AOS23-01

Room:201B

Time:May 24 14:15-14:30

Current states and future prospects of modeling studies for lower trophic level marine
ecosystem.
HASHIOKA, Taketo1∗
1

Japan Agency for Marine-Earth Science and Technology

Historically large scale ecosystem models for lower trophic level have been developed for understanding of global biogeochemical cycles such as global carbon budget. For this purpose, a concept of Plankton Functional Types (PFT), in which plankton
are categorized into several types depending on their roles on biogeochemical cycles, have been employed as one of effective
representations of marine ecosystem. Even now this approach of PFT modeling is the main force for a large scale modeling represented by earth system model. On the other hand, the demand on ecosystem modeling have been expanding and diversifying.
Namely interest in understanding of ecosystem itself being heightened (e.g., future impact of climate change on ecosystem rolesand diversity). As a results, modeling approach for explicit representations of plankton physiological response and ecologicalinteraction have been attracting attention in recent years. Large scale ecosystem modeling also being in transition. In this presentation, based on internal activities of CMIP (Coupled Model Inter Comparison Project) and MAREMIP (MARine Ecosystem
Model Intercomparison Project), we review the current state of PFT modeling and discuss future prospects of lower trophic level
modeling.

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AOS23-02

Room:201B

Time:May 24 14:30-14:45

Vector digram analysis of ocean carbon pumps: application to the climatological data andCMIP5 simulations
OKA, Akira1∗
1

Atmosphere and Ocean Research Institute, University of Tokyo

The ocean stores 60 times more carbon than the atmosphere and therefore the ocean carbon cycle has a critical role in controlling the atmospheric CO2 concentration. By using the three dimensional distribution of dissolved carbon concentration (DIC),
total alkalinity (ALK), phosphate, and salinity, four types of ocean carbon pumps (organic matter, calcium carbonate, gas exchange, and freshwater flux pumps) are defined here and I propose a method with which individual effects of four carbon pumps
on atmospheric CO2 concentration can be quantitatively evaluated. By applying this method to the climatology, the contributionsof four carbon pump components to atmospheric CO2 are clearly evaluated in one figure (the vector diagram); each carbon pumpcomponent is represented by one vector and its contribution to pCO2 can be measured from the difference in the contour values
between the beginning and the end of the vector. The same analysis is also applied to the CMIP5 earth system model simulations. Although all models reproduce the same level of the atmospheric CO2 concentration as the climatology, it is shown that
contributions from four carbon pumps are not the same among models. This study demonstrates that the vector diagram analysis
introduced here is a powerful tool for quantifying the individual contributions of the ocean carbon pumps on atmospheric CO2
concentration and also a useful tool for evaluating the reproducibility of ocean carbon cycle models.

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AOS23-03

Room:201B

Time:May 24 14:45-15:00

Anthropogenic CO2 uptake, transport, storage, and dynamical controls in the ocean: amodeling study
NAKANO, Hideyuki1∗ ; ISHII, Masao1 ; RODGERS, Keeth2 ; TSUJINO, Hiroyuki1 ; YAMANAKA, Goro1
1

Meteorological Research Institute, 2 Princeton University

Using an ocean carbon cycle model embedded in an ocean general circulation model, we examine how the budget of anthropogenic CO2 is dynamically controlled. The budget is composed of transport, storage rate, uptake from the atmosphere,
and density conversion. We estimate (1) vertically integrated budget, (2) three-layer budget, and (3) eleven-layer budget for theeleven sub-domain of the global ocean. This work is the first attempt to conduct the budget analyses in the density framework.
The vertically integrated budget is appropriate for examining the inter-basin transport of the anthropogenic CO2. The estimatedbudget is largely consistent with the previous studies. The three-layer budget allows us to identify how the meridional overturning
circulation related transport determines the thermocline inventories for anthropogenic CO2. It is found that Subtropical Cells andthe thermohaline circulation play a fundamental role for the budget in the Pacific and Atlantic Oceans, respectively. Along witha inventory map in each isopycnal layer, the eleven-layer budget is suitable for examining how anthropogenic CO2 is stored andtransported in various water masses. For the mode waters, which serve as reservoirs of anthropogenic CO2 accumulated in theocean interior, it is found that uptake via gas exchange is important but much of the uptake via gas exchange occurs non-locallyto the mode water formation regions through the Subtropical Cells
Keywords: anthropogenic carbon, OGCM, transport

