1,721,772 research outputs found
Adaptation and acclimatization to ocean acidification in marine ectotherms: An in situ transplant experiment with polychaetes at a shallow CO2 vent system
No full textMetabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO2. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO2 vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO2. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO2, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO2 environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO2. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification. © 2013 The Author(s) Published by the Royal Society. All rights reserved
Morphological plasticity in a calcifying modular organism: Evidence from an in situ transplant experiment in a natural CO2 vent system
No full textUnderstanding is currently limited of the biological processes underlying the responses of modular organisms to climate change and the potential to adapt through morphological plasticity related to their modularity. Here, we investigate the effects of ocean acidification and seawater warming on the growth, life history and morphological plasticity in the modular bryozoan Calpensia nobilis using transplantation experiments in a shallow Mediterranean volcanic CO2 vents system that simulates pH values expected for the year 2100. Colonies exposed at vent sites grew at approximately half the rate of those from the control site. Between days 34 and 48 of the experiment, they reached a possible ‘threshold’, due to the combined effects of exposure time and pH. Temperature did not affect zooid length, but longer zooids with wider primary orifices occurred in low pH conditions close to the vents. Growth models describing colony development under different environmental scenarios suggest that stressed colonies of C. nobilis reallocate metabolic energy to the consolidation and strengthening of existing zooids. This is interpreted as a change in life-history strategy to support persistence under unfavourable environmental conditions. Changes in the skeletal morphology of zooids evident in C. nobilis during short-time (87 days) exposure experiments reveal morphological plasticity that may indicate a potential to adapt to the more acidic Mediterranean predicted for the future. © 2015 The Authors
Settlement pattern of Posidonia oceanica epibionts along a gradient of ocean acidification: An approach with mimics
No full textEffects of ocean acidification (OA on the colonization/settlement pattern of the epibiont community of the leaves and rhizomes of the Mediterranean seagrass, Posidonia oceanica, have been studied at volcanic CO2 vents off Ischia (Italy), using "mimics" as artificial substrates. The experiments were conducted in shallow Posidonia stands (2-3 m depth), in three stations on the north and three on the south sides of the study area, distributed along a pH gradient. At each station, 4 rhizome mimics and 6 artificial leaves were collected every three months (Sept 2009-Sept 2010). The epibionts on both leaf and rhizome mimics showed clear changes along the pH gradient; coralline algae and calcareous invertebrates (bryozoans, serpulid polychaetes and barnacles) were dominant at control stations but progressively disappeared at the most acidified stations. In these extremely low pH sites the assemblage was dominated by filamentous algae and non calcareous taxa such as hydroids and tunicates. Settlement pattern on the artificial leaves and rhizome mimics over time showed a consistent distribution pattern along the pH gradient and highlighted the peak of recruitment of the various organisms in different periods according to their life history. Posidonia mimics at the acidified station showed a poor and very simplified assemblage where calcifying epibionts seemed less competitive for space. This profound difference in epiphyte communities in low pH conditions suggests cascading effects on the food web of the meadow and, consequently, on the functioning of the system
Low pH conditions impair module capacity to regenerate in a calcified colonial invertebrate, the bryozoan Cryptosula pallasiana
No full textMany aquatic animals grow into colonies of repeated, genetically identical, modules (zooids). Zooid interconnections enable colonies to behave as integrated functional units, while plastic responses to environmental changes may affect individual zooids. Plasticity includes the variable partitioning of resources to sexual reproduction, colony growth and maintenance. Maintenance often involves regeneration, which is also a routine part of the life history in some organisms, such as bryozoans. Here we investigate changes in regenerative capacity in the encrusting bryozoan Cryptosula pallasiana when cultured at different seawater pCO2 levels. The proportion of active zooids showing polypide regeneration was highest at current oceanic pH (8.1), but decreased progressively as pH declined below that value, reaching a six-fold reduction at pH 7.0. The zone of budding of new zooids at the colony periphery declined in size below pH 7.7. Under elevated pCO2 conditions, already experienced sporadically in coastal areas, skeletal corrosion was accompanied by the proportional reallocation of resources from polypide regeneration in old zooids to the budding of new zooids at the edge of the colony. Thus, future ocean acidification can affect colonial organisms by changing how they allocate resources, with potentially profound impacts on life-history patterns and ecological interactions. © 2017 Elsevier Lt
Italian Multicenter Cross-Sectional Study (AISAG) on light smoking and allergic diseases in adults
