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Dataset in support of the journal paper 'Evidence of nitrification associated with globally distributed pelagic jellyfish"'
No full textRaw nutrient data used in the paper "Evidence of nitrification associated with globally distributed pelagic jellyfish" Published in Limnology and Oceanography https://doi.org/10.1002/lno.11736</span
Dataset in support of the paper "Similarities between the biochemical composition of jellyfish body and mucus"
No full textRaw data used in the paper "Similarities between the biochemical composition of jellyfish body and mucus" Published in Journal of Plankton Research
https://doi.org/10.1093/plankt/fbab091</span
Investigating the role and interaction of jellyfish blooms and microbes in nutrient cycling and ecosystem productivity.
No full textNutrients, particularly nitrogen and phosphorus, play a major role in stimulating primary production, which in turn supports ecosystem productivity by providing organic matter to the marine food chain. While flowing towards higher trophic levels, organic matter is partially remineralised by heterotrophic microbes supplying nutrients back to primary producers. In coastal areas, jellyfish blooms represent a significant but largely overlooked source of organic matter that can impact microbial communities and ecosystem productivity via processes such as the excretion of dissolved inorganic nutrients (ammonium and phosphate) and dissolved organic matter (mucus). The overall objective of this thesis was to investigate the combined role of jellyfish and microbes in nutrient cycling and the consequences for ecosystem productivity, using a combination of incubations experiments and analytical measurements. I show evidence of microbes living in association with jellyfish thriving by oxidizing up to one-third of the ammonia excreted by their host to nitrite and nitrate. The results showed that the jellyfish-associated release of nitrogen can provide more than 100% of the nitrogen required for primary production and revealed a new pathway for pelagic nitrification. I also highlight the macromolecular and elemental similarity between the jellyfish body and mucus compositions and provide biochemical ratios to support the integration of jellyfish into trophic and biogeochemical models. To further investigate the jellyfish mucus, I finally show that jellyfish mucus is a source of organic and inorganic nutrients that is quickly utilised by microbes albeit at a low growth efficiency. These results suggest that jellyfish blooms and their associated microbes can locally support primary production while inducing changes in nutrient stoichiometry and microbial community composition. Overall, this thesis provides data and equations particularly suitable for the integration of jellyfish bloom populations into marine ecosystem models, which is essential to better understand and quantify their effects on the structure and function of coastal ecosystems
Environmental control of asexual reproduction and somatic growth of <em>Aurelia</em> spp. (Cnidaria, Scyphozoa) polyps from the Adriatic Sea
Get PDFPolyps of two moon jellyfish species, Aurelia coerulea and A.relicta, from two Adriatic Sea coastal habitats were incubated under multiple combinations of temperature (14, 21 °C), salinity (24, 37 ppt) and food regime (9.3, 18.6, 27.9 μg C ind‾¹ week‾¹) to comparatively assess how these factors may influence major asexual reproduction processes in the two species. Both species exhibited a shared pattern of budding mode (Directly Budded Polyps: DBP; Stolonal Budded Polyps: SBP), with DBP favoured under low food supply (9.3 μg C ind ‾1 week‾1) and low temperature (14 °C), and SBP dominant under high temperature (21 °C). However, A. coerulea showed an overall higher productivity than A. relicta, in terms of budding and podocyst production rates. Further, A. coerulea exhibited a wide physiological plasticity across different temperatures and salinities as typical adaptation to ecological features of transitional coastal habitats. This may support the hypothesis that the invasion of A. coerulea across coastal habitats worldwide has been driven by shellfish aquaculture, with scyphistoma polyps and resting stages commonly found on bivalve shells. On the contrary, A. relicta appears to be strongly stenovalent, with cold, marine environmental optimal preferences (salinity 37 ppt , T ranging 14-19 °C), corroborating the hypothesis of endemicity within the highly peculiar