Species composition and habitats are changing at unprecedented rates in the world’s oceans, potentially causing entire food webs to reorganise. Despite the severity of these regime shifts, elucidating their precise nature has remained difficult. Our study draws on complexity theory, and integrates the exponential random graph modelling (ERGM) framework, developed within social sciences, with community ecology. In contrast to previous research, ERGM approach makes clear assumptions of direction of causality and accommodates a dynamic perspective on the emergence of food webs. In this study, we use ERGM to investigate changes in ecological processes embedded in food webs before and after a regime shift. We find that previously reported regime shift appears to take place in part of the ecosystem, but is not a system-wide shift. Furthermore, we show that while main ecological processes have remained relatively same, although there are changes in the magnitude of these processes. Our study demonstrates the importance of using several, complementary methodologies for detecting and describing regime shifts. – Yletyinen et al. 2016.
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Johanna Yletyinen 
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