Produção integrada de corvinas (Argyrosomus regius) e ostras (Crassostrea gigas) em tanques de terra

Em Portugal e no Sul da Europa o regime semi-intensivo em aquacultura tem-se mostrado economicamente insustentável o que levou, nas últimas duas décadas, a uma diminuição acentuada do número de empresas piscícolas. Para inverter esta tendência tem-se vindo a analisar várias possibilidades de incrementar a rentabilidade destes sistemas de produção sem aumentar o impacto ambiental. Uma dessas possibilidades é a utilização de sistemas multitróficos integrados em tanques de terra. Os resíduos resultantes do processo de produção de peixe neste sistema são utilizados e assimilados por outros organismos, igualmente valorizados no mercado, permitindo a redução de desperdícios e aumentando a rentabilidade das explorações piscícolas. Este trabalho teve como objetivo determinar o efeito de duas combinações de diferentes biomassas de corvinas (Argyrosomus regius) e ostras (Crassostrea gigas), postas em cultivo integrado, na qualidade de água e desempenho animal (taxas de crescimento e eficiência alimentar) de forma a avaliar qual das combinações permitia atingir uma maior rentabilidade com um menor impacto ambiental dos efluentes. As duas combinações foram testadas em dois tratamentos com três replicados cada. Os parâmetros de qualidade de água monitorizados foram temperatura, oxigénio dissolvido, turbidez, pH, nutrientes e clorofilas e os das espécies em cultura foram o peso e a sobrevivência. Os parâmetros técnicos controlados foram a distribuição de ração, renovação de água, e o arejamento. As duas combinações de biomassa (alta de corvina + baixa de ostra, vs. baixa de corvina + alta de ostra) apresentaram diferenças significativas na turbidez, amónia, nitritos, nitratos, clorofilas e tempo de arejamento. As taxas de crescimento (0.25%.dia-1 nas corvinas e 0.57%.dia-1 nas ostras) e a taxa de conversão alimentar das corvinas (1,75 e 1,83 respetivamente para tratamentos de alta e baixa densidade de corvina) foram semelhantes nos dois tratamentos. A rentabilidade estimada para uma produção por ha para cada um dos tratamentos revelou uma diferença de 50000 euros a favor do tratamento com maior biomassa de ostra mostrando que é possível ter rentabilidade com uma aquacultura multitrófica integrada. Numa perspetiva dos serviços ecossistémicos a utilização de cultivo multitrófico de corvina e ostra mostrou-se uma mais valia com uma grande redução nos valores de nutrientes libertados para o ambiente e grande rentabilidade monetária. Sugere-se que no cultivo integrado a eficiência alimentar tenha em conta toda a biomassa criada dentro do sistema de forma a melhor interpretar a eficiência na utilização de ração que é o componente mais dispendioso em aquacultura em tanques de terra

Response of Marine Plankton Communities in Ponds to the Presence of Vertical Structures

The effects of bottom vertical structures like AquaMats® in enhancing plankton productivity was evaluated. One experimental earthen pond of 500 m2 was provided with AquaMats® increasing the surface substrate area 12 times and water quality, phytoplankton and zooplankton populations developed during almost 100 days was compared with a pond without AquaMats®. Their presence favored the development of Dinoflagellates (Miozoa, Dinophyceae), mostly Gymnodiniales, which may be of some concern since some species of this group have been associated with toxic algal blooms while in the ponds without AquaMats® Diatoms (Bacillariophyta) predominate. In both ponds plankton production was very much sculptured by external nutrients added to the systems. The balance between different nutrients is extremely important to regulate the phytoplankton populations with Diatoms blooming at silicate concentrations higher than 2 μM and below this level and at low nitrate and high ammonium being more appropriate for Dinoflagellates. The linkage between phytoplankton and zooplankton population in ponds is strong with zooplankton exerting control over the phytoplankton population and vice-versa. The use of vertical substrates enhances plankton productivity by increasing the substrate area for periphyton fixation. The main zooplankton taxonomic groups associated with the presence of AquaMats® were Calanoid and Harpacticoid copepodites and nauplii, veligers of gastropods and trochophore of polychaets, larval stages of organisms that except for calanoid copepods are benthic and correspond to the meroplanktonic phase in the life cycle of those organisms

