| 11. |
|
|
| 12. |
- Andrade, Carlos A. P., et al.
(författare)
-
Allometric Growth in Red Porgy Larvae : Developing Morphological Indices for Mesocosm Semi-Intensive Culture
- 2013
-
Ingår i: North American Journal of Aquaculture. - : Wiley. - 1522-2055 .- 1548-8454. ; 75:1, s. 42-49
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the morphological development, allometric growth, and cannibalistic behavior of Red Porgy Pagrus pagrus reared in mesocosm semi-intensive culture. The study was conducted from hatching to 32 d after hatching (DAH). Red porgy ontogeny was characterized by strong positive allometric growth of body depth at anus (BDA) to 6.7mm total length (TL) at about 2122 DAH. The BDA combined with standard length (SL) in a morphometric index was found to be better correlated with dry weight than TL and provided an improved method to estimate larval growth. Mouth size also exhibited strong positive allometric growth at early larval stages that, together with inflation of the swim bladder, may have contributed to improve feeding ability, in preparation for the high energy demands of metamorphosis. A predictive regression model developed for cannibalism underestimated prey size. Cannibalism coincided with the development of acidic digestion and was first evident at 27 DAH as larvae reached about 23% of their maximum size variation. We hypothesize that cannibalism is associated with larval size and condition, but is prompted by physiological and energetic factors. The bivariate morphometric index developed in this study can be used to mitigate cannibalism by controlling larval size variation and improving feed supply. The morphological measurements and morphometric indices that result from this study provide important tools for improving red porgy larvae culture. Received December 13, 2011; accepted July 12, 2012
|
|
| 13. |
- Andrade, Carlos A. P., et al.
(författare)
-
Red Porgy, Pagrus pagrus, Larvae Performance and Nutritional Condition in Response to Different Weaning Regimes
- 2012
-
Ingår i: Journal of the World Aquaculture Society. - : Wiley. - 0893-8849 .- 1749-7345. ; 43:3, s. 321-334
-
Tidskriftsartikel (refereegranskat)abstract
- Red porgy, Pagrus pagrus, is a candidate species for aquaculture diversification. The aim of this work was to assess whether an early supply of enriched Artemia (D1) or a direct step to dry diets (D3) would be advantageous weaning strategies for red porgy larvae, compared to a later supply of Artemia followed by dry diets (D2). Direct weaning to dry diet resulted in significantly lower growth, survival, pancreatic (trypsin and lipase), and intestinal (alkaline phosphatase) enzyme-specific activity, with the exception of leucine-alanine peptidase. The direct weaning strategy presented severe nutritional restrictions from early weaning stages with an associated delay of the maturation of digestive system. The two-step strategy presented in D1 and D2 resulted in comparable results in most parameters, including survival. Weaning using enriched Artemia as an intermediate step is confirmed as the most adequate strategy for red porgy larvae. Digestive enzymes and selected fatty acids correlated well with performance responses to dietary regimes, thereby supporting the use of these parameters as sensitive and reliable indicators of red porgy nutritional or physiological status during larval stages.
|
|
| 14. |
- Bernal, Ximena E., et al.
(författare)
-
Empowering Latina scientists
- 2019
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 15. |
- Bonaglia, Stefano, et al.
(författare)
-
Activated carbon stimulates microbial diversity and PAH biodegradation under anaerobic conditions in oil-polluted sediments
- 2020
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 248
-
Tidskriftsartikel (refereegranskat)abstract
- Biodegradation by microorganisms is a useful tool that helps alleviating hydrocarbon pollution in nature. Microbes are more efficient in degradation under aerobic than anaerobic conditions, but the majority of sediment by volume is generally anoxic. Incubation experiments were conducted to study the biodegradation potential of naphthalene-a common polycyclic aromatic hydrocarbon (PAH)-and the diversity of microbial communities in presence/absence of activated carbon (AC) under aerobic/anaerobic conditions. Radio-respirometry experiments with endogenous microorganisms indicated that degradation of naphthalene was strongly stimulated (96%) by the AC addition under anaerobic conditions. In aerobic conditions, however, AC had no effects on naphthalene biodegradation. Bioaugmentation tests with cultured microbial populations grown on naphthalene showed that AC further stimulated (92%) naphthalene degradation in anoxia. Analysis of the 16S rRNA gene sequences implied that sediment amendment with AC increased microbial community diversity and changed community structure. Moreover, the relative abundance of Geobacter, Thiobacillus, Sulfuricurvum, and methanogenic archaea increased sharply after amendment with AC under anaerobic conditions. These results may be explained by the fact that AC particles promoted direct interspecies electron transfer (DIET) between microorganisms involved in PAH degradation pathways. We suggest that important ecosystem functions mediated by microbes-such as hydrocarbon degradation-can be induced and that AC enrichment strategies can be exploited for facilitating bioremediation of anoxic oil-contaminated sediments and soils.
