Award: OCE-1155813

Many marine invertebrates and fish begin life in a planktonic larval stage than can range from days to months. The transport patterns of these early life larvae in the ocean is a critical part of the organismsÆ lifecycle as the larvae can be moved by the oceanÆs currents 10s to 100s of kilometers from one habitat to another. The goal of our project is to provide a better understanding of the transport of marine larvae between habitats in the coastal ocean. Our study area is the Southern California Bight (SCB), which is located off the coast of southern California. For this project, we used complex computer models of ocean currents in the SCB to predict transport patterns of marine larvae. There were three main areas of research in this project. The first area of research was an investigation of how sensitive the modeling results were to settings required for the computer models related to the life history of the larvae. These settings included the ocean depth where the larvae are first released, the number of larvae to release, and the length of time the larvae can be transported in the ocean. We developed guidelines on how to select model settings to produce the most accurate results. These guidelines are available to other scientists who run similar computer models and have been used for ocean models in different regions around the world. The second area of research was the development of a data set for the scientific community that provided travel times for larvae between coastal habitats throughout the coastline of the SCB, which is 700 kilometers. This data set divided the coastline of the SCB into 135 patches and provided transport times between these patches for twelve modeled years. The third area of research used modeling to understand why high numbers of larval fish were found inside an ocean eddy (~40 km diameter) off the coast of the SCB in one year but not in the next. An ocean eddy occurs when ocean currents form a closed circular pattern of flow. We discovered that the three-dimensional flow of the eddy was very different in the two years and that the eddy flow allowed the fish to be retained in the eddy one year but not the other. The results of this work is important to a wide range of disciplines including environmental protection, management of exploited stocks, invasive species control, and the planning and design of marine protected areas. Last Modified: 04/05/2016 Submitted by: Rachel D Simons