Associate ProfessorZiggy Marzinelli

Host-microbiome interactions in marine ecosystems

Humans rely on ecosystem goods and services provided by the ocean. Thus, understanding how marine ecosystems function and how to manage them is crucial. Microorganisms comprise the bulk of the diversity and biomass in the ocean, but prior to the recent revolution in environmental gene sequencing technologies ('omics') many of the key concepts and questions in modern ecology could simply not be addressed for microbes. Despite this technological advancement, the integration between studies of microorganisms and the well-established theory and practice of "macrobial" ecology remains a fundamental challenge. A key question is: Are ecological principles for microbial communities similar to those of higher organisms, or are they somehow fundamentally different? In this context, my research aims at bridging the disparate fields of molecular microbiology and benthic ecology, focusing on host-microbiome interactions. This approach is necessary in order to understand the ecology and function of "holobionts" (host plus their microbiome) that form the biogenic structure of coastal ecosystems, such as seaweeds, seagrasses and corals, because impacts on the interaction between these hosts and their associated microbiome can cascade throughout an entire ecosystem. Critically, such approach can be used to build resilience of these key holobionts in the face of environmental change.

Kelp forest ecology and restoration

Large brown seaweeds (macroalgae; "kelp") form extensive underwater forests that underpin biodiversity and key ecosystem functions and services on temperate rocky reefs worldwide. These productive forests are, however, declining globally due to multiple human impacts. My research aims at understanding the ecology of kelp forests in order to provide solutions. An example of this is my work on crayweed forests.

'Crayweed' (Phyllospora comosa) is an important habitat-forming alga that disappeared from the Sydney coastline in the early 1980's, possibly due to poor water quality. Despite significant improvements in water quality since the 1990's, crayweed has not re-established. This project - a.k.a. 'Operation Crayweed' - aims to determine the ecological processes and interactions that influence colonisation and survival of crayweed in order to restore crayweed forests and the biodiversity and functions they support.

Urban ecology

Most people live on the coast and that is where most interactions between humans and marine ecosystems occur, and thus where most impacts on marine systems occur. My research aims at understanding the ecological processes that drive biodiversity and ecosystem functioning in urbanised coastlines. The main focus is on effects of urbanisation on key habitat-forming organisms such as kelps as they underpin biodiversity and ecosystem functioning.

My research aligns with the Faculty of Science Research Strengths - Understanding Life on Earth, Understanding Our Planet, Complex Systems, Understanding and Treating Disease in Plants, Biodiversity Conservation, Climate and Environmental Change, Sustainability, Biosecurity, Healthy Ecosystems, Net Zero Technologies.