scholarly journals Quantifying carbon fluxes from primary production to mesopelagic fish using a simple food web model

2018 ◽  
Vol 76 (3) ◽  
pp. 690-701 ◽  
Author(s):  
Thomas R Anderson ◽  
Adrian P Martin ◽  
Richard S Lampitt ◽  
Clive N Trueman ◽  
Stephanie A Henson ◽  
...  
Keyword(s):  
Primary Production ◽  
Food Web ◽  
Flow Analysis ◽  
World Ocean ◽  
Field Studies ◽  
Mesopelagic Fish ◽  
Fish Biomass ◽  
Analysis Model ◽  
Surface Ocean ◽  
Carbon Transfer

Abstract An ecosystem-based flow analysis model was used to study carbon transfer from primary production (PP) to mesopelagic fish via three groups of copepods: detritivores that access sinking particles, vertical migrators, and species that reside in the surface ocean. The model was parameterized for 40°S to 40°N in the world ocean such that results can be compared with recent estimates of mesopelagic fish biomass in this latitudinal range, based on field studies using acoustic technologies, of ∼13 Gt (wet weight). Mesopelagic fish production was predicted to be 0.32% of PP which, assuming fish longevity of 1.5 years, gives rise to predicted mesopelagic fish biomass of 2.4 Gt. Model ensembles were run to analyse the uncertainty of this estimate, with results showing predicted biomass >10 Gt in only 8% of the simulations. The work emphasizes the importance of migrating animals in transferring carbon from the surface ocean to the mesopelagic zone. It also highlights how little is known about the physiological ecology of mesopelagic fish, trophic pathways within the mesopelagic food web, and how these link to PP in the surface ocean. A deeper understanding of these interacting factors is required before the potential for utilizing mesopelagic fish as a harvestable resource can be robustly assessed.

Protist grazing contributes to microbial food web at the upper boundary of the twilight zone in the subarctic Pacific

2020 ◽  
Vol 636 ◽  
pp. 235-241 ◽  
Author(s):  
HM McNair ◽  
S Menden-Deuer
Keyword(s):  
Primary Production ◽  
Food Web ◽  
Single Cell ◽  
Euphotic Zone ◽  
Twilight Zone ◽  
Particulate Carbon ◽  
Surface Ocean ◽  
Tropical Environments ◽  
The Impact ◽  
Upper Boundary

Grazing by herbivorous protists (microzooplankton) is a major loss pathway of primary production in the surface ocean, yet its impact below the well-lit surface ocean is largely unknown. The upper boundary of the twilight zone is critically important to understanding carbon cycling and is often the depth of highest attenuation of particulate carbon flux. Available measurements of primary production and grazing below the well-lit surface ocean suggest that the upper boundary of the twilight zone may harbor active but poorly constrained food web processes. Previous grazing rates from the base of the euphotic zone were measured in subtropical and tropical environments. Thus, the impact of protist grazing on prey populations remains unknown in colder conditions at higher latitudes. To advance understanding and provide mechanistic insight into processes occurring at the base of the euphotic zone (0.4-0.7% PAR), we measured predation rates on both phytoplankton and heterotrophic prokaryotes in the North Pacific, using a novel method that amplified the grazing signal by concentrating the predator community, enabling detection of grazing rates far below previous limits. Protists consumed 0.6% of the phytoplankton population daily and 12% of daily heterotrophic prokaryote growth. These conservative rate measurements document marginal removal of phytoplankton even in these colder regimes, implying flows of energy from single-cell primary producers and prokaryotes to single-cell protists at rates far below previous detection limits in this twilight region of a low-productivity system.

Management of Guidance and Counseling on Learning Discipline

2020 ◽  
Vol 10 (2) ◽  
pp. 60-74
Author(s):  
Muhammad Syauqi Mubarok
Keyword(s):  
Statistical Analysis ◽  
Descriptive Analysis ◽  
Field Studies ◽  
Guidance And Counseling ◽  
Analysis Method ◽  
Vocational High School ◽  
Analysis Model ◽  
Survey Techniques ◽  
Analysis Technique ◽  
Path Analysis Model

This article aims to examine and describe the influence of guidance and counseling management on learning discipline. The method used in this research is descriptive analysis method using survey techniques. Data collection techniques that used are documentation studies and field studies. Moreover, the data analysis technique that has been used to answer the research hypothesis is statistical analysis with a path analysis model. The location of the study was at the Ciledug Vocational High School Al-Musaddadiyah Garut, with 85 respondents taking part in the survey. The results of the discussion show that guidance and counseling management has a positive and significant effect on the discipline of learning

scholarly journals Analyzing Polyvinyl Chloride in Japan With the Waste Input−Output Material Flow Analysis Model

2009 ◽  
Vol 13 (5) ◽  
pp. 706-717 ◽  
Author(s):  
Shinichiro Nakamura ◽  
Kenichi Nakajima ◽  
Yoshie Yoshizawa ◽  
Kazuyo Matsubae-Yokoyama ◽  
Tetsuya Nagasaka
Keyword(s):  
Polyvinyl Chloride ◽  
Material Flow ◽  
Flow Analysis ◽  
Material Flow Analysis ◽  
Analysis Model

scholarly journals Contrasting pelagic ecosystem functioning in eastern and western Baffin Bay revealed by trophic network modeling

