Modelling Concepts Flashcards

1
Q

Ift. research for bentiske arter. Der har været innovation of the predictive modelling methodology of changes. Changes for hvad ift de bentiske arter?

A

Organism abundance, biomass, biodiversity, productivity/food webs, habitat provision

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2
Q

Ift. bentiske arter. -to facilitate predictive scenario modelling of “what will happen if” in future management - hvad for populations forhold kigger man så på?

A

Identification of casual relationships between community changes and driving forces (natural environmental, anthropogenic) to be able to predict

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3
Q

Nævn eksempler på benthic suspension feeders. Og hvad er det man gør - når man suspension feeder/exreater

A

Mussels, Clams, cockles, oysters, ascidians, worms, marine sponges

–Suspension-feeding
* Particle capture
* Water processing

–Nutrient release
* Excretion
* Faeces and pseudofaeces production

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4
Q

What do we need models for?

A

Desciption is a first step towards understanding a system and ecology.

Se systemer og trends: Man kan se dynamikker og relationships mellem prey og predator fx

Simple models can be helpful: Easy to run and experiment with them. Can help explain counter-intuitive observations. Can make different scenarios (billigere end at gå ud in the field og lave experiments).

Deling af modeller: Det er ikke alle der vil dele deres modeller.

Tid til at køre modeller: Det kan åbenbart tage flere uger, at køre nogle af de komplicerede modeller.

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5
Q

Kan man modellere life cycles dynamics?

A

ja Life cycle dynamics: Kan også modelleres.

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6
Q

Forklar om tun modellen

A

Tun model: Det er en af de mest udarbejdede fish-models der findes. Om tuns migration.

Der er fx en trait-based tun model hvor man har trait-based alle byttedyrene som tun spiser. På den måde kan man forudsige bl.a. byttedyrenes abundance hvis der kommer mere tun predation

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7
Q

Forklar om population dynamics model

A

Simulate changes in biomass or number of individuals

Most food-web models and biogeochemical models falls here

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8
Q

Hvis en fisk er føde for mange andre fisk - kan man så modellere systemet? Kan man modellere hvad der vil ske, hvis man begynder at fiske mere på dem?

A

Mesopelagiske fisk - er bytte for mange andre fisk. Så hvis man begynder at fiske mere på dem, så kan man modellere hvordan det vil påvirke de andre fisk i økosystemet.

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9
Q

Forklar Individual-based models

A

Tend to follow one single individual (or many simultaneously) -> super individual
Often demanding to run
Might need and optimization if they simulate decision making (fx migration)

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10
Q

Forklar Food web models

A

Food web models are network models that represent prey/predator interactions to quantify the pathways of energy between the different ecological groups of an ecosystem

Different levels of complexity.
Mange arter og deres interactions.

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11
Q

Forklar Species based vs. Trait-based models

A

Species based - great for parametrization of single species, but uncertancy increase if you have to simulate all species. Often used in management.

Trait-based: How to describe the interaction between the many species.
Describes ecosystems as consisting of individuals rather than species and characterizes individuals by few key traits that are interrelated through trade-offs. (Size, resource acquisition mode, feeding strategy).

  • focus on induviduals instead of species
  • individuals characterized by few taxadecending key traits
  • trade-offs associated with key traits
  • trait distribution in nature depends directly on trade-offs
  • in trait-based approach you need to quantify key-traits and trade-offs

It offers an alternative to classical species-centric approaches and has the potential to describe complex ecosystems in simple ways and to assess the effects of environmental change on ecosystem structure and function.

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12
Q

Forklar om modeller hvor man ikke har inkorporeret spatial dimensions.

A

We can run the model without any spatial dimension (0D models)
- We assume an environment forcing (fx nutrients and mean light in the mixed layer)

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13
Q

Forklar om modeller hvor spatial dimensions er implementeret? 1D og 3D. Hvad er trade-off med højere resolutions?

A

We can add a spatial dimension
- Water-column models (1D)
- 3D models (physical model or transport matrix) (Man behøver ikke vide alt om et økosystem, man kan bare koble til modeller der er bygget af et økosystem)
Global models are often ca. 1 degree resolution (111 km) og det er ikke så god resolution. Man prøver at lave dem bedre. Trade off between scale and resolution.

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14
Q

Forklar om earth system models. hvad er det, og hvilke dele er modelleret?

A

Earth system models
En kombination af forskellige modeller. Komplicerede.
Atmosfære. Land. Ocean. Vegetation. Chemistry. Atmosphere. Fysik. Biochemisty.

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15
Q

Hvordan vælger man en model? og hvad er tradeoffs når man bygger økosystemer?

