Climate-modulated volume transport through the coral triangle and its impacts on larval connectivity

Possessing complex bathymetry and regional circulation, the Coral Triangle (CT) is also the epicenter of marine biodiversity. Understanding regional circulation and the effects of intra-annual, seasonal and interannual processes on this circulation has important ramifications for larval transport, particularly in the context of changing climate. Using the Coral Triangle implementation of the Regional Ocean Modeling System (CT-ROMS), volume transport time series are assessed at 30 key passages throughout the region. Generally, seasonality seems to be the main modulator of volume transport along the South China Sea Throughflow (SCSTF), while the Indonesian Throughflow (ITF) volume transport is primarily influenced by interannual and secular changes in circulation. However, a ridge regression model which uses El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Pacific Decadal Oscillation (PDO) as explanatory variables is able to explain a significant portion of the volume transport through SCSTF passages. Many oceanic species have larval stages which behave similarly to passive particles; being able to track these passive particles and understand where they might go under certain oceanic conditions provides us information that researchers cannot easily obtain in situ. TRACMASS, an offline particle tracking code, is used to track passive particles for 20, 40, 60, 80, and 100 days in order to assess decadal and interannual variability in particle retention, and the ability of particular ecoregions to function as particle sources and sinks along the South China Sea Returnflow (SCSRF) and the ITF. Due to the complexity in regional circulation, results are often localized to particular ecoregions. However, particle retention is generally higher during El Niño conditions along the SCSRF and during the 1980s along the ITF. Generally, our results highlight the need for networks of Marine Protected Areas (MPAs) and dynamic MPAs including temporary, migratory, zoned and gear-restricted MPAs. In order for any of these management strategies to be successful, the social and political challenges of a given location need to be considered, and representatives of all stakeholder groups need to be included in management decisions.Ph.D.Includes bibliographical referencesby Sarah Lietzk