Flexibility of physiological traits underlying inter-individual growth differences in intertidal and subtidal mussels Mytilus galloprovincialis

14 páginas, 5 figuras, 2 tablas.-- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedMussel seed (Mytilusgalloprovincialis) gathered from the intertidal and subtidal environments of a Galician embayment (NW, Spain) were maintained in the laboratory during five months to select fast (F) and slow (S) growing mussels. The physiological basis underlying inter-individual growth variations were compared for F and S mussels from both origins. Fast growing seemed to be a consequence of greater energy intake (20% higher clearance and ingestion rate) and higher food absorption rate coupled with low metabolic costs. The enhanced energy absorption (around 65% higher) resulted in 3 times higher Scope for Growth in F mussels (20.5±4.9 J h−1) than S individuals (7.3±1.1 J h−1). The higher clearance rate of F mussels appears to be linked with larger gill filtration surface compared to S mussels. Intertidal mussels showed higher food acquisition and absorption per mg of organic weight (i.e. mass-specific standardization) than subtidal mussels under the optimal feeding conditions of the laboratory. However, the enhanced feeding and digestive rates were not enough to compensate for the initial differences in tissue weight between mussels of similar shell length collected from the intertidal and subtidal environments. At the end of the experiment, subtidal individuals had higher gill efficiency, which probably lead to higher total feeding and absorption rates relative to intertidal individualsThis work was funded by the project Physiology and Genetic of Growth in Commercial Bivalves ‘FIGEBIV’ (AGL2013-49144-C3-2-R). Jade Irisarri was funded by JAE-Predoc CSIC-FSE 2012–2015.Peer reviewe

Integration of physiological energetics, biometrics, proximate composition and fatty acids as biomarkers to asses the utilization of fish feed waste by mussels growing near fish cages

En esta tesis se realiza un estudio para evaluar el impacto ambiental y comportamiento alimentario del mejillón (Mytilus galloprovincialis) criado en bateas del polígono de Lorbé, en la ría de Ares-Betanzos (Galicia), algunas de ellas localizadas próximas a una piscifactoría de besugo (Pagellus bogaraveo). Se propone establecer métodos para optimizar su cultivo manteniendo la integridad ecológica del área. De este modo, se evaluará la aplicación potencial del concepto de acuicultura multitrófica integrada (IMTA), para lograr un futuro cultivo de mejillón basado en las transferencias de energía entre organismos. Para lograr dichos propósitos se establecen los siguientes objetivos para la tesis: 1. Comprender la interacción entre el cultivo del mejillón con el medio ambiente. 2. Estudiar componentes bioquímicos (carbohidratos, proteínas, lípidos y ácidos grasos), fracciones de clorofila y composición en isótopos estables (C y N) del seston. 3. Crecimiento del mejillón por métodos directos e indirectos. 4. Crecimiento potencial: Scope For Growth e isótopos estables, con el fin de estudiar cómo se lleva a cabo la transferencia de energía en la localización del cultivo. 5. Se realizarán los mismos análisis en aquellos organismos asociados al cultivo y que puedan utilizar los productos de desecho provenientes del cultivo de mejillón. 6. Cuantificación de la depleción de la biomasa de fitoplancton de la batea. Profundizando en los efectos ecológicos del cultivo de mejillón y en la variación del comportamiento alimentario en distintas condiciones ambientales se podrá posibilitar la gestión costera y manejo sostenible del cultiv

Integration of physiological energetics, biometrics, proximate composition and fatty acids as biomarkers to assess the utilization of fish feed waste by mussels growing near fish cages

248 páginasThis thesis was sponsored by the project Ecological Sustainability of Suspended Mussel Aquaculture (ESSMA) awarded by the Programa Nacional de Internacionalización I+D, Subprograma ‘Fomento de la Cooperación Científica Internacional (FCCI)’ by the Spanish Ministry of Science and Innovation (ACI2008-0780). This thesis would not have been possible without the financial assistance of the CSIC fellowship JAE-predoc 2012-2015, co-financed by the European Social Fund. I also express my gratitude to the EuroMarine FP7 mobility fellowship programme and Dr. Marleen De Troch for their support during my stay in Ghent University.Peer reviewe

Temporal and spatial variations in proximate composition and Condition Index of mussels Mytilus galloprovincialis cultured in suspension in a shellfish farm