Elem Sci Anth ◽  
2020 ◽  
Vol 8 ◽  
Author(s):  
Blanche Saint-Béat ◽  
Brian D. Fath ◽  
Cyril Aubry ◽  
Jonathan Colombet ◽  
Julie Dinasquet ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Food Web ◽  
Biological Data ◽  
The Arctic ◽  
Ecosystem Structure ◽  
Carbon Export ◽  
Baffin Bay ◽  
Planktonic Food ◽  
Carbon Transfer ◽  
Current Flows

Baffin Bay, located at the Arctic Ocean’s ‘doorstep’, is a heterogeneous environment where a warm and salty eastern current flows northwards in the opposite direction of a cold and relatively fresh Arctic current flowing along the west coast of the bay. This circulation affects the physical and biogeochemical environment on both sides of the bay. The phytoplanktonic species composition is driven by its environment and, in turn, shapes carbon transfer through the planktonic food web. This study aims at determining the effects of such contrasting environments on ecosystem structure and functioning and the consequences for the carbon cycle. Ecological indices calculated from food web flow values provide ecosystem properties that are not accessible by direct in situ measurement. From new biological data gathered during the Green Edge project, we built a planktonic food web model for each side of Baffin Bay, considering several biological processes involved in the carbon cycle, notably in the gravitational, lipid, and microbial carbon pumps. Missing flow values were estimated by linear inverse modeling. Calculated ecological network analysis indices revealed significant differences in the functioning of each ecosystem. The eastern Baffin Bay food web presents a more specialized food web that constrains carbon through specific and efficient pathways, leading to segregation of the microbial loop from the classical grazing chain. In contrast, the western food web showed redundant and shorter pathways that caused a higher carbon export, especially via lipid and microbial pumps, and thus promoted carbon sequestration. Moreover, indirect effects resulting from bottom-up and top-down control impacted pairwise relations between species differently and led to the dominance of mutualism in the eastern food web. These differences in pairwise relations affect the dynamics and evolution of each food web and thus might lead to contrasting responses to ongoing climate change.

scholarly journals Analysis of Prospective Mathematics Teachers Ability in Applying Scientific Approach Based The Curriculum 2013

2019 ◽  
Author(s):  
Mohammad Tohir ◽  
A. Wida Wardani
Keyword(s):  
Mathematics Teachers ◽  
Flow Analysis ◽  
Approaches To Learning ◽  
Learning Activities ◽  
Analysis Model ◽  
Practical Examination ◽  
Curriculum Structure ◽  
Scientific Approach ◽  
Qualitative Descriptive ◽  
Prospective Mathematics Teachers

This study aims to obtained description of the ability of prospective mathematics teachers in applying scientific approaches to learning activities in the classroom. This research is a qualitative descriptive study. The participants research were prospective mathematics teacher (PPL teachers) interns at SMP Negeri 2 Jember. Data collection techniques used were questionnaires, interviews, observation, and the results of supervision at the practical examination. Data analysis techniques in this study using a checklist and flow analysis model of Miles and Huberman. The results showed that: (1) PPL teachers' understanding of the learning model through a scientific approach gained 28.57% in the category is can and as much as 71.43% in the category is quite capable; (2) the ability of PPL teachers in preparing the learning device in accordance with the curriculum structure in 2013 gained as much as 100% in the category is capable; (3) the ability of PPL teachers in implementing the learning activities using scientific approaches gained as much as 57.14% in the category is can and as much as 42.86% in the category is quite capable; (4) the ability of PPL teachers formulate and implement authentic assessment gained 28.57% in the category is can and as much as 71.43% in the category is quite capable; (5) PPL students' response to the teacher during teaching (internship) gained as much as 42.86% in the category is accordance with the characteristics of students as a teacher of mathematics and as much as 57.14% in the category is according to the characteristics of students as a teacher of mathematics. While the barriers experienced by teachers PPL is the lack of experience in implementing the scientific approach to learning, especially on the activities of questioning and reasoning, the allocation of time, and still difficulties in conducting assessments based the Curriculum 2013.

Diel Vertical migration of marine organisms and the biological carbon pump

2021 ◽  
Author(s):  
Jerome Pinti ◽  
Tim DeVries ◽  
Tommy Norin ◽  
Camila Serra-Pompei ◽  
Roland Proud ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Food Web ◽  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Marine Organisms ◽  
Trophic Levels ◽  
Mesopelagic Fish ◽  
Pelagic Food Web ◽  
Carbon Pump ◽  
Biological Carbon Pump

