Trophic Networks and Ecosystem Functioning

Abstract

The geographic isolation of the Antarctic continent offers an interesting opportunity to quantify and qualify the actual ecological conditions and the most sensitive components from an ecosystem perspective. Antarctic coastal ecosystems are under severe stress as a consequence of climate change, which could facilitate biological invasions, reduced growth of macroalgal species, and local extinctions. The application of network analysis, representing the interactions among multiple species, allows us to quantify macroscopic (emergent) system properties, to assess overall health, to predict the propagation of direct and indirect effects, and to identify keystone species complexes within these complex ecological systems. Three theoretical frameworks are used here for this analysis: (1) ecological network analysis (ENA) considering thermodynamics and information theory (providing measures such as Ascendency), (2) semiquantitative (qualitative) mathematics based on the structure and local stability of community matrices (Loop Analysis), and (3) topological studies on interaction networks considering central node sets and defining keystone species complexes (KSCs). Therefore, the integration of ecosystemic properties and keystone species complexes could help us to facilitate the design and assessment of conservation and monitoring measures, especially when the Antarctic coastal marine ecosystems are being severely stressed. The protection of the Antarctic environment – as a whole – not only should be focused on biological populations and communities but also should consider changes in macroscopic properties, the propagation of direct and indirect influences in the networks, and keystone species complexes, which emerge using networks of interacting and coexisting species (or functional groups as system components).