Life Sciences Commons^™

What Drives Larval Condition For Northern Anchovy (Engraulis Mordax)? Implications For Coastal Pelagic Species Recruitment Fluctuations And Fishery Management Practices, Michelle Robidas

Theses

Discerning the causes of population boom and bust cycles for coastal pelagic species (CPS) has been a major focus of fisheries management research for over a century. Year-class strength is contingent on larval survival and condition, which can be influenced by larval size at age and growth rate. These two factors, in turn, can be affected by maternal investment and environmental variables such as water temperature, salinity, oxygen, and chlorophyll a. We evaluated each of these factors from 127 two to eight week-old Northern Anchovy (Engraulis mordax) larvae off the coast of San Diego to San Francisco, …

Crassostrea Gigas Invasion In Southern California: Macrofaunal Diversity And Local Community Impacts Of Ecosystem Engineers On Estuarine Habitats, Noah Jansen-Yee

Theses

Many marine ecosystems are facing the growing threat of biological invasions. These invasions can have a variety of different impacts on ecosystems and their inhabitants. The Pacific oyster, Crassostrea gigas, is currently in the relatively early stages of invasion in San Diego estuaries. Crassostrea gigas is a large, filter-feeding bivalve that forms dense oyster beds on hard substrate. These oysters are known to outcompete native counterparts and drastically alter habitats where they are present. Crassostrea gigas is an ecosystem engineer that, through shell creation and formation of a dense oyster matrix, impacts ecosystems in a variety of direct and indirect …

Using Aerial Photogrammetry And Sexually Dimorphic Measurements To Investigate Seasonal Differences In School Composition Of Delphinus Spp. Off Southern California, Samantha Gm Leander

Theses

Insights into school composition can provide a means to understand basic biology and ecology, including reproductive patterns. They can also be applied to conservation assessments, allowing for better understanding of the potentially differential vulnerability of demographic groups to natural or anthropogenic disturbances that may influence their populations. However, the two subspecies of common dolphins in the waters off California (Delphinus delphis delphis and D. d. bairdii) form large, energetic groups that make characterization of school composition difficult. Remotely controlled drones now offer the opportunity for the study of school composition in Delphinus spp., allowing for precise morphometric measurements …

The Effects Of Temperature And Body Size On The Metabolism And Hypoxia Tolerance Of White Abalone (Haliotis Sorenseni) And Red Abalone (H. Rufescens), Stephanie Fan

Theses

In 2001, white abalone, Haliotis sorenseni, became the first marine invertebrate to be listed under the U.S. Endangered Species Act. Allee effects due primarily to overharvesting and disease resulted in individuals being too far apart for successful fertilization. Despite the fishery closure in 1996, H. sorenseni still shows no signs of recovery. Today, the White Abalone Recovery Consortium (WARC), a group that includes federal and state agencies, aquaculture organizations, academic institutions, and public aquaria, is working to recover this endangered species back from the brink of extinction.

In order to better understand the metabolic demands and hypoxia tolerance of the …

Nearshore Vertical Distribution Of Barnacle Cyprids: Temporal Patterns And Hydrographic Variability, Gabriela Yamhure

Theses

Most benthic organisms living in the intertidal zone have planktonic larvae that reside temporarily in the water column before settling in their adult habitats. Larvae aggregate in offshore larval pools, and transport horizontally and vertically in the water to remain in the nearshore and during their pelagic life. While some horizontal transport of larvae can be attributed to advection, behavioral responses, like vertical swimming and buoyancy control, allow larvae to position themselves at depths where flow direction can be exploited. Thus, knowledge on how vertical larval distribution relates to physical processes can be fundamental to better understand larval transport. These …

The Effects Of Seasonal Variations, El Niño-Southern Oscillation, And Climate Change On The Tuna-Dolphin Association, Caitlynn Birch, Michael D. Scott, Zhi-Yong Yin, Lisa T. Ballance

Theses

Tuna and dolphins swim together in the waters of the eastern tropical Pacific, and this association has long benefitted tuna fishermen and intrigued scientists. Although the tuna-dolphin association is often referred to as a “mystery,” much is known about the association. Yellowfin tuna are primarily caught with spotted dolphins and, to a lesser extent, spinner dolphins; historically the spotted dolphin has borne the brunt of the bycatch mortality. The tuna-dolphin association is thought to be a product of the distinct oceanography of the ETP: a shallow mixed layer, a thick oxygen minimum zone, and warm surface waters. As the mixed …

