Changing seascapes, stochastic connectivity, and marine metapopulation dynamics.

Area of Science:

• Marine ecology
• Population dynamics
• Metapopulation theory

Background:

• Dispersal probability is crucial for understanding and predicting natural population dynamics.
• Potential connectivity between habitat patches can change over time, a factor often overlooked.
• Marine environments exhibit high temporal variability in connectivity due to transient features like eddies and jets.

Purpose of the Study:

• To assess the impact of temporal variability in potential connectivity on nearshore metapopulation dynamics.
• To compare metapopulation dynamics under constant (deterministic) versus time-varying (stochastic) connectivity.
• To determine the magnitude of these changes for nearshore marine species in the Southern California Bight.

Main Methods:

• Mathematical analysis to derive general conclusions on temporal variability effects.
• Realistic biophysical modeling to simulate nearshore metapopulation dynamics.
• Comparison of simulation outcomes between deterministic and stochastic connectivity scenarios.

Main Results:

• Temporal variability in potential connectivity generally affects metapopulation growth rates (when rare) and equilibrium abundances.
• Stochastic models, reflecting time-varying connectivity, yield lower outcomes than deterministic models.
• Reductions in population metrics due to stochasticity can be as high as 40%.

Conclusions:

• The temporal variability of marine connectivity is a critical factor influencing metapopulation dynamics.
• Management strategies relying on spatial information like connectivity must account for its dynamic nature.
• Stochasticity in connectivity can lead to significantly lower population growth and abundance than previously predicted.