10 páginas, 5 figuras, 5 tablasWe compared the seasonal variations in Condition Index (CI) and proximate composition of the mantle and the digestive gland of mussels (Mytilus galloprovincialis) cultivated at outer and inner regions of a raft polygon. The results are discussed in the context of the energy balance. The proximate composition and CI varied with the seasonal fluctuations in seston composition and the reproductive cycle described for the Galician Rías. Seston's nutritional quality peaked during the spring bloom and descended during winter downwelling. Proteins were first depleted in the gland during autumn, while the mantle maintained high levels until summer. Similarly, lipids were highest in the mantle during winter and decreased following the spring spawning, suggesting transference of reserves from the gland to the mantle to support gametogenesis. In contrast, glycogen was stored in the mantle during the summer and exhausted during winter, when food % POM was lowest. This opposite pattern suggested that glycogen was probably converted to lipids during gamete development. The variations in CI significantly correlated with the accumulation and expenditure of reserves. Mussels harvested in autumn had the highest CI and biochemical reserves, while minimum CI was in winter, when mussels had a low energy balance. Resuspension events in autumn–winter significantly diluted the particulate organic matter suspended at the innermost raft (38.91% POM) compared with the outer raft (60.52% POM). This was reflected in short-term reductions in CI, proteins' and lipids' reserves in innermost mussels. These temporal increases in turbidity did not seem to significantly affect bivalves' proximate composition and meat yield over a longer time scaleThis study was sponsored by the project Ecological Sustainability of Suspended Mussel Aquaculture (ESSMA) (ACI2008-0780) and the PROINSA-CSIC contract project (CSIC 0704101100001)Peer reviewe

Feeding behaviour and differential absorption of nutrients in mussel Mytilus galloprovincialis: Responses to three microalgae diets

6 pages, 1 table, 2 figuresWe aimed to evaluate three defined monoalgal diets, Isochrysis galbana clone T-ISO, Tetraselmis suecica and Rhodomonas lens, as a food source for Mytilus galloprovincialis to ascertain which of the diets maximized the feeding, digestion and the assimilatory balance of nutrients and energy. Mussels fed with Rhodomonas yielded the highest clearance and ingestion rates (CR and IR), suggesting that the dimensions of Tetraselmis and T-ISO might have restricted their capture by the mussels’ gill. Absorption efficiency (AE), an indicator of digestibility, was significantly higher for Rhodomonas (69.6%) than for Tetraselmis (38.4%) or T-ISO (23.6%) diets. This could be explained by the greater proportion of refractive non-digestible material contained in Tetraselmis and T-ISO diets, together with the low digestibility of the cell wall of Tetraselmis. The Rhodomonas diet showed the highest protein content, which was reflected in the highest ingestion and absorption of proteins compared with the other diets. However, the amount of carbohydrates and lipids ingested did not match the amount absorbed, probably owing to inefficient carbohydrate digestion and lipids lost through metabolic fecal losses. The total energy absorbed was higher for Rhodomonas (34.5 Jh− 1) than for T-ISO (20.1 J h− 1) or Tetraselmis (13.9 J h− 1) diet. The optimal feeding and digestive behaviour obtained for mussels fed with Rhodomonas diet, coupled with its ideal size, volume, weight and biochemical composition, might provide a better coverage for the anabolic demands of proteins during the seasonal growth cycle, especially during shell formation, gametogenesis and byssogenesis. Statement of relevance We state that this manuscript is relevant for the field of bivalve aquaculture and hatchery. We recommend that the main criteria in selecting algae for culturing mussels should be based on choosing the suitable dimension (size, volume, weight) of algal cell depending on the feeding capacity of mussels, which might vary between species and life stages (larvae, adult). The second main criteria should be based on selecting algae with high digestibility and balanced biochemical composition, to obtain a high absorption of energy that covers the nutritional requirements of each life stage of the mussels.This work was funded by the project FIGEBIV (AGL2013-49144-C3-2-R). Jade Irisarri is supported by JAE-Predoc CSIC-FSE 2012–2015 scholarship.Peer reviewe

Fatty acid composition of female and male clams (Ruditapes philippinarum): energy intake and temperature reliance

