| 1. |
- Andrade, Carlos A. P., et al.
(författare)
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Allometric Growth in Red Porgy Larvae : Developing Morphological Indices for Mesocosm Semi-Intensive Culture
- 2013
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Ingår i: North American Journal of Aquaculture. - : Wiley. - 1522-2055 .- 1548-8454. ; 75:1, s. 42-49
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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
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| 2. |
- Andrade, Carlos A. P., et al.
(författare)
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Red Porgy, Pagrus pagrus, Larvae Performance and Nutritional Condition in Response to Different Weaning Regimes
- 2012
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Ingår i: Journal of the World Aquaculture Society. - : Wiley. - 0893-8849 .- 1749-7345. ; 43:3, s. 321-334
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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.
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| 3. |
- Bonaglia, Stefano, et al.
(författare)
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Meiofauna increases bacterial denitrification in marine sediments
- 2014
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 5133-
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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.
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| 4. |
- Karlson, Agnes M. L., 1981-, et al.
(författare)
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Benthic fauna affects recruitment from sediments of the harmful cyanobacterium Nodularia spumigena
- 2012
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Ingår i: Harmful Algae. - : Elsevier BV. - 1568-9883 .- 1878-1470. ; 20, s. 126-131
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Tidskriftsartikel (refereegranskat)abstract
- Physical disturbance and feeding by macrofauna in the sediment can potentially affect bloom initiation of phytoplankton species that have benthic stages in their life cycle. In this experimental study, we investigated how different species of macrozoobenthos can affect the recruitment of Nodularia spumigena from the sediment to the water column. N. spumigena is a toxic, nitrogen-fixing filamentous cyanobacterium, which forms large summer blooms in the Baltic Sea. Benthic recruitment from resting stages (akinetes) and vegetative cells deposited on the seafloor have long been suspected to initiate the blooms. We found that, depending on species-specific traits, deposit-feeding macrofauna (an amphipod, Monoporeia affinis, a bivalve, Macoma balthica and an invasive polychaete, Marenzelleria cf. arctia) has the potential to either reduce or facilitate recruitment of this cyanobacterium. Shorter filament length in treatments with fauna than in the treatment without indicates feeding on or mechanical destruction of N. spumigena by the animals. Our results show the importance of an often overlooked aspect of phytoplankton bloom initiation, the role of macrozoobenthos.
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| 5. |
- Karlson, Agnes M. L., et al.
(författare)
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Higher diversity of deposit-feeding macrofauna enhances phytodetritus processing
- 2010
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 91:5, s. 1414-1423
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Tidskriftsartikel (refereegranskat)abstract
- The link between biodiversity and ecosystem functioning is an important question that remains unresolved, particularly in marine systems, in which cycling of organic matter by benthic organisms is of global significance. Direct observations of specific resource use by each species in single- and multispecies communities, as quantified by stable isotopes, facilitates a mechanistic understanding of the importance of each species for ecosystem functioning. We tested the effects of altered biodiversity (species richness) of deposit-feeding macrofauna on incorporation and burial of phytodetritus in combinations of three species representing natural communities found in the sediments of the species-poor Baltic Sea. The three species, two amphipods and a bivalve, had different rates of incorporation and burial and different needs for carbon (C) and nitrogen (N). The amphipods exhibited clear resource partitioning in sympatry, as a result of vertical separation in the sediment and consequent differential use of food. Communities of several species incorporated more C and N than expected from the respective single-species treatments, due to higher incorporation by surface feeders in multispecies treatments. Community incorporation of N in the most diverse treatment even exceeded N incorporation by a single-species treatment of the best-performing species, showing transgressive over-yielding. This over-yielding was primarily due to positive complementarity in all treatments. Diverse soft bottoms are also likely to be more productive in the long run, as species-specific traits (subsurface feeding) preserve fresh phytodetritus by burying it to depths in the sediment at which the mineralization rate is low. The more diverse sediment communities showed more efficient trophic transfer of phytodetritus, a finding of general significance for understanding biological processes driving the transformation of nutrients and energy in benthic ecosystems.
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| 6. |
- Massad, Eduardo, et al.
(författare)
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Risk of symptomatic dengue for foreign visitors to the 2014 FIFA World Cup in Brazil
- 2014
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Ingår i: Memórias do instituto Oswaldo Cruz. - : FapUNIFESP (SciELO). - 0074-0276 .- 1678-8060. ; 109:3, s. 394-397
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Tidskriftsartikel (refereegranskat)abstract
- Brazil will host the FIFA World Cup™, the biggest single-event competition in the world, from June 12-July 13 2014 in 12 cities. This event will draw an estimated 600,000 international visitors. Brazil is endemic for dengue. Hence, attendees of the 2014 event are theoretically at risk for dengue. We calculated the risk of dengue acquisition to non-immune international travellers to Brazil, depending on the football match schedules, considering locations and dates of such matches for June and July 2014. We estimated the average per-capita risk and expected number of dengue cases for each host-city and each game schedule chosen based on reported dengue cases to the Brazilian Ministry of Health for the period between 2010-2013. On the average, the expected number of cases among the 600,000 foreigner tourists during the World Cup is 33, varying from 3-59. Such risk estimates will not only benefit individual travellers for adequate pre-travel preparations, but also provide valuable information for public health professionals and policy makers worldwide. Furthermore, estimates of dengue cases in international travellers during the World Cup can help to anticipate the theoretical risk for exportation of dengue into currently non-infected areas.