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AOS23-04

Room:201B

Time:May 24 15:00-15:15

Modeling the global cycle of marine dissolved organic matter and its influence on marine
productivity
HASUMI, Hiroyasu1∗ ; NAGATA, Toshi1
1

AORI, UTokyoA three-dimensional numerical model is developed for studies on the marine biogeochemical cycles by dealing with couplingof planktonic and microbial processes. The coupling is achieved by explicitly representing generation and consumption ofdissolved organic matter (DOM). The model is applied to investigate mechanisms by which the global cycle of marine DOM
influences marine productivity. Two categories, biodegradable (DOMb) and refractory (DOMr), are considered for DOM. DOMb
is generated through phytoplankton exudation, zooplankton excretion, detritus decomposition, and photodissociation of DOMr.
Bacteria consume DOMb and generate DOMr. After the long-term adjustment, the observed amount of DOM was reproduced
from homogenous conditions of nutrients and plankton. Spatial distribution of bacterial abundance is reasonably validated
against recently observed large-scale data. Sensitivity experiments indicated that: i) over a multi-decadal timescale, contributionof DOMr to global biogeochemical cycles is negligible, ii) the existence of DOM significantly reduces the global marine primary
productivity, and iii) DOMb originated from phytoplankton exudation is transported to subtropical regions, leading to enhanced
primary productivity there as a consequence of nutrient supply associated with remineralization of transported DOMb.
Keywords: marine biogeochemical cycles, dissolved organic matter, microbial loop, marine productivity, numerical modeling

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AOS23-05

Room:201B

Time:May 24 15:15-15:30

Stable isotope study using Fe: implication to understand the Fe-biocycles in marine environment
YAMAGATA, Yuko1∗ ; TANAKA, Yuki1 ; TANABE, Shinsuke2 ; ITAI, Takaaki2 ; ISOBE, Tomohiko3 ;YAMADA K., Tadasu4 ; TAJIMA, Yuko4 ; HIRATA, Takafumi1
1

Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, 2 Center for Marine Environmental
Studies, Ehime University, 3 National Institute for Environmental Studies, 4 National Museam of Nature and Science

