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A DEBtox model to link molecular alterations to biological
eects in
exposed to radionuclides
Daphnia magna
1
1
1
F. Alonzo , D. Plaire , F. Parisot , C. Adam-Guillermin
1
and J. Garnier-Laplace
1
1 Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance,
13115, France
[email protected]
Understanding how toxic contaminants aect wildlife species at various levels of biological organization
(sub-cellular, histological, physiological, organism, population levels) is a major research goal in both
ecotoxicology and radioecology. Mechanistic links among the dierent observed perturbations are necessary to predict consequences for survival, growth and reproduction which are critical for population
dynamics. However, time scales at which such links are established in the laboratory are rarely relevant
for natural populations. With a small size and short life cycle, the cladoceran crustacean
Daphnia magna
is a particularly suitable biological model for studying eects of radioactive contaminants over several
generations. Multigenerational toxicity studies are much more relevant to the environmental context of
natural biota for which exposure can largely exceed individual longevity and involve many successive
generations.
Over the last decade, multigenerational investigations of toxic eects were conducted under controlled
conditions in
D. magna exposed to various radionuclides including depleted uranium, americium-241 and
cesium-137, representing respectively a dominantly chemotoxic metal, an alpha internal contamination
and a gamma external radiation. Results showed in all cases that toxic eects on physiology and life
history (survival, body size, fecundity) increased in severity across generations.
These observations
demonstrated that measured eects in one generation might not be representative of toxicity in the
following ospring generations, and ultimately of the population response.
Reduction in somatic growth and reproduction induced by depleted uranium were analyzed using a
DEBtox approach (dynamic energy budget applied to toxicology).
Modelling results suggested that
uranium primarily aects assimilation. This metabolic mode of action was conrmed by measurements
of assimilation reduction and observations of histological alteration of the digestive epithelium. However
the mechanisms involved in the transgenerational increase in sensitivity remained unknown.
A recent study investigating DNA damage in daphnids exposed to depleted uranium, demonstrated
that molecular alterations were accumulated in females over the course of exposure and transmitted to
their progeny. Such alterations were interpreted as the underlying mechanism causing the increase in
eect severity over generations and are now investigated during exposures to Cs-137 and, as a future
perspective, to Am-241.
A DEBtox model considering the accumulation and transmission of genetic
damage was used to analyze radionuclides eects in daphnids exposed over successive generations.
Keywords :
radionuclides, multigeneration, DEBtox, DNA alterations
1
Future of the international tele-course on Dynamic Energy
Budget theory (DEB)
Proposal for the 2017 tele-course, practical course and
international DEB symposium
S. Augustine
1
1
and JoLynn Carroll
1 Akvaplan-niva, Fram High North Research Centre for Climate and the Environment, 9296 Tromsø, Norway
[email protected]
Historically, the tele-course on Dynamic Energy Budget (DEB) theory takes place every two years and
it is organized by Sebastiaan A.L.M. Kooijman. This course was ahead of its time when it started and
remained a model e-learning course at the VU (Amsterdam, NL) for 15 years. Since 2009, the tele-course
has been followed by a practical course and a three day international symposium. The practical course
and symposium have been hosted by dierent workgroups in France, Portugal and the Netherlands. The
8th tele-course 2015 is the last one which will be organized by S.A.L.M. Kooijman as he retires this year.
In this talk we would like to present plans to organize the continuation of the tele-course, as well as host
the practical part of the course and the next (5th) international DEB symposium in Tromsø, Norway. It
is also our hope to stimulate discussion on dierent organization/ co-funding opportunities in addition to
presenting what possibilities we already have in place. Briey, Akvaplan-niva is integrating DEB theory
into its research with the aim to develop applications in several exciting elds: ecotoxicology, ecology
and physiology of Arctic organisms, reconstruction problems, DEB theory based experimental design
and data analysis. Tromsø is known as the `warm Arctic' and is situated in a scientic hotspot in terms
of extreme seasonality, rapid climate induced change, increasing pressure from human activities, and
development of dierent forms of aquaculture. Such topics will boost DEB theory based research in the
up-coming years and are highly complementary to research and problems tackled by many at this 4th
international DEB symposium. We are initiating plans to take on the responsibility of organizing the
2017 DEB tele-course and potentially to host in Tromsø the 8 or 9 day practical DEB course combined
with the 5th international DEB symposium. We suggest maintaining the same format as in past years
where the practical course and symposium follow the tele-course on DEB which occurs every two years.
We hope that another group can host the practical course and symposium in 2019.
In the past, the
tele-course took place on the Blackboard (an online educational platform provided by the VU) so we are
in the process of identifying suitable web-based e-learning platforms for the future tele-courses. We aim
to have a website for the 2017 DEB symposium and course up by the beginning of 2016. Finally, we
are exploring cost-sharing options with other organizations and industries to help pay for the logistical
arrangements and to reduce the costs for participants.
2
Eect of climate change on population growth rate: some insight
using DEB models of 2 benthic species
C. Bacher
1
1 Laboratoire d'écologie benthique, IFREMER Centre Bretagne, ZI de la Pointe du Diable, CS 10070, 29280 Plouzané,
France
[email protected]
Predicting the distribution of species is a major challenge for the management of coastal areas and the
evaluation of potential changes due to perturbation (e.g. environmental drivers, pressures due to human
activities, climate change). In this context, the Dynamic Energy Budget (DEB) modelling framework
can be used to simulate the life traits of species and assess response to environmental changes. We st
selected a range of potential habitats, relying on physical habitat maps and presence / absence data, for
the mussel
M. edulis
and the oyster
C. gigas
in the English Channel and the Bay of Biscay area. In a
second step, we developed an Individual Based Model (IBM) of population dynamics and estimated the
growth performance of populations on the selected habitats.
Reference simulations used temperature
and chlorophyll a forcing variables based on the outputs of biogeochemical models averaged over 10
years. Another series of simulations were run with time series of temperature extrapolated from trends
estimated over the past 25 years. The comparison of the new and the reference simulations showed an
increase of populations growth rates for the 2 species, but the range diered according to the habitat
and the species.
Keywords :
plankton
Mytilus edulis, Crassostrea gigas, DEB theory, habitat, population, temperature, phyto-
3
Modeling phagotrophy and toxicity in mixotrophic phytoplankton:
a dynamic energy budget approach
K. Barsakis
1,2
1
and K. Lika
1 Department of Biology, University of Crete, 70013, Heraklion, Greece
2 Stanford Blood Center, Stanford University School of Medicine, Palo Alto, CA, USA
[email protected]
Phytoplankton uses primary light and dissolved inorganic nutrients and are characterized as being primarily phototrophic.
However, the majority of phytoplankton, if not all, is in part osmotrophs and
many phytoplankton taxa are phagotrophs; a mode of nutrition termed mixotrophy.
Phagotrophy in
phytoplankton has been associated with nutrient limitation or with low light, but also it is found to
be a strategy to obtain limiting trace organic growth factors. Phagotrophy, when it involves the death
of other organisms, has implications not only on the growth of the mixotroph but also on the trophic
dynamics. Moreover, it has main contributions to bloom formation and toxicity of harmful algae. Within
a mixotroph the two processes (i.e., the phototrophic and the heterotrophic) do not simply add up or
simply compete; rather, there is a level of cooperation between them. We propose theoretical mechanisms for mixotrophy and put them in the context of the Dynamic Energy Budget (DEB) theory, using
the concept of the synthesizing unit (SU). We use ecological data to construct the three main nutritional
strategies of phagotrophic algae and ecophysiological data for toxic behaviour. Moreover, we simulate the
three nutritional strategies in a chemostat under dierent environmental conditions, including dierent
ratios of supplied inorganic nutrients such as nitrogen and phosphorus, axenic and non-axenic conditions,
absence of organic growth factors and dierent light regimes.
Consequently, the quantication of the
growth rate, the consumption rates of the various substrates and the changes in the toxin production rate
result in the prediction of the population dynamics of many harmful algae under dierent environmental
conditions.