A

Many models that do similar things
Hvordan vælger man?
Man finder ud af hvad man skal undersøge.
Hvem vil lave en model?
Flere modeller - man kan tjekke hvor godt en model passer på ens issue på en eller anden måde.

Bygge økosystemer kan være tricky. Der er trade-offs mellem om modellen er kompleks, hvor hurtigt den kører osv.

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16
Q

Hvad er et “trait” eksempler? og hvad er et key trait?

A key trait describes an organisms ability to feed, survive and/or reproduce (=the main components of fitness)

A

We identify three life-form transcending key generic traits:
body size,
resource acquisition mode,
defence.

Traits: Kan være;
- Størrelse / weight
- Krops form / shape
- Reproduktion
- Hvad de spiser / resource aquision strategy (also predation strategy)
- Hvor de bor henne / habitat
- Migration
- Colour
- Life cycle and (multicellular (køns-formering) or single cells som laver børn ved at dele sig)

A useful trait: transcends taxonomy (applies to many different species).

Traits can tell about ecosystem services: Når man får lavet ordentlige modeller kan man se hvordan de forskellige ting hænger sammen, systemets functionality og hvordan det påvirker ecosystem services.

Man skal helst ikke have for mange traits i sin model.

Key traits: Tag noget kompliceret og lav det simpelt. Fx Picasso der tegnede en tyr detaljeret men endte med at lave den meget simpel, men han har alle key-traits med.
An individual is characterized by a combination of many traits, and
the key traits are the few properties that capture the most of its
Darwinian fitness

17
Q

Hvorfor er trait-based modeller nice og hvad kan man bruge trait-based modelling til? Giv eksempler på trait-based modeller

A
  1. The trait based approach allows simple description of complex marin ecosystems
  2. By focusing on functional traits and mechanisms rather than species, the relation to the environment and ecosystem functions are derived more directly
  3. The approach is promising but still in its infancy and requires further development

This approach thus has the potential to tackle the overwhelming complexity of marine ecosystems in a relatively simple way

Brug og function af trait based models
Modeller der kan sige noget om;
- Carbon export rundt i havene (based on a trait-based model of the global microbial communities)
- Fish production in the oceans (predictions of fish biomass from a size and trait-based model)
- describe and model marine phytoplankton communities
Basically alt kan man lave det på - bakterier, zooplankton, fisk, osv

In most cases, the focus has been on competitive interactions between individuals within a single trophic level, typically phytoplankton, and with few attempts to consider multiple trophic level

18
Q

Why do we want do describe and model marine ecosystems?

A
  1. To achieve fundamental understanding. A model is based on assumptions, and if the model predicts observations, then we tend to believe the assumptions.
  2. How will ocean life change in the face of climate change, pollution, fishing, etc? A predictive model can be used to test the effect of pertubations
  • understand
  • predict
  • test effects
19
Q

Forklar hvad trade-offs er for certain traits

A

The cost and benefits of a certain trait
- Eat or be eaten
- Reproduce (instead of eating) and bigger predation risk

Trade-off is a source of diversity: Fordi hvis der ingen trade-offs var, så ville det være en super species. Den måde man differencierer sine metoder på, skaber diversitet.

The success in executing the three main functions of any organism—to acquire resources, survive, and reproduce—is the main determinant of its fitness, but the execution of any one of these functions may conflict with the others. For example, foraging typically exposes a grazer to elevated predation risk, or photosynthesis requires investment in expensive chloroplast thereby reducing the potential for growth. Thus, there are no “super-organisms” that perform optimally in all respects

20
Q

Trade-offs and optimality. In simple models conflicts are balanced through fitness optimization. Hvad er formlen for fitness? og hvad kan vi forudse med det?

Fitness = gain / risk.
og = Mate encounter rate / mortality rate

From simple models and fitness optimization one can predict
- Time allocation
- Swimming velocity
- Mortality magnitudes
- Population structure (sex ratio)
- Minimum population sizes

A

Finally, trade-offs can be further constrained through optimality modelling, i.e. typically by estimating the allocation of
resources or the behaviour that yields the organism with the highest fitness.

21
Q

Nævn de 4 step / components i trait-based approach

A
  1. Individual (identify key traits and quantify trade-offs for the main life forms in the ocean)
  2. Models (Predict trait distributions from 1’eren. Asses effects of environmental change - make your trait-based model)
  3. Nature (Describe trait distributions in nature from observations. Compare with prediction.)
  4. Function (Quantify ecosystem functions from trait distributions. Fx functions of communities and ecosystems som nutrient recycling, carbon tranfer osv)
22
Q

Zooplanktons feeding traits fx. Zooplankton er diverse. Kan man lave en simple trait beskrivelse der transcends taxonomi?

