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Population Connectivity

PCpic.JPGObjective: to examine how dispersal of early life stages (eggs, larvae, juveniles) influences patterns of biodiversity and resilience, and how different geographic areas may represent important sources and sinks for new recruits.

The exchange of individuals or ‘connectivity’ is critical for the stability of spatially separated populations, or metapopulations, and the management of species. The life history of many marine species includes a dispersive planktonic larval stage before their benthic adult life. Larval dispersion links these metapopulations across fragmented habitats, such as conservation areas. During this stage >90% of larvae can be lost directly through predation and starvation or indirectly through transport by currents  away from suitable habitats. Populations of a given species can be classified as ‘sources’ or ‘sinks’. ‘Source’ populations provide a net export of individuals; the opposite is true for ‘sink’ populations. Marine connectivity and persistence of populations depends on the effectiveness of dispersal of individuals.

It is difficult to determine whether populations are ‘sources’ or ‘sinks’ underscoring the importance of understanding oceanographic and behavioural mechanisms that drive larval transport and supply.  Estimating connectivity depends on quantifying dispersal which is extremely challenging, but understanding the dynamics of fragmented populations is essential in predicting the risk of extinction and responses to environmental change, management strategies, and resource exploitation


CHONe’s Population Connectivity research projects focus on understanding these dispersal dynamics and will:Close up Northeast Channel.  Photo credit: A. Metaxas, ROPOS

1.  Evaluate the role of larval dispersal in regional source-sink dynamics, using marine reserves of different designs

      • by determining how the movement of larvae, which represent the major dispersal phase for many marine organisms, influences the geographic distribution of populations;
      • establishing which populations are the major suppliers of successful recruits to future generations. 

2.  Compare population connectivity using different metrics of dispersal

      • by comparing multiple metrics of dispersal from small to large scales,  to evaluate their relative strengths and weaknesses.


The research combines:

      • Field research;
      • Laboratory studies of biology and physics;
      • Passive tracer releases;
      • Genetic analyses of population structure;
      • Historical data;  
      • Statistical and dynamic modeling to understand how metapopulations of key species are interconnected.


The research will result in:

      • Comprehensive evaluation of scientific outcomes, including comparisons among different metrics of dispersal;
      • Recommendations for evaluating the role of connectivity in the conservation of fragmented populations for commercially important species;
      • Tools and cost-benefit analysis of tools to assess source and sink effectiveness of MPAs; 
      • A flowchart of analytical approaches to evaluate connectivity and the effectiveness of MPAs in achieving their management objectives.


See project list, for more information on individual projects within this theme.


See publication list for research publications and presentations within this theme.


See CHONe presentation at Fishermen and Scientists Research Society for overview of CHONe lobster research .


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