No full textAllergic rhinitis, allergic dermatitis, and food allergy are extremely common diseases and are frequently associated to each other and to asthma. Smoking is a potential risk factor for these conditions, but so far, results from individual studies have been conflicting. On the basis of these contradictory data in the literature we have carried out a multicenter cross-sectional study to evaluate the relationship between some allergic conditions and exposure or not to active light smoking. The study was carried out between May 2013 and November 2013 in 22 different Italian hospitals. Patients with respiratory and/or food allergy, and aged 18 years and over, visited at Allergy Outpatient Clinics, were invited to participate. A total of 1586 allergic patients (21.6% smokers) with a mean age of 39.2 years (standard deviation, SD = 15.1) were included. We demonstrated that the prevalence of tobacco smoking was higher in patients with food allergy and in asthmatic patients in stage III-IV. But no other statistical differences were found at univariate analysis. The sensitization patterns of non-smokers and smokers were similar. Furthermore, tobacco smoking was associated with higher risk of food allergy and lower risk of asthma. Moreover, tobacco smoking was an independent risk factor for persistent respect to intermittent rhinitis, and for asthma GINA stage III-IV with respect to stage I-II
Biomineralization in bryozoans: Present, past and future
No full textMany animal phyla have the physiological ability to produce biomineralized skeletons with functional roles that have been shaped by natural selection for more than 500 million years. Among these are bryozoans, a moderately diverse phylum of aquatic invertebrates with a rich fossil record and importance today as bioconstructors in some shallow-water marine habitats. Biomineralizational patterns and, especially, processes are poorly understood in bryozoans but are conventionally believed to be similar to those of the related lophotrochozoan phyla Brachiopoda and Mollusca. However, bryozoan skeletons are more intricate than those of these two phyla. Calcareous skeletons have been acquired independently in two bryozoan clades - Stenolaemata in the Ordovician and Cheilostomata in the Jurassic - providing an evolutionary replicate. This review aims to highlight the importance of biomineralization in bryozoans and focuses on their skeletal ultrastructures, mineralogy and chemistry, the roles of organic components, the evolutionary history of bimineralization in bryozoans with respect to changes in seawater chemistry, and the impact of contemporary global changes, especially ocean acidification, on bryozoan skeletons. Bryozoan skeletons are constructed from three different wall types (exterior, interior and compound) differing in the presence/absence and location of organic cuticular layers. Skeletal ultrastructures can be classified into wall-parallel (i.e. laminated) and wall-perpendicular (i.e. prismatic) fabrics, the latter apparently found in only one of the two biomineralizing clades (Cheilostomata), which is also the only clade to biomineralize aragonite. A plethora of ultrastructural fabrics can be recognized and most occur in combination with other fabrics to constitute a fabric suite. The proportion of aragonitic and bimineralic bryozoans, as well as the Mg content of bryozoan skeletons, show a latitudinal increase into the warmer waters of the tropics. Responses of bryozoan mineralogy and skeletal thickness to oscillations between calcite and aragonite seas through geological time are equivocal. Field and laboratory studies of living bryozoans have shown that predicted future changes in pH (ocean acidification) combined with global warming are likely to have detrimental effects on calcification, growth rate and production of polymorphic zooids for defence and reproduction, although some species exhibit reasonable levels of resilience. Some key questions about bryozoan biomineralization that need to be addressed are identified. Biological Reviews © 2015 Cambridge Philosophical Society
A comparison of life-history traits in calcifying Spirorbinae polychaetes living along natural pH gradients
No full textLow-pH vent systems are ideal natural laboratories to study the consequences of long-term low-pH exposure on marine species and thus identify life-history traits associated with low-pH tolerance. This knowledge can help to inform predictions on which types of species may be less vulnerable in future ocean acidification (OA) scenarios. Accordingly, we investigated how traits of calcifying polychaete species (Serpulidae, Spirorbinae) varied with pH using a functional trait analysis at 2 natural pH gradients around the Castello Aragonese islet off Ischia, Italy. We first observed the distribution and abundance patterns of all calcifying polychaete epiphytes in the canopy of Posidonia oceanica seagrass across these gradients. We then used laboratory trials to compare fecundity, settlement success, and juvenile survival in the dominant species from a control (Pileolaria militaris Claparède, 1870) and a low-pH site (Simplaria sp.). We found significantly higher reproductive output, juvenile settlement rates, and juvenile survival in Simplaria sp. individuals from the low-pH site, compared to P. militaris individuals from control pH sites, when observed in their respective in situ pH conditions. Our results suggest that tolerance to low pH may result, in part, from traits associated with successful reproduction and rapid settlement under low-pH conditions. This finding implies that other species with similar life-history traits may respond similarly, and should be targeted for future OA tolerance research. © Inter-Research 2018
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
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