Population connectivity (i.e., larval dispersal or migration) is critical for metapopulation persistence, range expansion, and a species’ ability to cope with climate change, and is fundamental to our understanding of population dynamics, biodiversity patterns, and the conservation and management of species. Unfortunately, understanding this complex bio-physical process and identifying the important biological drivers and the resultant spatial patterns remains a great challenge. Our research focuses on understanding connectivity from demographic and ecological scales to long-term evolutionary patterns. We use an integration of oceanographic models, landscape analysis, GIS, dynamic modelling, network analysis, spatial statistics, and field and lab data to ask three general questions:
- What are the biological and physical ocean drivers of population connectivity and persistence? This research question is spatially explicit and depends on the spatial and temporal scale of the process of interest.
- How does population connectivity (at various scales) contribute to the biogeographic patterns we observe in nature? Connectivity may be integral to abundance patterns, species diversity, gene flow and genetic diversity, and community assembly.
- How can this information assist resource managers in making spatially and ecologically informed conservation decisions and priorities? The ecology of the system, as well as knowledge about governance and the social structures, is critical for prioritising management actions. I am using network analysis to explore the complex linkages between the ecological networks (e.g., metapopulations), the management networks (e.g., protected areas, jurisdictions), and the social network (i.e., who is working together?)
Current Research Projects:
- Reef Resilience in Port Phillip Bay. (PIs: C Johnson, University of Tasmania; S Swearer, University of Melbourne; and others) The primary goals are a) to estimate regional connectivity for key functional groups (macroalgae, macro-invertebrate grazers, fish), b) to determine the important life-history, ecological, and environmental drivers of connectivity and the ability of reef communities to recover from disturbance, and c) to identify key populations important to metapopulation persistence for targeted management actions. Funding: Victorian Department of Sustainability and the Environment. Collaborators: DPI, University of Sydney, Deakin University, and others. Figure: Dispersal networks of PPB in geographic space (left) and connectivity space (right).
- Marine Biodiversity and Population Connectivity of the Indo-Pacific. (PIs: E Treml, C Riginos, and H Possingham) The objectives of this research are to 1) identify the probable dispersal routes and spatial population structure for several marine species throughout the biodiversity hotspots of the Coral Triangle, and 2) integrate these connectivity estimates into marine conservation planning. This spatially-explicit research integrates a network-based approach with population genetic methods and biophysical modelling to quantify the spatial structure of marine metapopulations. Funding: The World Wildlife Fund Fuller Fellowship (Treml), ARC Discovery (Riginos & Possingham). Collaborators: P. Barber (UCLA), K Carpenter (ODU), P Halpin (Duke University). Figure: Multispecies biophysical dispersal corridors and barriers across the Indo-Pacific.
- Reconciling competing objectives for the design of marine reserve networks. (PIs: P Mumby, H Possingham, C Riginos, G Jones, & E Treml) This project uses a decision-theoretic framework to balance the often conflicting marine conservation objectives of preserving biodiversity and building food security for local communities in the socially and ecologically complex region of the Coral Triangle. A new reserve design will boost biodiversity conservation and better support livelihoods. Funding: ARC Linkage Program; USAID Coral Triangle Support Partnership; World Bank.
- Conservation Networks and Ecological Neighbours. (PIs: Treml) Conservation plans seek to accommodate functional connectivity by establishing regional priorities regarding the size and placement of protected areas. Using model-based connectivity estimates and existing conservation/management frameworks (e.g., countries, ecoregions), our goal is to help (re)define partnerships and assist in coordinating policy actions for a more effective planning process. Funding: The World Wildlife Fund Fuller Fellowship (Treml); WWF-US, CTSP. Collaborators: C Riginos & H Possingham (UQ), P Halpin (Duke University), S. Kininmonth and O Bodin (Stockholm Resilience Centre), P Fidelman (University of Sunshine Coast). Figure: Ecological-Institutional (Mis)alignment among IWP countries.
- Hydrodynamic modelling of coastal seas: (PIs: Treml). The fate of marine larvae is largely dependent on the local-scale environment (meters to 10s of meters) where they are released and where they settle. Yet to characterise the long-distant dispersal potential of larvae, one must also consider the broad-scale ocean dynamics (10s to 1000s of kilometres). To bridge this scaling problem, I use a coastal circulation modelling system (ADCIRC) based on a variable resolution finite element mesh structure to develop current prediction in the near shore environment. I develop current predictions, validated with drogue and ADCP measurements, and couple these with a larval dispersal model to estimate the fine-scale dispersal structure of marine larvae. Figure: Nearshore current estimates around Tutuila in American Samoa depicting leeward island eddies, exposure and retention zones, and strong tidal flows between the island Aunu’u.