranging from 0 to 2 as indicators of their veracity. The mean ratio for the 84 papers included in this analysis was 0.9, indicating that most publications contained too many flaws. It is not surprising that MP have been noted in shellfish guts globally. What is surprising is the extremely low level of particles routinely recorded (see Table 1 and references therein). The presence of MP in molluscs has been shown repeatedly, with little regard for quality assurance and control measures. The inconsistencies across studies and lack of proper sampling design have inundated the literature with incomparable studies and inappropriate claims. Common mistakes in field studies from collection through digestion and MP characterization are discussed and identified in 128 studies. Suggestions are made to improve field studies at every stage. The data to date clearly demonstrate extremely low numbers (<10 per individual) of MP in filter-feeding bivalve molluscs globally. There are no data demonstrating presence of MP in these molluscs is a serious risk to human health, and few data to demonstrate negative impacts on the shellfish at environmentally relevant concentrations. Many of the studies on suspension-feeding bivalve molluscs and other invertebrates are weak or fatally flawed. There is a recurring presence in the published literature of misunderstanding of the feeding processes, capabilities for particle selection and rejection, and species-specific differences that all lead to misinformation, misinterpretation, and incorrect assumptions regarding potential impacts. There are major shortcomings to many laboratory studies that examined uptake and accumulation of MP by bivalves and their subsequent effects. The shortcomings have led to a seriously flawed literature on purported interactions and impacts of MP on these animals. If potential investigators do not possess the necessary knowledge and skills to carry out the study, they should engage a collaborator that has the requisite expertise. Bivalves and other particle-feeding molluscs are complex living organisms with extraordinary capabilities for the control of selective capture, ingestion, and egestion of particulate material. They should be recognized and treated as such in any attempt to describe impacts of stressors, including different particle types, on their feeding and ability to accumulate materials. Any future experimental studies need to be focused carefully, based upon clear questions, use standardized analytical procedures, demonstrate a knowledge of the animals being studied, and an understanding of the literature extant. The hype needs to be curtailed and scientists should not imply impacts or potential impacts when there are no data to support the suppositions at environmentally relevant concentrations of MP. The case is further strengthened to stop advocating for the use of bivalve molluscs as reliable indicators of MP in the environment. Recommendations are offered for future efforts including harmonization of methodologies. Finally, a plea is made for editors of scientific journals to make a stronger effort to engage qualified peer-reviewers and stop the flow of poorly done studies and superficial reviews that do nothing more than confuse the literature and reinforce inadequate studies and prior reviews. This review is presented from the viewpoint and consideration of experts in shellfish physiology, and represents the opinions of, and assessments made by, the authors. [ABSTRACT FROM AUTHOR]

ABSTRACT The sea scallop Placopecten magellanicus (Gmelin, 1791) fishery is the most valuable wild scallop fishery in the world. Landings are primarily adductor muscles, which are ideally creamy white and [...]

ABSTRACT In recent years, the scientific publishing world has seen the creation and rapid growth of online journals, which do not respect the long-standing gentleman's agreement that has functioned as [...]

Author(s): Sandra E. Shumway [sup.1] Author Affiliations: (Aff1) 0000 0001 0860 4915, grid.63054.34, Department of Marine Sciences, University of Connecticut, , 1080 Shennecossett Road, 06340, Groton, CT, USA The primary [...]

ABSTRACT Harmful algal blooms cause serious problems to public health and the economic viability of shellfish industries in Alaska. The most common phycotoxins in this region are saxitoxin and its [...]

ABSTRACT Observations are presented to elucidate the complex and highly efficient feeding mechanisms and habits in the common Atlantic slippersnail, Crepidula fornicata. Using a newly designed video system coupled with [...]

A recent publication by Belton et al. raises points for policy-makers and scientists to consider with respect to the future of aquaculture making recommendations on policies and investments in systems and areas of the world where aquaculture can contribute most. Belton et al. take an 'us versus them' approach separating aquaculture by economics, livelihood choices, and water salinity. They conclude "that marine finfish aquaculture in offshore environments will confront economic, biophysical, and technological limitations that hinder its growth and prevent it from contributing significantly to global food and nutrition security." They argue that land-based freshwater aquaculture is a more favorable production strategy than ocean/marine aquaculture; they disagree with government and non-governmental organizations spatial planning efforts that add new aquaculture to existing ocean uses; they advocate for open commons for wild fisheries as opposed to aquaculture; and they oppose 'open ocean' aquaculture and other types of industrial, capital-intensive, 'carnivorous' fish aquaculture. They discredit marine aquaculture rather than explain how all aquaculture sectors are significantly more efficient and sustainable for the future of food than nearly all land-based animal protein alternatives. As an interdisciplinary group of scientists who work in marine aquaculture, we disagree with both the biased analyses and the advocacy presented by Belton et al. Marine aquaculture is growing and is already making a significant contribution to economies and peoples worldwide. None of the concerns Belton et al. raise are new, but their stark statement that farming fish in the sea cannot 'nourish the world' misses the mark, and policy-makers would be wrong to follow their misinformed recommendations. [ABSTRACT FROM AUTHOR]

ABSTRACT Biofouling ascidians represent a serious and costly problem for aquaculture. Although the subject of intensive study for the past decade, little is still known about the timing, intensity, and [...]

To determine the proportion of inviable oocytes that are spawned along with normal oocytes in marine bivalves, we turned to a time‐honored technique not previously used on invertebrate oocytes: the neutral red vital stain. Despite the difficulty in obtaining induced spawns from field‐collected Cerastoderma edule (L), the results and insights from this simple procedure to answer a simple question were unexpected and far‐reaching. Mean proportions of inviable oocytes in the spawns of cockle C. edule ranged from 35% to 85%, with the vast majority represented by atresic (autolyzing) oocytes. These levels are in agreement with previous quantitative histological observations of prespawning atresia in both C. edule and the Manila clam Tapes philippinarum. Such elevated prefertilization inviability mirrors the known high level of postfertilization inviability in bivalves. Together, these high levels of inviability may account for much of the early mortality in the type III survivorship curves typical of marine bivalves. The combination of high fecundity and high oocyte inviability suggests a Red Queen‐type reproductive dilemma in these species. In addition, the great degree of interindividual variation observed in oocyte inviability suggests that cockles, and perhaps other intertidal bivalves, present a Sweepstakes Reproductive Strategy, in which highly variable individual fecundity confronts a highly variable environment. The neutral red technique promises to be a useful tool for investigating prespawning inviability in other marine taxa, as well as for aquaculture, conservation, restocking, ecophysiology, and environmental monitoring. [ABSTRACT FROM AUTHOR]

ABSTRACT Shell closure and restriction of filtration are behavioral responses by which bivalve molluscs can limit exposure of soft tissues to noxious or toxic agents, including harmful microalgae. In this [...]

ABSTRACT We describe a novel sensor based on fiber optic technology for fine scale (~0.1 mm) laboratory measurements of valve gape in bivalve molluscs. We have illustrated the operation of [...]

Robert 'Bob' Guillard was an icon in all senses of the word. Many tributes to him have been and will be written (see Wikfors 1996, Anderson 2011, Sunda 2017). This [...]