10 pages, 5 figures, 2 tablesWe analysed the effect of temperature, coupled with food ingestion rate (IR), on the fatty acid (FA) profile of female and male clams conditioned in two groups: L (low IR at 14 and 18 °C) and H (high IR at 18 and 22 °C). Significant differences for group L, both 18L and 14L with low IR and slow gonadal development, owed to differences in energy balance between 18L clams (negative energy balance) and 14L clams (positive energy balance). Plasmalogens (DMA 18:0) and non-methylene-interrupted FAs might protect against reactive oxygen species and preserve the integrity of the cell membranes during food stress in 18L clams. Differences in composition for group H, both 18H and 22H with high food intake, positive energetic balance and complete and similar gonadal occupation index (GOI), probably owed to the greater energy levels at 18 °C than at 22 °C. Clams at 22 °C H increased the oxidation of short-chained PUFA 18:3ω3 and 18:3ω6 to maintain the same GOI as 18H clams. Regarding the sexual differences, the greater accumulation of 20:5ω3 and 20:4ω6 in females might be related with oocyte maturation and release during spawning, while the greatest levels of 22:6ω3 in males might be involved in spermatocyte membranes synthesis.Funding was provided by MEC, project number: AGL2004-07023-C02-02/ACU.Peer reviewe

Fatty acid composition in Mytilus galloprovincialis organs: trophic interactions, sexual differences and differential anatomical distribution

14 páginas, 5 figuras, 1 tablaThe fatty acid (FA) profiles in neutral lipids (NLs) and polar lipids (PLs) of the gills, digestive gland and mantle of female and male mussels Mytilus galloprovincialis (cultured in Ría de Arousa, Galicia, NW Spain, and studied during an annual seasonal cycle) reflected dietary, sexual and functional differences. Seasonal differences arose from variations in the trophic environment, with diatom FA biomarkers dominating during the spring bloom, biomarkers from dinoflagellate-rich diets dominating during winter mixing, and a combination of both sources apparent during the summer and autumn transitory periods. The influence of diet was more pronounced in the NL (energetic reserves) than in the PL (structural membrane components) FA signatures of all organs, although dietary changes were mirrored more clearly in the digestive gland. Differences between males and females were restricted to the mantle and probably resulted from gonadal ripeness during spring. The NL and PL FA profile of the mantle was characterized by the abundance of 14:0, 16:0 and 16:1n-7 in females and predominance of 18:0, 18:3n-3 and 22:6n-3 in males, suggesting that each gender has distinct energetic and structural requirements during gametogenesis. Lipids containing alkenyl ethers or non-methylene interrupted (NMI) FAs were mostly found in the PLs of the gills and the mantle, supporting their role as structural and functional components in the membranes of organs directly exposed to physicochemical fluctuations. Competition between NMI and polyunsaturated fatty acids (PUFAs) was only evident in the mantle, suggesting that deficiencies in PUFAs might provoke de novo biosynthesis of NMI to satisfy reproductive demandsThis study was funded by the project Xunta de Galicia PGIDIT02RMA40202PR. J.I. is supported by a JAE-Predoc CSIC-FSE 2012− 2015 scholarshipPeer reviewe

Growth variations within a farm of mussel (Mytilus galloprovincialis) held near fish cages: Importance for the implementation of integrated aquaculture

15 páginas, 6 figuras, 6 tablasFish farming releases extensive amounts of particulate organic waste that can be exploited by bivalves in integrated culture. We tested if mussels Mytilus galloprovincialis cultured at two depths (1 and 6 m) in a raft, moored 170 m from a fish farm had greater growth than bivalves held 550 m from the fish cages. Mussel growth was monitored monthly, covering the second phase of the culture, from thinning-out to harvest (March to November 2011). We also studied if fish solid and dissolved nutrients increased the organic content of the seston and chlorophyll-a levels near the fish cages through weekly samples. Results showed no differences in seston, chlorophyll and physiochemical characteristics of the water among rafts. Maximum growth and Condition Index (CI) occurred during spring–summer (April–August), when mussels had access to greater food quality and quantity. Mussels cultivated close to the cages showed similar shell length, weight and CI compared with mussels distant from the fish farm. Average shell length, meat dry weight and CI at harvest were 76.31 mm, 2.51 g and 23%. Bivalves cultured distant from the fish cages displayed 26% higher biomass than the other raft at the end of the experiment. Differences in biomass were explained by the significantly higher recruitment of mussel seed observed at the raft distant from the fish cages from June to November. The lack of a significant enhancement in growth of the bivalves cultured next to finfish is discussed.This study was supported by the projects Ecological Sustainability of Suspended Mussel Aquaculture (ESSMA) (ACI2008–0780) and the PROINSA–CSIC contract project (CSIC 0704101100001). J. Irisarri was funded by JAE-Predoc CSIC-FSE 2011 scholarship.Peer reviewe