habitat of the Mljet lake. By exposing A. relicta polyps to slightly higher temperature (21 °C), a previously unknown developmental mode was observed, by the sessile polyp regressing into a dispersive, temporarily unattached and tentacle-less, non-feeding stage. This may allow A. relicta polyps to escape climatic anomalies associated to warming of surface layers and deepening of isotherms, by moving into deeper, colder layers. Overall, investigations on species-specific eco-physiological and ontogenetic potentials of polyp stages may contribute to clarify the biogeographic distribution of jellyfish and the phylogenetic relationships among evolutionary related sister clades
Similarities between the biochemical composition of jellyfish body and mucus
No full textRecognition of the importance of jellyfish in marine ecosystems is growing. Yet, the biochemical composition of the mucus that jellyfish constantly excrete is poorly characterized. Here we analyzed the macromolecular (proteins, lipids and carbohydrates) and elemental (carbon and nitrogen) composition of the body and mucus of five scyphozoan jellyfish species (Aurelia aurita, Chrysaora fulgida, Chrysaora pacifica, Eupilema inexpectata and Rhizostoma pulmo). We found that the relative contribution of the different macromolecules and elements in the jellyfish body and mucus was similar across all species, with protein being the major component in all samples (81 ± 4% of macromolecules; 3.6 ± 3.1% of dry weight, DW) followed by lipids (13 ± 4% of macromolecules; 0.5 ± 0.4%DW) and carbohydrates (6 ± 3% of macromolecules; 0.3 ± 0.4%DW). The energy content of the jellyfish matter ranged from 0.2 to 3.1 KJ g−1 DW. Carbon and nitrogen content was 3.7 ± 3.0 and 1.0 ± 0.8%DW, respectively. The average ratios of protein:lipid:carbohydrate and carbon:nitrogen for all samples were 14.6:2.3:1 and 3.8:1, respectively. Our study highlights the biochemical similarity between the jellyfish body and mucus and provides convenient and valuable ratios to support the integration of jellyfish into trophic and biogeochemical models
Jellyfish in coastal ecosystems: advances in our understanding of population drivers, role in biogeochemical cycling, and socio-economic impacts
No full textJellyfish (herein, cnidarians and ctenophores) are natural members of marine ecosystems, and are widely distributed in the coastal zone. Flexibility in their physiology, trophic ecology and life history enable several species to form population outbreaks or blooms. Because of the potential impacts blooms have on ecosystem structure and function and human activities, research focuses on understanding their causes and consequences. A brief introduction to jellyfish research from the last 20 years is followed by three areas of recent research: 1) In the complex metagenic life cycle of scyphozoans, which life-stages(s) are the key determinants of population fluctuation? 2) What is the role of jellyfish in nutrient cycling and ecosystem productivity? 3) How are jellyfish detrimental and beneficial to human activity
Evidence of nitrification associated with globally distributed pelagic jellyfish
Get PDFBioavailable nitrogen is a scarce resource in most of the surface oceanand often limits primary productivity. Although Pelagic jellyfish excretesubstantial amounts of ammonia (the preferred form of nitrogen formost phytoplankton), they are overlooked players in marine nitrogencycling. Here, we observed high rates of nitrification (NH4+ → NO3-, 5.7– 40.8 nM gWW-1 (wet weight) h-1) associated with the scyphomedusaeAurelia aurita, Chrysaora hysoscella and Chrysaora pacifica and low ratesof incomplete nitrification (NH4+ → NO2-, 1-2.7 nM gWW-1 h-1)associated with Chrysaora fulgida, Chrysaora hysoscella and Chrysaorapacifica. These observations indicate that microbes living in associationwith the jellyfish thrive by oxidizing the readily available ammonia tonitrite and nitrate. The four studied species are abundant over a largegeographic distribution and exhibit frequent population outbreaks. Weshow that, during such outbreaks, jellyfish-associated release of nitrogencan provide more than 100% of the nitrogen required for primaryproduction. These findings reveal a so far overlooked pathway whenassessing pelagic nitrification rates that might be of particular relevancein nitrogen depleted surface waters and at high jellyfish populationdensities
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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