4
Estimation of dynamic energy budget (DEB) parameters for the
green-lipped mussel
Perna viridis
1
M.C.F. Cheng , A. Rinaldi
2,3
, G. Sara
3
and G. A. Williams
1
1 Univ. Hong Kong, Swire Inst Marine Sci, Hong Kong, Hong Kong, China
2 Univ. Messina, Dipartimento Ecol Marina, Messina, Italy
3 Univ. Palermo, Dipartimento Sci Terra & Mare, I-90128 Palermo, Italy
[email protected]
Environmental temperature is a key factor contributing to the physiological performance of species' and,
consequently, their geographic distribution. Marine ectotherms are especially inuenced by temperature
because their body temperatures largely depend on the environmental conditions (e.g. air and seawater
temperatures) they experience. Environmental temperatures, therefore, have important cascading eects
on organismal metabolism, energy utilization and subsequent life history traits.
Understanding the
strategies used to allocate energy for growth and reproduction under dierent environmental conditions,
therefore, represents an important step towards being able to forecast changes in life history traits such
as maximum body size, lifespan and reproductive success of a species.
To this purpose, DEB model
parameterization has been used to develop a mechanistic model for the prediction of life history traits
of the green-lipped mussel,
Perna viridis. P. viridis
is an abundant, wide-spread, and ecologically and
commercially important species across the southeastern Asian coast and North America. By combining
experimentally derived species-specic parameters and other compound parameters from the literature,
together with real-time and future predicted environmental data, we were able to construct a DEB model
for
P. viridis.
This DEB model is being used to derive life history traits of the mussel, to understand how
it may respond under changing environmental conditions and, therefore, allow prediction of the future
distribution of
P. viridis
under projected climate change scenarios.
5
A General Metabolic Model for Economies and Organisms
1
1
T. Domingos , T. Sousa
1 MARETEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
[email protected]
We develop a general metabolic model for growing systems, which has as particular cases the Solow
and other models of economic growth, models for the growth of cities and the DEB model for the
growth of organisms (see gure). The model is based on a rigorous thermodynamic approach, namely
guaranteeing mass and energy conservation and entropy production in all energy ows/transformations.
State variables are classied in two types: material; information. Material state variables have mass and
energy content and have an overhead cost associated to them. Information state variables are measured
by the past energy investment on them and have overhead cost equal to 1. State variables either require
maintenance (structure and maturity in DEB theory; capital and labour in economic growth theory) or
do not (reserves, in both contexts). Energy ows are analysed according to three main stages: primary
energy (energy ow from outside the system); nal energy (energy in a form compatible with the needs
of the system); useful energy (energy which is going to be used to satisfy the system's requirements).
The ow of useful energy can be purely dissipative, when it is used for maintenance or for the increase
in non-material state variables, or part of it can be incorporated in a state variable, when it is used
for building up material state variables. Growth in this generalised context means increase in the state
variables. Balanced growth (the weak homeostasis condition in DEB) is the particular situation where
all state variables (or just the material state variables) increase at the same rate. In the general case, all
energy transformation processes are function of some (or all) of the state variables. The functions that
express this output as a function of the state variables are called production functions. A particularly
important class of production functions are the homogeneous degree 1 functions, that lead to the existence
of balanced growth. An analysis of the relevant stylised facts for the growth of organisms and economies
provided by this model is carried out, together with insights gained from comparing the two elds of
application.
6
Comparing anchovy and sardine life traits in the Bay of Biscay in
the context of DEB theory
1
P. Gatti , M. Huret
1
2
and P. Petitgas Pierre
1 Laboratoire de Biologie Halieutique (LBH), IFREMER Centre Bretagne - ZI de la Pointe du Diable - CS 10070 - 29280
Plouzané, France
2 Unité Ecologie et Modèles pour l'Halieutique (EMH), IFREMER Centre de Nantes - rue de l'Ile d'Yeu - BP 2110544311
Nantes Cedex 03
[email protected]
Small pelagic species are worldwide known for their major importance both ecologically, as a critical
intermediate trophic level in marine food webs, and economically, as they support around the third of
the global catches. European sardine (
Sardina pilchardus ) and anchovy (Engraulis encrasicolus ) are two
small pelagic species very common in the Bay of Biscay. These two clupeids display common life history
traits: rapid growth, relatively short life span (especially for anchovy), and strong interannual variability
in biomass index and recruitment success, usually attributed to their sensitivity to environmental conditions. Nethertheless these species show distinct life history strategies: separate temperature anities,
distinct migratory patterns, feeding and especially spawning behaviours that can certainly be explained
by dierence in physiology and associated habitat requirements.
To better understand and compare
the impacts of environmental conditions on both species, we implemented a DEB model that has the
ability to integrate (biotic and abiotic) environmental conditions (food, temperature, . . . ) and predict
sh growth, condition and spawning. An intensive work has already been carried out on anchovy's DEB
calibration (in the Bay of Biscay and the Gulf of Lion) but is still scarce for sardine in these areas. The
purpose of this study is to calibrate a DEB model for sardine with a credible set of parameters, using a
large eld observation dataset (scientic surveys and commercial sampling) and the knowledge acquired
from previous work on anchovy's DEB parameters. The model was run in 0-dimension, using average
temperature and food availability elds in the Bay of Biscay.
To ensure that dierences observed in
model outputs arise from life history traits or strategies and not just from the model parameterisation
itself, parameters of both species need to be as similar as possible. For that we tried to stick as much
as possible to the body-size scaling relationship. Then we explored in which extent how dierences in
spawning strategies can emerge, in the context of DEB theory, from dierences in temperature anities
and feeding behaviour. This DEB model, with parametrisation for both species, will later be implemented
in an Individual Based Model (IBM) to explore and compare, through time and space, environmental
respective sensitivity, plasticity and resilience of both species.
7
DEB-based modeling of environmental eects on the structure,
metabolism and diversity of sh communities
J. Guiet
1,2
3
4
,J.-C. Poggiale , O. Aumont
1,2
and O. Maury
1 Institut de Recherche pour le Développement (IRD), UMR 212 EME, CRH, av. Jean Monnet, B.P. 171, 34203 Sète
cedex, France
2 International laboratory ICEMASA, Department of Oceanography, University of Cape Town, Private Bag X3, Rondebosch
7701, Cape Town, South Africa
3 Aix-Marseille University, CNRS/INSU, IRD, MIO, UM 110, 13288 Marseille, Cedex 09, France
4 IRD-LOCEAN, IPSL, 4 place Jussieu, 75252 Paris, Cedex 05, France
[email protected]
Physical and bio-geochemical changes of the oceans have intricate eects on marine ecosystems. Variations of temperature and primary production aect metabolic rates at the individual level, biomass uxes
at the population level, and trophic structure at the community level. In ne, the full range of services
that marine ecosystems provide to humanity is aected by climate-associated environmental changes.
Using a DEB-based and trait-based mechanistic model of the community spectrum of upper trophic
levels (Maury and Poggiale, 2013), we asses the impact of temperature and primary production changes
on the structure, metabolism and diversity of sh communities. In this model, individual level metabolic
processes derived from the dynamic energy budget theory are associated to opportunistic trophic interactions to derive species size-spectra for every possible life-history characterized by maximum specic size.
The community spectrum is then obtained by integrating species size-spectra along the maximum size
dimension. The environment is acting at the individual level and we observe the steady state response
of ecosystems at the aggregated communities level, focusing on induced variations of sh biomass. We
focus on the independent eects of changes of primary production or temperature. Both induce a three
phases response of the relationship between primary production or temperature and sh biomass. Their
convoluted impact is then observed along a latitudinal gradient of average environmental conditions,
from 70°S to 70°N. Along this gradient we asses the ability of the model to reproduce known patterns
of structure, metabolism and diversity. We use the properties of the modeled communities along this
gradient to estimate the potential impact of climate change on sh production. Mid latitudes appear as
the most sensitive to perturbations of the temperature and primary production.
Trait-based size spectrum model, Dynamic Energy Budget theory, Biodiversity, Climate
change, Ecosystems structure
Keywords :
References
Maury, O. and Poggiale, J. C. (2013) From individuals to populations to communities: A dynamic energy
budget model of marine ecosystem size-spectrum including life history diversity,
52-71
8
J. Theo. Biol., 324(0),
The eccentric life history of marine copepods
T. Jager
1
, I. Salaberria
2
2
and B. H. Hansen
1 DEBtox Research, De Bilt, the Netherlands
2 SINTEF, Trondheim, Norway
[email protected] - www.debtox.info
Calanoid copepods form an important part of the marine zooplankton, but so far, they have not been
the subject of dedicated DEB-based studies. The calanoid life cycle has several interesting features that
require further investigation in the DEB context.
