Application of real time PCR technology to quantify larval dispersaland recruitment dynamics in the marine environment

摘要

Although invertebrate larvae are often assumed to disperse as passive particles in the marine environment, an empirical understanding of dispersal patterns in declining marine species is of paramount importance for restoration efforts. Studies of marine larval dispersal are relatively rare, but may include indirect methods such as population genetics. Direct empirical investigations utilizing light microscopy for identification and enumeration are time-intensive, and thus place severe limits on the scope of larval distribution studies. To enable high-throughput detection of larvae in seawater samples, we developed a PCR-based identification assay amplifying an abalone-specific fragment of the mtDNA cytochrome oxidase (COI) gene yielding presence-absence data for 95 samples in about two hours in a conventional thermal cycler. To quantify larvae, we also developed an abalone-specific real time PCR test that can reliably discriminate the presence of individual relative to multiple larvae in seawater samples. Before extension to field applications, we will first test the application of these PCR assays in a series of mesocosm studies, designed also to provide baseline information on larval dispersal. We will use a progression of experimental trials of increasing size and complexity to characterize diel vertical migration patterns under temperature and salinity stratifications. Ultimately, controlled field release and collection experiments will be conducted to examine larval dispersion patterns via sampling over short and long post-release times. Investigations of larval dispersal will provide empirical data on larval behavior in the field and will aid in Pinto abalone restoration efforts.