<p>Diel Vertical Migration (DVM) is a key feature of pelagic and mesopelagic ecosystems, mainly driven by predator-prey interactions along a time-varying vertical gradient of light. Marine organisms including meso-zooplankton and fish typically hide from visual predators at depth during daytime and migrate up at dusk to feed in productive near-surface waters during nighttime. Specific migration patterns, however, vary tremendously, for instance in terms of residency depth during day and night. In addition to environmental parameters such as light intensity and oxygen concentration, the migration pattern of each organism is intrinsically linked to the patterns of its conspecifics, its prey, and its predators through feedbacks that are hard to understand—but important to consider.</p><p>DVM not only affects trophic interactions, but also the biogeochemistry of the world’s oceans.  Organisms preying at the surface and actively migrating vertically transport carbon to depth, contributing to the biological carbon pump, and directly connecting surface production with mesopelagic and demersal ecosystems.</p><p>Here, we present a method based on a game-theoretic trait-based mechanistic model that enables the optimal DVM patterns for all organisms in a food-web to be computed simultaneously. The results are used to investigate the contributions of the different food-web pathways to the active component of the biological carbon pump. We apply the method to a modern pelagic food-web (comprised of meso- and macro-zooplankton, forage fish, mesopelagic fish, large pelagic fish and gelatinous organisms), shedding light on the direct effects that different trophic levels can have on the DVM behaviours of each other. The model is run on a global scale to assess the carbon export mediated by different functional groups, through fecal pellet production, carcasses sinking and respiration.</p><p>Finally, the model output is coupled to an ocean inverse circulation model to assess the carbon sequestration potential of the different export pathways. Results indicate that the carbon sequestration mediated by fish is much more important than presently recognised in global assessments of the biological carbon pump. The work we present relates to contemporary ecosystems, but we also explain how it can be adapted to fit any pelagic food-web structure to assess the contribution of the active biological pump to the global carbon cycle in past ecosystems.</p>

scholarly journals Nitrate supply and uptake in the Atlantic Arctic sea ice zone: seasonal cycle, mechanisms and drivers

2020 ◽  
Vol 378 (2181) ◽  
pp. 20190361 ◽  
Author(s):  
Sian F. Henley ◽  
Marie Porter ◽  
Laura Hobbs ◽  
Judith Braun ◽  
Robin Guillaume-Castel ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Nutrient Availability ◽  
Seasonal Cycle ◽  
Nitrate Uptake ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Surface Ocean ◽  
Nitrate Supply

Nutrient supply to the surface ocean is a key factor regulating primary production in the Arctic Ocean under current conditions and with ongoing warming and sea ice losses. Here we present seasonal nitrate concentration and hydrographic data from two oceanographic moorings on the northern Barents shelf between autumn 2017 and summer 2018. The eastern mooring was sea ice-covered to varying degrees during autumn, winter and spring, and was characterized by more Arctic-like oceanographic conditions, while the western mooring was ice-free year-round and showed a greater influence of Atlantic water masses. The seasonal cycle in nitrate dynamics was similar under ice-influenced and ice-free conditions, with biological nitrate uptake beginning near-synchronously in early May, but important differences between the moorings were observed. Nitrate supply to the surface ocean preceding and during the period of rapid drawdown was greater at the ice-free more Atlantic-like western mooring, and nitrate drawdown occurred more slowly over a longer period of time. This suggests that with ongoing sea ice losses and Atlantification, the expected shift from more Arctic-like ice-influenced conditions to more Atlantic-like ice-free conditions is likely to increase nutrient availability and the duration of seasonal drawdown in this Arctic shelf region. The extent to which this increased nutrient availability and longer drawdown periods will lead to increases in total nitrate uptake, and support the projected increases in primary production, will depend on changes in upper ocean stratification and their effect on light availability to phytoplankton as changes in climate and the physical environment proceed. This article is part of the theme issue ‘The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.

The relation of oceanic primary production to available photosynthetic irradiance

1976 ◽  
Vol 27 (3) ◽  
pp. 441 ◽  
Author(s):  
HR Jitts ◽  
A Morel ◽  
Y Saijo
Keyword(s):  
Primary Production ◽  
Surface Ocean ◽  
Surface Samples ◽  
In Situ Method ◽  
Wide Range ◽  
Total Irradiance ◽  
Highly Correlated ◽  
Bodies Of Water ◽  
High Degree

Primary production was measured at 14 stations covering a wide range of oceanic waters. Measurements were made by both the in situ method (Pi) and the simulated in situ method (Ps) Production v. constant irradiance (P v. I) was also measured. Available photosynthetic irradiance [Eq(350-700) in quanta m-2 s-1] was calculated from continuous records of total irradiance and measurements of the percentage submarine transmission of irradiance were made with a quantum meter. Using the P v. I curves and Eq(350-700), primary production at several depths at each station was calculated (P,). Pc was shown to be a precise estimate of Ps at all depths. Pc was also highly correlated with Pi, but both Pc and Pi overestimated Pi at the surface by 40 %. Some experiments at three stations showed that a 2-mm thickness of clear glass placed over surface samples in the measurement of Ps could increase Ps by about 50%. This suggested that U.V. irradiance in surface ocean waters decreased Pi and could explain the overestimates by Pc and Ps. The results showed the need for precise information of spectrai composition of irradiance in studies of primary production but demonstrated the kalidity of Eq(350-700) as an estimate of available photosynthetic irradiance. They also showed that Pc could estimate Pi with a high degree of precision, and that such a calculative method could provide a useful way of continuously monitoring the primary production of large bodies of water for extended periods.

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