Copepods go through six naupliar-larva stages (of
which the rst two do not feed), followed by six copepodite stages (which dier in shape, and sometimes
also in growth rate, from the nauplii). After the moult to the last stage, while still far removed from
their asymptotic size, somatic growth ceases and reproduction is initiated.
Many species build up a
considerable lipid storage over the last few copepodite stages to sustain them over a diapause, and to
initiate gonad maturation (and even reproduction), in the absence of food.
These features do not t
smoothly into the standard DEB framework, and perhaps bear a closer resemblance to the life history of
holometabolic insects. We modied the reserveless DEBkiss model to construct an energy budget for two
Calanus
species based on data from the literature.
C. sinicus
occurs in shelf waters around China, and
the available life-history data could be captured by minor modications of the DEBkiss model (mainly
to catch the sudden stop of growth after the nal moult). For C. nmarchicus, occurring in the Northern
Atlantic, a more complete data set is available, which required a larger number of modications to capture
its life history.
Here, we preliminarily used the maturity concept to trigger switches in physiological
behaviour, and treat the lipid storage as a reproduction buer.
Many uncertainties remain as to the
optimal model for representing calanoid life histories. Especially the dynamics of the build-up and use of
the lipid storage requires further study, as well as the fuelling of the reproductive output, and dedicated
experimental work is underway.
9
From physiological energetics to shery management: the case of
Pacic bluen tuna
1
M. Jusup , T. Klanjscek
2
and R. Nisbet
3
1 Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan
2 Division for Marine and Environmental Research, Ruder Boskovic Institute, 10000 Zagreb, Croatia
3 Department of Ecology, Evolution and Marine Biology, University of California Santa-Barbara, CA 93106, USA
[email protected]
Thunnus orientalis,
We develop a physiologically structured population model for Pacic bluen tuna (
PBT) by combining approaches that operate at two levels of biological organization.
At the level of
an individual, we rely on a Dynamic Energy Budget (DEB) representation of physiological energetics
to describe metabolic processes regulating food intake, growth, maturation, and reproduction of PBT.
Consequently, the modeled sh state (i.e. reserve energy, structural length, and the maturation/ reproduction investment) depends on the environmental conditions (i.e. food availability and temperature),
allowing us to break free from the constraints of statistical (i.e. static) length-at-age and fecundity-at-age
relationships often used as the underlying assumptions of population dynamics. At the population level,
a matrix formulation based on the DEB model oers a relatively straightforward way to determine how
fecundity and survival rates regulate population growth. The former rate is read o the fecundity-at-age
relationship generated at the individual level, whereas the latter rate follows from natural and shing
mortalities found in the latest PBT stock assessment. We apply the model to estimate the uncertainty in
the growth rate of the wild PBT population caused by the unclear feeding ecology of this species during
spawning migrations. In particular, we show that if PBT experience reduced food availability while migrating, the eect on the growth rate of an individual sh may be negligible, whereas the fecundity rate
may suer a 40% decline. Such a decline has a negative eect on the population growth rate, whichfor
the purpose of robust shery managementhas to be compensated for by reducing shing eort. We nd
that a reduction across all age groups of about 17 % relative to the present-day (2007-2009) harvesting
is needed.
A somewhat counterintuitive consequence is that the total catch in terms of biomass may
actually increase upon implementing the reduction due to, among other factors, the dominance of larger
sh in the catch.
10
One lump or two? The energetics of a major latitudinal transition
in reproductive allocation in a viviparous lizard
1
M. R. Kearney , M. J. Caley
1
and L. Schwarzkopf
1
1 Univ Melbourne, Dept Zool, Melbourne, Vic 3010, Australia
[email protected]
Viviparity constrains the frequency of reproduction in many organisms because the interval between
reproductive bouts is extended by long gestation times. For this reason, increased reproductive interval
typically prevents multiple reproductive events per annum in viviparous ectotherms. In contrast to this
widespread pattern, we report geographic variation in reproductive frequency, one versus two repro-
Eulamprus quoyii ),
ductive bouts per annum, in a viviparous lizard (
and assess the potential roles of
physiological adaptation and environmental constraints in driving this life history variation. We develop
an integrated model of the energetics of growth and reproduction in this lizard using Dynamic Energy
Budget theory, and apply it in conjunction with biophysical calculations of body temperature and activity time across its geographic range. Our model indicates that geographic variation in body temperature
alone explains the observed pattern of litter frequency, suggesting that dierences in energy allocation
among populations is unlikely to be a major cause of dierences in litter frequency in
E. quoyii.
suggests that natural selection should favour xation of litter size in the transition zone.
11
It also
Physiologically-based model of organismal response to oxidative
stress, applicable to ecotoxicology and nanotoxicology
T. Klanjscek
1,2
1
, E.B. Muller , and R.M. Nisbet
1
1 Department of Ecology, Evolution and Marine Biology, University of California Santa-Barbara, CA 93106, USA
2 Division for Marine and Environmental Research, Ruder Boskovic Institute, 10000 Zagreb, Croatia
[email protected]
Toxicants, radiation, and other stressors profoundly aect cell function and, consequently, energy budgets. Currently, DEB theory captures some of these eects by subjecting one or more DEB parameters
to a stressor density as experienced by an organism, such as the body burden of toxicant. In most applications, one or more DEB parameter values increase linearly with this stressor density less some no-eect
concentration, which represents the capacity of an organism to mitigate adverse stressor eects. This
approach has several shortcomings. First, it lacks the core ambition of DEB theory to nd and describe
those processes that are shared by all genera.
The DEBtox approach of a priori assuming that some
parameter(s) is (are) principally aected more than others appears to be at odds with the homeostasis assumptions of the theory. In addition, this approach neither explains the roots of no-eect concentration,
nor has a mechanistic way of estimating energy costs of countering stress. Furthermore, the current DEB
approach does not capture cumulative eects of stress (runaway damage): if the experienced stressor
density stabilizes, the stress-related eects remain constant (but see Jager and Kooijman, 2005,
Sci. Technol.
39,
8307).
Environ.
This is inconsistent with data where, although eective levels of exposure
are reduced or even stopped, eects continue to escalate. Although such description may occasionally
be good enough for ecological contexts, it lacks in ability to describe eects of stress on shorter time
scales often encountered in experimental setups. We start by considering an example of biochemical and
regulatory network of a cell. We then suggest a theoretical framework that abstracts the basic cellular
processes to model dynamics of damage-inducing compounds and cellular damage (Figure). The suggested models address many of the aforementioned issues, as they: (i) can be related to measurables,
(ii) capture dynamics of damage and repair based on metabolism, (iii) oer a mechanistic description of
the no-eect concentration, and (iv) describe tipping points leading to runaway increase in damage as a
function of level and duration of exposure. Our models have a stronger mechanistic foundation than the
current formulation in DEB theory and may provide a process-based platform for modeling sublethal
toxic eects on DEB process, which is a current focus of research in our group. The new framework could
replace the current DEB representations of damage inducing compounds and damage in DEB theory,
without compromising the other components.
12
Figure 1: Model structure. Metabolism and stress produce ROS.
ROS is inactivated into harmless metabolites through controlled
reactions without damaging the cell, or through spontaneous, uncontrolled reactions that produce damage.
Damage can also be
produced directly by stress and reduced by regulated damage repair.
Unrepaired damage increases ROS production.
Since the
model focuses on cellular processes rather than aging, the denition of damage-inducing compounds is expanded to include anything that damages cellular function (e.g. proteins with reduced
function), not just the irreversible DNA damage that permanently
aects cellular function (e.g. by producing 'wrong' proteins) included in DEB theory. We refer to damage-inducing compounds
as ROS to avoid confusion between DEB and our denitions, and
to highlight connections of our state variables with measurables.
13
Dynamic Energy Budget theory and Adaptive Dynamics approach
together with bifurcation analysis and aggregation techniques
B. W. Kooi
1
1 Dept. of theoretical Biology, VU Amsterdam, De Boelelaan 1985, 1081 HV Amsterdam, The Netherlands
[email protected]
An overview is given some mathematical tools for the analysis of the long-term dynamics of population and ecosystem models based on DEB theory.
