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1.
Harmful Algae ; 91: 101632, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32057342

RESUMO

There is increasing concern that accelerating environmental change attributed to human-induced warming of the planet may substantially alter the patterns, distribution and intensity of Harmful Algal Blooms (HABs). Changes in temperature, ocean acidification, precipitation, nutrient stress or availability, and the physical structure of the water column all influence the productivity, composition, and global range of phytoplankton assemblages, but large uncertainty remains about how integration of these climate drivers might shape future HABs. Presented here are the collective deliberations from a symposium on HABs and climate change where the research challenges to understanding potential linkages between HABs and climate were considered, along with new research directions to better define these linkages. In addition to the likely effects of physical (temperature, salinity, stratification, light, changing storm intensity), chemical (nutrients, ocean acidification), and biological (grazer) drivers on microalgae (senso lato), symposium participants explored more broadly the subjects of cyanobacterial HABs, benthic HABs, HAB effects on fisheries, HAB modelling challenges, and the contributions that molecular approaches can bring to HAB studies. There was consensus that alongside traditional research, HAB scientists must set new courses of research and practices to deliver the conceptual and quantitative advances required to forecast future HAB trends. These different practices encompass laboratory and field studies, long-term observational programs, retrospectives, as well as the study of socioeconomic drivers and linkages with aquaculture and fisheries. In anticipation of growing HAB problems, research on potential mitigation strategies should be a priority. It is recommended that a substantial portion of HAB research among laboratories be directed collectively at a small sub-set of HAB species and questions in order to fast-track advances in our understanding. Climate-driven changes in coastal oceanographic and ecological systems are becoming substantial, in some cases exacerbated by localized human activities. That, combined with the slow pace of decreasing global carbon emissions, signals the urgency for HAB scientists to accelerate efforts across disciplines to provide society with the necessary insights regarding future HAB trends.

2.
J Appl Toxicol ; 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31960457

RESUMO

Environmental contamination can negatively impact fish populations. In addition to acute toxicity leading to death, toxicants can reduce fish growth and lower reproduction. The potential for adverse population level effects of environmental contaminants are estimated to conduct risk assessments from laboratory toxicity tests that most often measure apical endpoints related to growth, survival and reproduction. The relationships between these effect endpoints are being evaluated to predict shifts in fish population demography better after exposure to environmental toxicants. Environmental contaminants can also affect fish populations indirectly by reducing prey biomass. However, estimating the magnitude of the combined effects of prey reduction and direct toxicity is difficult and rarely attempted. Here we describe a toxicity test designed to estimate the effect on Japanese medaka of both reduced food and chronic exposure to diazinon, an acetylcholinesterase inhibiting organophosphate pesticide. Fish were reared with limited food ration and/or diazinon exposure through a full life cycle to assess possible interactions between the two stressors in their effects on growth and reproduction. Diazinon exposure (10 or 20 µg/L), reduced ration (50% and 25% of ad libitum), or combinations of both lowered growth rates and reproductive output of Japanese medaka. In addition, growth and reproduction alone were modeled, and then various relationships between the two stressors (diazinon and ration) and how they relate to growth and reproduction were modeled.

3.
Mar Drugs ; 18(2)2020 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-31991871

RESUMO

:A bibliographic database of scientific papers published by authors affiliated worldwide, especially focused in Europe and in the European Atlantic Area, and containing the keywords "microalga(e)" or "phytoplankton" was built. A corpus of 79,020 publications was obtained and analyzed using the Orbit Intellixir software to highlight the evolution of the research domain. Publication rates from 1960 to 2019, organization of the research, collaboration networks between countries and organizations, emerging and fading research concepts, major studied species, and associated concepts, as well as journals publishing microalgae research were considered. As a result, of the 79,020 papers published worldwide, 26,137 included authors from Europe (33% of world production) and 6989 from the European Atlantic Area (AA) (27% of European production, 9% of world production). The main worldwide scientific research topics found in this study were phytoplankton, community, bloom, diatoms, distribution, ecosystem, coastal, chlorophyll, zooplankton, photosynthesis, and primary production. At the European scale, the most studied topics were related to the environment, food, chemicals, pigments, protein, feed, and drugs. The highest scientific trends and market opportunities analysis identified bioplastics and biostimulants as top emerging concepts at the European level and agricultural, animal feed, and blue biotechnology at the European AA level.