Fatty acids as tracers of trophic interactions between seston, mussels and biodeposits in a coastal embayment of mussel rafts in the proximity of fish cages

11 páginas, 5 figuras, 3 tablasWe traced the food sources of mussel Mytilus galloprovincialis cultured in suspension in Ría Ares-Betanzos (N.W. Spain) by means of fatty acid (FA) biomarkers. The FA profile of seston, mussels' mantle, digestive gland and feces was analyzed during five seasons. Due to the proximity of a fish farm to the bivalve aquaculture site, we also tested if mussels and seston situated 170 m distant from the fish cages incorporated fish feed FA markers compared with samples obtained 550 m away. The principal FA in the mussels' organs were 16:0, 16:1ω7, EPA (20:5ω3) and DHA (22:6ω3), while 16:0 predominated in the feces. Seasonal fluctuations in the seston composition were mirrored in the FA signature of mussels' organs and feces, although the digestive gland had the closest resemblance to the seston FA profile. In general, diatom and bacteria derived-biomarkers predominated in mussels' organs and feces during the upwelling period (spring–summer), while dinoflagellates were the dominant dietary source during downwelling (autumn–winter). The higher concentration of EPA and DHA in both organs and the feces compared with the seston suggested a preferential accumulation of these ω3 FA in the mussels' tissues. The results showed a lack of assimilation of fish feed FA biomarkers in the seston and mussel samples. This might be due to the dispersion of uneaten feed particles by high current velocity, substantial distance between the fish and mussel culture, the limited amount of nutrient waste released by the fish farm and dilution of feed particles in the large mussel standing stockThis study was supported by the project Ecological Sustainability of Suspended Mussel Aquaculture (ESSMA) Spanish Ministry of Science and Innovation (ACI2008-0780) and the contract-project PROINSA Mussel Farm, codes CSIC 0704101100001. M. De Troch is a postdoctoral researcher at the Ghent University (BOF-GOA 01GA1911W). J. Irisarri was funded by a CSIC JAE-Predoctoral fellowship co-financed by the European Social Fund and by the EuroMarine FP7 mobility fellowship programmePeer reviewe

Effects of seasonal variations in phytoplankton on the bioenergetic responses of mussels (Mytilus galloprovincialis) held on a raft in the proximity of red sea bream (Pagellus bogaraveo) net-pens

13 páginas, 7 tablas, 5 figurasThe seasonal variability of the physiological components of the Scope for Growth (SFG) of mussels Mytilus galloprovincialis was investigated in a raft adjacent (170 m) to fish net-pens and compared with a raft 550 m distant from the cages in Ría Ares-Betanzos (Galicia, Spain). Chlorophyll and phytoplankton size-classes were determined in the field, simultaneously with SFG. Average chlorophyll-a was 0.65 ± 0.24 μg l− 1, while nanophytoplankton (2–20 μm) was the most abundant size-class, ranging from 50 to 70% of the total chlorophyll. The temporal pattern found for chlorophyll-a and phytoplankton size-classes reflected the upwelling–downwelling events and were correlated with the feeding, digestive and metabolic rates. Nanophytoplankton and microphytoplankton were preferentially cleared and ingested by mussels. There were no significant differences between the chlorophyll and phytoplankton size-classes among rafts. The lack of any enhancement in food availability resulted in no significant increase in the SFG of mussels beside the fish cages. Maximum SFG corresponded with the autumn (16.60 ± 7.90 J h− 1) and spring (12.72 ± 9.32 J h− 1) chlorophyll maximums. An abnormally hot summer and reduced chlorophyll levels resulted in lower energy intake, significantly higher metabolic expenditure and a negative SFG (− 34.57 ± 12.55 J h− 1). Any particulate wastes and potential fish-derived chlorophyll enhancement would be rapidly diluted by the currents, while the placement of bivalves too distant from the fish farm in an environment with high supplies of natural seston may explain the lack of an augmented SFG of the co-cultured musselsThis study was sponsored by the project Ecological Sustainability of Suspended Mussel Aquaculture (ESSMA) (ACI2008-0780) and the PROINSA-CSIC contract project (CSIC 0704101100001). Jade Irisarri is supported by JAE-Predoc CSIC-FSE 2012–2015 scholarship.Peer reviewe