In order to describe evolutionary processes due to
changing physiological (ecology) or behaviour (game theory) processes the Adaptive Dynamics approach
formulation can be used. Case study examples from the literature will be discussed to illustrate solving
ecological problems by aggregation techniques and bifurcation analysis.
References
Kooi, B.W. and Troost, T. (2006) Advantages of storage in a uctuating environment,
70(4),
Theo. Pop. Biol.,
527-541
Auger P., Kooi B.W., Bravo de la Parra R., Poggiale J-C. (2006) Bifurcation analysis of a predator-prey
model with predators using hawk and dove tactics,
J. Theo. Biol., 238, 597-607
Kooi, B.W., van der Meer J. (2010) Bifurcation theory, adaptive dynamics and DEB-structured populations of iteroparous species,
Phil. Trans. R. Soc., 365, 3579-3590
Kooi, B.W. (2015) Modelling the dynamics of traits involved in ghting-predators-prey system,
Biol., accepted
14
J. Math.
How to include the eect of salinity on the physiological response
of eastern oyster,
, in a Dynamic Energy
Budget model?
Crassostrea virginica
1
2
3
R. Lavaud , M. LaPeyre , C. Bacher
4
and J. LaPeyre
1 School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA
2 U.S. Geological Survey, Louisiana Cooperative Fish and Wildlife Research Unit, School of Renewable Natural Resources,
Louisiana State University, AgCenter, Baton Rouge, LA 70803
3 Laboratoire d'écologie benthique, IFREMER Centre Bretagne, ZI de la Pointe du Diable, CS 10070, 29280 Plouzané,
France
4 Veterinary Science Unit, School of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA,
70803, USA
[email protected], [email protected], [email protected],
[email protected]
According to DEB theory, two environmental parameters inuence the dynamics of energy between the
environment and the organism, and within the organism: food availability and temperature. However,
in some species, these two forcing variables are not sucient to accurately simulate changes in physiological state. In particular, estuarine organisms are often exposed to highly variable environments (i.e.,
salinity, pH, oxygen, chemicals) which place signicant demands on the organism, potentially aecting
maintenance and physiological state. In this study we attempt to include the eect of salinity on the
life history of the eastern oyster, Crassostrea virginica. In northern Gulf of Mexico estuaries, this intertidal species experiences large variations in salinity, which has been shown to be a primary factor
aecting reproduction, growth and mortality.
Two approaches were tested and compared in order to
incorporate salinity eects within a DEB model: (1) the use of empirical equations from pre-existing net
production models, implementing the impacts of salinity on respiration and ltration rates; and (2) the
calibration of the surface-area linked specic somatic maintenance rate
˙ },
{pT
following the hypothesis
that a change in salinity would require increased maintenance of osmolarity gradients.
A rst set of
parameters was estimated using literature data and will be improved thanks to ongoing ecophysiological experiments conducted in the lab at Louisiana State University at the range of nGoM temperature
(16-30 °C) and salinity (3-25) conditions. The hypotheses were tested against several datasets obtained
from experimental oysters placed in Louisiana estuaries over the last years.
15
What the shell can tell about the scallop? Insights from an
inverted DEB model
R. Lavaud
1,2
3
, E. Rannou , F. Jean
1
1
and J. Flye-Sainte-Marie
1 Laboratoire des Sciences de l'Environnement Marin, Institut Universitaire Européen de la Mer, Rue Dumont d'Urville,
29280 Plouzané, France
2 U.S. Geological Survey, Louisiana Cooperative Fish and Wildlife Research Unit, School of Renewable Natural Resources,
Louisiana State University, AgCenter, Baton Rouge, LA 70803
3 Laboratoire de Mathématiques de Bretagne Atlantique, Université de Bretagne Occidentale, Brest, France
[email protected]
In the past decade, many studies using DEB theory to model the growth of marine invertebrates have
emphasized the challenge of dening accurate food proxies. Sometimes it is indeed really dicult to gain
access to this type of information. In the search for useful characterizations, it might then be helpful
to invert the argument: use observed growth and temperature pattern to reconstruct the assimilation
energy and relate it to potential food proxies.
We developed a reconstruction method relying on a
single equation for growth and four core parameters (ν˙ ,
k˙ M , Lwm
and
δM ).
This equation is a second
order dierential equation derived from the dierential system describing the dynamics of state variables
according to the DEB theory.
Each solution of the linear equation is therefore a solution of a DEB
model, and vice versa. Additionally, it gives access to the reconstruction of reserve state variable, reserve
density, mobilization and somatic maintenance rates. The great scallop, Pecten maximus, provides high
frequency records of their past history thanks to the incremental growth of their shell. It is therefore a
good material to investigate the potential of this approach. Starting from a theoretical case, we explored
the resolution and sensitivity limits of the method. The tting of a cubic spline through growth trajectory,
as usually recommended prior to use the data, was not appropriate as the growth equation makes use
of secondary derivative, leading to excessive variability in the reconstructed functional response.
A
smoothing procedure, based on growth assumptions emerging from DEB theory, was developed to deal
with the high-frequency variations displayed in growth pattern. We then applied this procedure to a large
set of growth trajectories along the distribution range of the great scallop. The features of reconstructed
functional response along latitudinal and bathymetric gradients indicated that its variation frequency
and its amplitude could explain the observed growth patterns.
16
A Dynamical Energy Budget for the whole life-cycle of
holometabolous insects
1
2
3
4
3
A. L. Llandres , G. M. Marques , J. Maino , S.A.L.M. Kooijman , M. R. Kearney
and J. Casas
1
1 Institut de Recherche sur la Biologie de l'Insecte, Université de Tours, UMR CNRS 635, Avenue Monge-Parc Grandmont,
37200, Tours, France
2 Environment and Energy Section, DEM, and IN+ Center for Innovation Technology and Policy Research, Instituto
Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
3 Department of Zoology, Melbourne University, Victoria, Australia
4 Department of Theoretical Biology, Vrije Universiteit, NL-1981 Amsterdam, the Netherlands
[email protected]
Alterations of the amount and quality of food consumed during ontogeny can aect dierent life-history
traits, such as growth rate, developmental time, survival, adult size and tness.
Understanding the
dynamics of such interactions is particularly challenging in the case of holometabolous insects due to
their strikingly dierent life-stages.
Here we show how whole-life-cycle energy and mass budgets can
be achieved for holometabolic insects through Dynamic Energy Budget (DEB) theory, permitting the
fate of stored nutrients to be followed over a complete life cycle. We extended the Standard Model of
the Dynamic Energy Budget theory to model the whole life-cycle energetics of an endo-parasitic wasp,
Venturia caenescens
(Hymenoptera: Ichneumonidae). Data on embryo, larval and pupal dry weights,
imago longevity and fecundity were used for assessing the goodness of t of the model.
The model
enabled us to distinguish and follow the energy invested in eggs through capital and income reserves and
implies that feeding wasps produce almost twice as many eggs as non-feeding wasps by incorporating
income resources and living longer. The mechanisms leading to the double costs of being small - a shorter
life under starving conditions and fewer eggs - were identied by running the model for varying amounts
of food eaten early in life, according to host sizes. In small hosts, early instars gather small amounts of
energy. The smaller imagoes that result then have to use a larger proportion of their capital energy for
maintenance, rather than for reproduction. A rich environment during adult life does not enable them
to make up for their bad start. The holistic nature of our modeling framework led to the identication of
several understudied aspects of insect energetics and shifted the emphasis from the imago to the earlier
instars. Our model is general for insects and has applications for a wide range of applied and theoretical
questions about insect energetics.
17
Coupling of physiological and ecological models to explore food
uctuation eects on the sex change in hermaphrodite species
1
2
3
D. Louati , S. Ben Miled , R. Jaroudi , G. Haddad
4
1 Université de la Manouba, Ecole Nationale des Sciences de l'Informatique, Laboratoire RIADI, Tunisie
2 Université de Tunis El Manar, Institut Supérieur d'Informatique, Tunisie
3 Université de Tunis El Manar, Faculté des Sciences de Tunis, Tunisie
4 Université de Tunis El Manar, Institut Pasteur de Tunis, Groupe de Bioinformatique et Modélisation, Tunisie
[email protected]
One of the major evolutionary questions about sequential hermaphrodite is to determine where the direction and the timing of sex change are viewed as responses to demographic and environmental parameters
(Charnov, 1982).