Spatial And Temporal Variation In The Diet Composition Of Zooplankton In Mission Bay, Bryanna Paulson

Theses

Analyses of quantitative data on zooplankton diets are vital for understanding the drivers of zooplankton abundance within an ecosystem. Such analyses also provide insight into trophic pathways within the lower planktonic food web, which support populations of higher trophic level species. This study used carbon and nitrogen stable isotope ratios of size-fractionated plankton in Mission Bay, San Diego, CA to examine the spatial and temporal variation in zooplankton trophic ecology and determine potential environmental drivers of zooplankton community structure. Carbon stable isotopes reflect primary production sources in an organism’s diet, and nitrogen stable isotope ratios can be used to estimate …

Bubble Stream Production By Belugas (Delphinapterus Leucas), Megan Slack

Theses

Bubble stream production in belugas has been poorly characterized and its function is not well understood. I examined behavioral states when producing bubble streams (“bubbling”), and when bubbling calls, to determine whether bubbling was significantly associated with a particular call category or behavioral state. Using 19 hours of video and audio recordings collected over a two-day period, I quantified bubble streams of a 4-month old calf and an unrelated adult female housed together. Based on the overall activity budgets and pool of vocalizations for both animals, I calculated the expected counts of bubble streams with and without vocalizations, assuming that …

Time-Activity And Energy Budgets Of Eared Grebes (Podiceps Nigricollis) At Salton Sea, Samantha San Francisco

Theses

Time-activity budgets have been a widely accepted way of approximating the daily energy expenditure of many species, including waterbirds. For this study, focal animal sampling was used to study Eared Grebes (Podiceps nigricollis) at their post-wintering stopover site, Salton Sea. Daylight time-activity budgets were converted to energy budgets using energy equivalents for diving, preening, swimming, and resting on water developed for Eared Grebes previously by H. I. Ellis (1994). Post-wintering Eared Grebes arrive at Salton Sea in waves at differing times in the spring. As a result, there can be individuals in a variety of physiological states during …

Plasma Metabolites Reveal Changes In Physiological State Of Eared Grebes (Podiceps Nigricollis) During Three Non-Migratory Periods, Allison A. Yoshida

Theses

Energy storage and use during the annual cycle of migratory birds is dynamic especially during migration. However, considerable amounts of the annual cycle are spent not migrating, and the physiological state of birds during these non-migratory periods is not well understood. We compared plasma metabolites (TRIG, BUTY, URIC, GLY) in Eared Grebes (Podiceps nigricollis) residing at three important areas when they are not migrating: fall staging (postbreeding at Mono Lake, California), spring staging (pre-breeding at Great Salt Lake, Utah), and an extended stopover prior to spring staging (Salton Sea, California). Plasma metabolites were also measured in resting and active grebes …

Evaluation Of Reproductive Strategies In Captive California Yellowtail (Seriola Dorsalis) Using Genetic Parentage Analyses, Elizabeth K. Smith, Mark Drawbridge Ms, John Hyde Phd, Geoffrey Morse Phd

Theses

A good understanding of spawning dynamics of species in aquaculture is vital in order to maximize egg production and quality as well as efficient allocation of food and space resources. The breeding program of California yellowtail (CYT; Seriola dorsalis previously Seriola lalandi) at Hubbs-SeaWorld Research Institute (HSWRI) is set up such that up to 30 wild caught brood fish can broadcast spawn in a group setting, just as CYT reproduce in the wild. The population of brood fish were originally caught offshore from Southern California, and are maintained under ambient sea water and natural lighting conditions. The spawning season …

Biological And Physiological Condition Of Juvenile California Halibut (Paralichthys Californicus) Exposed To A Contamination Gradient In Mission Bay, Ca, Kevin Stolzenbach

Theses

Contaminated sediments in marine environments have been shown to be good indicators of ecological risk and a means to assess anthropogenic impacts on marine habitats and the animals that inhabit them (Long et al. 1995, Rattner 2009). Estuarine sediments are especially complex media with regard to physical, chemical, and biological characteristics that trap, store, modify and sometimes release contaminants to the biota (Long et al. 1995). Especially vulnerable are animals that are in constant contact with the sediments, such as flatfishes that partially bury themselves for camouflage (Costa et al. 2011). Impacts can be assessed in a number of ways, …