Seagrass meadows improve inflowing water quality in aquaculture ponds

Water quality is critical for fish health in aquaculture production. In flow-through systems, the inflowing water normally requires quality controls and treatments for being supplied from coastal water bodies that can be polluted by nutrients, suspended solids, and microorganisms. Here we assess how seagrass meadows benefit aquaculture systems through the provision of ecosystem services (water filtration, biological control, and regulation of dissolved gasses) in the water reservoir that supplies earthen ponds in an aquaculture system in southern Portugal. In the 1.45-ha reservoir, seagrasses retained daily an estimate of 0.8–1.8 kg d−1 of nitrogen, 0.04–0.07 kg d−1 of phosphorus in their biomass, and 0.7–1.1 kg dw d−1 of suspended total particulate matter, bringing benefits in terms of nutrient and particle removal from the water column. Diel and spatial variation in faecal coliforms levels (Escherichia coli) in the reservoir suggested that seagrasses, in combination with light exposure, may reduce the levels of this pathogen. Furthermore, the seagrass-dominated system oxygenated the water through photosynthesis at a faster rate than the respiratory oxygen consumption, maintaining the system above the aquaculture minimum oxygen. This study demonstrates that seagrasses can be used as a nature-based solution to overcome water quality challenges in flow-through aquaculture ponds.Foundation of Science and Technology of Portugal through projects PTDC/MAR-EST/3223/2014 and UIDB/04326/2020 and through fellowships SFRH/BPD/119344/2016 and SFRH/BD/118601/2016, and was further funded by MAR2020 through project DIVERSIAQUA (MAR202016-02-01-FMP-0066).info:eu-repo/semantics/publishedVersio

GeoERA Raw Materials Monograph : the past and the future

ABSTRACT: GeoERA Minerals projects have produced data aimed at supporting Europe’s minerals sector and to assist the European Commission to realise its goals for raw materials. Data has been compiled on mineral occurrences and mineral provinces across Europe, in particular, areas with potential to host Critical Raw Materials. Anecdotal evidence from the minerals sector provides an indication of the likelihood of exploration leading to mine development. For every 1,000 mineral showings examined, only 100 may receive further exploration work and of those 100, only 10 may warrant more detailed sampling either through trenching, drilling or other means and of those 10 only 1 may proceed to an evaluation through a full feasibility study which itself has only 50% chance of being positive. Following this, any project for which a mine proposal is made must undergo a full evaluation and permitting by authorities including full public consultation. The proposal may or may not pass this scrutiny. In terms of a schedule, the generally accepted minimum time frame from discovery to production is 10 years and usually much more, up to 20 years.info:eu-repo/semantics/publishedVersio

Emmerich, Volker/Steiner, Udo: Wirtschaftliche Betätigung der öffentlich-rechtlichen Rundfunkanstalten