To connect the sexual behaviour of hermaphrodites to the environment parameters
(e.g. food availability and population density) it is indispensable to couple models at physiological and
ecological scales. In this work, we aim to investigate the food uctuation eect on the optimal individual
sex change size and on population sex-ratio. Our approach is based on the study of the sex-ratio and
sex change size as emergent parameters from individuals behaviour which is based on energy allocation
rules.We de- veloped an agent based model coupling Dynamic Energy Budget model (Kooijman, 2010)
at individual scale and sexual allocation models at the population scale (Ghiselin, 1969, Warner, 1988
and West, 2009). We designed experiments to determine the most relevant parameters and study the
eects of uctuating food on the individual and population scales. At constant food availability, both
growth and maturation predicted by the model t well with eld observations.
References
Princeton University Press
Quart. Rev. Biol., 44:189-208
Kooijman, S. (2010) Dynamic Energy Budget theory for metabolic organisation, Cambridge University
Press
Warner, R. (1988) Sex change and the size-advantage model, T. Ecol. Evol., 3(6):133-136
West, S. (2009) Sex allocation, Princeton University Press
Charnov, E. (1982) The theory of sex allocation,
Ghiselin, M. T. (1969) The evolution of hermaphroditism among animals,
18
From data to parameters : a preliminary DEB model for
loggerhead turtles (
)
Caretta caretta
1
2
N. Marn , S. Kooijman , T. Klanjscek
1
1 Division for Marine and Environmental Research, Rudjer Boskovic Institute, Zagreb
2 Department of Theoretical Biology, Vrije Universiteit Faculty of Earth & Life Sciences, Amsterdam
[email protected]
Sea turtles have been swimming in the world oceans, and adapting to the changing environment for the
last 200 million years. Despite their successful adaptation, all seven species of sea turtles are currently
considered globally threatened in the IUCN classication and are protected by the CITES convention
(see Turtle Taxonomy Working Group, 2012 for details).
Research and conservation of sea turtles increased in quality in quantity over the last two decades
(see Hays, 2008 for review), with some of the areas gaining special attention.
One of them is the
development of models focusing on energetic budgets (Hays, 2008), with the goal to combine information
on their metabolic rate, energy density of prey and ingestion rates to assess energy balance over long
periods (Hays, 2008). A well dened Dynamic Energy Budget (DEB) model has the additional potential
to predict growth, maturation and reproduction of individuals under dierent food and temperature
conditions (Koojiman, 2010), and relate laboratory data to eld data and predictions. Estimating the
parameter values for such a model highly depends on the availability, selection and quality of data.
Caretta caretta )
Loggerhead turtles (
are one of the best studied marine turtles.
Research includes
studies of incubation, growth of captive reared and wild individuals, isotope studies, genetic studies,
and various growth models. Studies often focus on individuals belonging to a specic life stage (embryo,
juvenile, adult), or to a specic geographic region (North Atlantic, Mediterranean etc). When comparing
individuals, variability is often observed in growth rates, size at the onset of reproduction (considered to
be sexual maturity), and/or age at sexual maturity. There is considerable variability among individuals
et.al., 2006), and even more variability among individuals of
et.al., 2005 ; Margaritoulis et.al., 2003).
of the same life stage or region (e.g. Stokes
dierent life stages or regions (e.g. Byrd
The source of variability could be dierent conditions in the environment (e.g. food density, temperature),
or dierent perception of same conditions by dierent individuals, the latter translating into variation
of individual-specic parameter values of a well designed mechanistic model. One of such mechanistic
models is a DEB model, and we used it to test some possible sources of variabitlity. Ideally, data used
for estimating parameter values should be obtained under standardized temperature and food density,
which would remove some sources of variability. Despite the long and fruitful interest that people have
in loggerhead turtles, it is hard to nd examples of data describing the full life cycle, that were obtained
under such standardized conditions.
To estimate values of model parameters, we used data collected
from the Atlantic and Mediterranean region, for wild and captive reared individuals. Chosen data sets
were passed to DEBtool parameter regression routines, and dierent food density and temperature were
accounted for. Model predictions obtained with the preliminary parameter set show a satisfactory t
with data (F IT
> 7)
.
References
Byrd, J., Murphy, S., and von Harten, A. (2005) Morphometric analysis of the northern subpopulation
of
Caretta caretta
in South Carolina,
USA. Marine Turtle Newsletter, 107:1-4
Hays, G. C. (2008) Sea turtles: A review of some key recent discoveries and remaining questions,
19
Journal
of Experimental Marine Biology and Ecology, 356(1-2):1-7.
behavioural ecology and conservation biology.
In:
Sea turtles: physiological, molecular and
Kooijman, S. (2010) Dynamic Energy Budget theory for metabolic organisation.
Press, GreatBritain.
Cambridge University
Margaritoulis, D., Argano, R., Baran, I., Bentivegna, F., Bradai, M., Caminas, J., Casale, P., Metrio, G.
D., Demetropou-los, A., Gerosa, G., Godley, B., Haddoud, D., Houghton, J., Laurent, L., and Lazar, B.
(2003) Loggerhead turtles in the mediterranean sea: Present knowledge and conservation perspectives,
Bolten, A. and Witherington, B., editors, Loggerhead Sea Turtles,
Washington D.C.
In
175-198.
Smithsonian Books,
Stokes, L., Wyneken, J., Crowder, L. B., and Marsh, J. (2006) The inuence of temporal and spatial
Caretta caretta )
origin on size andearly growth rates in captive loggerhead sea turtles (
States,
Herpetological Conservation and Biology, 1(2):71-80.
Turtle Taxonomy Working Group (2012) Turtles of the world, 2012 update:
in the United
Annotated checklist of
Conservation Biology of Freshwater
Turtles and Tortoises: A Compilation Project of the IUCN/SSC Tortoise and Freshwater Turtle Specialist
Group, Chelonian Research Monographs No. 5, 5:000.243-000.328.
taxonomy, synonymy, distribution, and conservation status.
20
In
Implementing phylogenetic constraints on DEB parameter
estimation: a new multispecies estimation procedure
G. M. Marques
1,2
3
, S. A. L. M. Kooijman , T. Domingos
2
4
and L. Pecquerie
1 CIMO,Instituto Politécnico de Bragança,Campus de Santa Apolónia, Apartado 1172, 5301-855 Bragança, Portugal
2 MARETEC, Instituto Superior Técnico, Universidade de Lisboa,Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
3 Department of Theoretical Biology, Vrije Universiteit, de Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
4 Institut de Recherche pour le Développement (IRD), Laboratoire des Sciences de l'Environnement Marin (LEMAR, UMR
6539), Institut Universtaire Européen de la Mer, France
[email protected], [email protected], [email protected],
[email protected]
The Dynamic Energy Budget (DEB) theory has been used to describe a great number of organisms
through their mass and energy uxes (Kooijman, 2010).
Dierences between species are reected in
dierences in their parameter values and the DEB framework also provides the body size scaling relationships, an inter-specic relation between the parameters of dierent species. Here we show that the
estimation of DEB parameters (Lika
et.al.,
2011) is enhanced by using these relationships. The body
size scaling relationships can allow for the estimation of the parameter set of a target species even in the
case when full data sets are not available, by using a new multispecies procedure that includes datasets
of other closely related species. The data of closely related species and the body size scaling relationships provide the necessary constraints for the estimation. We will present an example of multispecies
estimation with 3 species.
References
S. A. L. M. Kooijman (2010) Dynamic Energy Budget Theory for Metabolic Organization,
University Press, Cambridge
Cambridge
Lika, K., Kearney, M.R., Freitas, V., van der Veer, H.W., van der Meer, J., Wijsman, J.W.M., Pecquerie,
L., Kooijman, S.A.L.M., (2011) The co-variation method for estimating the parameters of the standard
Dynamic Energy Budget model I: Philosophy and approach,
21
J. Sea Res.
66,
270-277
A simple model predicts complex adaptive patterns of energy
allocation between growth and storage in sh
1
B. T. Martin , R. M. Nisbet
1
and E. Danner
2
1 Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, USA CA 93106-9610,
USA
2 NOAA/National Marine Fisheries Service - Southwest Fisheries Science Center, Santa Cruz, USA
[email protected]
Fish of the same species dier drastically in energy density (typically by a factor of 2), nearly all of which
is explained by dierences in storage lipids.
