2 Pathogens in ecosystems: naturally a key player

In this section we aim to illustrate the ubiquity and natural occurrence of parasites as a grounding for the later section which looks specifically at algal pathology in aquaculture. You will start with looking at familiar terrestrial examples and then move on to look at aquatic examples on algal blooms, on parasites impact on food web and wider environmental processes. We have taken this approach as often when there is a spotlight on a disease it relates to its social or economic impact.