Life Sciences Commons^™

Practical Solutions To The Invasion Of Lionfish In Utila, Honduras: Science, Education, Food, And Jewelry, Carolyn Corley

Undergraduate Honors Theses

Lionfish (Pterois sp.) are invasive species capable of devastating coral reef ecosystems due to their lack of predators, large appetites, generalist diet, high fecundity, and rapid spawning rates. As lionfish have expanded their distribution across the Caribbean, many conservation groups have taken it upon themselves to systematically remove these predators from environments where they are threatening native species. However, few have involved the community the way I observed while interning with the Whale Shark and Oceanic Research Center in Utila, Honduras. Protecting coral reefs is extremely important, especially in small communities like Utila, where the majority of people’s …

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, …

Assessing The Effectiveness Of Integrated Multi-Trophic Aquaculture For Growing West Coast Venus Clams, Avery Wallace

Theses

With demand for sustainable sources of seafood on the rise, California is looking to expand aquaculture with a focus on innovative culturing methods and use of native or resident species. Therefore, this study examined the potential for culturing native North American west coast venus clams (Chione californiensis and Chione undatella) using integrated multi-trophic aquaculture (IMTA). An ITMA approach was chosen because it is a culture method that uses species from different but functionally complementary trophic levels that have been found to reduce the potential negative effects of traditional monoculture. California sea cucumber (Parastichopus californicus) and the seaweeds red ogo (Gracilaria …

Ichthyofaunal Utilization Of A Man-Made Salt Marsh Creek In Mission Bay, California, 25 Years After Creation, Maria Angst, Drew M. Talley

Research Month

Abstract: Southern California's wetlands are drastically declining due to human activities. Increasingly, marsh restoration and creation are being used to mitigate such losses. This study used minnow traps to resample the ichthyofauna of a created marsh (Crown Point Mitigation Site; CPMS) and an adjacent natural marsh (Kendall Frost) in Mission Bay, California, 26 years following the marsh creation. These data were compared to data collected from 1995-1998, immediately after marsh creation. Fishes trapped included Fundulus parvipinnis, Gillichthys mirabilis, Ctenogobius sagittula, Atherinops affinis, and Mugil cephalus. Species richness and dominance measures were higher in the natural …

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 …

The Effect Of Marine Snow Particle Distribution On The Foraging Behavior Of Calanus Pacificus, Elena Beckhaus

Theses

Marine snow is a major component of the biological pump, through which carbon is exported to the deep ocean. The sinking of marine snow can be disrupted by organisms, including many species of zooplankton that ingest or break up aggregates. These processes can have important impacts on planktonic food web dynamics and carbon export. Marine snow can have vertically patchy distributions, occurring in thin layers, which may further affect interactions with zooplankton. In this lab-based study, we examined how the presence of a marine snow layer affects copepod behavior and ingestion.

We conducted a series of experiments in which copepods …

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 …

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 …

Developing A Method To Track Marine Snow Aggregation Through Individual Collisions Using Stereoscopic Imaging, Riley Henning

Theses

The aggregation of individual phytoplankton into marine snow allows particles to sink more quickly, thus resulting in the transport of particulate organic carbon from surface waters to the deep ocean. Aggregate formation has previously been measured in experiments indirectly by quantifying how particle size or particle concentration changes over time. Here, I present my thesis in which I applied high-resolution imaging to quantify aggregate formation using two different methodologies.

We conducted experiments to investigate aggregate formation using stereoscopic imaging, tracking individual particles directly in a 3D volume. Phytoplankton cultures were rolled in cylindrical tanks and imaged by two cameras illuminated …

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 …

Algal Wrack Community Composition And Succession On A Sandy Beach In San Diego, Ca, Marisol Palomares

Theses

Sandy beaches are high-energy impact zones that produce little to no organic material. Much of the organic matter on beaches is washed up on shore in the form of algal wrack, providing a vital source of nutrients, food, and habitat for a variety of organisms on the sandy beach. Over time wrack will decay and decompose, releasing nutrients including nitrogen and phosphorus, which are consumed by benthic microalgae and bacteria. The type of wrack and geomorphology of the beach environments affect decomposition, which in turn supports a variety of different wrack associated macrofaunal communities. Different species of algal wrack will …

The Effect Of Phytoplankton Properties On The Ingestion Of Marine Snow By Calanus Pacificus, Grace Cawley

Theses

The aggregation of phytoplankton into marine snow provides a mechanism by which smaller particles can coagulate to form larger particles, which can be consumed at various depths or readily transported to the deep ocean and sequestered from the atmosphere on time scales of a thousand years or more. Zooplankton interacting with these large carbon-rich aggregates can obtain nutrition in environments where the phytoplankton size spectrum is small and not directly available, enhancing the possibility of obtaining adequate nutrition in environments dominated by small cells. In addition, interactions between zooplankton and marine snow can result in fragmentation, thus affecting the particle …

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 …

The Effects Of Density Gradients On The Distribution And Behavior Of Copepods, Connor Cayson