This variation has important ecological consequences, as
lipids are required for survival during unfavorable conditions and are an energy reserve for reproduction.
We reviewed the literature and identied 3 stylized facts or patterns of interspecic variation in energy
density among sh:
1. Energy density increases through ontogeny
2. Energy density changes across seasons, with depletion over winter, but increases fastest in periods of
transition between conditions favorable and unfavorable for growth (e.g. fall)
3. Energy density varies across habitats, but in a direction opposite of that predicted by standard DEB
theory (e.g. anadromous sh in freshwater habitats grow slowly but have high energy densities, while
sh in marine environments growth quickly but have low energy densities)
We show that all three patterns are predicted by a simple variant of the DEBkiss model, where the
(1−κ)
energy ux is allocated to lipid storage rather than to increasing complexity (the maturity state variable).
As in DEBkiss, maintenance costs are paid from the
κ (growth) ux, thus the relative proportion of energy
xed in storage lipids vs. somatic tissue increases with ontogeny due to dierential scaling of assimilation
(L2) and maintenance costs (L3).
Likewise, the model predicts the proportion of energy allocated to
storage is greater in periods of low to intermediate food (e.g. fall or freshwater habitats) than in more
favorable conditions for growth (e.g.
a larger fraction of the
κ
summer or marine habitats) because maintenance costs deplete
(growth) ux. Thus, without the addition of any parameters, our variant of
DEBkiss predicts the dynamics of an additional measurable state variable that is ecologically relevant.
Finally, our model provides a mechanistic explanation for why smaller individuals are more vulnerable
to starvation.
22
Application of the Dynamic Energy Budget Theory to model
growth and reproduction in of established population of the
non-native green mussel
in southwest Florida coastal
waters
Perna viridis
K. McFarland
1,2
2
, F. Jean , R. Lavaud
2,3
A.K. Volety
1,4
1 Department of Marine and Ecological Sciences, Florida Gulf Coast University, 10501 FGCU Blvd. South, Fort Myers,
FL 33965, USA
2 LEMAR UMR 6539, Institute Universitaire Européen de la Mer, Université de Bretagne Occidentale, Rue Dumont
d'Urville, Place Nicolas Copernic, 29280 Plouzané, France
3 School of Renewable Natural Resources, Louisiana State University, Baton Rouge, LA, 70803, USA (current address)
4 Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Rd., Wilmington,
NC, 28403, USA (current address)
[email protected]
As an invasive species ecological concerns have risen with regards to the spread and success of the green
mussel Perna viridis throughout southeastern United States and Caribbean coastal regions. As a subtidal
marine and estuarine species the arrival to new locations often goes unnoticed until the populations have
become established. Application of the Dynamic Energy Budget (DEB) theory allows for the inclusion
of a changing environment and a systemic response from the organism. Through the application of the
DEB theory a set of parameters was established to accurately model the growth and reproduction of
green mussels forced by dynamic environmental conditions. Environmental variables, particularly food
and temperature, are driving forces of both growth and reproduction and thus play an essential role
in the foundation of the DEB predictions. The model was calibrated using data from eld monitoring
of growth and reproduction throughout a two year monitoring period to ensure realistic outputs and
validated using an external data set to assure the ability to use this information for populations across
a wide geographic span simply by changing the environmental parameters.
23
Mathematical Modelling of Human Obesity: a Condition of Low
Micronutrient:Macronurient Ratio Diets.
A.-T. McGill
1
and J. Baas
2
1 School of Population Health, University of Auckland, New Zealand
2 Centre for Ecology and Hydrology, Science of the Environment, UK
[email protected]
Introduction: Central obesity related metabolic syndrome (MetS) is associated with the degenerative
diseases of type II diabetes mellitus, cardiovascular disease and cancer.
It is hypothesised that the nuclear factor-erythroid 2-related factor 2 system (NRF2) uses (phyto)chemicals
for energy ecient cell metabolism and in humans became an antioxidant and antitoxicant amplifying
cell protection system allowing human longevity.
Mathematical systems modelling should show that high micronutrient:macronutrient ratio food diets in
humans involve highly ecient energy metabolism and tissue repair via the NRF2 system, and this will
prevent both excess central fat accumulation and related MetS.
Aim: To formulate a comprehensive multistep mathematical model of the energy-ecient phytochemicaldependant human antioxidant/antitoxicant cell protection NRF2 system.
Methods: Involve
1) Developing an energy concentration compartment-based equation in humans into which a reserve for
micronutrient action can be inserted
2) Altering the Add-my-pet data for modern day obese humans into the Dynamic Energy Budget (DEB)
framework at the DEB2015 school
and, in future
3) Running metabolomics analysis from tissue/blood samples of various human models, particularly
assessing before and after change from westernised (energy dense) to whole food (micronutrient dense)
diets
4) Using mathematico-engineering systems modelling of the actual ux of energy in the NRF2 system,
and calculating the energy potentials of (Michael) reactions involving plant chemicals
5) Modifying the DEB and other models as more human-specic energy ux data becomes available,
within the above theory
(Apr 2015, Marseille, France http://deb2015.mio.univ-amu.fr)
Results: Progress and the DEB2015 project will be presented.
Conclusion: The results will be discussed in the light of human dietary evolution
24
DEB Modeling of Tree Performance to Predict Functional Trait
Drivers, Species Distributions, and Responses to Global Change
1
2
2
3
4
5
1
4
R.M. Nisbet , G. Ledder , S. Russo , M. Bartlett , C. Farrior , V. Couvreur , E.B. Muller , A. Peace ,
3
6
L. Sack , F. Sterck , D. Way
7
and E. Zimmer
8
1 University of California, Santa Barbara, USA
2 University of Nebraska, Lincoln, USA
3 University of California, Los Angeles, USA
4 National Institute for Mathematical and Biological Synthesis, USA
5 University of California, Davis, USA
6 Wageningen University, The Netherlands
7 University of Western Ontario, Canada
8 ibacon GmbH, Roÿdorf, Germany
[email protected]
To date, there are few DEB modeling studies of the ecology of plants.
A recently formed working
group at the National Institute for Mathematical and Biological Synthesis (NIMBioS) aims to develop a
mechanistic dynamic energy budget model to predict the growth and survival of individual tropical trees.
The model will couple DEB-inspired representations of carbon and nitrogen uxes to a hydraulic model
describing water potential.
The coupling is necessary because water potential in leaves and stomatal
conductance aect rates of photosynthesis.
The model will simulate plant growth and survival based
on measured functional trait values and responses to environmental variation, including irradiance, soil
moisture and nutrients, and temperature. We aim to identify combinations of functional and biomassand nutrient-allocation traits that maximize net photosynthetic carbon gain (C-gain) and survival at
the level of the whole tree. We will test this model by comparing predicted trends in functional traits,
growth, and survival along resource availability gradients with data for Bornean and Bolivian tree species.
The model aims to predict:
(1) species distributions based on dierences in performance of trees in
response to variation in resources, such as along natural environmental gradients; and (2) responses of
trees to environmental shifts caused by global change. The presentation will describe formulation of a
prototype model, drawing on previous modeling of carbon gain in trees by Sterck and Schieving (2011),
DEB concepts from Kooijman (2010), plant hydraulics (Osborne and Sack, 2012), and DEB theory on
syntrophy (Muller et al., 2009).
References
Kooijman, S.A.L.M (2010) Dynamic Energy Budget theory for Metabolic Organization,
versity Press
Cambridge Uni-
Muller, E.B., Kooijman, S.A.L.M., Edmunds, P.J., Doyle, F.J., and Nisbet, R.M. (2009) Dynamic energy budgets in syntrophic symbiotic relationships between heterotrophic hosts and photoautotrophic
symbionts,
J. Theo. Biol.
259,
44-57
Osborne, C.P., and Sack, L. (2012). Evolution of C-4 plants: a new hypothesis for an interaction of CO2
and water relations mediated by plant hydraulics.