RésuméIntegrated MultiTrophic Aquaculture (IMTA) is based on the production of fed species (e.g., finfish) along with extractive species which re-use the inorganic (e.g., seaweeds) and organic (e.g., suspension-feeders) nutrients excess. To increase the development of IMTA practices, it is important to understand the trophic relationship within the system. In Mediterranean earthen ponds, meagre (Argyrosomus regius), white seabream (Diplodus sargus) and mullet (Mugil chepalus) are three fish species of different trophic levels that are good candidates to be cultured with oysters (Crassostrea gigas) and sea lettuce (Ulva flexuosa) but their trophic behavior are not well known under polyculture. The aim of this study was to identify the food sources used by fish and oysters using fatty acids (FA) as well as carbon (δ13C) and nitrogen (δ15N) stable isotopes. Within the Era Net COFASP project IMTA-Effect, experiments were conducted in 6 earthen ponds at IPMA´s Estação de Piscicultura de Olhão, south of Portugal. Similar biomass and proportions of meagre, white seabream and mullet were introduced in each pond and three different combinations of organisms were tested: fish-oysters, fish-macroalgae, fishoysters-macroalgae. According to the combination, oyster spats were introduced while autochthonous macroalgae were let grown or removed from the ponds. Fish were fed daily with a commercial diet. At the end of the experiment, fish and oyster tissues were collected as well as all potential food sources present in ponds: commercial pellet, macroalgae, suspended particulate organic matter (SPOM) and polychetes. FA composition as well as δ13C and δ15N values of samples were determined. The combinations of organisms had no effect on FA composition of fish and oysters. FA composition of fish were significantly different between species. FA composition of meagre and white seabream was close to those of feed. FA composition of mullet was farther than those of feed with lower proportion of C18:1ꞷ9 and C18:2ꞷ6 and higher proportion of C22:6ꞷ3. Compared to feed, polychetes also have lower proportion of C18:1ꞷ9 and C18:2ꞷ6 and higher proportion of C22:6ꞷ3. FA markers of macroalgae were not found in fish. FA composition of oysters was similar to those of SPOM and FA markers of commercial feed were not detected. The combinations of species had no effect on δ13C and δ15N values of fish. Meagre, white seabream and mullet were slightly enriched in 13C and 15N in respect to feed. However, mullet were more 13C-enriched than the other fish species and closer to polychetes. Oysters cultured in the fish-oysters-macroalgae combination were 13C and 15N depleted compared to those from the fish-oysters combination. Similar results were found for SPOM. Our results highlighted that meagre and white seabream only consumed commercial feed while mullets consumed feed and probably, some polychetes whatever the combination of organisms. Macroalgae were not consumed by fish but influenced inorganic C and N recycling in ponds. Oysters fed on SPOM but not on particulate feed. FA and stable isotope analysis are two complementary trophic tracers powerful to study trophic transfers between species co-cultivated in IMTA ponds

Fatty acids and stable isotopes as tracers of food assimilation in fish-oyster-macroalgae integrated multitrophic aquaculture ponds

RésuméIntegrated MultiTrophic Aquaculture (IMTA) is based on the production of fed species (e.g., finfish) along with extractive species which re-use the inorganic (e.g., seaweeds) and organic (e.g., suspension-feeders) nutrients excess. To increase the development of IMTA practices, it is important to understand the trophic relationship within the system. In Mediterranean earthen ponds, meagre (Argyrosomus regius), white seabream (Diplodus sargus) and mullet (Mugil chepalus) are three fish species of different trophic levels that are good candidates to be cultured with oysters (Crassostrea gigas) and sea lettuce (Ulva flexuosa) but their trophic behavior are not well known under polyculture. The aim of this study was to identify the food sources used by fish and oysters using fatty acids (FA) as well as carbon (δ13C) and nitrogen (δ15N) stable isotopes. Within the Era Net COFASP project IMTA-Effect, experiments were conducted in 6 earthen ponds at IPMA´s Estação de Piscicultura de Olhão, south of Portugal. Similar biomass and proportions of meagre, white seabream and mullet were introduced in each pond and three different combinations of organisms were tested: fish-oysters, fish-macroalgae, fishoysters-macroalgae. According to the combination, oyster spats were introduced while autochthonous macroalgae were let grown or removed from the ponds. Fish were fed daily with a commercial diet. At the end of the experiment, fish and oyster tissues were collected as well as all potential food sources present in ponds: commercial pellet, macroalgae, suspended particulate organic matter (SPOM) and polychetes. FA composition as well as δ13C and δ15N values of samples were determined. The combinations of organisms had no effect on FA composition of fish and oysters. FA composition of fish were significantly different between species. FA composition of meagre and white seabream was close to those of feed. FA composition of mullet was farther than those of feed with lower proportion of C18:1ꞷ9 and C18:2ꞷ6 and higher proportion of C22:6ꞷ3. Compared to feed, polychetes also have lower proportion of C18:1ꞷ9 and C18:2ꞷ6 and higher proportion of C22:6ꞷ3. FA markers of macroalgae were not found in fish. FA composition of oysters was similar to those of SPOM and FA markers of commercial feed were not detected. The combinations of species had no effect on δ13C and δ15N values of fish. Meagre, white seabream and mullet were slightly enriched in 13C and 15N in respect to feed. However, mullet were more 13C-enriched than the other fish species and closer to polychetes. Oysters cultured in the fish-oysters-macroalgae combination were 13C and 15N depleted compared to those from the fish-oysters combination. Similar results were found for SPOM. Our results highlighted that meagre and white seabream only consumed commercial feed while mullets consumed feed and probably, some polychetes whatever the combination of organisms. Macroalgae were not consumed by fish but influenced inorganic C and N recycling in ponds. Oysters fed on SPOM but not on particulate feed. FA and stable isotope analysis are two complementary trophic tracers powerful to study trophic transfers between species co-cultivated in IMTA ponds

