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Introduction: Bivalve aquaculture has direct and indirect effects on plankton communities, which are highly sensitive to short-term (seasonal, interannual) and long-term climate changes, although how these dynamics alter aquaculture ecosystem interactions is poorly understood. Methods: We investigate seasonal patterns in plankton abundance and community structure spanning several size fractions from 0.2 µm up to 5 mm, in a deep aquaculture embayment in northeast Newfoundland, Canada. Results: Using flow cytometry and FlowCam imaging, we observed a clear seasonal relationship between fraction sizes driven by water column stratification (freshwater input, nutrient availability, light availability, water temperature). Plankton abundance decreased proportionally with increasing size fraction, aligning with size spectra theory. Within the bay, greater mesozooplankton abundance, and a greater relative abundance of copepods, was observed closest to the aquaculture lease. No significant spatial effect was observed for phytoplankton composition. Discussion: While the months of August to October showed statistically similar plankton composition and size distribution slopes (i.e., food chain efficiency) and could be used for interannual variability comparisons of plankton composition, sampling for longer periods could capture long-term phenological shifts in plankton abundance and composition. Conclusions provide guidance on optimal sampling to monitor and assess aquaculture pathways of effects. [ABSTRACT FROM AUTHOR]

ABSTRACT The protozoans Perkinsus marinus, Perkinsus olseni, Bonamia ostreae, Bonamia exitiosa, and Marteilia refringens are responsible for some of the most detrimental diseases in the production of cultivated shellfish worldwide [...]

ABSTRACT In this study, broodstock animals of the tropical scallop Nodipecten nodosus were submitted to maturation trials using two dietary sources of astaxanthin: dried microalgae Haematococcuspluvialis (Algamac AST) and live [...]

The basket cockle ( Clinocardium nuttallii) is a candidate species for aquaculture in the northeast Pacific. The aim of the current research was to assess the feasibility of C. nuttallii grow-out, with an emphasis on growth performance and qualities affecting product marketability. In this article, we investigated the combined effects of culture mode (intertidal and off-bottom suspended culture) and initial stocking density (1500, 3000, 10 500 and 21 000 ind m−2) on C. nuttallii survival and growth during the first year of grow-out ( May through October). In intertidal culture, cockles exhibited low survival and poor growth rates. In suspended culture, survival was consistently high (>96%) at all stocking densities tested; growth and condition parameters had the highest values at 1500 and 3000 ind m−2. The edible portion (meat yield) exceeded 40% of the whole wet weight at all stocking densities, occurrences of fouled and deformed cockles were <1% and no commensal species were observed. Depending on the minimum harvestable size and stocking density chosen, harvestable proportions constituted from 1.1% to 15.2% by October of the first grow-out year in the suspended system. The effects of stocking density and depth on second year grow-out performance of C. nuttallii are reported in a companion paper (Dunham et al. in this issue). [ABSTRACT FROM AUTHOR]

We investigated the effects of culture mode (intertidal and off-bottom suspended culture) and initial stocking density (5%, 10%, 35% and 70% bottom cover) on survival, growth and condition indices of three size cohorts (16, 22 and 32 mm initial shell length) of the basket cockle, Clinocardium nuttallii, during a second year of grow-out. In addition, we evaluated the effects of depth (2, 4 and 6 m) in suspended culture. All size cohorts demonstrated significantly higher growth rates, soft-tissue biomass and condition indices in the off-bottom suspended system compared to the intertidal one. In suspended culture, however, C. nuttallii exhibited sub-optimal survival, shell deformities and heavy fouling. For all size cohorts, stocking density had a significant effect on most growth and condition parameters, except meat yield indices, in both culture modes. An initial maximum stocking density of 10% cover is recommended for all size cohorts. Culture depth did not have a consistent statistically significant effect on any of the growth or condition parameters. Depending on the grow-out scenario, stocking density and harvestable size chosen, the cumulative harvestable proportion after the second year of grow-out constituted 15.5-63.1% of the seed planted. Our results could be used to develop and improve culture techniques for C. nuttallii and other cockle species. [ABSTRACT FROM AUTHOR]