4.
Neuron ; 103(6): 1073-1085.e6, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31400829

RESUMO

Injured axons fail to regenerate in the adult CNS, which contrasts with their vigorous growth during embryonic development. We explored the potential of re-initiating axon extension after injury by reactivating the molecular mechanisms that drive morphogenetic transformation of neurons during development. Genetic loss- and gain-of-function experiments followed by time-lapse microscopy, in vivo imaging, and whole-mount analysis show that axon regeneration is fueled by elevated actin turnover. Actin depolymerizing factor (ADF)/cofilin controls actin turnover to sustain axon regeneration after spinal cord injury through its actin-severing activity. This pinpoints ADF/cofilin as a key regulator of axon growth competence, irrespective of developmental stage. These findings reveal the central role of actin dynamics regulation in this process and elucidate a core mechanism underlying axon growth after CNS trauma. Thereby, neurons maintain the capacity to stimulate developmental programs during adult life, expanding their potential for plasticity. Thus, actin turnover is a key process for future regenerative interventions.

5.
J Am Med Inform Assoc ; 26(10): 920-927, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31321427

RESUMO

OBJECTIVE: The purpose of this study was to determine if medication cost transparency alerts provided at time of prescribing led ambulatory prescribers to reduce their use of low-value medications. MATERIALS AND METHODS: Provider-level alerts were deployed to ambulatory practices of a single health system from February 2018 through April 2018. Practice sites included 58 primary care and 152 specialty care clinics totaling 1896 attending physicians, residents, and advanced practice nurses throughout western Washington. Prescribers in the randomly assigned intervention arm received a computerized alert whenever they ordered a medication among 4 high-cost medication classes. For each class, a lower cost, equally effective, and safe alternative was available. The primary outcome was the change in prescribing volume for each of the 4 selected medication classes during the 12-week intervention period relative to a prior 24-week baseline. RESULTS: A total of 15 456 prescriptions for high-cost medications were written during the baseline period including 7223 in the intervention arm and 8233 in the control arm. During the intervention period, a decrease in daily prescribing volume was noted for all high-cost medications including 33% for clobetasol propionate (p < .0001), 59% for doxycycline hyclate (p < .0001), 43% for fluoxetine tablets (p < .0001), and a non-significant 3% decrease for high-cost triptans (p = .65). Prescribing volume for the high-cost medications overall decreased by 32% (p < .0001). CONCLUSION: Medication cost transparency alerts in an ambulatory setting lead to more cost-conscious prescribing. Future work is needed to predict which alerts will be most effective.

7.
Mar Biol ; 165(9): 147, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30220737

RESUMO

Stable isotope ratios (SIR) are widely used to estimate food-web trophic levels (TLs). We built systems dynamic N-biomass-based models of different levels of complexity, containing explicit descriptions of isotope fractionation and of trophic level. The values of δ15N and TLs, as independent and emergent properties, were used to test the potential for the SIR of nutrients, primary producers, consumers, and detritus to align with food-web TLs. Our analysis shows that there is no universal relationship between TL and δ15N that permits a robust prognostic tool for configuration of food webs even if all system components can be reliably analysed. The predictive capability is confounded by prior dietary preference, intra-guild predation and recycling of biomass through detritus. These matters affect the dynamics of both the TLs and SIR. While SIR data alone have poor explanatory power, they would be valuable for validating the construction and functioning of dynamic models. This requires construction of coupled system dynamic models that describe bulk elemental distribution with an explicit description of isotope discriminations within and amongst functional groups and nutrient pools, as used here. Only adequately configured models would be able to explain both the bulk elemental distributions and the SIR data. Such an approach would provide a powerful test of the whole model, integrating changing abiotic and biotic events across time and space.

