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- Anthropogenic particles ingestion by fish larvae in important nursery areas of Iberia (South Europe)Publication . Zeri, Giulia; Baptista, Vânia; Teodosio, Maria; Cruz, JoanaMicroplastics (MPs) are now widespread in the marine environment, and their levels are expected to rise as larger plastic debris continues to break down and new plastic waste enters the ocean. Microplastics ingestion has been documented in fish larvae, which are already particularly vulnerable to predation, environmental stressors, and starvation. This study examines for the first time MPs ingestion by wild fish larvae in Southern Iberia, focusing on two key nursery ecosystems of Portugal: the Ria Formosa coastal lagoon and the Guadiana River estuary. Fish larvae collected monthly from surface water, between April 2023 and March 2024, exhibited encounter rates (ER - Total number of ingested particles/ Total number of organisms analysed *100) of 12.99% in Ria Formosa and 11.54% in the Guadiana estuary. No significant differences were observed in ER among taxa and locations. The ingested particles ranged in size from 20 μm to 2 mm and were predominantly made of rayon, transparent and in the form of fibres. No correlation was found between the size of the larvae and that of the ingested particles. Although larval size had a positive effect on MP ingestion, this effect was not significant. There were no differences in polymer type ingestion among taxa. Our results underline the role of nursery areas as exposure spots and the underestimated pressure of the textile industry on marine ecosystems. Further research is needed to assess the potential consequences of this exposure for larval survival, recruitment success, and the health of adult fish populations.
- Blackfordia virginica in non-native distribution range: a potential food source for humans?Publication . Cruz, Mariana; Dias, Ester; Custódio, Luísa; Encarnação, João Pedro da Silva; Cruz, Joana; Baptista, Vânia; Teodosio, MariaThe seasonal occurrence of the Black Sea jellyfish Blackfordia virginica Mayer, 1910 blooms is a reason of concern in the Guadiana estuary in the South of Portugal (South-West Europe), causing considerable economic and ecological impacts to fisheries. Due to jellyfish biochemical properties, they may represent an opportunity as an alternative food source for humans. In this context, this work evaluated the nutritional profile of B. virginica (proximate composition, amino acids, minerals, and fatty acids methyl ester content). Blackfordia virginica biomass may be adequate for human consumption, as it has nutritional properties resembling other edible jellyfish species, with relevant levels of minerals, moderate content in crude protein, low-fat content, and a low energetic value. The high Cd levels in the biomass of B. virginica from the Guadiana Estuary may compromise its safety as a food source. Moreover, if these jellyfishes are proven as an edible invasive species, their management through fisheries should evaluate the cost effectiveness of investments.
- A comparison of olfactory sensitivity in seawater- and freshwater-adapted bass, dicentrarchus iabraxPublication . Velez, Zélia; Hubbard, Peter; Guerreiro, Pedro MiguelFish rely heavily on olfaction for many aspects of their lives including foraging, defense, migration, and reproduction. Olfactory receptor neurons in the olfactory epithelium are in direct contact with the water, and are, therefore, exposed to changes in water chemistry. The European seabass, Dicentrarchus labrax, uses estuaries as feeding grounds and migrates between seawater and brackish water; but some can be found in 100% freshwater. However, little is known about how the olfactory system adjusts to waters of such different ionic composition and whether this affects its function and ability to discriminate between odorants. The aim of this study was, therefore, to compare olfactory sensitivity in seabass adapted to either seawater (SW) or freshwater (5 ppt; FW), to odorants conveyed at different salinities, using multi-unit recording from the olfactory nerve. In SW-adapted fish, olfactory sensitivity to amino acids (AA) was consistently higher when AA were presented in seawater (SW-AA) than when presented in freshwater (FW-AA), whereas in FW-adapted fish, olfactory sensitivity to FW-AA was either equal or slightly lower to SW-AA. SW-adapted fish responded to decreases in external [Ca2+] and to increases in external [Na+ ]. FWadapted fish responded to increases of both ions. In SW-adapted fish, Ca2+-free artificial seawater (ASW) completely inhibited olfactory responses to amino acids, whereas Na+ -free ASW had no effect. However, in FW-adapted fish, lack of either ion in the water had no effect. Taken together, these results suggest that, as a primarily marine species, the olfactory system of the seabass is more sensitive in seawater; however, it can still function in freshwater, albeit with reduced sensitivity. Furthermore, in seawater, the olfactory transduction process is likely mediated by influx of external Ca2+, but not Na+ . In FW-adapted fish, the transduction process relies on neither external Ca2+ nor Na+ , suggesting that the process of hyperosmoregulatory ability to adjust to life in ion-poor water. Further work is needed to clarify how changes in salinity affect olfactory sensitivity, and the mechanisms by which euryhaline species are able to adapt to such changes when moving between media of different ionic composition and variable pH.