Iron is one of the most important inorganic nutrients for almost all plants and animals. For marine organisms, because of very
low concentration range of Fe (<10−7 wt%) in the seawater, intake efficiency of Fe could become very high to avoid possible
loss of many biochemical functions associated with Fe. This is well demonstrated by the small changes in the Fe isotope ratios(56 Fe/54 Fe and 57 Fe/54 Fe) among the marine organisms of various trophic levels (TL) (e.g., plankton, shrimp, tuna : Jong et al.,2007; Bergquist and Boyle, 2006). This lack in the changes in the Fe isotope ratios can be explained by the high-intake efficiency
of Fe from the dietary foods. This is contrasting with those for the land organisms. For land organisms, the 56 Fe/54 Fe and57
Fe/54 Fe ratios vary significantly with the increase of the trophic level (Walczyk and Blankenburg, 2002, 2005). This could be
explained as reflecting the large isotope effects on Fe isotopes, mainly due to the low intake-efficiency of Fe. In fact, availabilityof Fe for land organisms would be much higher than that for marine organisms, because Fe concentrations in the most rocks,
minerals or soils would be much greater than that in the seawater. However, the intake efficiency would not be a major sourceof the changes in the Fe isotope ratios. Chemical form or oxidation status of Fe would also affect be magnitude of isotope effecton Fe. Moreover, it should be noted that the Fe bio-cycle can not be evaluated only by the traditional trophic level, defined by
the 13 C/12 C and 15 N/14 N ratios, which should reflect the food chain of the organic substances, such as amino acids or proteins.
This suggests that the conventional trophic level did not reflect the food chain of Fe. To investigate this, we have measured the56
Fe/54 Fe and 57 Fe/54 Fe for series of marine organisms, especially for higher trophic level animals.
In this presentation, Peponocephala electra (n=23; TL=4.3), Thunnus alalunga (n=7; TL=4.0), Thunnus obesus (n=1; TL=4.0),
Kajikia audax (n=1; TL=4.0), Berryteuthis magister (n=5; TL=3.4), and Octopus longispadiceus (n=2; TL=3.3) were subsidized to the Fe isotope ratio analysis. After the chemical decomposition and chemical separation procedures, the 56 Fe/54 Fe and57
Fe/54 Fe ratios were measured by the multiple collector-ICP-mass spectrometer (MC-ICP-MS). The measured 56 Fe/54 Fe and57
Fe/54 Fe ratios varied significantly from those for lower trophic level organisms. Several important features of the Fe isotopes
for marine organisms could be derived from the present results. The changes in the 56 Fe/54 Fe isotopes could be explained either
by the poor intake efficiency of Fe from the dietary foods, or by the changing chemical form of Fe in the dietary foods for themarine organisms of higher trophic levels. If in the case that the Fe was adsorbed as a heme-Fe (Fe(II)) from the dietary foods,
the magnitude of the isotope fractionation would be smaller than that found in adsorption of non-heme Fe (e.g., Fe (III)). Thissuggests that the major source of Fe for higher trophic animals would be non-heme Fe. Another possible cause of changes in
the 56 Fe/54 Fe ratio would be originating from the definition of the trophic level of the marine organisms. This suggests that the
food-chain for the inorganic nutrients should be defined by the separate definitions. The details of the mechanism in the variationof the 56 Fe/54 Fe ratios for the marine organisms will be discussed in this presentation.

Keywords: stable isotope of iron, iron biocycle, marine organisms, multiple collector-ICP-mass spectrometry, trophic level

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AOS23-06

Room:201B

Time:May 24 15:30-15:45

New Models of the Flexible Response of Plankton Ecosystems: from Theory to Practical
Implementation
SMITH, S. lan1∗ ; YOSHIKAWA, Chisato2 ; SASAI, Yoshikazu3 ; CHEN, Bingzhang3 ; GARCIA-COMAS, Carmen3
1
3

Marine Ecosystem Dynamics Research Group, RCGC, JAMSTEC & CREST, JST, 2 Institute of Biogeosciences, JAMSTEC,
Marine Ecosystem Dynamics Research Group, RCGC, JAMSTEC

For over two decades, detailed models have been developed to reproduce the flexible response of phytoplankton, and to alesser extent of zooplankton, as well known from laboratory experiments. This research has yielded scientific insights, andsome of those detailed models have been applied in coupled physical-biological ocean models. However, such detailed models
are in general too complex for practical applications in large-scale and long-term ocean modeling studies. Therefore, mostcurrent marine ecosystem models do not account for the flexible physiological response of plankton. Nevertheless, large-scaleand long-term ocean modeling studies are necessary in order to test the theoretical ideas embodied in these detailed models
against oceanic observations and to explore the impact of flexibility on the response of plankton ecosystems to environmental
change. In order to advance scientific understanding of plankton ecosystems in the ocean, we aim to reconcile the results oflaboratory experiments, theoretical modeling, and oceanic observations. For this purpose, we are developing new, relatively
simple models of the flexible response of interacting phytoplankton and zooplankton communities, which can be applied inpractical ocean modeling. Recent results will be presented from one-dimensional (vertical) coupled physical-biological modelsof the ocean compared to oceanic observations. These results include: 1) the impact of the process of photo-acclimation on thevertical distributions of phytoplankton biomass, particulate organic nitrogen, and chlorophyll, and 2) the potential role of the
hypothesised Kill-the-Winner grazing effect for sustaining plankton biodiversity.
Keywords: plankton, ecosystem modelling, ocean, observation, validation, trade-off

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AOS23-07

Room:201B

Time:May 24 15:45-16:00

Phytoplankton coexistence based on niche differentiation studied by an OGCM
MASUDA, Yoshio1∗ ; YAMANAKA, Yasuhiro1
1

Hokkaido Univ.