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| 7. |
- Nascimento, Francisco J. A., et al.
(författare)
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Diversity of larger consumers enhances interference competition effects on smaller competitors
- 2011
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 166:2, s. 337-347
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Tidskriftsartikel (refereegranskat)abstract
- Competition between large and small species for the same food is common in a number of ecosystems including aquatic ones. How diversity of larger consumers affects the access of smaller competitors to a limiting resource is not well understood. We tested experimentally how species richness (0-3 spp.) of benthic deposit-feeding macrofauna changes meiofaunal ostracods' incorporation of fresh organic matter from a stable-isotope-labeled cyanobacterial bloom, using fauna from the species-poor Baltic Sea. Presence of macrofauna mostly decreased meiofaunal incorporation of bloom material, depending on the macrofauna species present. As expected, the species identity of macrofauna influenced the incorporation of organic matter by meiofauna. Interestingly, our results show that, in addition, species richness of the macrofauna significantly reduced meiofauna incorporation of freshly settled nitrogen and carbon. With more than one macrofauna species, the reduction was always greater than expected from the single-species treatments. Field data from the Baltic Sea showed a negative correlation between macrofauna diversity and meiofaunal ostracod abundance, as expected from the experimental results. We argue that this is caused by interference competition, due to spatial niche differentiation between macrofauna species reducing the sediment volume in which ostracods can feed undisturbed by larger competitors. Interference from macrofauna significantly reduces organic matter incorporation by meiofauna, indicating that diversity of larger consumers is an important factor controlling the access of smaller competitors to a limiting food resource.
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| 8. |
- Nascimento, Francisco J. A., et al.
(författare)
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Meiofauna enhances organic matter mineralization in soft sediment ecosystems
- 2012
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Ingår i: Limnology and Oceanography. - : Wiley. - 0024-3590 .- 1939-5590. ; 57:1, s. 338-346
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the influence of meiofauna on the benthic decomposition of a radiolabeled diatom bloom by measuring the production of (CO2)-C-14 in a laboratory microcosm. Mineralization of the diatom bloom material in the sediment was significantly enhanced in the treatment with high meiofauna abundance, with cumulative mineralization values, on average, 50% greater in the treatment with high meiofaunal abundance after 17 d, compared to sediments with low meiofauna abundance. In addition, bacteria species composition in the treatment with high meiofauna abundance was significantly different from the treatment with low meiofauna abundance, indicating that the activities of meiofauna in the sediments had an effect on the bacterial community composition. Meiofauna can enhance the mineralization of organic matter, probably by stimulating the activity of sediment bacterial community, indicating that positive biological interactions such as facilitation from meiofauna are important for ecosystem processes in soft sediments.
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| 9. |
- Nascimento, Francisco J.A.
(författare)
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Trophic ecology of meiofauna : Response to sedimentation of phytoplankton blooms in the Baltic Sea
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Marine soft sediments are the second largest habitat on Earth. How animal communities in this habitat are structured is a central issue in marine ecology. Food is an important limiting factor for many benthic populations, and settling organic matter from phytoplankton blooms is of vital importance to them. This thesis discusses the effects of settling phytoplankton blooms on benthic meiofaunal populations in the Baltic Sea and how species interactions affect the fate of settled organic matter. Eutrophication in the Baltic Sea has altered phytoplankton community dynamics, with indications that toxin-producing cyanobacterial blooms may reach the benthos in greater quantity than previously. Paper I found that meiofauna feed on settled cyanobacteria, yet suffer no increase in mortality. However, growth of meiofauna is significantly slower on a diet of cyanobacteria than when fed spring bloom diatoms, indicating that the studied cyanobacteria are nutritionally poor (Paper II). In Paper III we found that the presence of macrofauna reduces the access of meiofauna to settled organic matter, presumably through interference competition that increases when several macrofauna species are present. We also found that meiofaunal populations influence the provision of ecosystem services by benthic microbes. Paper IV shows that when meiofauna is abundant, mineralization of organic matter is positively affected, presumably through facilitation mechanisms. In contrast, paper V reports that degradation of the contaminant naphtalene decreases significantly at high meiofauna abundance.In conclusion, this thesis shows that type and quality of organic matter available, as well as competition from macrofauna, affect how meiofauna grow and incorporate nutrients. Furthermore we found meiofauna to be an important functional component of the benthic ecosystem, with marked effects on ecosystem processes such as nutrient regeneration and contaminant degradation.
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| 10. |
- Nascimento, Francisco, et al.
(författare)
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Meiofauna enhances organic matter mineralization in soft sediment ecosystems
- 2010
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Organic matter mineralization in soft sediments is a key process mediated by benthic fauna and bacteria that is crucial for sustaining primary production in aquatic systems. Few studies have examined the effect of meiofauna on the degradation of labile organic matter in soft sediments. Here we investigated the influence of meiofauna on the benthic decomposition of a radiolabelled diatom bloom by measuring the production of 14CO2 in a laboratory microcosm. Mineralization of the diatom bloom material was significantly enhanced when meiofauna was present in higher abundances, with cumulative mineralization values after 17 days being on average 50% greater in the treatment with high meiofauna abundance compared to sediments with low meiofauna abundance. Our experiment shows that meiofauna can enhance the mineralization of organic matter, probably by stimulating the activity of sediment bacterial community, indicating that positive biological interactions such as facilitation from meiofauna are important for ecosystem processes in soft sediments.
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