  Energy transport in photosynthetic systems can be tremendously efficient. In
particular we study exciton transport in the Fenna-Mathews-Olsen (FMO) complex
found in green sulphur bacteria. The exciton dynamics and energy transfer
efficiency is dependent upon the interaction with the system environment. Based
upon realistic, site-dependent, models of the system-bath coupling, we show
that this interaction is highly optimised in the case of FMO. Furthermore we
identify two transport pathways and note that one is dominated by coherent
dynamics and the other by classical energy dissipation. In particular we note a
strong correlation between energy transport efficiency and coherence for
exciton transfer from bacteriochlorophyll (BChl) 8 to BChl 4. The existence of
two clear pathways and the role played by BChl 4 also challenges assumptions
around the coupling of the FMO complex to the reaction centre.