8.
Ecotoxicol Environ Saf ; 162: 438-445, 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30015190

RESUMO

The Medaka Extended One Generation Reproduction Test (MEOGRT) is a Tier 2 test within U.S. Environmental Protection Agency's (USEPA) Endocrine Disruptor Screening Program (EDSP), designed to characterize the potential adverse effects to fish of exposure to chemical that can cause disruption of the endocrine system. The MEOGRT focuses primarily on adverse effects to reproduction while collecting information regarding effects on growth, survival, and endocrine-related endpoints. However, the risk assessment process for fish, as mandated by legislation such as the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) or the Toxic Substances Control Act (TSCA), could benefit from a more detailed assessment of effects on growth. Typically, fish growth data in support of risk assessment are obtained from full life-cycle tests or early life stage tests using the fathead minnow. As an alternative to these tests, a modified MEOGRT was conducted to assess the effects of diazinon on the various parameters measured in the MEOGRT. Diazinon is an organophosphate insecticide that is detected in the environment, and whose efficacy is a result of inhibition of the acetylcholine esterase enzyme at neuromuscular junctions and synapses of the nervous system. Diazinon (2.9, 5.2, 10.3, 19.8, and 40.2 µg/L) was tested with the MEOGRT protocol, and the lowest observable effect concentrations of 2.9 µg/L for fecundity and 5.2 µg/L for growth were determined. Additional growth measurements were added to the MEOGRT protocol to more robustly define growth rates and to determine the impact size has on reproductive performance. Fish size starting at the first measurement day (i.e. 21 days post-fertilization), and continuing through the duration of the test was reduced with exposure to 5.2 µg/L and higher, and asymptotic size predicted from growth modeling was reduced at 10.3 µg/L and higher. By simply adding non-destructive growth measurements at two additional time points, the MEOGRT provided enough data for the parameterization of growth models, which could be used to characterize the reproductive implications of growth impairment.


Assuntos
Diazinon/toxicidade , Disruptores Endócrinos/toxicidade , Exposição Ambiental/efeitos adversos , Fertilidade/efeitos dos fármacos , Oryzias/fisiologia , Praguicidas/toxicidade , Reprodução/efeitos dos fármacos , Animais , Cyprinidae/fisiologia , Sistema Endócrino/efeitos dos fármacos , Feminino , Fungicidas Industriais/toxicidade , Inseticidas/toxicidade , Estágios do Ciclo de Vida , Masculino , Organofosfatos/toxicidade , Oryzias/crescimento & desenvolvimento , Estados Unidos , United States Environmental Protection Agency
9.
J Urol ; 200(4): 843-847, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29654804

RESUMO

PURPOSE: In this study we aimed to define the prevalence of preoperative and postoperative post-micturition incontinence or post-void dribbling after anterior urethroplasty for urethral stricture disease. We also sought to determine risk factors for its presence. MATERIALS AND METHODS: We retrospectively reviewed a prospectively maintained, multi-institutional urethral stricture database to evaluate post-micturition incontinence using a single question from a validated questionnaire, "How often have you had a slight wetting of your pants a few minutes after you had finished urinating and had dressed yourself?" Possible answers were never-0 to all the time-3. The presence of post-micturition incontinence was defined as any answer greater than 0. Comparisons were made to stricture type and location, repair type and patient medical comorbidities. RESULTS: Preoperative and postoperative post-micturition incontinence questionnaires were completed by 614 and 331 patients, respectively. Patients without complete data available were excluded from study. Preoperative post-micturition incontinence was present in 73% of patients, of whom 44% stated that this symptom was present most of the time. Overall postoperative post-micturition incontinence was present in 40% of patients and again it was not predicted by stricture location or urethroplasty type. Of the 331 patients with followup questionnaires 60% reported improvement, 32% reported no change and 8% reported worsening symptoms. The overall rate of de novo post-micturition incontinence was low at 6.3%. CONCLUSIONS: The prevalence of preoperative post-micturition incontinence is high and likely under reported. In most patients post-micturition incontinence improves after urethroplasty and the prevalence of de novo post-micturition incontinence is low. The presence of post-micturition incontinence was not predicted by stricture length or location, or urethroplasty repair type.


Assuntos
Complicações Pós-Operatórias/epidemiologia , Uretra/cirurgia , Estreitamento Uretral/cirurgia , Incontinência Urinária de Urgência/epidemiologia , Adulto , Idoso , Estudos de Coortes , Bases de Dados Factuais , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Minimamente Invasivos/efeitos adversos , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Complicações Pós-Operatórias/diagnóstico , Prevalência , Estudos Retrospectivos , Inquéritos e Questionários , Fatores de Tempo , Estreitamento Uretral/diagnóstico por imagem , Incontinência Urinária de Urgência/etiologia , Micção , Procedimentos Cirúrgicos Urológicos Masculinos/efeitos adversos , Procedimentos Cirúrgicos Urológicos Masculinos/métodos
10.
PLoS Comput Biol ; 14(4): e1006118, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29702650

