(9:00-9:15)
[1 - 180-239]: Urban Oases: City Microhabitat and the Hydric Physiology of a Widespread Ectotherm
Stella Raymond★, Emily TaylorDepartment of Biological Sciences, ★Speaker
Urbanization drastically restructures environments and can often impose thermal and hydric constraints on urban-dwelling organisms. In urban areas, increased temperature (Urban Heat Island Effect) and increased water availability (Urban Oasis Effect) work in tandem to produce novel conditions that might not exist otherwise. Despite increasing human activity, we lack a general understanding of how relative and combinatorial effects of urban conditions affect wildlife. The objective of this study was to analyze how the thermal and hydric characteristics of microhabitats relate to ectotherm physiology. Across 11 Southern California colleges, we logged microclimatic conditions at paired urban and non-urban sites. During spring (rainy) and fall (dry), we measured the hydric physiology of Western Fence Lizards (S. occidentalis) at each site. We discovered that urban sites had higher ambient humidity and soil moisture. This was associated with lower temperatures, likely due to greater water availability. Regardless of site, plasma osmolality was lower in spring compared to fall. Urban lizards had lower osmolality both in spring and fall, indicating higher hydration than non-urban lizards. Cutaneous evaporative water loss of lizards was similar between sites in spring, but declined in non-urban lizards in fall, likely to prevent desiccation during the dry season. Our results suggest that irrigation on college campuses may mitigate the detrimental effects of urbanization. This work has implications for sustainable urban planning and highlights the importance of microhabitats for urban-dwelling organisms. |
(9:15-9:30)
[2 - 180-239]: Exploring Pismo Clam (Tivela stultorum) Recruits Between the Intertidal and Subtidal Zones
Madeleine Yang★§, Olivia Halter, Ben RuttenbergDepartment of Biological Sciences, §Santa Rosa Creek Foundation Support, ★Speaker
Pismo Clams are an ecologically important species as they contribute to sandy beach ecosystems and support recreational fisheries. Understanding the recruitment pattern of Pismo Clams is crucial for assessing population recovery and sustainability. While intertidal surveys have provided insight into what is occurring on the beach, there is limited knowledge on the distribution of Pismo clam recruits in the subtidal zone. This study investigates whether there is a difference in recruit abundance between the intertidal and subtidal zones to improve understanding of early life-stage habitat use. We analyzed intertidal data using an existing field survey dataset to identify patterns in recruit presence and abundance. To sample the subtidal zone, we developed sampling methods for subtidal dive surveys. On each dive, we surveyed three 30m transects and sifted sediment samples at three-meter intervals. We sifted the sediment samples using a 1mm sieve and brought any recruits or organisms we encountered to the surface to identify. To ensure repeatability, we standardized procedures, including alternating sampling sides, consistent transect spacing, and documenting sample collection on dive slates. We have yet to obtain data on where Pismo clam recruits occur in the subtidal zone. However, we successfully developed a structured, replicable methodology for subtidal sampling, which includes detailed logistical protocols for dive plans, transect deployment, sediment collection and processing, and surface data collection. Ultimately, we intend to improve understanding of where recruits occur across the intertidal and subtidal zones and to support ongoing research on the distribution of the Pismo clam population. |
(9:30-9:45)
[3 - 180-239]: Patterns and thermoregulatory impacts of catastrophic molt in male northern elephant seals
Halley Carson1†★§, Rachel Survilas1, Emily Robinson2, Heather Liwanag11 Department of Biological Sciences, 2 Department of Statistics, †Frost Support, §Santa Rosa Creek Foundation Support, ★Speaker
Many animals undergo molt (shedding of skin, hair, feathers, or shell) to facilitate growth and development. Northern elephant seals (Mirounga angustirostris, NES) exhibit an unusual physiological phenomenon known as a “catastrophic molt,” which involves the shedding of hair and cornified epidermis over a short period of time. Although NES are well studied, there is surprisingly little information about their annual molt, a time when they are constrained to fasting on land. In this project, we documented the molt pattern and surface temperatures of subadult and adult male NES during the annual catastrophic molt, as well as the timing of their haulout for the molt. To do this, we performed visual observations and collected infrared thermal images of molting male NES at the Piedras Blancas rookery across two molting seasons, and we examined 6 years of haulout data to examine the timing of the male molt over time. From our visual observations, we created a molt code to describe the predictable pattern of molt we observed; seals began molt on the head and flippers, followed by the chest shield and dorsum, and finished with the ventrum. From the thermal imaging, we found that freshly molted body regions were associated with increased surface temperature, suggesting that NES may increase blood flow to the skin to facilitate the molting process. Analysis of male molt phenology is ongoing, and the results may have implications for how these animals respond to climate change, as shifts in haulout times will likely affect the timing of at-sea foraging. This is the first study to document the pattern and thermal consequences of the catastrophic molt in male NES. Future work will compare these results to molt in other NES age classes. |
(9:45-10)
[4 - 180-239]: Developing a Model Bryozoan (Watersipora sp.) for Assessment of Biofouling
Zoey C. Wall1★, Sean F. Craig2, Nikki L. Adams11 Department of Biological Sciences, 2 Cal Poly Humboldt, ★Speaker