Oceanic phytoplankton have high diversity. Observational studies estimate that there are over 70,000 phytoplankton species.
In mechanisms which enable the high diversity, we focused on niche differentiation, and inspected it by using an oceanic generalcirculation model (OGCM). We also explored effects of advection and diffusion on the phytoplankton diversity.
Based on NEMUEO and MEM, we developed a marine ecosystem model which can express a few hundred phytoplankton
species and combined it to a physical oceanic model, MRI.com. The physical field represents idealized subpolar and subtropicalgyres in a rectangular model domain of 30 by 30 degrees. To explore effects of advection and diffusion, an offline model(hereafter 0D model) is also developed, in which only concentration of phytoplankton and zooplankton are prognostic variables,
and advection and diffusion of the two variables are set to be zero.
We seeded 240 phytoplankton species which have different trait for temperature, light and nutrient, and 31 species survive. In
the 0D model, the same experiment results in 85 surviving species, in which only one species survives in one grid box. Therefore
advection and diffusion increase alpha diversity but decrease gamma diversity.
We divided a surviving species into 8 species, in which optimum temperature is slightly different. As a result of competitionof 248 (31∗8) species, 125 species survive. This is not considered to be the upper limit of niche differentiation, and further
differentiation would be possible. We found coexistence of two species which differ only 0.1 degrees in optimum temperature.
The fact that slight difference of niche enables coexistence is considered to be significant to explain the high diversity of oceanic
phytoplankton.

Keywords: Phytoplankton diversity, marine ecosystem model, OGCM

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AOS23-08

Room:201B

Time:May 24 16:15-16:30

Arctic sea ice algae modeling: Response to shelf-basin water transport
WATANABE, Eiji1∗
1

JAMSTEC

Seasonal and interannual variability in biogenic particle flux was captured by the multi-year bottom-tethered sediment trap
moorings in the Northwind Abyssal Plain (Station NAP: 75N, 162W, 1975 m water depth) of Chukchi Borderland. The trappedsinking flux of biogenic particles had an obvious peak and the major component of diatom valve flux was sea ice-related species
Fossula arctica in August 2011. On the other hand, the observed summer particle flux was considerably smaller in 2012 than thosein 2011. The suppression of sinking materials would attribute to the extension of oligotrophic Beaufort Gyre water toward theStation NAP. In this study, to address an impact of water mass condition on biogenic particle flux during the summer season, sea
ice algae component was newly incorporated into the lower-trophic marine ecosystem model NEMURO. The original NEMURO
coupled to the pan-Arctic sea ice-ocean physical model COCO represented pelagic plankton species (i.e., diatom, flagellate, andcopepod) and reproduced the early-winter peak of sinking flux of Particulate Organic Nitrogen (PON) [Watanabe et al., 2014]∗.
Whereas the mesoscale shelf-break eddies played a great role in the early-winter peak, the simulated summertime peak wassignificantly delayed behind the trap data partly owing to lack of sea ice algae component in the previous experiment.
In the developed model, the major habitat of sea ice algae was assumed to be a 2 cm-thick skeletal layer at sea ice-ocean
boundary. Since sea ice bottom temperature was always kept at the freezing point of underlying sea water, the growth rate ofsea ice algae was calculated following light availability and nutrient uptake terms. Light transmission through snow and sea ice
column was given using empirical extinction rates. Sea ice-ocean nutrient exchange was formulated in the different manner for
sea ice freezing and melting periods. We assume that sea ice algae can utilize nutrients (nitrate, ammonium, and silicate) both in
the skeletal layer and in the ocean surface layer, according to nutrient availability in each layer. This hybrid-type nutrient uptake
formulation is considered to represent more realistic characteristics of sea ice algae biology. In addition, the modeled PON
was divided into two components with different sinking speeds so that sea ice assemblage could sink faster than other particles
derived from pelagic plankton. The one-year experiment from October 2010 to September 2011 demonstrated reasonable spatial
distribution and seasonal transition in sea ice algae biomass and the related sinking particle flux during the summer season. Theinterannual variability and possible background mechanisms (e.g., influence of Beaufort Gyre variation) will also be discussed.
∗Watanabe, E., J. Onodera, N. Harada, M. C. Honda, K. Kimoto, T. Kikuchi,
S. Nishino, K. Matsuno, A. Yamaguchi, A. Ishida, and M. J. Kishi (2014)
Enhanced role of eddies in the Arctic marine biological pumpNature Communications, 5:3950, doi:10.1038/ncomms4950.