RESUMO

Nutrient acquisition is a critical determinant for the competitive advantage for auto- and osmohetero- trophs alike. Nutrient limited growth is commonly described on a whole cell basis through reference to a maximum growth rate (Gmax) and a half-saturation constant (KG). This empirical application of a Michaelis-Menten like description ignores the multiple underlying feedbacks between physiology contributing to growth, cell size, elemental stoichiometry and cell motion. Here we explore these relationships with reference to the kinetics of the nutrient transporter protein, the transporter rate density at the cell surface (TRD; potential transport rate per unit plasma-membrane area), and diffusion gradients. While the half saturation value for the limiting nutrient increases rapidly with cell size, significant mitigation is afforded by cell motion (swimming or sedimentation), and by decreasing the cellular carbon density. There is thus potential for high vacuolation and high sedimentation rates in diatoms to significantly decrease KG and increase species competitive advantage. Our results also suggest that Gmax for larger non-diatom protists may be constrained by rates of nutrient transport. For a given carbon density, cell size and TRD, the value of Gmax/KG remains constant. This implies that species or strains with a lower Gmax might coincidentally have a competitive advantage under nutrient limited conditions as they also express lower values of KG. The ability of cells to modulate the TRD according to their nutritional status, and hence change the instantaneous maximum transport rate, has a very marked effect upon transport and growth kinetics. Analyses and dynamic models that do not consider such modulation will inevitably fail to properly reflect competitive advantage in nutrient acquisition. This has important implications for the accurate representation and predictive capabilities of model applications, in particular in a changing environment.


Assuntos
Modelos Biológicos , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/fisiologia , Transporte Biológico Ativo , Carbono/metabolismo , Biologia Computacional , Alimentos , Cinética , Consórcios Microbianos , Fenômenos Microbiológicos , Movimento/fisiologia , Fitoplâncton/citologia
11.
Nat Commun ; 9(1): 74, 2018 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-29311545

RESUMO

Photosynthesis by marine diatoms plays a major role in the global carbon cycle, although the precise mechanisms of dissolved inorganic carbon (DIC) uptake remain unclear. A lack of direct measurements of carbonate chemistry at the cell surface has led to uncertainty over the underlying membrane transport processes and the role of external carbonic anhydrase (eCA). Here we identify rapid and substantial photosynthesis-driven increases in pH and [CO32-] primarily due to the activity of eCA at the cell surface of the large diatom Odontella sinensis using direct simultaneous microelectrode measurements of pH and CO32- along with modelling of cell surface inorganic carbonate chemistry. Our results show that eCA acts to maintain cell surface CO2 concentrations, making a major contribution to DIC supply in O. sinensis. Carbonate chemistry at the cell surface is therefore highly dynamic and strongly dependent on cell size, morphology and the carbonate chemistry of the bulk seawater.


Assuntos
Carbonatos/metabolismo , Microambiente Celular , Diatomáceas/metabolismo , Fitoplâncton/metabolismo , Transporte Biológico , Carbono/química , Carbono/metabolismo , Dióxido de Carbono/química , Dióxido de Carbono/metabolismo , Carbonatos/química , Anidrases Carbônicas/metabolismo , Diatomáceas/citologia , Concentração de Íons de Hidrogênio , Modelos Biológicos , Fotossíntese , Fitoplâncton/citologia , Água do Mar/química
12.
J Appl Phycol ; 29(6): 2713-2727, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29213181

RESUMO

Algal biofuels have been offered as an alternative to fossil fuels, based on claims that microalgae can provide a highly productive source of compounds as feedstocks for sustainable transport fuels. Life cycle analyses identify algal productivity as a critical factor affecting commercial and environmental viability. Here, we use mechanistic modelling of the biological processes driving microalgal growth to explore optimal production scenarios in an industrial setting, enabling us to quantify limits to algal biofuels potential. We demonstrate how physiological and operational trade-offs combine to restrict the potential for solar-powered algal-biodiesel production in open ponds to a ceiling of ca. 8000 L ha-1 year-1. For industrial-scale operations, practical considerations limit production to ca. 6000 L ha-1 year-1. According to published economic models and life cycle analyses, such production rates cannot support long-term viable commercialisation of solar-powered cultivation of natural microalgae strains exclusively as feedstock for biofuels. The commercial viability of microalgal biofuels depends critically upon limitations in microalgal physiology (primarily in rates of C-fixation); we discuss the scope for addressing this bottleneck concluding that even deployment of genetically modified microalgae with radically enhanced characteristics would leave a very significant logistical if not financial burden.