|
|
| 16. |
- Bonaglia, Stefano, et al.
(författare)
-
Capping with activated carbon reduces nutrient fluxes, denitrification and meiofauna in contaminated sediments
- 2019
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 148, s. 515-525
-
Tidskriftsartikel (refereegranskat)abstract
- Sediment capping with activated carbon (AC) is an effective technique used in remediation of contaminated sediments, but the ecological effects on benthic microbial activity and meiofauna communities have been largely neglected. This study presents results from a 4-week experiment investigating the influence of two powdered AC materials (bituminous coal-based and coconut shell-derived) and one control material (clay) on biogeochemical processes and meiofauna in contaminated sediments. Capping with AC induced a 62‒63% decrease in denitrification and a 66‒87 % decrease in dissimilatory nitrate reduction to ammonium (DNRA). Sediment porewater pH increased from 7.1 to 9.0 and 9.7 after addition of bituminous AC and biomass-derived AC, respectively. High pH (>8) persisted for at least two weeks in the bituminous AC and for at least 24 days in the coconut based AC, while capping with clay had no effect on pH. We observed a strong impact (nitrate fluxes being halved in presence of AC) on nitrification activity as nitrifiers are sensitive to high pH. This partly explains the significant decrease in nitrate reduction rates since denitrification was almost entirely coupled to nitrification. Total benthic metabolism estimated by sediment oxygen uptake was reduced by 30 and 43 % in presence of bituminous coal-based AC and coconut shell-derived AC, respectively. Meiofauna abundances decreased by 60‒62 % in the AC treatments. Taken together, these observations suggest that AC amendments deplete natural organic carbon, intended as food, to heterotrophic benthic communities. Phosphate efflux was 91 % lower in presence of bituminous AC compared to untreated sediment probably due to its content of aluminum (Al) oxides, which have high affinity for phosphate. This study demonstrates that capping with powdered AC produces significant effects on benthic biogeochemical fluxes, microbial processes and meiofauna abundances, which are likely due to an increase in porewater pH and to the sequestration of natural, sedimentary organic matter by AC particles.
|
|
| 17. |
- Bonaglia, Stefano, et al.
(författare)
-
Meiofauna improve oxygenation and accelerate sulfide removal in the seasonally hypoxic seabed
- 2020
-
Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136 .- 1879-0291. ; 159
-
Tidskriftsartikel (refereegranskat)abstract
- Oxygen depleted areas are widespread in the marine realm. Unlike macrofauna, meiofauna are abundant in hypoxic sediments. We studied to what extent meiofauna affect oxygen availability, sulfide removal and microbial communities. Meiofauna were extracted alive and added to intact sediments simulating abundance gradients previously reported in the area. A total of 324 porewater microprofiles were recorded over a 3-week incubation period and microbial community structure and cable bacteria densities were determined at the end of the experiment. At high abundances meiofauna activity deepened oxygen penetration by 85%, 59%, and 62% after 5, 14, and 22 days, respectively, compared to control sediment with scarce meiofauna. After 6 days, meiofauna increased the volume of oxidized, sulfide-free sediment by 68% and reduced sulfide fluxes from 8.8 to 0.4 mmol m(-2) d(-1). After 15 days, the difference with the control attenuated due to the presence of a cable bacteria population, which facilitated sulfides oxidation in all treatments. 16S rRNA gene analysis revealed that meiofauna affected microbial community structure (beta diversity). Thus, meiofauna bioturbation plays an important role in deepening oxygen penetration, counteracting euxinia and in structuring microbial diversity of hypoxic sediments. Co-existence with cable bacteria demonstrates neutralism interaction between these two ecosystem engineers.
|
|
| 18. |
- Bonaglia, Stefano, et al.