Watersipora is a genus of bryozoans that are invasive in marine fouling communities. The presence of colonies serves as a settlement point for other invasive taxa, exacerbating negative effects. Colonies pose additional financial burdens by encrusting on boats and machinery and leading to high maintenance costs. As biocidal copper coatings have been widely applied to ships, Watersipora has shown a rapid and unique evolution of tolerance. This history of rapid adaptation makes Watersipora an ideal organism for testing novel anti-fouling coatings. This study aims to identify optimal laboratory conditions for the growth of Watersipora as a step towards establishing it as a model organism. Colonies of Watersipora were collected from San Luis Obispo Bay and spawned. Larvae were successfully settled into laboratory tanks and metamorphosed into adult colonies. Colonies have continued to grow over five months in a closed system kept at 14ºC with a mixed microalgal diet grown on-site at the Cal Poly Pier. Cultivation of this species has mirrored the unique success seen at Cal Poly Humboldt. We are currently initiating experiments testing optimal diets and temperatures for Watersipora growth to establish it as a model to test anti-fouling (or foul-release) paints. |
(10-10:15)
[6 - 180-239]: Investigating age-size relationships in historical and current Pismo clams (Tivela stultorum)
Lucy Thackray★§, Jami Clayton, Marissa Bills, Benjamin RuttenbergDepartment of Biological Sciences, §Santa Rosa Creek Foundation Support, ★Speaker
Pismo clams were a popular recreational fishery species on the central coast of California throughout the mid-20th century. The fishery thrived until the 1980s when it crashed for unknown reasons, likely including overharvesting and predation. In recent years, populations have begun to increase, and effective management will be essential for the species’ success and recovery. Since the 1980s when Pismo clams were last abundant, ocean conditions have changed, including a decrease in the pH of the ocean, and an increase in sea surface temperatures, which could impact growth rates and the ability of clams to calcify. We examined historical specimens of Pismo clam shells from the Santa Barbara Museum of Natural History and the Los Angeles County Natural History Museum, as well as current shells from Pismo Beach, in order to better understand differences between historical and current populations. We aged each specimen, and measured the weight, length, width and thickness of each shell. We are investigating the relationships between these variables, and comparing how the relationships differ between historical and current shells. We are also comparing these variables across locations throughout the coast of California and Baja California, Mexico.
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(10:15-10:30)
[7 - 180-239]: Exposure of female sea urchins (Strongylocentrotus purpuratus) to polyethylene microfibers causes developmental abnormalities in offspring
Treasure Joyce★§, Nikki Adams§Department of Biological Sciences, §Santa Rosa Creek Foundation Support, ★Speaker
Microplastics (plastic particles <5 mm in size, with diverse compositions and shapes) are widespread in marine environments. Polyethylene is a common polymer found in products such as plastic bags, disposable water bottles, and synthetic fibers. Our laboratory has observed a high prevalence of microfibers (MFs) in organisms and sediments in Morro Bay and in tissues of the California purple sea urchin (Strongylocentrotus purpuratus), a model and ecological indicator species in California ecosystems, with planktonic larvae that are highly sensitive to pollutants. The objective of this study was to determine whether a microplastic-rich maternal environment, specifically polyethylene microfibers (PEMFs), produces carryover effects that alter offspring development. Adult females were exposed to 1 mm PEMFs under control (0 PEMFs per individual), low (50 PEMFs), and high (100 PEMFs) treatments for four months. Eggs from exposed females were fertilized with sperm from unexposed males. Development was assessed by measuring timing of first cleavage and subsequent development, including timing and morphological normality, every 24 hours for four days. Maternal exposure to PEMFs did not affect early cleavage rates. However, increased exposure significantly reduced the proportion of embryos developing normally, indicating a negative relationship between PEMF exposure and developmental success (p<0.05). |
(10:30-10:45)
[8 - 180-239]: Influence of gear type selectivity on diet composition of nearshore rockfish
Sasha Evans†★, Helen Lee, Elsa Simenstad, Erin Johnston, Benjamin Ruttenberg, Dean WendtDepartment of Biological Sciences, †Frost Support, ★Speaker
Understanding the status of nearshore fish stocks requires information about species
abundance, catch data, and ecological interactions. These components, along with life history
information from fisheries research projects, feed into stock assessment models and strengthen
our understanding of nearshore fish stocks. The California Collaborative Fisheries Research
Program (CCFRP) is one such program that conducts research to evaluate marine protected
areas and the status of nearshore fish populations. This study investigates how the dietary
preferences of Blue rockfish (Sebastes mystinus) and Olive rockfish (Sebastes serranoides)
influence the gear types they are likely to be caught with. Specifically, we ask whether different
gear types (unbaited and baited shrimp fly and lingcod bar) correspond to variation in gut
contents and whether these differences vary temporally.
Over the course of two summers, CCFRP conducted hook-and-line surveys at Point
Buchon and Piedras Blancas. For each captured fish, species, length, weight, and gear type were
recorded, and stomachs were preserved for laboratory analysis. Gut fullness and contents were
analyzed by prey occurrence and diversity.Our preliminary findings indicate a variance of prey
preferences across gear types and years. These differences may reflect the different foraging
habits between Blue and Olive rockfish. Results will inform future ecological studies by
highlighting the importance of gear choice in trophic research and may have implications for
fisheries monitoring and ecosystem-based management strategies. |