scholarly journals Optimization of a micronekton model with acoustic data

2014 ◽  
Vol 72 (5) ◽  
pp. 1399-1412 ◽  
Author(s):  
Patrick Lehodey ◽  
Anna Conchon ◽  
Inna Senina ◽  
Réka Domokos ◽  
Beatriz Calmettes ◽  
...  
Keyword(s):  
Primary Production ◽  
Functional Groups ◽  
Spatial Dynamics ◽  
Likelihood Estimation ◽  
Environmental Forcing ◽  
Acoustic Data ◽  
Population Dynamics Model ◽  
Ocean Ecosystem ◽  
Parameter Values

Abstract In the pelagic foodweb, micronekton at the mid-trophic level (MTL) are one of the lesser known components of the ocean ecosystem despite being a major driver of the spatial dynamics of their predators, of which many are exploited species (e.g. tunas). The Spatial Ecosystem and Population Dynamics Model is one modelling approach that includes a representation of the spatial dynamics of several epi- and mesopelagic MTL functional groups. The dynamics of these groups are driven by physical (temperature and currents) and biogeochemical (primary production, euphotic depth) variables. A key issue to address is the parameterization of the energy transfer from the primary production to these functional groups. We present a method using in situ acoustic data to estimate the parameters with a maximum likelihood estimation approach. A series of twin experiments conducted to test the behaviour of the model suggested that in the ideal case, that is, with an environmental forcing perfectly simulated and biomass estimates directly correlated with the acoustic signal, a minimum of 200 observations over several time steps at the resolution of the model is needed to estimate the parameter values with a minimum error. A transect of acoustic backscatter at 38 kHz collected during scientific cruises north of Hawaii allowed a first illustration of the approach with actual data. A discussion followed regarding the various sources of uncertainties associated with the use of acoustic data in micronekton biomass.

scholarly journals Integrating tagging and fisheries data into a spatial population dynamics model to improve its predictive skills

2020 ◽  
Vol 77 (3) ◽  
pp. 576-593 ◽  
Author(s):  
Inna Senina ◽  
Patrick Lehodey ◽  
John Sibert ◽  
John Hampton
Keyword(s):  
Population Dynamics ◽  
Stock Assessment ◽  
Spatial Dynamics ◽  
Likelihood Estimation ◽  
Fish Population ◽  
Environmental Data ◽  
Diffusion Reaction ◽  
Population Dynamics Model ◽  
The Pacific ◽  
Age Structured

SEAPODYM is a model developed for investigating spatiotemporal dynamics of fish populations under the influence of both fishing and the environment. The model simulates age-structured population dynamics using advection–diffusion–reaction equations describing movement, recruitment, and natural and fishing mortality. The dynamic processes are constrained by environmental data and distributions of prey species. Model parameter estimation using fishing data was implemented earlier based on a maximum likelihood estimation (MLE) approach and adjoint technique. Here, we describe the integration of tagging data into the existing MLE approach with application to skipjack tuna (Katsuwonus pelamis) in the Pacific Ocean. We find that tagging data improve estimates of species habitat parameters and movement rates and hence allow better representation of spatial dynamics of fish population. Due to estimated lower diffusion and higher advection rates, the model predicts less non-observed “cryptic” biomass, which leads to the stock sizes being closer to those estimated by stock assessment models commonly used by tuna commissions.

scholarly journals Promoting Instrument Development for New Research Avenues in Ocean Science: Opening the Black Box of Grazing

2021 ◽  
Vol 8 ◽  
Author(s):  
Susanne Menden-Deuer ◽  
Wayne Homer Slade ◽  
Heidi Dierssen
Keyword(s):  
Primary Production ◽  
Collaborative Research ◽  
Spatial Dynamics ◽  
Predictive Ability ◽  
Ecosystem Functions ◽  
Planktonic Food ◽  
Ocean Science ◽  
Predictive Understanding ◽  
New Research

