AMP Toolbox

End to end Models
Step 1- Setting the scene
Activity 1.4- Scenario analysis (including risk assessment)

The main objective of “End to End” models is to simulate and predict changes in the state of the marine ecosystem in response to different drivers and management scenarios with the overall aim of supporting the decision-making process.

According to Rose (2012) an “End-to-End” model is a model that: (1) aims to represent the entire food web (including multiple species or functional groups at each of the key trophic levels as well as top predators in the system) and the associated abiotic environment; (2) requires the integration of physical and biological processes at different scales; (3) implements two-way interaction between ecosystem components; and (4) accounts for the dynamic forcing effect of climate and human impacts at multiple trophic levels. Moreover, the representation of the physics should be modifiable by climate inputs and human aspect (e.g. fishery) and should be represented in a dynamic (state-dependent) manner.
In MEECE FP7 project (, for example, “End to End” models have been developed to represent the entire ecosystem by including all relevant processes in the system, from physics to chemistry, and plankton to fish. The overall aim of this project is to explore the impacts of both climate drivers such as acidification and temperature, and human-induced drivers like fishing, invasive species and pollution on marine ecosystems.
To achieve this, three types of models or components have been coupled: (i) hydrodynamic models, lower trophic level (LHL) models (bacteria, phytoplankton and zooplankton) and higher trophic level (HTL) models (mainly fish species) into a single modelling framework. Moreover, two types of experiments have been performed using the coupled physical-lower trophic level models (biogeochemical)-higher trophic level models: (i) re-analysis forced simulations; and, (ii) climate-scenario forced simulations.
In addition, in the PERSEUS project efforts are also being made to achieve the “End to End” approach needed to investigate the ecosystem attributes underlying the definition of Good Environmental Status and the Marine Strategy Framework Directive descriptors. These “End to End” approaches include the three components mentioned above as well (i.e. a hydrodynamic model, a lower trophic level (LTL) or biogeochemical model and a higher trophic level (HTL) model.

In Table 4, some of the models employed within the PERSEUS project are mentioned and classified under the three main components mentioned above.
Table 4: List of different models' examples used within PERSEUS project to develop an “End to End” approach.

Within the PERSEUS project these “End to End” approaches have been followed for two case studies at basin scale (the entire Mediterranean and the Black Sea) and for six case studies at regional scale (Alboran Sea, North-Western Mediterranean Sea (including the Gulf of Lions and the Catalan Sea), Northern Adriatic Sea, Northern Aegean Sea, Western Black Sea and the Eastern Black Sea) in order to address different issues.
In addition, within the “Model library” of the Meece project (, for example, additional models can be chosen depending on the region, the descriptor (sensu Marine Strategy Framework Directive) and the attribute (e.g. habitat distribution, population size or nutrient levels) under study.

In essence, three types of models are coupled in “End to End” models or approaches:
(1) a hydrodynamic model which is forced by both re-analysis data (for validation purposes) and a coupled ocean-atmosphere general circulation model (for exploring the behaviour of the system under possible future climate change conditions);
(2) a lower trophic level model (bacteria, phytoplankton and zooplankton) including biogeochemical cycling; and
(3) a higher trophic level model (mainly fish species).

The IMAGE model can be used to provide land-based (e.g. nutrient inputs) forcing.


High, due to the costs associated with data collation as well as the expertise or technical skills required to use and run the models efficiently. Additionally, in some cases a licence could be needed.

High. This is a technical process that requires expertise using modeling techniques as well as knowledge of the interactions within the biophysical environment.
Background requirements
Presumably high in general. Data requirements unknown

Low. It is a technical exercise where no stakeholder participation is required.

Time range
Moderate - high. Significant time (i.e. months) is required to tune the model, to run a simulation and to complete the process. Moreover, it can take years to develop a model.

Source of information
  • PERSEUS project´s results webpage.
  • PERSEUS Deliverable 4.4: LTL-HTL regional model coupling to establish E2E modeling systems and assessment of the models skill.
  • Rose K.A. (2012). End-to-end models for marine ecosystems: Are we on the precipice of a significant advance or just putting lipstick on a pig? Scientia Marina, 76, 195-201.
  • MEECE project´s models webpage.