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This studentship will be of 3 years duration with stipend and fees for a UK/EU student. (Final funding arrangements under negotiation)

Marine microbes (viruses, bacteria, phytoplankton) are a key component of the marine food web and of the most important biogeochemical cycles on Earth. Because of their rapid generation and vast amount of offspring, these organisms evolve in timescales that are similar to the individual's lifetime. Therefore, phenotypic plasticity (dynamic responses to environmental changes) and evolution interact necessarily during the single-organism life span. However, in these communities ecological and evolutionary matters are normally studied separately.

This project aims to study how considering these interactions may challenge current predictions about the long-term behaviour of marine microbes. The project will use existing mathematical models, and develop new ones, able to account for these interactions and dynamics. Due to the highly nonlinear ecological relations between organism, stochasticity inherent to mutations, and overlap between ecology and evolution, the study and analysis of these models will require from sophisticated (and probably innovative) mathematical and numerical methods. This project will be important to understand how the lower trophic levels in particular, and the complete marine food web in general, react to e.g. different climate change scenarios.

MSY has become the standard basis on which fishery management reference points, such a Fishing mortality rate (F) and Spawning Stock Biomass(SSB), are set.

In almost all stocks these reference points are estimated using single species steady state models that assume invariance of life history parameters such as growth reproduction and natural mortality. There are good reasons to suppose that these life history parameters are not constant and it would be expected that natural mortality would change as a result of species interactions. Thus while it might be possible to fish at a value of F based in single species models, there is not good reason to believe that by so doing, SSB and catch will be achieved. Despite this major difficulty many analyses of the status of global fish stock are based on the assumption that single species MSY is observable and has been used to estimate foregone catch and estimate “safe” limits for SSB.

The purpose of this project will be to use current ecosystem models to assess the implications for both realised SSB and catch when stocks in a multispecies complex are all fished at single species Fmsy. The project would also examine methods that have been used to classify the exploitation status of stocks based on catch data alone when it has been assume that single species MSY is observable. Based on this analysis alternative reference points will be proposed that take into account species interactions and hence provide a more robust basis for fishery management.

MSY has become the standard basis on which fishery management reference points, such a Fishing mortality rate (F) and Spawning Stock Biomass(SSB), are set.

In almost all stocks these reference points are estimated using single species steady state models that assume invariance of life history parameters such as growth reproduction and natural mortality. There are good reasons to suppose that these life history parameters are not constant and it would be expected that natural mortality would change as a result of species interactions. Thus while it might be possible to fish at a value of F based in single species models, there is not good reason to believe that by so doing, SSB and catch will be achieved.

Despite this major difficulty many analyses of the status of global fish stock are based on the assumption that single species MSY is observable and has been used to estimate foregone catch and estimate “safe” limits for SSB. The purpose of this project will be to use current ecosystem models to assess the implications for both realised SSB and catch when stocks in a multispecies complex are all fished at single species Fmsy.

The project would also examine methods that have been used to classify the exploitation status of stocks based on catch data alone when it has been assume that single species MSY is observable. Based on this analysis alternative reference points will be proposed that take into account species interactions and hence provide a more robust basis for fishery management.