13.
Environ Toxicol Chem ; 36(12): 3387-3403, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28857258

RESUMO

In response to various legislative mandates, the US Environmental Protection Agency (USEPA) formed its Endocrine Disruptor Screening Program (EDSP), which in turn, formed the basis of a tiered testing strategy to determine the potential of pesticides, commercial chemicals, and environmental contaminants to disrupt the endocrine system. The first tier of tests is intended to detect the potential for endocrine disruption mediated through estrogen, androgen, or thyroid pathways, whereas the second tier is intended to further characterize the effects on these pathways and to establish a dose-response relationship for adverse effects. One of these tier 2 tests, the Medaka Extended One Generation Reproduction Test (MEOGRT), was developed by the USEPA for the EDSP and, in collaboration with the Japanese Ministry of the Environment, for the Guidelines for the Testing of Chemicals of the Organisation for Economic Co-operation and Development (OECD). The MEOGRT protocol was iteratively modified based on knowledge gained after the successful completion of 9 tests with variations in test protocols. The present study describes both the final MEOGRT protocol that has been published by the USEPA and the OECD, and the iterations that provided valuable insights into nuances of the protocol. The various tests include exposure to 17ß-estradiol, 4-t-octylphenol, o,p'- dichlorodiphenyltrichloroethane, 4-chloro-3-methylphenol, tamoxifen, 17ß-trenbolone, vinclozolin, and prochloraz. Environ Toxicol Chem 2017;36:3387-3403. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.


Assuntos
Disruptores Endócrinos/toxicidade , Poluentes Ambientais/toxicidade , Oryzias/fisiologia , Reprodução/efeitos dos fármacos , Androgênios/fisiologia , Animais , Guias como Assunto , Japão , Organização para a Cooperação e Desenvolvimento Econômico , Testes de Toxicidade , Estados Unidos , United States Environmental Protection Agency
14.
J Appl Phycol ; 29(4): 1829-1840, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28775656

RESUMO

We explore approaches to minimise impacts of zooplanktonic pests upon commercial microalgal crops using system dynamics models to describe algal growth controlled by light and nutrient availability and zooplankton growth controlled by crop abundance and nutritional quality. Losses of microalgal crops are minimised when their growth is fastest and, in contrast, also when growing slowly under conditions of nutrient exhaustion. In many culture systems, however, dwindling light availability due to self-shading in dense suspensions favours slow growth under nutrient sufficiency. Such a situation improves microalgal quality as prey, enhancing zooplankton growth, and leads to rapid crop collapse. Timing of pest entry is important; crop losses are least likely in established, nutrient-exhausted microalgal communities grown for high C-content (e.g. for biofuels). A potentially useful approach is to promote a low level of P-stress that does not adversely affect microalgal growth but which produces a crop that is suboptimal for zooplankton growth.

15.
Environ Toxicol Chem ; 36(12): 3254-3266, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28631836

RESUMO

The medaka extended one-generation test (MEOGRT) was developed as a multigenerational toxicity test for chemicals, particularly endocrine-disrupting chemicals. Briefly, 3 generations of Japanese medaka (Oryzias latipes) are exposed to a chemical over a 20-wk period: 3 wk in the parental generation (F0), 15 wk in the first generation (F1), and 2 wk in the second generation (F2). The present study reports the first MEOGRT results concerning branched isomer mixtures of 4-nonylphenol (NP). Adult F0 medaka exposed to NP at 5 actual concentrations (1.27, 2.95, 9.81, 27.8, 89.4 µg/L) were unaffected in terms of reproduction, although vitellogenin in the male liver was increased dose-dependently at concentration of 2.95 µg/L and higher. In F1, in contrast, total egg (fecundity), fertile egg, and fertility decreased as NP increased; lowest-observed-effect concentrations (LOECs) for total egg, fertile egg, and fertility were 1.27, 1.27, 27.8 µg/L, respectively. In F1, but not in F0, secondary sex characteristics (i.e., anal fin papillae in males) were suppressed at 27.8 µg/L NP. Vitellogenin induction in adult male fish was slightly weaker in F1 than it was in F0, however. Gonadal sex abnormality and sex reversal occurred at 27.8 and 89.4 µg/L NP in F1 subadults. At 89.4 µg/L NP, all genotypic F1 males in breeding pairs had female phenotype, and some even demonstrated spawning. Concentrations of NP lower than 89.4 µg/L did not affect F2 survival or hatching. The highest detected NP level in environmental freshwater in Japan was approximately a half of the LOEC (1.27 µg/L for F1 fecundity); in other countries, however, environmental concentrations above the LOEC are reported, suggesting that NP may be affecting fish populations. Environ Toxicol Chem 2017;36:3254-3266. © 2017 SETAC.


