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- Impact of live feed substitution with formulated diets on the development, digestive capacity, biochemical composition, and rearing water quality of European lobster (Homarus gammarus, L.) larvaePublication . Goncalves, Renata; Pfalzgraff, Tilo; Lund, IvarThe obster aquaculture industry, constrained by limited access to viable and cost-effective feed sources, prompted an investigation into the potential of replacing live feeds with formulated diets for Homarus gammarus larval culture, exploring alternative protein ingredients. Four diets were tested on newly-hatched H. gammarus: live Artemia nauplii (ART), an extruded control diet with krill meal and fishmeal as main protein sources (CTRL), and diets with 15% of dietary protein replaced by shrimp waste meal (SWM) or black soldier fly meal (BSF). Results revealed significant diet-induced effects on digestive enzymes in H. gammarus larvae. ART-fed lobsters exhibited increased trypsin and amylase activities but lower lipase activity than those fed extruded diets, suggesting more efficient utilization of protein and carbohydrate in ART-fed larvae, while formulated diets compensated with efficient lipid utilization. BSF and SWM diets increased exo- and endochitinase activities, likely due to chitin presence. Additionally, CTRL and BSF-fed larvae exhibited elevated body glycogen content. ART-fed larvae displayed a significantly higher ratio of low DNA to high DNA bacteria in their rearing water, indicative of lower nutrient loading. Despite these diet-induced impacts, there was no dietary effect on growth and survival during H. gammarus larval development. The study suggests successful formulated feed utilization by homarid larvae, even with alternative ingredients like BSF and SWM, offering a promising solution to reduce reliance on live feeds in lobster aquaculture. Further research is crucial to assess the long-term implications of the observed physiological responses to the different diets in later life stages.
- Shrimp processing waste in aquaculture feed: nutritional value, applications, challenges, and prospectsPublication . Eggink, Kylian Manon; Goncalves, Renata; Skov, Peter VilhelmThe global shrimp processing industry generates substantial amounts of solid waste (head, abdominal exoskeleton, and tail), with a considerable part currently being disposed of in landfills. It holds significant potential as an alternative ingredient in aquaculture feed due to its relatively high crude protein content, balanced amino acid profile, and presence of bioactive compounds. However, one of the main challenges with shrimp processing waste is its rapid spoilage. Consequently, shrimp solid processing waste must undergo further refinement to produce shrimp-derived products suitable as aquaculture feed ingredients, such as meal, hydrolysate, or silage. This literature review describes the nutritional value, applications, challenges, and prospects of these shrimp-derived products in aquaculture feed. Among the investigated shrimp-derived products, shrimp hydrolysate has the highest nutritional value considering the high crude protein content, balanced amino acid profile, low chitin content, and low ash content. However, producing shrimp hydrolysate requires extensive processing, which can be costly, limiting its applications to high-value aquaculture species. On the other hand, shrimp meal and shrimp silage, which require less energy-intensive processing, may be more suitable for lower-value aquaculture species that naturally consume feeds high in ash and chitin. The prospects for using shrimp-derived products in aquafeed are promising, with advances in processing technologies showing potential to reduce costs, improve nutritional value, and enhance product quality and safety. Ultimately, shrimp-derived products could replace current aquafeed ingredients while simultaneously utilizing current shrimp solid waste streams, provided that quality and safety measures are carefully considered.
- Preliminary insight into winter native fish assemblages in guadiana estuary salt marshes coping with environmental variability and non-indigenous fish introductionPublication . Goncalves, Renata; Teodosio, Maria; Cruz, Joana; Ben-Hamadou, Radhouan; Correia, Ana Dulce; Chicharo, LuisThis work aims to undertake a preliminary characterization of winter fish assemblages in the salt marsh areas of Guadiana lower estuary (South-East Portugal) and discusses the potential risks of habitat dominance by a non-indigenous species (NIS). To this effect, six field campaigns were carried out in four sampling sites during winter season targeting the collection of fish species. A total of 48 samples were collected. Individuals from seven different taxa (marine and estuarine) were collected, although the assemblage was dominated by two estuarine species—the native Pomatoschistus sp. (goby) and the NIS Fundulus heteroclitus (mummichog). Goby was the most abundant taxa in the majority of salt marsh habitats, except for one specific, marsh pool, where extreme environmental conditions were registered, namely high temperature and salinity. Such conditions may have boosted the intrusion of mummichog in this area. This species is well adapted to a wide range of abiotic factors enabling them to colonize habitats where no predators inhabit. Impacts of mummichog introduction in the Guadiana salt marsh area are still unpredictable since this is the first time they have been recorded in such high density. Nevertheless, in scenarios of increased anthropogenic pressure and, consequently, habitat degradation, there is a potential risk of mummichog spreading to other habitats and therefore competing for space and food resources with native species.