12 pages, 3 tables, 3 figures, Global production of shell calcium carbonate (CaCO3) from bivalve aquaculture amounts about 13.6 million metric tons per year. Shells, traditionally considered a waste of aquaculture activities, have recently acquired an interest under the current framework of zero waste circular economy. Shell CaCO3 is a sustainable biomaterial that could partly replace the presently dominating non-renewable mineral sources in some applications. Although the carbon footprint of powdered CaCO3 production from biological or mineral sources are about the same, the environmental impact is notably different. Furthermore, bivalve CaCO3 contributes to sequester anthropogenic carbon dioxide (CO2) during shell formation, although this is still controversial. Anyway, the integration of bivalve aquaculture in the carbon trading market would demand that shell CaCO3 is employed in activities that sequester their CO2 for prolonged time periods. Ideally, these activities should combine 1) providing the maximum added value to the biomaterial; 2) producing the lowest carbon footprint during their life cycle; and 3) preserving the CaCO3 integrity as long as possible. In this review, we analyse the effect of bivalve consume habits, particularly mussel, on the availability of shells and their possible agricultural, industrial, and environmental engineering applications from these multiple perspectives. Furthermore, global, continental and regional demands of CaCO3 are matched with their respective mussel aquaculture productions in an effort to scale up offer and demand, This work has been funded by the EU H2020 Research and Innovation Programme AquaVitae project (Grant Agreement No 818173), Peer reviewed

17 pages, 9 figures, 2 tables.-- Under a Creative Commons license, Interest on the potential CO2 sequestration of marine bivalve aquaculture has increased during the last decade. However, there is still some controversy about which biological processes are involved and how to estimate their contribution to the carbon footprint of bivalve aquaculture. This work considers the dissolved inorganic carbon, CO2 and alkalinity fluxes linked to flesh and shell growth, calcification, respiration, faeces egestion, and ammonia excretion, accounting also for the RDOC production associated to these processes. We have developed an algorithm for a dynamic estimation of these fluxes based on a net production DEB growth model for mussels. The resulting model has been implemented in Python to create a toolbox with a graphical user interface. This toolbox allows the selection of different culture strategies, in terms of seeding date, seed size and culture length, and consequently analyzes the carbon footprint and impact on the carbonate chemistry of seawater of aquaculture management, This study has been funded by EU H2020 project Aquavitae (EU 818173). MP also acknowledges support from grant FJC2019–041397-I funded by MCIN/AEI/ 10.13039/501100011033, Peer reviewed

13 pages, 3 figures, 4 tables, The aquaculture industry must continue to reduce its reliance on finite marine ingredients and promote biocircularity to enhance sustainability. This study evaluated the effects of no-fishmeal (FM) diets and fish protein hydrolysates (FPHs) on the growth performance, antioxidant status, and immune responses of gilthead seabream (Sparus aurata). Following established conditions, two FPHs were prepared from the enzymatic hydrolysis of discards from whole-body blue whiting (Micromesistius poutassou) and gurnard heads (Trigla spp.); the former contained a higher proportion of large peptides (LPs), while the latter had more small peptides (SPs). Four isoproteic (48%) and isolipic (16%) diets were tested: a commercial (COM)-like diet with 35% FM, 10% poultry meal, and 5% soy protein concentrate; a FUTURE (FUT) diet, without FM or soy protein concentrate, containing 25% poultry meal; and two FUT diets supplemented with FPH (FUTLP and FUTSP). Gilthead seabream (initial weight ± 8.0 g) was distributed into 500 L tanks at an initial density of 1.4 kg m−3 and fed the experimental diets to apparent satiety for 8 weeks. Sampling was performed at the end of the growth trial, followed by a digestibility trial. Nutrient and energy digestibilities were significantly lower in the FUT than in the COM diet, with protein and energy digestibilities being 7% and 16% lower, respectively, in the FUT treatment, leading to higher nitrogen losses. Growth performance and feed utilization were negatively impacted in the FUT treatment, with weight gain of only 310 ± 33% compared to 482 ± 22% in the COM treatment. Additionally, immune responses in plasma and antioxidant status in the liver were slightly impaired in the FUT treatment. Supplementation of FPH to the FUT diet mitigated or even reversed these negative effects. The results confirmed that including small- and medium-sized peptides in no-FM diets is more beneficial than using larger ones, This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement no. 818173), the Xunta de Galicia (Grupos con Potencial de Crecemento [IN607B 2021/11]), and Portuguese national funds from Fundação para a Ciência e Tecnologia (projects [UIDB/04326/2020], [UIDP/04326/2020], [LA/P/0101/2020], and contract [DL57/2016/CP1361/CT0033]), Peer reviewed