P. Trans. Roy. Soc. B
25
367,
583-600
Daphnia magna
DNA alterations and eects on energy budget in
during chronic external gamma irradiation over three successive
generations
1
2
1
F. Parisot , J.-P. Bourdineaud , C. Adam-Guillermin , J.-C. Poggiale
3
and F. Alonzo
1
1 Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PRP-ENV/SERIS/LECO, Cadarache, St Paul-lez-Durance,
13115, France
2 UMR 5805 EPOC OASU, Station marine d'Arcachon, Université Bordeaux 1, 33120 Arcachon, France
3 UMR 7294 MIO Institut PYTHEAS (OSU) Université Aix-Marseille, 13288 Marseille Cedex 9, France
[email protected]
Anthropogenic activities related to the nuclear industry contribute to continuous discharges of radionuclides into terrestrial and aquatic ecosystems.
Over the past decade, ecosystems protection against
ionizing radiation has become a growing public, regulatory and scientic concern. Until recently, ecological risk assessment for ionizing radiation has been based for a vast majority on studies investigating
eects under acute dose and short exposure time, far from realistic environmental conditions in which
natural biota are actually exposed. Conducting studies at chronic low doses over several generations is
necessary to increase our understanding of the long-term eects of low doses of ionizing radiation and
adequately protect the environment.
In this context, the present study examined chronic eects of external Cs-137 gamma radiation over three
successive generations (F0, F1 and F2) of the cladoceran crustacean,
Daphnia magna.
The objectives
were threefold: (i) to examine whether environmentally relevant dose rates of gamma radiation (from
0.007 to 35.4 mGy.h-1) induced increasing eects on survival, growth and reproduction over generations,
(ii) to test a possible accumulation and transmission of DNA alterations (from adults to ospring) and
(iii) to compare responses to chronic gamma radiation between the molecular and organismal levels of
biological organization.
Results showed a signicant reduction in fecundity at 35.4 mGy.h-1 in generation F0, a relatively slighter
reduction in fecundity at 35.4 mGy.h-1 in generation F1, and a signicantly increasing delay in growth
and brood release from 0.070 mGy.h-1 in generation F2. In parallel, DNA alterations became signicant:
(i) at decreasing dose rates over the course of generation F0 (from 4.70 mGy.h-1 at hatching to 0.007
mGy.h-1 after 21 days), (ii) at only the highest dose rates in generation F1 and (iii) at decreasing dose
rates (from 0.07 mGy.h-1 at hatching to 0.007 mGy.h-1 after 21 days) over the course of generation F2.
This study suggested that an accumulation and transmission of DNA alterations occurred from generations F0 to F2, together with an increase in eect severity on growth and reproduction. Transient DNA
repair leading to some recovery at the organism level was suggested in generation F1. A DEBtox model
is currently developed to mechanistically describe how an accumulation and transmission of DNA alterations can explain changes in growth and reproduction eects over successive generations and explore
the metabolic modes of action associated with gamma radiotoxicity.
Keywords :
Gamma radiation, Daphnia magna, multigeneration, DNA alterations, DEBtox
26
Growth increment formation in sh larvae otoliths: Exploring
mechanisms with a DEB modelling approach applied to
Atlanto-Iberian sardine (
)
Sardina pilchardus
1
2
2
3
2
3
4
4
L. Pecquerie , S. Garrido , S. Ferreira , A. M. Santos ; P. Ré , C. Nunes , G. M. Marques , T. Sousa ,
5
R. Fablet
and H. de Pontual
6
1 Institut de Recherche pour le Développement (IRD), Laboratoire des Sciences de l'Environnement Marin (LEMAR, UMR
6539), Institut Universtaire Européen de la Mer, France
2 Universidade de Lisboa, Faculdade de Ciências, Departamento de Biologia Animal, Portugal
3 Instituto Português do Mar e da Atmosfera (IPMA), Departamento do Mar e Recursos Marinhos (DMRM), Portugal
4 Instituto Superior Técnico (IST), Universidade de Lisboa, Portugal
5 Telecom Bretagne, Département Signal et Communications, France
6 IFREMER, Unite Sci & Technol Halieut, F-29280 Plouzane, France
[email protected]
Estimating age and growth of sh larvae is often required in connectivity and recruitment studies. When
validated, daily growth increment formation in sh larvae otoliths allows such estimations of larval age
and growth. However, several experimental studies showed that otolith distinguishable increments are not
always formed at a daily scale, which biases age and growth reconstruction. Here, to better understand
the factors controlling the formation of a sh larvae otolith, we propose to further develop a bioenergeticmodeling framework previously applied to the seasonal (yearly) formation of sh otoliths. This model
couples both the growth of an otolith and its opacity to the metabolism of the organism. The model relies
on well-tested properties of the Dynamic Energy Budget (DEB) theory, which predicts individual growth,
development and maintenance as a function of food density and temperature conditions. We apply the
model to sagittae of Atlanto-Iberian sardine larvae Sardina pilchardus. Data on otolith diameter and
growth increment numbers, together with individual known age and total length, from larvae reared
in laboratory under four dierent food conditions (high, intermediate, low and starvation conditions)
showed that increment deposition was signicantly less than one per day. We use data at two dierent
food levels (high and low) to calibrate the otolith module.
We rst test the ability of the model to
reproduce the otolith and sh size for the two other food conditions (intermediate and starvation). We
then test the assumption that individuals do not deposit sucient material of contrasted opacity for an
increment to be formed at low food levels. We discuss the use of this model to reconstruct growth and
feeding conditions when increments widths are measured and the assumptions required to downscale the
model to the daily scale.
otolith daily growth, opacity, bioenergetics, Dynamic Energy Budget (DEB) theory, growth
reconstruction, larvae, Sardina pilchardus
Keywords :
27
Modelling eects of food and temperature on the growth of
Northern krill,
Meganyctiphanes norvegica
1
E. Ravagnan
and T. Jager
2
1 International research Institute of Stavanger (IRIS), Marine Environment, Postbox 8046 | 4068 Stavanger, Norway
2 DEBtox Research, De Bilt, the Netherlands
[email protected]
The northern krill is one of the key species in the sub-Arctic and North Atlantic. It is an important prey
for pelagic and benthic species as well as for birds, and a primary consumer for the lower trophic levels.
It is important to study its population dynamics to evaluate the risk of anthropogenic impacts, like
aquaculture or oil and gas exploitation. Unfortunately, laboratory data on life history are not abundant,
and eld data are incomplete. To study the Northern krill's growth pattern, we applied the DEBkiss
model, which is a simplied DEB model that removes the reserve compartment (all biomass is treated as
structure or reproduction buer; an acceptable simplication for small invertebrates). Assuming that the
growth of Northern krill follows the von Bertalany model in a constant environment, it is possible to use
the estimates for Lwm (maximum physical length at abundant food) and rB (von Bertalany growth rate
constant) to reconstruct the environmental conditions underlying the growth data for cohorts sampled
from the eld. Several eld growth curves (Kattegat, Clyde Sea and Ligurian Sea) were available from the
literature. The main factors aecting growth are the food availability and the environmental temperature.
Because of the krill's dial migration along the water column, it is challenging to dene a representative
seasonal temperature. The average temperatures in summer and winter (between 25m and 100m) were
used to dene a sine function representing the daily temperature. Next, the food availability over the
year could be predicted based on the size-at-age data, combined with the expected temperature prole.
This predicted food level shows a marked seasonality, with peak feeding conditions coinciding with the
algal blooms at the dierent locations.
Furthermore, the energy-budget parameters could be used to
predict other physiological traits of this species, such as respiration and feeding rates.
28
Trade-os in the life history of birds through the application of
Dynamic Energy Budget theory
C. M. G. L. Teixeira
1,2
2
, S. A. L. M. Kooijman , T. Sousa
1
, T. Domingos
1
1 MARETEC/LARSYS, Environment and Energy Scientic Area, DEM, Instituto Superior Técnico, Universidade de
Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal
2 Department of Theoretical Biology, Faculty of Earth and Life Sciences, VU University Amsterdam, de Boelelaan 1085,
1081 HV Amsterdam, the Netherlands
[email protected]
The study of the life history evolution of birds has relied mostly on attempts to quantify the relative
eect of exogenous drivers such as predation, food limitation and behavioural strategies, on life history
traits. As far as endogenous drivers are concerned the focus has almost exclusively been on the eects
of body size and phylogeny using statistics or comparative genomics.
In recent years the need to identify and describe the physiological and proximate mechanisms mediating
and constraining the eect of exogenous and endogenous drivers on the life history traits of animals has
been frequently stated in the scientic literature.
Primary and compound DEB parameters are closely related with the physiology and metabolism of
organisms. Here we hypothesise that dierences in DEB parameter values between bird species can shed
light on dierences in particular life history traits.
