Many nearshore species are distributed in habitat patches connected only through larval dispersal. Genetic research has shown some spatial structure of such metapopulations and modeling studies have shed light onto possible patterns of connectivity and barriers. However, little is known about human impact on their spatial structure and patterns of connectivity. We examine the effects of fishing on the spatial and temporal dynamics of metapopulations of sedentary marine species (red sea urchin and red abalone) interconnected by larval dispersal.
We constructed a metapopulation model to simulate abalone and sea urchin metapopulations experiencing increasing levels of fishing mortality. We performed the modularity analysis on the yearly larval connectivity matrices produced by these simulations, and analyzed the changes of modularity and the formation of modules over time as indicators of spatial structure. The analysis revealed a strong modular spatial structure for abalone and a weak spatial signature for sea urchin. In abalone, under exploitation, modularity takes step-wise drops on the path to extinction, and modules breakdown into smaller fragments followed by module and later metapopulation collapse. In contrast, sea urchin showed high modularity variation, indicating high- and low-mixing years, but an abrupt collapse of the metapopulation under strong exploitation.
The results identify a disruption in larval connectivity and a pattern of collapse in highly modular nearshore metapopulations. These results highlight the ability of modularity to detect spatial structure in marine metapopulations, which varies among species, and to show early changes in the spatial structure of exploited metapopulations.
Research news | 2018-05-21
Four cases of participatory foresight exercises show impact is not a given. Here’s how to fix it
Research news | 2018-05-17
Applying Elinor Ostrom’s principles on common pool resources management demonstrates how forest management in the Pamir Mountains may not be so tragic after all. But Soviet era legacy lingers, new research shows
Research news | 2018-05-14
To create change in coastal districts of Kenya and Mozambique, dominant narratives must be challenged by stories rooted in people’s lived experiences
Research news | 2018-04-26
Construction of roads and water channels across Colombia’s Ciénaga Grande de Santa Marta wetlands has altered the landscape to the point of surpassing mangrove ecosystem tipping points
Research news | 2018-04-26
Over 100 scientists, architects, journalists, artists, designers and activists provide perspectives on what future urban sustainability should look like
Research news | 2018-04-19
New study of UNESCO biosphere reserves sheds light on how people learn to live with social-ecological complexity