A

Der er 3 ways of feeding som transcends taxonomy.

Ambush feeder
Cruise feeder
Feeding current (hovering)

Mange arter som hører under disse kategorier:

Diversity of ambush feeders: Taxa transcending. Fordi der både er snegle med mucus net, ambush feeding copepods og flere

23
Q

Quantifying trade-offs. Advantages vs. cost. Fx for foraging trade-offs.
Nævn fordele/ulemper for Active feeding-current foraging vs. passive sit-and-wait forging

A

Active feeding-current foraging: Risky but efficient

vs. passive sit-and-wait forging; Safe but inefficient

ved ik helt note: Dem som er active hunters fanger mere (active er cruise og current feeding ift til ambush). Men de bliver også mere spist af andre. The ambush feeder bliver mindre spist end passive feeders så fordelen ved dog mindre mad er højere overlevelse.

24
Q

Man kan også tilføje excess glucose til bakterier så de ikke løber tør for dette for at teste selektivt press og hvad der påvirker om de overlever (foruden adgang til mad).
Man kan også sørge for excess lys er til stede - hvorfor?

A

Når man vil teste en hypotese om fx fytoplankton eller bakteriers overlevelses strategier kan man teste hvordan bestemte faktorer påvirker deres strategier. Fx hvis man vil teste om fotosyntese-alger som enten er high-light adapted eller low-light adapted opfører sig hvis man tilføjer nærringsstoffer og om de er winnie the poo strategists så: The environmental condition required to follow this strategy would obviously be excess light available for photosynthesis, a condition presumably met in the surface layer of
oligotrophic oceans.

25
Q
  1. Hvad måler man fytoplankon biomasse på ? Eller altså man måler noget i vandet som er en proxy for hvor mange fytoplankton der er - hvad er det man måler?

Man kan også måle det med to andre metoder? Hvad er det

A
  1. For monitoring purposes, phytoplankton biomass is estimated by chlorophyll a (Chl a) concentration. The amount of Chl a is not a direct proxy for phytoplankton biomass because of a highly variable ratio of cellular carbon to Chl a in phytoplankton

Man kan bruge satellit billeder

eller lave cell-counts i mikroskop

26
Q

Why care about PP?? Forklar Ift. O2, fossel fuels, carbon pump, food webs, harvest from ocean og proxy for havet.

A
  • Photosynthetic activity in oceans created current
    O2-rich atmosphere
  • Plankton form ocean sediments & fossil fuels
  • Plankton are a critical part of “carbon pump” that
    influences ( removes) atmospheric CO2
  • Phytoplankton form the base of food webs and
    associated biological diversity
  • Limits to productivity may limit the amount of
    harvestable biomass from ocean ecosystems
  • A good proxy for the state of the ocean
27
Q

Hvordan måler man fytoplanktons respiration i en flaske?

A

Man tager havvand i flere flasker. En med lys, en uden lys og en kontrol for hver. Så måler man respiration ift til iltindhold i vandet efter 1 dag.

28
Q

We argue that these three generic “traits” (body size, ressource aqquisition and defense) and the unicellular/
multicellular dichotomy capture the most important aspects of
the ecology of an organism, and that they provide a sufficient basis for a generic trait-based description or model of an ecosystem.

Forklar hvad the unicellular/ multicellular dichotomy beskriver

A

In addition to these life-form transcending generic traits, there
is an important life-form transition, namely from uni- to multicellularity, that has important implications to the ecology of an
organism and the dynamics of the system in which it occurs. The
important difference between the two life forms is that the former
multiply by cell division (mainly) and hence vary by only a factor
of about 2 in size, while the latter have “life histories”, and produce offspring that are typically smaller or much smaller than 1%
of adult size (Neuheimer et al., 2015). Thus adults and offspring
may occupy different niches and forage on different size classes of
prey.

29
Q

The “currency” of tradeoffs are …

Sådan hvad er det man får ud af at vælge et bestemt trait

og hvad er det det gør, at et bestemt trait bliver det som organismen har

A

Trade-offs are described at the level of the individual and the currency of tradeoffs are eventually growth and mortality rates.

The benefits of feeding depend on the availability of food, and the risk of feeding on the abundance of predators. The environment selects the trait that optimizes the trade-off.

30
Q

ambush feeding will be favoured in environments with ….

(many or few predators and much or little prey?)

A

in environments with high concentrations of both prey and predators,

31
Q

Active feeders will be favoured in what environmenst?

(many or few predators and much or little prey?)

A

In environments with little prey and few predators