Introduction
The rapid expansion of invasive species within marine ecosystems poses significant ecological and economic threats, frequently resulting in the displacement of native biodiversity and the destabilization of coastal environments (Mancinelli et al., 2021). However, these ecological challenges also present an opportunity: invasive species may serve as valuable, yet underutilized, biological resources. In aquaculture, their use as alternative protein sources presents a promising, sustainable solution to reduce dependence on conventional feed ingredients and support circular economy.
Along the Italian coastline, several alien species have been identified, with potential for valorization, notably:
This study investigates the potential of incorporating these invasive species into the diet of juvenile seabass (Dicentrarchus labrax), aiming to turn an environmental liability into a sustainable asset for Mediterranean aquaculture.
Materials and Methods
This trial was conducted at the Laboratory of Aquaculture, Department of Veterinary Medical Sciences, University of Bologna (Cesenatico, Italy). Juvenile seabass (Dicentrarchus labrax; initial average weight 5 ± 2 g) were sourced from Panittica Italia and acclimated for two weeks. Fish (n= 100/tank) were randomly stocked into nine 450 L square tanks (three replicates per dietary treatment) and reared for ~30 days. Tanks operated within a closed recirculating aquaculture system (RAS) equipped with mechanical sand filtration, ultraviolet lights, and a biofiltration as described by Parma et al. (2023). Water parameters were maintained at 24 ± 1.0 °C, 25 ± 5.0 g/L salinity and oxygen levels at 8.0 ± 1.0 mg/L using a liquid oxygen system. Fish were fed pelleted isoproteic and isolipidic diets, containing varying levels of Anadara soft tissue meal (AM) and whole blue crab meal (BCM): 0% (control), 5% AM + 5% BCM (diet A), 5% AM + 10% BCM (diet B). Feeding was performed to satiation with a 10% surplus twice daily (8:30 and 16:30) six days per week.
At the beginning and end of the experiment, all fish are anesthetized or euthanized with tricaine methanesulfonate (MS-222). Growth performance and whole-body and dietary proximate analyses parameters are calculated. Gene expression related to digestion (amyl, lip and pept), appetite (pomc a, ghrl, cart), growth (gh, igf1, oxidative stress (sod and cat) and physiological stress (hsp70 and hsp90) are analyzed to evaluate the nutritional and physiological response to the different diets. All experimental procedures were approved by the Ethical Scientific Committee for Animal Experimentation of the University of Bologna (ID 113/2020-PR), following European Directive 2010/63/EU.
Results and Discussion
Preliminary results suggest that the inclusion of blue crab meal and Anadara meal could positively influence the growth performance and feed intake of juvenile seabass. Blue crab meal, with its high protein percentage (> 40%) and abundance of essential fatty acids and minerals (Arena et al., 2024), may promote enhanced growth rates, although its high chitin content from the carapace could pose digestibility challenges if not properly managed. Anadara meal, known to be a fish attractant could increase the ingestion rate, while its high hemoglobin-derived iron content may contribute to improved oxygen transport, enzymatic activity and immune support in fish. Nevertheless, potential risks such as heavy metal accumulation in Anadara tissues highlight the need for careful sourcing and balanced formulation (Solang et al.,2021).
Conclusion
These preliminary findings support the broader concept of utilizing invasive species to reduce dependence on conventional fishmeal, fostering a more sustainable and circular aquaculture system.
References
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Parma, L., Busti, S., Ciulli, S., Volpe, E., Errani, F., Oterhals, Å., Romarheim, O.H., et al. 2023. «Growth, plasma biochemistry and immune-related gene expression of European sea bass (Dicentrarchus labrax) fed bioactive peptides from farmed salmon by-products». Aquaculture 563:738982. https://doi.org/10.1016/j.aquaculture.2022.738982.
Solang, M., Lamondo, D., Utina, R., Kumaji, S., Zuliyanto Z. 2021. «Assessment of Zinc, Iron, and Microbes concentrations in Blood Cockles (Anadara granosa) as Complementary Foods and Implications for reducing of Micronutrition Deficiency». Research Journal of Pharmacy and Technology 14(6):3399-3. doi: 10.52711/0974-360X.2021.0059.1