Food web in Mediterranean coastal integrated multi-trophic aquaculture ponds: Learnings from fatty acids and stable isotope tracers

International audienceEcosystem responsible aquaculture practices are today imperative to feed the world increasing population. Theculture of extractive species such as oyster with fed species such as fish is a promising solution to recycle wastestreams, which would be otherwise lost and discharged into the surrounding environment. In Mediterraneanearthen ponds, meagre (Argyrosomus regius), white seabream (Diplodus sargus) and grey mullet (Mugil cephalus)are three fish species of different trophic levels that are good candidates to be raised in integrated multi-trophicaquaculture (IMTA) pond with oysters (Magallana gigas) and macroalgae (Ulva flexuosa). Trophic links betweenspecies raised in IMTA ponds were inferred using the analysis of body fatty acid composition as well as in carbonand nitrogen stable isotopes. A combination of 3 treatments was tested: fish, oysters, phytoplankton and mac-roalgae (T1); fish, oysters and phytoplankton (T2); fish, phytoplankton and macroalgae (T3). Our results high-lighted that the three fish species were in competition for food sources as they mainly fed on commercial feedwhatever the treatment. However, grey mullet also consumed polychaetes that naturally grown in ponds.Macroalgae were not used by fish. In T1 and T2, oysters actively consumed the excess of phytoplankton. In T2,the absence of macroalgae reduce nutrient competition for phytoplankton growth and oysters have moreavailable food. In earthen ponds, the production of fish with macroalgae or fish with oyster should be privilegedcompared to usual semi-intensive fish polyculture as the presence of extractive species reduced fish waste

Rearing larvae of dusky grouper, Epinephelus marginatus (Lowe, 1834), (Pisces: Serranidae) in a semi-extensive mesocosm | La cría de larvas de mero, Epinephelus marginatus (Lowe, 1834), (Pisces: Serranidae), en un mesocosmos de tecnología semiextensiva

One of the major obstacles to propagating dusky grouper, Epinephelus marginatus, is the difficulty of rearing the early larvae. We have successfully raised dusky grouper larvae in mesocosms using a mixed diet of endogenous plankton grown in the rearing tank and an exogenous supply of Brachionus plicatilis and Artemia sp. Newly hatched larvae at an initial density of 1.3 ind.l-1 were stocked in partially shaded 3 m3 circular outdoor tanks during the summers of 2007 and 2008. Before introducing newly hatched larvae, the water was left for six days to promote plankton growth. Larval growth occurred at two different rates: i) a faster rate from first feeding to the beginning of metamorphosis, and ii) a slower rate at transformation. Survival at the beginning of metamorphosis was less than 10% (33 DPH) in 2007 and between 25 and 50% (25 DPH) in 2008. High mortalities were observed during larval transformation. The estimated minimum food requirement per grouper larvae increased more than 300% from the beginning of the notochord flexion to the beginning of metamorphosis. To meet such a high feeding requirement the number of larger prey organisms/copepods in the mesocosm should be eight times higher during this time period