A database comprising 40 bird species, one for each of the 40 orders of birds existing today, was compiled
and supplemented with published or original growth data obtained from captive breeding programs. By
applying the covariation method of estimation, sets of parameters were estimated using the `DEB tool'
(http://www.bio.vu.nl/thb/deb/deblab/debtool/) and `Add My Pet' libraries.
The diversity of values estimated for the set of DEB parameters generally reect the diversity of life
history traits observed in birds.
One important result consists in the very high average value of
(0.98) that we observed. Among the DEB parameters,
coecients of variation, while
κ
and
[EG]
eH
b
,
H
k˙ J , eH
x , ep , ν˙
and
[pM ]
κ
exhibit the higher
are the parameters exhibiting the lowest degrees of variation.
We can thus observe that a high allocation of energy to somatic growth and maintenance has been the
general trend in birds, possibly subject to strong phylogenetic inertia. A great part of the phenotypic
and adaptive plasticity we observe today as well as most of the evolution that has taken place in birds
and that has determined the phylogenetic structure of this group, may have resulted from the plasticity
associated with maturity, reserve mobilisation and somatic maintenance costs.
Thus, currently living
species will probably not be able to adapt quickly to current global environmental change, by allocating a
larger fraction of energy to reproduction in detriment of somatic growth and maintenance (i.e., changing
κ)
due to the apparent phylogenetic stability and low variation associated to this parameter, but may
be able to adapt through the apparently higher plasticity in maturity-related and reserve mobilisation
traits.
In order to explore how the dierent DEB parameters may be associated with the currently observed
variation in the life histories of birds, we compared the estimated DEB parameter values according
to dierent categories allocating species according to several evolutionary and ecological factors such as
taxonomy (the Superorder in which the species are grouped), development type (the altricial to precocial
spectrum), foraging habitat, ight ability and migratory capacity, among others.
We observe that the Neognathae have signicantly higher ? values than the Palaeognathae. Considering
the low coecient of variation of
κ,
this suggests that the evolution of the Neognathae went towards
a higher investment in somatic growth and maintenance, instead of the maximisation of reproduction
29
as has been previously suggested.
Higher somatic maintenance requirements in the Neognathae also
seem to have co-evolved with higher reserve mobilisation rates and higher growth rates. These changes
support the emergence of important features in the Neognathae, such as the ability to y and migrate.
Additionally, higher growth rates may have played a strategic role in the adaptation of bird species
to higher levels of predation during the brooding period. One important trade-o may have been the
reduction of reserve and fasting capacities.
We also highlight that altricial and semi-altricial species seem to have signicantly higher values of
[pM ]
and
r˙B ,
ν˙ ,
than precocial species, suggesting that these may have been the metabolic options used
to reach adult size faster. We also observe that marine or pelagic species seem to have a signicantly
higher
κ than the ones that inhabit and forage terrestrial habitats, which supports previous observations
regarding pelagic bird species and their reduced reproductive output. A third example regards migratory
behavior. We observed that migratory species exhibit signicantly higher values for
κ, ν˙
and
p˙Am
than
non-migratory species, characteristics that enable relevant traits of many migratory birds such as the
capacity to frequently develop muscle tissue (hypertrophy) and assimilate high quantities of energy to
prepare for long migratory distances.
Our results oer explicit metabolic explanations for life history patterns that have been previously
described in birds but for which only their statistical association to body size or a few ecological traits
had been available.
Keywords :
birds, diversity, life history trait, evolution, trade-o
30
Simple, but accurate approximations to scaled age at birth and
scaled initial amount of reserves (egg costs) when κ = 1
J. van der Meer
1,2
1 Royal Netherlands Inst Sea Res NIOZ, NL-1790 AB Den Burg, Netherlands
2 Vrije Univ Amsterdam, Dept Theoret Biol, Amsterdam, Netherlands
[email protected]
Kooijman (2000, 2010) provides some approximations to scaled age at birth and scaled initial amount of
reserves, but these are not very accurate. This implies that the system of coupled dierential equations
has to be solved numerically. I present another (ad-hoc) approximation, discuss the consequences and
provide a challenge for an analytical approach.
31
Modelling appendicularians life cycle: which details to consider?
1
M. Vaugeois , F. Diaz
1
1
and F. Carlotti
1 Aix Marseille Université, CNRS/INSU, IRD, Mediterranean Institute of Oceanography (MIO), UMR 7294, 13288 Marseille
[email protected]
As part of the zooplankton community, appendicularians have a specic functional role in the pelagic
ecosystem by making the link between high and low trophic levels.
They are well known for their
capacity to bloom. In fact, they have a short lifetime but can produce a large amount of gametes in a
single reproduction event. This particular feature underlines a particular energy metabolism strategy,
known as the waste to hurry strategy. Appendicularians also present an uncommon anatomical and
physiological characteristic: they secrete an extra-corporal structure, namely the house, where they live
and which they use as a food reservoir qualitatively and quantitatively regulated. As such, this structure
might delay the organism perception of a food depletion for a considerable period.
In order to analyse if the house should be considered when modelling the life cycle of appendicularian, we
used the Dynamic Energy Budget (DEB) theory. First, a standard DEB model which does not explicitly
take into account the house production nor its impacts on energy acquisition processes was developed.
Results highlight the metabolic particularity of appendicularians with respect to other organisms of the
zooplankton community, such as copepods, and also point out the closeness of appendicularians with
salps, another group of gelatinous zooplankton.
Then, a second version of the model (based on its standard version) which explicitly represents the houses
and their eects on energy acquisition process was build. The two model versions were compared under
constant and uctuating food concentration conditions. Both versions of the model produced the same
results in terms of organism size prediction for constant food concentration conditions.
However, the
results about sizes simulations were signicantly dierent between the two model versions for uctuating
food concentration conditions.
32
DEBtox for plants: a case study of common duckweed exposed
to cadmium
E. I. Zimmer
1,2
2
3
2
, N. Horemans , N. Cedergreen , H. Vandenhove
and T. Jager
4
1 ibacon GmbH, Roÿdorf, Germany
2 Belgian Nuclear Research Centre, SCK-CEN, Mol, Belgium
3 University of Copenhagen, Denmark
4 Vrije Universiteit Amsterdam, The Netherlands
[email protected]
Dynamic Energy Budget (DEB) theory has been widely used in the analysis of ecotoxicological experiments with animals (Kooijman
et.al.,
1996, Jager
et.al.,
2006). While there have recently been a few
applications to mircoorganisms (Klanjscek, 2013), no DEBtox model has been applied to plants yet. We
here present a simplied DEBtox model for common duckweed, Lemna minor.
L. minor is a oating
macrophyte that grows mainly in surface area, which allows for assuming V1-morphic growth on population level. Following the principles of the simplied DEBtox model for animals (Jager
et.al., 2012), we
developed a simple DEBtox model for L. minor with one reserve and one structure.
We here present the application of a DEBtox model to data on L. minor exposed to a range of cadmium
concentrations. Cadmium has been shown to increase the production of reactive oxygen species (ROS)
in various organisms and is in general found to be phytotoxic and an eective inhibitor of photosynthesis.
Eects include a decrease in chlorophyll content, the increase of lipid peroxidation, and a general inhibition of production of antioxidant enzymes. While the data analysis reveals that eects on assimilation
can explain the observed patterns, other eects such as on maintenance rate or cost for growth can
capture the patterns as well. We here discuss the possible inuence of the model assumptions on the
data analysis, and the potential further use of the model in ecotoxicology.
References
Kooijman, S. A. L. M. ; Bedaux, J. J. M. (1996) The analysis of aquatic toxicity data,
press, Amsterdam
VU University
Jager, T.; Heugens, E. H. W.; Kooijman, S. A. L. M. (2006) Making sense of ecotoxicological test results:
towards application of process-based models,
Ecotox., 15, 301-315
Klanjscek, T., Nisbet, R. M., Priester, J. H., Holden, P. A. (2013) Dynamic energy budget approach to
modeling mechanisms of CdSe quantum dot toxicity,
Ecotox., 22, 319-330
Jager, T., Zimmer, E. I. (2012) Simplied Dynamic Energy Budget model for analysing ecotoxicity data,
Ecol. Mod., 225, 74-81
33