Theses

Observations of fine-scale behavioral dynamics of zooplankton may shed insight into much larger-scale ecosystem patterns and phenomena. Some zooplankton, such as copepods, are known to aggregate near density gradients; however, it is not clear the extent to which density gradients alone affect copepod distribution and behavior, since these gradients are often associated with phytoplankton layers. In this study, we investigated the behavior of Calanus pacificus in response to salinity gradients through laboratory experiments observed with high-resolution video and analyzed using computational techniques. Image data were collected using two cameras recording continuously for a duration of 30 minutes or more, allowing …

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 Impact Of Copper On Non-Indigenous And Native Species Of Suspension-Feeding Bivalves In Mission Bay, San Diego, California, Brian Juhl

Theses

Native (Chione californiensis) and non-indigenous bivalve species [Musculista senhousia (now known as Arcuatula senhousia), and Venerupis philippinarum] were collected from Mission Bay, San Diego, California and exposed to copper contaminated water at estimated concentrations of 0 ppb, 25 ppb, and 50 ppb over the course of two experimental periods of 18 days and 12 days. Bivalves were placed in tanks in a temperature controlled environment, and measurements of a number of parameters were taken during and after the exposure to copper: survivorship, feeding rates, growth, mucus production, and tissue copper concentrations for the entire body, …

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 …

Effect Of Adult Chemical Cues On Molting Of Fiddler Crab Megalopae In Low Salinity Seawater, Sydney Rilum

Undergraduate Honors Theses

Three species of fiddler crabs, Uca minax, U. pugnax, and U. pugilator, are commonly found in estuaries along the Atlantic coast, each with distinct adult habitats differing in salinity and sediment grain size. Prior research has found evidence for larvae exhibiting selective settlement; however, the degree to which and the method by which they choose their species-appropriate habitat to settle in is still unknown. Additionally, a recent study determined that chemical cues from adult crabs stimulate molting in field-caught fiddler crab megalopae, as previously determined in lab-reared megalopae; however, in 35 ppt seawater, few U. minax molted. …

Copepod Distribution In Relation To Environmental Parameters On Diel And Tidal Time Scales In Mission Bay, San Diego, California, Joy Renee Shapiro

Theses

The vertical distribution of copepods in estuaries is known to vary in relation to environmental factors. However, the relationships between environmental conditions (e.g., tides, hydrography) and copepod distributions are not well understood. This project examined connections between environmental parameters and copepod distribution in Mission Bay, San Diego, California. Copepods (adults, juveniles, and nauplii) were collected every two hours over a diel cycle at three sites across the bay. A plankton pump was used to draw ~2 m³ of water from each of two depths - just below the surface and just above the bottom. Copepods were retained in a …

Understanding And Optimizing Growth And Development Of California Yellowtail (Seriola Dorsalis) In Aquaculture Using Physiological Tools, Laura Schwebel

Theses

Physical fitness metrics were used to assess the health and development of California Yellowtail, Seriola dorsalis, in an aquaculture environment during two grow-out experiments. The first experiment sought to evaluate the effects of a common aquaculture deformity (an improperly inflated swim bladder) that has been hypothesized to impact energy allocation, growth, and development. Metrics including metabolic rate, critical swimming speed, feed conversion ratio, and growth rate, were monitored over a 32-week period in three groups of California Yellowtail: wild-caught (“wild”), healthy hatchery-reared (“inflated”), and hatchery-reared with uninflated swim bladders (“uninflated”). At the start of the grow-out period, wild fish …

Vertical And Cross-Shore Distributions Of Barnacle Larvae In La Jolla, Ca Nearshore Waters: Implications For Larval Transport Processes, Malloree Lynn Hagerty

Theses

Many marine organisms begin their lives as tiny larvae that are at the mercy of ocean currents. Understanding the transport and subsequent dispersal of larvae is crucial, as it drives population connectivity in the ocean. Larval transport is a complex process involving both physical motions of the water and larval behavior. Vertical positioning is especially important because currents vary throughout the water column, and larvae at different depths will be advected differently. With swimming speeds insufficient to swim against currents, marine larvae can mediate cross-shore transport by controlling their depth distributions. Thus, the overall objective of this study was to …

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 …

Larval Rockfish Diversity Abundance Dynamics In Association With A Marine Protected Area In The Southern California Bight, Dustin Chen

Theses

Marine protected areas (MPAs) are areas aimed at protecting natural and cultural resources that are often proposed as a way to alleviate the effects of overfishing on populations of targeted species; these areas have varying degrees of fishing and recreational use restrictions. In order to assess MPA efficacy, it is important to determine the mechanisms by which the presence of MPAs affect reproductive output within and potentially even beyond their boundaries. I attempted to address this through studying the responses of rockfish (Sebastes spp.) larval abundances to the presence of the Cowcod Conservation Areas (CCAs) located within the Southern California …

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 …

Settlement Of Larval Spotted Sand Bass (Paralabrax Maculatofasciatus) Within Mission Bay, San Diego Ca In Relation To Environmental Conditions, Anthony J. Basilio

Theses

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 …