The basket cockle, Clinocardium nuttallii, is a candidate species for aquaculture in British Columbia, Canada. Previous research on broodstock conditioning, embryonic development and larval rearing of C. nuttallii demonstrated the potential for reliable hatchery production of cockle seed. In this paper, we investigated the effects of culture density (50% and 150% bottom cover in a monolayer) and substratum (none and fine sand) on cockle seed survival, growth, behaviour and shell morphology to improve the efficiency of the nursery production phase. Low stocking density (50% cover) yielded a shell length increase from 3 to 7 mm over a 4-week period. High stocking density (150% cover) negatively impacted some of the growth and condition parameters studied, but did not have a statistically significant effect on seed survival. Growing seed without substratum did not significantly affect seed survival or growth, but led to shell deformities (at shell length >15 mm) and lower burrowing rates when cockles were subsequently placed on sand. We recommend planting seed for grow-out at a shell length not exceeding 15 mm. Acclimating seed to the substratum before planting may increase the burrowing rates, thereby reducing the risks of seed dislocation and mortality. Additional studies are required to determine optimal substratum acclimation times and techniques. [ABSTRACT FROM AUTHOR]

Transmissible cancers are clonal lineages of neoplastic cells able to infect multiple hosts, spreading through populations in the environment as an infectious disease. Transmissible cancers have been identified in Tasmanian devils, dogs, and bivalves. Several lineages of bivalve transmissible neoplasias (BTN) have been identified in multiple bivalve species. In 2019 in Puget Sound, Washington, USA, disseminated neoplasia was observed in basket cockles (Clinocardium nuttallii), a species that is important to the culture and diet of the Suquamish Tribe as well as other tribes with traditional access to the species. To test whether disseminated neoplasia in cockles is a previously unknown lineage of BTN, a nuclear locus was amplified from cockles from Agate Pass, Washington, and sequences revealed evidence of transmissible cancer in several individuals. We used a combination of cytology and quantitative PCR to screen collections of cockles from 11 locations in Puget Sound and along the Washington coastline to identify the extent of contagious cancer spread in this species. Two BTN lineages were identified in these cockles, with one of those lineages (CnuBTN1) being the most prevalent and geographically widespread. Within the CnuBTN1 lineage, multiple nuclear loci support the conclusion that all cancer samples form a single clonal lineage. However, the mitochondrial alleles in each cockle with CnuBTN1 are different from each other, suggesting mitochondrial genomes of this cancer have been replaced multiple times during its evolution, through horizontal transmission. The identification and analysis of these BTNs are critical for broodstock selection, management practices, and repopulation of declining cockle populations, which will enable continued cultural connection and dietary use of the cockles by Coast Salish Tribes., (© 2025 John Wiley & Sons Ltd.)

The impacts of oocyte parasites on the reproductive success of molluscs are largely unknown. In this study, we evaluated the presence of gonad parasites in 6 species of marine bivalve molluscs native to southern Brazil. Cultured bivalves included the mangrove oyster Crassostrea gasar (sometimes called C. brasiliana), the brown mussel Perna perna, the lion's paw scallop Nodipecten nodosus and the wing pearl oyster Pteria hirundo. Another species of mangrove oyster, C. rhizophorae, and the carib pointed venus clam Anomalocardia brasiliana (syn. A. flexuosa) were collected from the wild. Molluscs were collected in winter 2009 and summer 2010 for histopathological and molecular evaluation. An unknown ovarian parasite (UOP) was observed in histopathological sections of female gonads of C. gasar and C. rhizophorae. The UOP possessed features suggestive of amoebae, including an irregular outer membrane, frothy cytoplasm, a nucleus with a prominent central nucleolus and a closely associated basophilic parasome. PCR analysis was negative for Marteilioides chungmuensis, Perkinsus spp. and Paramoeba perurans. However, real-time PCR successfully amplified DNA from oyster gonads when using universal Paramoeba spp. primers. Also, conventional PCR amplified DNA using primers specific for Perkinsela amoebae-like organisms (syn. Perkinsiella), which are considered as endosymbionts of Parameoba spp., previously thought to be the parasome. Our results suggest that this UOP is a species of amoeba belonging to 1 of the 2 families of the order Dactylopodida, possibly related to Paramoeba spp. This study represents the first report of this type of organism in oysters. We found that C. gasar and C. rhizophorae were the most susceptible molluscs to these UOPs.