Keywords: Arctic marine ecosystem model, ice algae, Beaufort Gyre, particle flux

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AOS23-09

Room:201B

Time:May 24 16:30-16:45

Mesoscale eddies, 3D turbulence, internal waves and associated nutrient flux in the Kuroshio
Front
NAGAI, Takeyoshi1∗
1

Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology

The Kuroshio, one of western boundary currents in the North Pacific, plays very important roles in transporting heat, organicand inorganic constituents. Because it also carries many pelagic fish larvae along with its strong current from their spawning
grounds toward feeding grounds, the Kuroshio-Oyashio confluent regions, primary and associated secondary production in the
Kuroshio are considered to be critical for their recruitments. In this study, we attempt to quantify the nutrient fluxes to the
Kuroshio, which sustain the biological production there, through variety of physical processes, including along isopycnal fluxes:(1) mesoscale eddy flux, (2) subduction and obduction near the front, and diapycnal fluxes: (3) turbulent mixing and (4) doublediffusive mixing.
We conducted field campaigns to measure three-dimensional density structures and microscale turbulent kinetic energy dissipation rates in the Kuroshio Extension Front in Oct., 2009. Results from the Oct. 2009 cruise suggest that low salinity water issubducted from the surface to over 300 m depth, forming low salinity tongue on the north side of the front. The simultaneous
nitrate measurements show that within this tongue, nitrate concentration is high, suggesting that subduction of the low sanity
water could also contribute to the nutrient flux to the Kuroshio. Using an Omega-equation, we estimate that O(10 m/day) verticalvelocity could lead large nitrate flux of O(100 mMol/m−2 day−1 ) at 60 m depth. However, because of the alternating meandersof the front, how much net nitrate flux to the Kuroshio euphotic zone occurs is still unclear. The series of microstructure measurements taken near the Kuroshio Front suggest that turbulence is enhanced under the Kuroshio main stream in the thermocline,
where bands of ageostrophic shear is frequently accompanied. The shear bandings could be due to wind-induced near-inertial
internal waves. However, our hypothesis is that the meandering Kuroshio Front can spontaneously radiate near-inertial internal
waves. The 1-km horizontal resolution numerical simulation shows that near inertial waves are generated from the meandering
front with no external forcing. Because near inertial waves can be trapped and dissipated near the front (Kunze 1985, Whitt andThomas 2013), this spontaneous near inertial waves with wind-induced inertial waves could be source of turbulent nutrient flux
right under the Kuroshio main stream. Our measurements using a microstructure profiling float and EM-APEX floats, support
the hypothesis. In this talk, the results from eddy-resolving simulation to evaluate the eddy nutrient flux to the Kuroshio will also
be presented.
Keywords: Kuroshio, Turbulence, Mesoscale eddies, Internal waves, Double diffusion, Nutrients

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AOS23-10

Room:201B

Time:May 24 16:45-17:00

Ecosystem modeling using Ecopath with Ecosim and fishery related data for practical application
KIYOTA, Masashi1∗
1

