Marine Biology 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, …

Distribution Patterns Of The Invasive Mussel Arcuatula Senhousia In Mission Bay, San Diego, California: Effects Of Sediment Grain Size And Byssus Thread Production On Predation, Samantha Ahlman

Theses

The ability of bivalves to avoid predation by using defensive behaviors such as burrowing and byssus production may vary depending on the sediment characteristics of a given habitat. The varying sediment characteristics that change with water velocity within estuaries may influence the distribution of bivalves and limit them to areas that optimize their ability to defend against predators. We examined the distribution patterns of the invasive Asian date mussel Arcuatula senhousia relative to the sediment grain size distribution in Mission Bay, an urban estuary located in San Diego, California, USA. Mussels and sediment were collected using an Ekman grab at …

Movement Patterns Of The Shovelnose Guitarfish (Pseudobatos Productus) And California Bat Ray (Myliobatis Californica) In The Southern California Bight, Annabel Gong

Theses

While the movement patterns of large elasmobranch species have been studied extensively, those of smaller, mesopredatory species remain understudied. The shovelnose guitarfish (Pseudobatos productus) and the California bat ray (Myliobatis californica) are among the least studied elasmobranchs in the Southern California Bight. This study quantified the broad- and fine-scale movement patterns of these species using passive acoustic telemetry. Twelve guitarfish were surgically implanted with coded acoustic transmitters at a known aggregation site off La Jolla (San Diego County), California, USA and tracked for 849.5 days each, on average. Six bat rays were also implanted here and tracked for …

Historical Ecology Of The San Diego Sport Fishery: Catch Composition, Species Trends, And Fishing Effort From 1959 To 2011, Rebecca Schwartz Lesberg

Theses

Like ocean systems around the world, species targeted by the San Diego sportfishery are subject to myriad threats from human activity, with several species already showing documented decline. However, long-term fisheries datasets are often lacking, limiting natural resource managers’ ability to appropriately manage these ecologically and economically important species. Therefore, this study used daily reports published in two Southern California newspapers to examine changes in catch composition, effort, and catch per unit effort (CPUE) from 1959-2011 for the San Diego commercial passenger fishing vessel (CPFV) sportfishery. This study then tested the relationship between those patterns and three large scale oceanographic …

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 …

Otolith Microchemistry Reveals Low Habitat Connectivity Of California Killifish (Fundulus Parvipinnis) Across A Range Of Spatial Scales, Lisa Robison

Theses

As wetlands face continued fragmentation worldwide, an understanding of habitat connectivity and how fishes that rely on these environments is imperative to conduct effective marine management. Site fidelity and habitat connectivity are vital measures of the interdependence of fish populations living in neighboring marshes (or in regions of a single marsh).

Here, we examine the habitat connectivity, site fidelity, and movement of California killifish (Fundulus parvipinnis) within and among three estuaries in Southern California through otolith microelemental analysis. Assessing the site fidelity of estuarine fishes is important to determine the level of connectivity between spatially distinct populations within …

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 …

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 …

The Temporal And Spatial Dynamics Of Larval Supply, Settlement, And Adult Populations Of Chthamalus Fissus Within The La Jolla, California Rocky Intertidal, Catharine Hargenrader

Theses

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 …

Long-Term Changes In A Spatially Subsidized Insular Ecosystem In The Archipelago Of Bahía De Los Ángeles, Baja California, Mexico, Thais Fournier

Theses

Interactions between climate change and the processes that structure coastal communities are poorly understood.Long – term weather patterns that include extreme events (e.g., El Niño Southern Oscillation, or “ENSO”) allow us to test hypotheses of how changes in weather (e.g., precipitation) will influence communities over long time frames. One system that is particularly vulnerable to climate changes is the coastal ecotone, which occupies 8% of the earth’s surface. A large exchange of resources (spatial subsidies) link habitats across this ocean – land interface, often with dramatic consequences for the recipient systems. Spatial subsidies such as marine input influence …

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 …