Cefas proposal wins 2005 Buckland Summer Studentship
Cefas are pleased to announce that a proposal submitted by Jenny Dawson (a student from the University of York, supervised by Cefas scientist Steve Mackinson) has been awarded the prestigious Buckland Summer Studentship for 2005.
The Summer Studentship scheme is in its fifth year. The Buckland Foundation are keen that it becomes an established supporter of students on marine courses .
Jenny’s abstract of the winning study follows:
The implications of model structure in ecosystems models of marine systems
Jenny Dawson, University of York
Supervisor: Dr. Steve Mackinson, Cefas laboratory, Lowestoft
The ecosystem approach to fisheries management has been widely advocated in recent years as a way to avoid the problems encountered with single species approaches. However, there is little consensus on what this entails and what the results might be. Since we are not able to perform ecosystem-scale experiments, modelling is an important tool that can provide insight of the possible ecosystem effects of fisheries.
Ecopath with Ecosim is a popular ecosystem modelling approach that models ecosystems by the construction of food web accounts. However, whilst Ecopath with Ecosim has been used widely for scenario modelling and policy exploration, little is known about the effects of different model structures and varying data quality on the predictions.
Once a models’ structure has been specified at the beginning of a project, little thought is often given to the impacts that the structure may have on the results. There is evidence that models can be biased towards particular species, such as those most commercially important, or parts of the food web most favoured by the researcher, e.g. marine mammals. Models may also be structured with varying degrees of complexity due to both data availability and modeller’s choice. It is inevitable that not all links in a food web will be captured during data collection and it is also unlikely that a modeller would want to include all known interactions since very complex models lose a lot of their predictive power.
Due to the large numbers of Ecopath with Ecosim models currently developed and applied to ecosystem management-related questions, it is important to determine how differences in model structure affect model predictions so that modellers and managers can have a measure of their reliability.
This project aims to determine the effects of varying model structure on predictions of ecosystem stability and species persistence using an Ecopath with Ecosim model of the North Sea. The model has already been developed using the large amounts of data available on North Sea species feeding interactions. This project aims to:
- Determine the effects of biased model structure by aggregating some levels of the food web so that particular species or groups are disproportionately represented in the model.
- Determine the effects of different levels of complexity by:
- changing the number of links between species in the food web.
- changing the number of species defined within the model
The effects of these changes in model structure will be quantified using indices of ecosystem stability and species persistence. The results of this project will show whether comparisons between models constructed in different ways are possible and will form part of ongoing research by Cefas into the application of ecosystem modelling in fisheries management.
