Date of Award

Summer 8-30-2016

Document Type

Thesis: Open Access

Degree Name

MS Marine Science

Department

Environmental and Ocean Sciences

Committee Chair

Dr. Steven Searcy

Committee Member

Dr. Nathalie Reyns

Committee Member

Dr. Andrew Thompson

Abstract

Monitoring the number of larvae that have recently settled and how this varies in relation to environmental conditions provides insight into future population strength, which is a fundamental goal of marine ecology as well as fisheries management. This research focused on characterizing the settlement patterns of spotted sand bass (Paralabrax maculatofasciatus), a recreationally important species that utilizes bays and estuaries as nursery habitat. To quantify P. maculatofasciatus settlement patterns, three larval collectors were installed near the mouth of Mission Bay, San Diego CA, and retrieved weekly from June – October of 2012 – 2015. Larvae were counted, and individuals were measured for standard length, dry weight, body condition, as well as otolith derived growth rates and age at settlement. To determine whether environmental conditions affected settlement, or individual characteristics of larvae at settlement, we examined how these factors varied in relation to chlorophyll a (Chl-a), sea surface temperature (SST), wind speed, wave height and direction, alongshore transport and upwelling. Settlement of P. maculatofasciatus was significantly lower in 2014-15, and appeared to be the result of low food conditions associated with the formation of the pacific warm anomaly, or “blob”, which reached the coast of southern California in the summer of 2014. The characteristics of larvae at settlement were also consistent with a poor feeding environment. This study has implications for understanding future settlement and recruitment of fishes in southern California, as ocean temperatures continue to rise in the face of climate change.

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