- Evaluating repetitive mucus extraction effects on mucus biomarkers, mucus cells and skin-barrier status in a marine fish modelPublication . Sanahuja, Ignasi; Guerreiro, Pedro Miguel; Girons, Albert; Fernández-Alacid, Laura; Ibarz, AntoniAmong all the mucosal barriers, the skin and its surrounding mucus are possibly the main defensive tools used by fish against the environment. Due to its less-invasive extraction, the study of its production and functions has gained high interest in the last years. However, there are still many gaps in research, such as the possible alteration of mucus composition or the skin integrity resulting from the sampling process. In the current study, skin mucus extraction impacts were determined by comparing the effects of one-single extraction (SEG; single extraction group) and three successive extractions (REG; repetitive extractions group, separated by 4 days) on mucus properties and on skin epithelial integrity. In terms of analytical evaluation, plasma biomarkers and plasma antibacterial capacity were also determined. With regard skin histology and skin barrier properties, both SEG and REG did not evidence differences with respect to intact skin (ØEG). Interestingly, the repetitive mucus extraction protocol seemed to activate skin mucus turnover, significantly increasing the number of low-size mucus cells (cell area < 100 µm2 ) and reducing the number of high-size mucus cells (cell area > 150 µm2 ). Repetitive extraction of skin mucus diminished the amounts of soluble protein and glucose in mucus with regard to one-single extraction and increased cortisol exudation. These metabolites remained unaltered in plasma, indicating the different response among both sampling targets. Despite mucus biomarkers modification, the antibacterial capacity against the pathogenic bacterial (P. anguilliseptica and V. anguillarum) was maintained in both plasma and mucus irrespective of the number of mucus extractions. Overall, the mucus sampling protocol scarcely affected skin integrity and mucus antibacterial properties and only modified metabolites exudation, evidencing a feasible and minimally invasive method for studying fish health and welfare as an alternative or as a complement to plasma. The knolwdege provided here highlighted that this methodology is putatively transferable to farm culture conditions and showed that it is very useful for the study of threatened species aimed at preserving fish welfare.
- Evaluation of fatty acids profile as a useful tool towards valorization of by-products of agri-food industryPublication . Ferreira, Rui; Lourenço, Sílvia; D. Lopes, André; Andrade, Carlos; Câmara, José S.; Castilho, Paula; Perestrelo, RosaWorldwide, the food industry generates a large number of by-products from a wide variety of sources. These by-products represent an interesting and economical source of added value components with potential functionalities and/or bioactivities, which might be explored for industrial purposes, encouraging and promoting the circular economy concept. In this context, the current work aimed to evaluate the fatty acids (FAs) profile using gas chromatography–flame ionization detector (GC–FID) and Fourier Transform Infrared (FTIR), as well as the determination of related health lipid indices (e.g., atherogenic (AI) and thrombogenic (TI)) as a powerful strategy to investigate the potential applications of different agri-food by-products for human nutrition and animal feeding. This work results showed that polyunsaturated fatty acids (PUFAs) are the predominant group in grape pomace (72.7%), grape bunches (54.3%), and brewer’s spent grain (BSG, 59.0%), whereas carrot peels are dominated by monounsaturated fatty acids (MUFAs, 47.3%), and grape stems (46.2%), lees (from 50.8 to 74.1%), and potato peels (77.2%) by saturated fatty acids (SFAs). These findings represent a scientific basis for exploring the nutritional properties of agri-food by-products. Special attention should be given to grape pomace, grape bunches, and BSG since they have a high content of PUFAs (from 54.3 to 72.7%) and lower AI (from 0.11 to 0.38) and TI (from 0.30 to 0.56) indexes, suggesting their potential to provide a variety of health benefits against cardiovascular diseases including well-established hypotriglyceridemia and anti-inflammatory effects, products to which they are added.