(författare)
-
Meiofauna increases bacterial denitrification in marine sediments
- 2014
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 5133-
-
Tidskriftsartikel (refereegranskat)abstract
- Denitrification is a critical process that can alleviate the effects of excessive nitrogen availability in aquatic ecosystems subject to eutrophication. An important part of denitrification occurs in benthic systems where bioturbation by meiofauna (invertebrates <1mm) and its effect on element cycling are still not well understood. Here we study the quantitative impact of meiofauna populations of different abundance and diversity, in the presence and absence of macrofauna, on nitrate reduction, carbon mineralization and methane fluxes. In sediments with abundant and diverse meiofauna, denitrification is double that in sediments with low meiofauna, suggesting that meiofauna bioturbation has a stimulating effect on nitrifying and denitrifying bacteria. However, high meiofauna densities in the presence of bivalves do not stimulate denitrification, while dissimilatory nitrate reduction to ammonium rate and methane efflux are significantly enhanced. We demonstrate that the ecological interactions between meio-, macrofauna and bacteria are important in regulating nitrogen cycling in soft-sediment ecosystems.
|
|
| 19. |
- Bonaglia, Stefano, 1983, et al.
(författare)
-
Meiofauna Shaping Biogeochemical Processes
- 2023
-
Ingår i: New Horizons in Meiobenthos Research. - Cham : Springer. - 9783031216220
-
Bokkapitel (refereegranskat)abstract
- Biogeochemical processes at the sediment–water interface are essential for the functioning of marine ecosystems. It is a central question in benthic ecology how these processes are controlled and mediated by biotic factors. Particularly, the role of meiobenthos, the most abundant and diverse faunal component in these systems, is little understood and requires more attention. In this chapter, we discuss the impact of meiofauna bioturbation in marine sediments on significant mechanisms and processes in (a) carbon degradation and oxygen penetration, (b) sulfide dynamics, and (c) nitrogen cycling. Particularly in the growing hypoxic areas of the seafloor where meiofauna is often the only animal group present, the role and bioturbative activities of this central component of the benthos need further scrutiny regarding the decrease of oxygen and increase of toxic hydrogen sulfide. These knowledge gaps in the interaction between meiofauna and marine biogeochemistry are the background for our concluding outlines: We present current research frontiers in order to assess the role of meiofauna as regulators of geochemical processes and microbial activities. These goals require combination of quantitative and qualitative meiobenthos investigations with state-of-the-art experimental work.
|
|
| 20. |
- Bonaglia, Stefano, et al.
(författare)
-
Methane fluxes from coastal sediments are enhanced by macrofauna
- 2017
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- Methane and nitrous oxide are potent greenhouse gases (GHGs) that contribute to climate change. Coastal sediments are important GHG producers, but the contribution of macrofauna (benthic invertebrates larger than 1 mm) inhabiting them is currently unknown. Through a combination of trace gas, isotope, and molecular analyses, we studied the direct and indirect contribution of two macrofaunal groups, polychaetes and bivalves, to methane and nitrous oxide fluxes from coastal sediments. Our results indicate that macrofauna increases benthic methane efflux by a factor of up to eight, potentially accounting for an estimated 9.5% of total emissions from the Baltic Sea. Polychaetes indirectly enhance methane efflux through bioturbation, while bivalves have a direct effect on methane release. Bivalves host archaeal methanogenic symbionts carrying out preferentially hydrogenotrophic methanogenesis, as suggested by analysis of methane isotopes. Low temperatures (8 °C) also stimulate production of nitrous oxide, which is consumed by benthic denitrifying bacteria before it reaches the water column. We show that macrofauna contributes to GHG production and that the extent is dependent on lineage. Thus, macrofauna may play an important, but overlooked role in regulating GHG production and exchange in coastal sediment ecosystems.
|
|
