Date of Award

Spring 5-25-2018

Document Type

Thesis: Open Access

Degree Name

MS Marine Science

Department

Environmental and Ocean Sciences

Committee Chair

Dr. Nathalie Reyns

Committee Co-Chair

Dr. Jennifer Prairie

Committee Member

Dr. Jennifer Prairie

Committee Member

Dr. Jesus Pineda

Abstract

The role of post-settlement processes in benthic invertebrate recruitment dynamics has been well established; however, more recently, studies have been resolving the pre-settlement processes and environmental variables that may shape initial settlement. We examined the major space occupying barnacle Chthamalus fissus to determine the spatial and temporal dynamics of settlement in relation to larval supply, adult populations, and habitat characteristics (including elevation as a proxy for immersion, proximity to water’s edge, and the availability of free space) within the La Jolla, CA rocky intertidal. With respect to habitat characteristics, we investigated the influence of available free space on the dynamics of settlement through intensification, defined as a higher concentration of settlers with less available free space. Six larval traps were deployed daily to quantify larval supply, 12-14 PVC plates were deployed daily or weekly to quantify settlement, and 12-14 surveys were conducted during new moon periods every month to quantify adults and habitat cover. There was temporal variability, specifically with high rates of settlement, and high percentages of adult populations and habitat cover occurring mainly in the summer periods. Spatially, of the 14 locations studied within the site, two locations exhibited some of the highest settlement rates when compared to larval supply or adults and habitat cover. There was a non-significant relationship between larval supply and settlement, suggesting that the environment played a more important role in shaping spatial and temporal population dynamics. Settlement, when compared with habitat cover, was primarily driven by available free space, which was determined by live barnacle and algae cover. We observed the highest settlement when free space was lowest, demonstrating evidence of intensification within our site. These results suggest that in some cases habitat dynamics may play a more important role in shaping settlement than larval supply. Understanding the extent of this role may help to more holistically establish the dynamics that shape initial benthic invertebrate settlement. Therefore, understanding the role of the environment in shaping settlement dynamics of benthic invertebrates can help further inform the importance of rocky intertidal locations in contributing to coastal marine productivity and diversity.

Comments

This thesis project was a part of the larger NSF grants OCE-1357290, OCE-1357327, OCE-1630459, and OCE-1630474, lead by primary investigators Dr. Nathalie Reyns, Dr. Jesus Pineda, and Dr. Steven Lentz.

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