While recent research has provided increasing insight into ocean ecosystem functions and rapidly improving predictive ability, it has become clear that for some key processes, including grazing by zooplankton, there simply is no currently available instrumentation to quantify relevant stocks and rates, remotely or in situ. When measurement capacity is lacking, collaborative research between instrument manufacturers and researchers can bring us closer to addressing key knowledge gaps. By necessity, this high risk, high rewards research will require iterative steps from best case scenarios under highly controlled and often artificial laboratory conditions to empirical verification in complex in situ conditions with diverse biota. To illustrate our point, we highlight the example of zooplankton grazing in marine planktonic food webs. Grazing by single-celled zooplankton accounts for the majority of organic carbon loss from marine primary production but is still measured with logistically demanding, point-sample incubation methods that result in reproducible results but at insufficient resolution to adequately describe temporal and spatial dynamics of grazer induced impacts on primary production, export production and the annual cycle of marine plankton. We advance a collaborative research and development agenda to eliminate this knowledge gap. Resolving primary production losses through grazing is fundamental to a predictive understanding of the transfer of matter and energy through marine ecosystems, major reservoirs of the global carbon cycle.

Reductive Cleavage of Secondary Sulfonamides: Converting Terminal Functional Groups into Versatile Synthetic Handles

2019 ◽  
Author(s):  
Patrick Fier ◽  
Suhong Kim ◽  
Kevin M. Maloney
Keyword(s):  
Functional Groups ◽  
Late Stage ◽  
Reductive Cleavage ◽  
Bioactive Molecules ◽  
General Method

Sulfonamides are pervasive in drugs and agrochemicals, yet are typically considered as terminal functional groups rather than synthetic handles. To enable the general late-stage functionalization of secondary sulfonamides, we have developed a mild and general method to reductively cleave the N-S bonds of sulfonamides to generate sulfinates and amines, components which can further react <i>in-situ</i> to access a variety of other medicinally relevant functional groups. The utility of this platform is highlighted by the selective manipulation of several complex bioactive molecules.

scholarly journals Temporal Variability of Suspended-Solids Concentration in the Estuarine Channel of Patos Lagoon, Southern Brazil

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 646
Author(s):  
Rafael André Ávila ◽  
Priscila Mulattieri Suarez Orozco ◽  
Mauro Michelena Andrade ◽  
Osmar Olinto Möller
Keyword(s):  
Temporal Variability ◽  
Suspended Solids ◽  
Southern Brazil ◽  
Patos Lagoon ◽  
Reliable Technique ◽  
Acoustic Data ◽  
Solids Concentration ◽  
Estuarine Hydrodynamics ◽  
Inflow Conditions

The assessment of suspended-solids dynamics is crucial for the effective monitoring of estuarine environments. As the recurring in-situ sampling is usually problematic, the calibration of the backscattering from acoustic Doppler profilers has shown to be a reliable technique to estimate the suspended-solids concentration (SSC) in estuaries and rivers. In this study, we obtained a linear model that provides SSC estimates for the estuarine channel of Patos Lagoon by calibrating turbidity and acoustic data with in-situ concentration samples. The model output was analyzed in terms of its relationship with estuarine hydrodynamics and temporal variability. In this estuary, the supply of suspended solids is known to be due the runoff from its main tributaries, but also through the exchanges between the estuary and the coastal ocean. Both sources provide sediments and organic solids which affect water quality, geomorphology, and harbor operations. Results show that SSC is strongly linked to estuarine hydrodynamics, where concentrations increase with streamflow. During outflow periods, higher concentrations are associated with river runoff, whereas with inflow conditions they are induced by southern and southwesterly winds. However, relationship between SSC and streamflow is asymmetrical, meaning that the largest concentrations are majorly linked to outflow currents and downstream transport.

