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Full-Text Articles in Life Sciences

The Effects Of Density Gradients On The Distribution And Behavior Of Copepods, Connor Cayson Aug 2018

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 Aug 2018

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 May 2018

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 May 2018

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 …


Copepod Distribution In Relation To Environmental Parameters On Diel And Tidal Time Scales In Mission Bay, San Diego, California, Joy Renee Shapiro Jan 2018

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 …