National Research Institute of Far Seas Fisheries, Fisheries Resarch Agency

Concepts and methods of ecosystem-based fisheries management have not been fully discussed in Japan, and thus data collection, assessment and conservation planning of marine ecosystems have not yet been established. However, fishery-related
surveys and oceanographic monitoring have long been conducted around Japan and the resultant data are accumulated. It will
be helpful to evaluate the current status of marine ecosystems and assess fisheries interactions using these existing data. In thisrespect, Fisheries Research Agency have examined feasibility of ecosystem modeling using fishery-related data and Ecopath
with Ecosym (EwE).
EwE is an end-to-end model that expresses an ecosystem as flows of biomass. A simple relationship between consumption(Qi ), production (Pi ), respiration (Ri ) and unassimilated excretion (Ui ) of a functional group i is represented as,
Qi = Pi + Ri + Ui … (1).
A mass balance equation is presumed which means input and output of a functional group is balanced as,
Pi ‒ Yi ‒ M2i ‒ Pi (1 ‒ EEi ) ‒ EXi ‒ BAi = 0 … (2)where Yi is fishery catch, M2 is predation mortality, Pi (1 ‒ EEi ) is other mortality (EEi is a ratio called ecotrophic efficiency),
EXi is export,∑ and BAi is biological assimilation. The predation mortality is divided into consumption of prey i by predator j,
M2i = Qj DCji … (3)which leads to linear simultaneous equations of predator-prey relationships (DCji is the ratio of prey i in the diet of predatorj). By solving the equations, Ecopath estimates the flows of biomass and estimates trophic levels, trophic interactions and network properties. However, comparison of network properties between different models is not effective because these values varydepending on the model structure. Ecopath is more suited to summarize flows and biomasses into trophic levels and calculate
system productivity or transfer efficiency.
Mean trophic level of catch (MTLc, Pauly et al. 1998), primary production required (PPR) to support catch (Pauly & Christensen 1995), loss of food for higher trophic levels caused by fishery removals (L index, Libralato et al. 2008) and other indicesof fishery impacts can be calculated using the outputs. Comparison of Ecopath models of several waters around Japan with worldmodels published in literature revealed that the Japanese commercial fisheries harvested over relatively wide range of trophic
levels and had moderate impacts on marine ecosystems.
Ecosim uses the left part of formula (2) as the differential equation of biomass and simulates the temporal dynamics after themass balance is broken. Dynamic behavior of Ecosim is largely dependent on the vulnerability parameter, which determines
the functional response of a predators to prey density change. The vulnerability parameters can be tuned if time series data on
relative abundance of functional groups are available.
Many expanded functions are added to recent versions of EwE such as age-structure, spatial heterogeneity (Ecospace), economic evaluation (Value chain) and management strategy evaluation (MSE). Ecospace simulates spatio-temporal dynamics andis used for predicting the effect of spatial management but it also stands on the balanced homogeneous state of Ecopath.
EwE appears to be a good starter of marine ecosystem modeling for understanding foodweb structure and fishery impacts
because Ecopath is tailored to take fishery related information as input data in the form of ratios to biomass (P/B, Q/B) or dietcomposition (DC). The assumption of mass balance does not necessarily mean that the system is in steady balanced state but israther understood as that the biomass budget is balanced at an average condition over a certain space and period. Preparation of
relevant data by appropriate spatio-temporal scale and comparison and/or coupling with other models while exploring data andmodeling gaps will be effective steps for the development and practical application of ecosystem modeling to management.
Keywords: ecosystem-based fisheries management, fishery impacts, marine food web, mass balance model, monitoring data

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AOS23-11

Room:201B

Time:May 24 17:00-17:15

Numerical analysis of controlling factors of the interannual variations of Japanese common squid around JapanYOSHIE, Naoki1∗ ; GUO, Xinyu1 ; WANG, Yucheng1 ; KUBOTA, Taishi1
1