13 pages, 6 figures, 4 tables, Transparent and precise information on the environmental impacts of products is critical for informed decision-making. In the EU, gilthead seabream (Sparus aurata) is among the most profitable aquaculture species. The environmental impacts of aquaculture vary depending on input factors. Despite the importance of hatcheries and nurseries in aquaculture, there are currently several knowledge gaps related to footprints, particularly outside of salmonid life cycle assessments.
This study analysed the environmental footprint of a case study on rearing juvenile gilthead seabreams, and the implications of utilising byproducts from blue mussel (Mytilus galloprovincialis) aquaculture as a fish feed ingredient following the LCA principles in the Product Environmental Footprint (PEF). Data were collected from a research facility where fish juveniles were fed diets with fishmeal partially or fully substituted with blue mussel meal at 100%, 50%, or 0% in a triplicate study design. The results showed that the use of electricity and the feed were the largest contributors to most impact categories. Electricity use was primarily driven by the indoor flow-through facility's high-water renewal and lighting requirements. The sensitivity analyses showed a high uncertainty related to the impacts from the blue mussel meal.
The total environmental footprint of juveniles was significantly higher when compared to fully grown finfish from aquaculture per functional unit, mirroring the higher input requirements during early life stages. Blue mussel meal shows to be similar to fishmeal from a palatability and growth perspective, however, its use may increase environmental impacts. Nevertheless, as the aquaculture industry continues to expand to meet global food demands, utilising a current waste stream might be among few feasible options to cover nutrient demands of marine fish, This research was funded by UiT—The Arctic University of Norway, project SECURE (Norwegian research information repository project ID 2061344), by the European Union's Horizon 2020 Research and Innovation Programme project AquaVitae (grant agreement number 818173), the Portuguese national funds from Fundação para a Ciência e Tecnologia (projects [UIDB/04326/2020], [UIDP/04326/2020], [LA/P/0101/2020]), and the Xunta de Galicia (Grupos con Potencial de Crecemento [IN607B 2021/11]), Peer reviewed

Aim of study: To evaluate the effects of different fish feeding rates on the growth performance, water quality, and water microbiology in the integrated culture of lebranche mullet (Mugil liza) and whiteleg shrimp (Penaeus vannamei) using biofloc technology.
Area of study: Southern Brazil.
Material and methods: A 46-day experiment was performed to assess four feeding rates (0%, 1%, 2%, and 3% of mullet biomass) with four replicates per treatment. Shrimp were fed according to a feeding table. Eight-hundred L tanks were used for shrimp culture, while 90 L tanks were utilized for mullet culture, employing recirculation between the tanks through a submerged pump (Sarlo-Better 650 L hour-1).
Main results: Water quality variables and water microbiology, evaluated through bacterial counts, were unaffected by the fish feeding rates (p>0.05). Regarding growth performance, while shrimp were unaffected (p>0.05), mullet final mean weight, biomass, daily growth coefficient, and yield significantly increased with higher fish feeding rates (p<0.05). Mullet feed conversion ratio and survival were not influenced by the feeding management (p>0.05). Furthermore, linear regression models for the overall system productivity showed a positive correlation with the fish feeding rate. As the fish feeding rate increased, the yield of the integrated culture system also increased (p<0.05).
Research highlights: These findings emphasize the importance of considering appropriate feeding rates to maximize the productivity and overall performance of integrated aquaculture systems using biofloc technology.