- First assessment of the thryssa vitrirostris (Engraulidae) beach seine fishery in northeastern mozambiquePublication . Manuessa, Bonifácio; Morais, Eurico; Borges, Teresa Cerveira; Teodosio, Maria; Leitão, FranciscoMonthly length-frequency data, from 2009 to 2014, was used to estimate the growth parameters, mortality, and spawning season, and to assess the exploitation status of Thryssa vitrirostris (Engraulidae) fisheries in Pebane. The von Bertalanffy asymptotic length (L∞) and growth rate (K) were 25.1 cm (standard length) and 0.41 per year (standard length), respectively. Two proxy recruitment peaks were found: the first peak of recruitment occurs from April to July, and the second recruitment peak from September to October. The total estimated mortality rates (Z), natural mortality (M), and fishing mortality (F) were Z = 1.31, M = 0.92, and F = 0.39. For the beach seine gear, the size at first catch of T. vitrirostris was Lc25 = 4.43 cm. The 50% retention size of the catch was Lc50 = 5.39 cm. The retention probability analyses revealed a large rate of juvenile fishing mortality (54.2%). The estimated exploitation rate (0.30) was below the maximum exploitation rate (0.48), and above the optimal sustainable exploitation rate (E50 = 0.28), evidencing a sustainable fishery. However, under such an exploitation regime, it is advised that a continuously monitoring-survey of T. vitrirostris is maintained. An increase in migration of fishermen has been recently recorded in Pebane, due to its rich fisheries, which can increase the fishing effort and the risk of overexploitation if management measures (such as mesh size increase) are not taken in advance.
- Lab-scale optimization of aurantiochytrium sp. culture medium for improved growth and DHA productionPublication . Trovão, Mafalda; Pereira, Hugo; Costa, Margarida; Machado, Adriana; Barros, Ana; Soares, Maria; Carvalho, Bernardo; Silva, Joana Teles; Varela, João; Silva, JoanaThraustochytrids have gained increasing relevance over the last decades, due to their fast growth and outstanding capacity to accumulate polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA). In this context, the present work aimed to optimize the growth performance and DHA yields by improving the culture medium of Aurantiochytrium sp. AF0043. Accordingly, two distinct culture media were optimized: (i) an inorganic optimized medium (IOM), containing only monosodium glutamate and glucose as nitrogen and carbon sources, respectively; and (ii) an organic and sustainable waste-based optimized medium (WOM), containing corn steep powder and glycerol, added in fed-batch mode, as nitrogen and carbon sources, respectively. Overall, the lab-scale optimization allowed to increase the biomass yield 1.5-fold and enhance DHA content 1.7-fold using IOM. Moreover, WOM enabled a 2-fold increase in biomass yield and a significant improvement in lipid contents, from 22.78% to 31.14%. However, DHA content was enhanced almost 3-fold, from an initial content of 10.12% to 29.66% of total fatty acids contained in the biomass. Therefore, these results strongly suggest, not only that the production pipeline was significantly improved but also confirmed the potential use of Aurantiochytrium sp. AF0043 as a source of DHA.