Center for Marine Environmental Studies, Ehime University

Japanese common squid (Todarodes pacificus ) is one of the most important fish resources to Japan, Korea and China. It has aclear life cycle: spawns from the shelf slope of East China Sea to southwestern area of the Japan Sea; makes a feeding migrationfrom its spawning area to Japan Sea or Pacific side of Japan; makes a spawning migration back to the East China Sea after growing up in the Japan Sea and Pacific side of Japan. In past several decades, its resources in the Japan Sea and Pacific side of Japan
have large interannual variations. Although some studies paid attention on influences of environmental conditions (mainly sea
surface temperature) on its spawning area, there is still no quantitative argument on what is the most important factor controllinginterannual variation of Japanese common squid resources. In this study, we use a particle tracking model to simulate feeding
migration of Japanese common squid larvae to the Japan Sea and South of Japan from 1992 to 2012. In our model, we consider
the transport of larvae by ocean current and random walk, the survival condition of larvae by water temperature, and the influenceof parent stock on larvae number. Our model results show that the parent stock is likely the most important factor controlling theinterannual variation of Japanese common squid resources.
Keywords: Japanese common squid, particle tracking model, interannual variation

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AOS23-12

Room:201B

Time:May 24 17:15-17:30

Impacts of global warming on fish resources in North Pacific
SHIBANO, Ryota1∗ ; YAMANAKA, Yasuhiro1 ; SHIGEMITSU, Masahito1
1Faculty of Environmental Earth Science, Hokkaido University

Some recent researches reported global warming impact to marine ecosystem. Cheung et al. (2013) estimated the impacts
in global ocean using a habitat model. The model provided the future distributions of fishes due to preferred environments andlogistic function. However, they deal no components for ecosystem as predation (e.g. primary production) and a few scenario.
We develop a habitat model referred from Cheung et al. (2008; 2013) and estimate the impacts to fishes resources using the resultsof climate model. We deal primary productions for preferred environment to ecosystem component and some RCP scenarios. In
this presentation, we show the results calculated by a climates model: MIROC-ESM.
Keywords: fishery resources, global warming, climate model, habitat model

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AOS23-13

Room:201B

Time:May 24 17:30-17:45

Modeling large-amplitude recruitment variability of marine fish
ITOH, Sachihiko1∗ ; HASUMI, Hiroyasu1
1

Atmosphere and Ocean Research Institute, The University of Tokyo

Marine ecosystem modeling has advanced considerably in the past few decades, enabling quantitative evaluation of biogeochemical cycles in the ocean. Some models are incorporated into the earth system model and applied for projecting future climatechange. However, many of these models consider trophic levels up to zooplankton and do not include fish and other nekton. Although abundances of some marine fish species show large interannual fluctuations synchronous to environmental variations,few model frameworks had capability of explicit analyses on their linkage. A recently developed approach for fish modelingtakes both biomass and number of individuals into consideration, which is one of necessary factors of fish community structure;
however, even with this approach, present fish models do not usually reproduce drastic variation in the abundances of some small
pelagic fishes such as sardine and anchovy. In the present study, we step into recruitment processes of marine fish, which has
been suggested by field studies to be determinants of the population size. A food-web model for planktivorous and piscivorous
fishes was developed, which will be coupled with a lower trophic ecosystem model and a hydrodynamic model. We focus on theenvironmental variability in the western North Pacific and the accompanied responses of sardine and anchovy, and test several
growth and survival models during early life stages of these fishes. In the presentation, possible amplification processes fromplankton to fish will also be discussed.

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AOS23-P01

Room:Convention Hall

Time:May 24 18:15-19:30

Satellite remote sensing data analysis of the quantum yield of photosynthesis for marine
ecosystem model development
HIRATA, Takafumi1∗
1Faculty of Environmental Earth Science, Hokkaido University