Assuntos
Disruptores Endócrinos/toxicidade , Oryzias/fisiologia , Fenóis/toxicidade , Reprodução/efeitos dos fármacos , Animais , Feminino , Fertilidade/efeitos dos fármacos , Água Doce , Japão , Fígado/química , Fígado/efeitos dos fármacos , Masculino , Caracteres Sexuais , Testes de Toxicidade , Vitelogeninas/análise
16.
Ecotoxicol Environ Saf ; 136: 8-13, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27810580

RESUMO

Because of various Congressional mandates to protect the environment from endocrine disrupting chemicals (EDCs), the United States Environmental Protection Agency (USEPA) initiated the Endocrine Disruptor Screening Program. In the context of this framework, the Office of Research and Development within the USEPA developed the Medaka Extended One Generation Reproduction Test (MEOGRT) to characterize the endocrine action of a suspected EDC. One important endpoint of the MEOGRT is fecundity of medaka breeding pairs. Power analyses were conducted to determine the number of replicates needed in proposed test designs and to determine the effects that varying reproductive parameters (e.g. mean fecundity, variance, and days with no egg production) would have on the statistical power of the test. The MEOGRT Reproduction Power Analysis Tool (MRPAT) is a software tool developed to expedite these power analyses by both calculating estimates of the needed reproductive parameters (e.g. population mean and variance) and performing the power analysis under user specified scenarios. Example scenarios are detailed that highlight the importance of the reproductive parameters on statistical power. When control fecundity is increased from 21 to 38 eggs per pair per day and the variance decreased from 49 to 20, the gain in power is equivalent to increasing replication by 2.5 times. On the other hand, if 10% of the breeding pairs, including controls, do not spawn, the power to detect a 40% decrease in fecundity drops to 0.54 from nearly 0.98 when all pairs have some level of egg production. Perhaps most importantly, MRPAT was used to inform the decision making process that lead to the final recommendation of the MEOGRT to have 24 control breeding pairs and 12 breeding pairs in each exposure group.


Assuntos
Grupos Controle , Disruptores Endócrinos/toxicidade , Poluição Ambiental/análise , Reprodução/efeitos dos fármacos , United States Environmental Protection Agency/estatística & dados numéricos , Animais , Sistema Endócrino/efeitos dos fármacos , Poluição Ambiental/estatística & dados numéricos , Fertilidade/efeitos dos fármacos , Oryzias , Estados Unidos
17.
J Appl Phycol ; 28(6): 3203-3212, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28035173

RESUMO

Various innovative photobioreactor designs have been proposed to increase production of algae-derived biomass. Computer models are often employed to test these designs prior to construction. In the drive to optimise conversion of light energy to biomass, efforts to model the profile of irradiance levels within a microalgal culture can lead to highly complex descriptions which are computationally demanding. However, there is a risk that this effort is wasted if such optic models are coupled to overly simplified descriptions of algal physiology. Here we demonstrate that a suitable description of microalgal physiology is of primary significance for modelling algal production in photobioreactors. For the first time, we combine a new and computationally inexpensive model of irradiance to a mechanistic description of algal growth and test its applicability to modelling biofuel production in an advanced photobioreactor system. We confirm the adequacy of our approach by comparing the predictions of the model against published experimental data collected over a 2 ½-year period and demonstrate the effectiveness of the mechanistic model in predicting long-term production rates of bulk biomass and biofuel feedstock components at a commercially relevant scale. Our results suggest that much of the detail captured in more complicated irradiance models is indeed wasted as the critical limiting procedure is the physiological description of the conversion of light energy to biomass.