- No significant projected climate change effects on the geographic ranges of marine aquaculture species under the sustainable scenario (SSP 1-1.9, 1.5°C warming)Publication . Mackintosh, Amy Leigh; Hill, Griffin Goldstein; Costello, Mark John; Assis, JorgeAquaculture is increasingly relied upon for global seafood production, projected to be the leading supplier by 2030. Climate change impacts on species health and industry productivity are already evident, creating uncertainties around long-term aquaculture development. While these impacts have been projected for some species, around 62% of aquaculture production remains unassessed. We utilized climate dissimilarity to assess the exposure of 327 species—including those previously unassessed—in their native ranges to changing climates under three climate scenarios: SSP1-1.9, SSP3-7.0, and SSP5-8.5. We projected that under a sustainability scenario (SSP1-1.9), 41% of Exclusive Economic Zones (EEZ) remained unexposed, including high-value aquaculture regions. However, under increased emissions scenarios (SSP3-7.0 and SSP5-8.5) all current aquaculture EEZ are projected to be exposed. Semi-enclosed seas, like the Baltic, Black, and Red Seas, experience the largest dissimilarity, alongside equatorial regions. Our findings suggest widespread mitigation efforts are necessary to ensure the long-term resilience of marine aquaculture.
- The potential fish provisioning services of vegetated and unvegetated habitat in a lagoon nurseryPublication . Erzini, Karim; Sadat, Zineb; Bentes, Luis; Coelho, Rui; Lino, Pedro; Monteiro, Pedro; Oliveira, Frederico; Ribeiro, Joaquim; Gonçalves, Jorge M.S.The potential fish provisioning services of the Ria Formosa lagoon (Portugal) were calculated for single cohorts of 7 commercially fished species, based on densities of juveniles sampled with beach seines on a monthly basis over a 17-month period at 41 locations. The potential maximum yield per recruit (F0.1 criteria) was calculated for vegetated (V) and unvegetated (UV) habitat for low and high natural mortality values. Vegetated habitat enhanced yield (g m− 2 ) of 5 of the 7 species, with the greatest enhancement for the herbivore Sarpa salpa (137 and 150 fold for low and high M). At F0.1, the calculated total potential yield of the 7 cohorts was 463 tons (low M) and 333 tons (high M), worth EUR 5,649,084 and 3,651,881, respectively. Mean annual landings of the 7 species from 1997 to 2017 ranged from 407 to 577 tons, with a mean of 495 tons (s.e. = 11.1), highlighting the importance of the lagoon nursery as a major source of recruits for local small-scale coastal fisheries. The methodology used here is the first to calculate the potential maximum yield and the corresponding fishing mortality (F0.1) for single cohorts and for different habitats within an important fish nursery. It provides more realistic values of potential fish provisioning services and economic contribution to local fisheries than studies that do not consider fishing mortality.
- Preliminary evaluation of moniliformin as a potential threat for teleostsPublication . Gonçalves, Rui A.; Tarasco, Marco; Schatzmayr, Dian; Gavaia, PauloAquaculture feed manufacturers and producers increasingly recognize the importance of mycotoxins, which contaminate plant-based meals used in compound aquafeeds, and their potential to negatively impact production. Though data on the worldwide occurrence of legislated mycotoxins e.g., trichothecenes and zearalenone (ZEN) are well documented, relatively little information is available regarding other mycotoxins also produced by Fusarium, notably moniliformin (MON). Given that MON is known to affect the survival, growth, skeletal formation and bone mineralization in terrestrial species, its widespread occurrence on maize and maize by-products typically used in aquaculture makes it relevant to study these parameters in teleost fish. In the present work we have tested the effect of MON exposure on survival, bone development and mineralization using zebrafish (Danio rerio) as a model species and fish derived osteo-chondroprogenitor cell line for in vitro studies. Moniliformin exposure did not decrease bone mineralization in zebrafish larvae or extracellular matrix mineralization in the mineralogenic cell line VSa13. Here, the minimal in vitro cytotoxicity concentration was found to be 1000 µg L−1 MON. Incidence of deformities was also not altered by MON at the concentration tested (450 µg L−1 ) although larval growth was affected, as shown by a decrease in the standard length of exposed specimens at 20 days post fertilization. Survival decreased significantly in larvae exposed to MON concentrations higher than 900 µg L−1 . Influence of MON on survival and growth might be relevant for aquaculture industry. As MON is a water-soluble mycotoxin, its leaching from feed is highly probable, so MON assimilation into the surrounding aqueous environment should also be considered. Tested levels in fish larvae are within the reported occurrence levels of MON in commercial feed and plant meals.