Marine ecosystem models attempt to model interactions between different organisms in addition to between physiology andenvironment. The models require a number of physiological/ecological parameters in general, and the parameters are usually
fixed within the model. On the other hand, the parameters are expected to vary in reality. This gap can be one of the reasons forgenerating uncertainty of the model result. Purpose of this work is two-fold: 1) analysis of ocean colour satellite data to clarify
spatio-temporal variability of group-specific quantum yield of photosynthesis of phytoplankton, a physiological parameter thatplays a significant role in modeling a light limitation in marine ecosystem models, 2) generating a satellite data set of the groupspecific quantum yield for marine ecosystem model parameterization. Our study areas are Japanese waters including Kuroshio,
Kuroshio-extension and quasi-stationary jet regions, and our analysis is made for a decade of 1998-2007. Satellite ocean colour
data obtained from NASA Goddard Space Flight Centre was used in this work. The satellite data were processed to obtain
primary productivity of total phytoplankton community (Behrenfeld et al., 2005), phytoplankton group-specific chlorophylla concentration (Hirata et al., 2011) and the optical absorption coefficient of total phytoplankton community (Smyth et al.,2006). Using these satellite data, monthly climatology of the phytoplankton group-specific quantum yield of photosynthesis wascomputed using a satellite new algorithm. Our result shows that spatial distribution of the quantum yield of photosynthesis for
diatom was correlated to that of diatom chlorophyll-a over seasons. Meanwhile, spatial distribution of the quantum yield ofphotosynthesis for haptophytes was correlated to that of haptophytes chlorophyll-a only in May-October. The quantum yield ofphotosynthesis for cyanobacteria was not correlated to cyanobacteria chlorophyll-a through a year. Thus, the quantum yield ofphotosynthesis varies over space, time and phytoplankton community. A ten-year satellite database of the phytoplankton groupspecific quantum yield of photosynthesis was generated and we expect the dataset to contribute to a better parameterization ofphotosynthesis in marine ecosystem models.
Keywords: Phytoplankton, Satellite Remote Sensing, Quantum yield of photosynthesis

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AOS23-P02

Room:Convention Hall

Time:May 24 18:15-19:30

A challenge to evaluate effect of climate change on Japanese anchovy (Engraulis japonicus) in the East China Sea.
ITO, Shin-ichi1∗ ; KOMATSU, Kosei1 ; TAKASUKA, Akinori2 ; YOSHIE, Naoki3 ; OKUNISHI, Takeshi2 ;KITAJIMA, Satoshi2 ; TAKAHASHI, Motomitsu2 ; HASEGAWA, Toru2 ; SETOU, Takashi2
1

The University of Tokyo, AORI, 2 Fisheries Research Agency, 3 Ehime University

To evaluate climate change (global warming) effects on Japanese anchovy in the East China Sea, we conducted numericalsimulations including two dimensional horizontal migration of Japanese anchovy. Sea surface temperature, velocity and preyplankton fields were obtained by simulations with CHOPE-eNEMURO (Max-Planck-Institute Ocean Model coupled with a marine ecosystem model extended NEMURO (eNEMURO) , an extended version of a marine ecosystem model NEMURO (North
Pacific Ecosystem Model for Understanding Regional Oceanography), using current and future climate forcing. The environmental conditions were used to integrate a bioenergetics model (CHOPE-eNEMURO.FISH ) and the growth of Japanese anchovy wascalculated from the difference between energy intake by consumption and other dissipation terms including respiration, egestion,
excretion, specific dynamic action, etc. Although NEMURO.FISH was originally developed for Pacific saury and herring, it israther easily possible to apply to other planktivorous fish species. The initial spawning grounds were assumed in the area which
depth is less than 1000 m and the sea surface temperature is between 15.6 and 27.8 degC. The fish growth and migration was
integrated for one year since the spawning. Under the contemporary condition, 78 % of the total anchovy larvae, which advectedto the western side of Kyushu, entered to the southern part of Kyushu. However, under the future climate, larvae advected to thesouthern part of Kyushu decreased by 50 % while those to the northern part increased by 170%. As a result the ratio enteringto the southern part became 40 %. The total number of larvae advected to the western coast of Kyushu was not changed. It wassuggested that the northward shift of the spawning ground caused the modification of the location where larvae were advected.
The body length of advected larvae increased in the northern part of Kyushu, while those in the southern part did not change.
Keywords: ecosystem model, fish growth-migration model, Japanese anchovy, climate change

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