In situ assessment of the daily primary production of the temperate symbiotic coral Cladocora caespitosa

2013 ◽  
Vol 58 (4) ◽  
pp. 1409-1418 ◽  
Author(s):  
C. Ferrier-Pagès ◽  
F. Gevaert ◽  
S. Reynaud ◽  
E. Beraud ◽  
D. Menu ◽  
...  
Keyword(s):  
Primary Production ◽  
Cladocora Caespitosa ◽  
In Situ Assessment

Cu(II)-Catalyzed [3+2] Annulation of Thioamides with AIBN: Facile Access to Highly Functionalized Thiazolidine-4-ones

Synthesis ◽  
2021 ◽  
Author(s):  
Pragya Pali ◽  
Dhananjay Yadav ◽  
Gaurav Shukla ◽  
Maya Shankar Singh
Keyword(s):  
Double Bond ◽  
Functional Groups ◽  
Dual Role ◽  
Direct Access ◽  
One Pot ◽  
Simple Method ◽  
Two Component ◽  
Thiazolidine Ring ◽  
Coupling Partner

An efficient and versatile copper-catalyzed unprecedented intermolecular radical [3 + 2] annulation of thioamides with azobisisobutyronitrile (AIBN) is described. This two-component one-pot copper(II)-catalyzed transformation has been achieved via cascade formation of C-S/C−N bonds through the cyclization of in situ generated N,S-acetal intermediate from β-ketothioamide. This operationally simple method allows direct access to synthetically demanding thiazolidin-4-ones in good to excellent yields containing diverse functional groups of different electronic and steric nature. Remarkably, the readily available reaction partners, avoidance of expensive/toxic reagents and the gram scale synthesis are additional attributes to this strategy. AIBN here plays a dual role as radical initiator and unusual source of two carbon coupling partner. Notably, the products possess Z-stereochemistry with regard to the exocyclic C=C double bond at the 2-position of the thiazolidine ring.

scholarly journals Evolution Mechanism of Macromolecular Structure in Coal during Heat Treatment: Based on FTIR and XRD In Situ Analysis Techniques

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Dun Wu ◽  
Wenyong Zhang
Keyword(s):  
Heat Treatment ◽  
Infrared Spectroscopy ◽  
Infrared Spectrum ◽  
Functional Groups ◽  
Coal Sample ◽  
Diffraction Peak ◽  
Coal Rank ◽  
Coal Structure ◽  
Temperature Range

Owing to the complexity and heterogeneity of coal during pyrolysis, the ex situ analytical techniques cannot accurately reflect the real coal pyrolysis process. In this study, according to the joint investigation of Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), the structural evolution characteristics of lignite-subbituminous coal-bituminous coal-anthracite series under heat treatment were discussed in depth. The results of the infrared spectrum of coal show that the different functional groups of coal show different changes with the increase of coal rank before pyrolysis experiment. Based on in situ infrared spectroscopy experiments, it was found that the infrared spectrum curves of the same coal sample have obvious changes at different pyrolysis temperatures. As a whole, when the pyrolysis temperature is between 400 and 500°C, the coal structure can be greatly changed. By fitting the infrared spectrum curve, the infrared spectrum parameters of coal were obtained. With the change of temperature, these parameters show regular changes in coal with different ranks. In the XRD study of coal, the absorption intensity of the diffraction peak (002) of coal increases with increasing coal rank. The XRD patterns of coal have different characteristics at different pyrolysis temperatures. Overall, the area of (002) diffraction peak of the same coal sample increases obviously with the increase of temperature. The XRD structural parameter of coal was obtained by using the curve fitting method. The changing process of two parameters (interlayer spacing (d002) and stacking height (Lc)) can be divided into two main stages, but the average lateral size (La) does not change significantly and remains at the 2.98 ± 0.09 nm. In summary, the above two technologies complement each other in the study of coal structure. The temperature range of both experiments is different, but the XRD parameters of coal with different ranks are reduced within the temperature range of less than 500°C, which reflects that the size of coal-heated aromatic ring lamellae is reduced and the distance between lamellae is also reduced, indicating that the degree of condensation of coal aromatic nuclei may be increased. Correspondingly, the FTIR parameters of coal also reflect that, with increasing temperature, the side chains of coal are constantly cracked, the oxygen-containing functional groups are reduced, and the degree of aromatization of coal may be increased.

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