18.
Proc Biol Sci ; 283(1833)2016 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-27358373

RESUMO

Coccolithophorids are enigmatic plankton that produce calcium carbonate coccoliths, which over geological time have buried atmospheric CO2 into limestone, changing both the atmosphere and geology of the Earth. However, the role of coccoliths for the proliferation of these organisms remains unclear; suggestions include roles in anti-predation, enhanced photosynthesis and sun-screening. Here we test the hypothesis that calcification stabilizes the pH of the seawater proximate to the organisms, providing a level of acidification countering the detrimental basification that occurs during net photosynthesis. Such bioengineering provides a more stable pH environment for growth and fits the empirical evidence for changes in rates of calcification under different environmental conditions. Under this scenario, simulations suggest that the optimal production ratio of inorganic to organic particulate C (PIC : POCprod) will be lower (by approx. 20%) with ocean acidification and that overproduction of coccoliths in a future acidified ocean, where pH buffering is weaker, presents a risk to calcifying cells.


Assuntos
Calcificação Fisiológica , Haptófitas/metabolismo , Água do Mar/química , Concentração de Íons de Hidrogênio , Oceanos e Mares , Fotossíntese
19.
PLoS One ; 11(4): e0151739, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27082737

RESUMO

The critical role played by copepods in ocean ecology and biogeochemistry warrants an understanding of how these animals may respond to ocean acidification (OA). Whilst an appreciation of the potential direct effects of OA, due to elevated pCO2, on copepods is improving, little is known about the indirect impacts acting via bottom-up (food quality) effects. We assessed, for the first time, the chronic effects of direct and/or indirect exposures to elevated pCO2 on the behaviour, vital rates, chemical and biochemical stoichiometry of the calanoid copepod Acartia tonsa. Bottom-up effects of elevated pCO2 caused species-specific biochemical changes to the phytoplanktonic feed, which adversely affected copepod population structure and decreased recruitment by 30%. The direct impact of elevated pCO2 caused gender-specific respiratory responses in A.tonsa adults, stimulating an enhanced respiration rate in males (> 2-fold), and a suppressed respiratory response in females when coupled with indirect elevated pCO2 exposures. Under the combined indirect+direct exposure, carbon trophic transfer efficiency from phytoplankton-to-zooplankton declined to < 50% of control populations, with a commensurate decrease in recruitment. For the first time an explicit role was demonstrated for biochemical stoichiometry in shaping copepod trophic dynamics. The altered biochemical composition of the CO2-exposed prey affected the biochemical stoichiometry of the copepods, which could have ramifications for production of higher tropic levels, notably fisheries. Our work indicates that the control of phytoplankton and the support of higher trophic levels involving copepods have clear potential to be adversely affected under future OA scenarios.


Assuntos
Ácidos/química , Dióxido de Carbono/química , Copépodes/fisiologia , Oceanos e Mares , Fitoplâncton/fisiologia , Zooplâncton/fisiologia , Animais , Dióxido de Carbono/fisiologia , Ecologia , Água do Mar
20.
Protist ; 167(2): 106-20, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-26927496

RESUMO

Arranging organisms into functional groups aids ecological research by grouping organisms (irrespective of phylogenetic origin) that interact with environmental factors in similar ways. Planktonic protists traditionally have been split between photoautotrophic "phytoplankton" and phagotrophic "microzooplankton". However, there is a growing recognition of the importance of mixotrophy in euphotic aquatic systems, where many protists often combine photoautotrophic and phagotrophic modes of nutrition. Such organisms do not align with the traditional dichotomy of phytoplankton and microzooplankton. To reflect this understanding, we propose a new functional grouping of planktonic protists in an eco-physiological context: (i) phagoheterotrophs lacking phototrophic capacity, (ii) photoautotrophs lacking phagotrophic capacity, (iii) constitutive mixotrophs (CMs) as phagotrophs with an inherent capacity for phototrophy, and (iv) non-constitutive mixotrophs (NCMs) that acquire their phototrophic capacity by ingesting specific (SNCM) or general non-specific (GNCM) prey. For the first time, we incorporate these functional groups within a foodweb structure and show, using model outputs, that there is scope for significant changes in trophic dynamics depending on the protist functional type description. Accordingly, to better reflect the role of mixotrophy, we recommend that as important tools for explanatory and predictive research, aquatic food-web and biogeochemical models need to redefine the protist groups within their frameworks.


Assuntos
Eucariotos/classificação , Cadeia Alimentar , Fitoplâncton/classificação , Zooplâncton/classificação , Animais , Metabolismo Energético/fisiologia , Eucariotos/metabolismo , Eucariotos/fisiologia , Processos Fototróficos , Filogenia , Fitoplâncton/metabolismo , Fitoplâncton/fisiologia , Zooplâncton/metabolismo , Zooplâncton/fisiologia
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