What are the energetic costs of low tide? Dynamic energy budget modeling of intertidal organisms
While it might not seem like it on the surface, organisms living in the intertidal are living in an extreme environment. For a marine organism, spending half of your life out in the air could mean that you deal with a different set of costs than those who are submerged. Not only do you run the risk of thermal stress from solar radiation, but being exposed at low tide means you don't have access to food or potentially oxygen! I am currently investigating what the costs of low tide are for the intertidal barnacle, Balanus glandula. By combining field measured growth and environmental data with lab measured physiological responses to temperature, I am modeling how low tide exposure at different temperatures changes metabolic rates and energy demands. Understanding energetic costs of aerial exposure is critical when trying to determine how organisms respond to climate change. The ultimate goal of this work is to test respiration and feeding rates of different populations of barnacles along the west coast of the United States. Based on location, certain populations experience vastly different thermal regimes and will likely have different responses to temperature and ultimately, different responses to climate change. While this work is being done on barnacles, the idea of modeling energy use and demand for intertidal organisms can be applied to other, more economically important species like mussels and oysters.
In prep: Ober, G.T. and Gilman, S.E. “Quantifying the cost of low tide in the barnacle Balanus glandula.”
In prep: Ober, G.T. and Gilman, S.E. “Quantifying the cost of low tide in the barnacle Balanus glandula.”
How does the combination of ocean acidification and eutrophication affect seaweeds?
The main focus of my Ph.D. work has been to quantify how coastal organisms react to the combination of ocean acidification and eutrophication (nutrient loading). While ocean acidification is already proving to be detrimental to calcifying marine organisms, things like corals and shellfish, seaweeds are projected to be successful in the future. As the base of many marine food webs, seaweeds play a critical role in the health and function of ecosystems, so any impact that climate change has on them is likely going to be felt throughout an ecosystem. I have studied how different seaweeds respond to high levels of carbon dioxide and high levels of nutrients by testing growth rates, productivity, and competition; ultimately parsing out which species will be the "winners" under future conditions and how seaweed community structure will change.
2017 - Ober, G.T. and Thornber, C.S. “ Divergent responses in growth and nutritional quality of coastal macroalgae to the combination of increased of pCO2 and nutrients.” Marine Environmental Research
2017 - Ober, G.T. and Thornber, C.S. “ Divergent responses in growth and nutritional quality of coastal macroalgae to the combination of increased of pCO2 and nutrients.” Marine Environmental Research
Do grazers have the ability to mitigate expected seaweed growth under future climate conditions?
The combination of ocean acidification and eutrophication are expected to enhance the growth of seaweeds, but before we rush to say that seaweeds are going to take over ecosystems, we have to understand how the rest of the community is going to respond. I tested how the feeding rates, feeding preferences, and stress levels of marine herbivores were affected by increased carbon dioxide and nutrients. If herbivores can eat more seaweed in the future, they may be the key to maintaining balance within ecosystems.
In prep: Ober, G.T., Grear, J.S., and Thornber, C.S. “Ocean acidification but not nutrient enrichment reduces grazing and alters diet preference in a common marine snail.” Oecologia
In prep: Ober, G.T., Grear, J.S., and Thornber, C.S. “Ocean acidification but not nutrient enrichment reduces grazing and alters diet preference in a common marine snail.” Oecologia
How does ocean acidification alter turf algal community growth and biodiversity?
Turf algae have typically been treated as one "entity" despite being comprised of a diverse range of algal species. Funded by the NSF EAPSI program and working alongside Dr. Guillermo Diaz-Pulido of Griffith University (Nathan, QLD), we tested the response of coral reef associated turf algal communities to different levels of carbon dioxide (ocean acidification). We wanted to understand how future acidification impacts the overall community growth and community diversity of turf algae.
2016 - Ober, G.T., Diaz-Pulido, G., and Thornber, C.S. "Ocean acidification influences the biomass and diversity of reef-associated turf algal communities." Marine Biology 163.10 (2016): 204.
2016 - Ober, G.T., Diaz-Pulido, G., and Thornber, C.S. "Ocean acidification influences the biomass and diversity of reef-associated turf algal communities." Marine Biology 163.10 (2016): 204.
COLLABORATIONS:
Sea Level Rise X Algal Blooms: Working alongside Dr. Rose Martin, we investigated the combination of sea level rise and algal bloom deposition on the health and productivity of salt marsh grasses, concurrently we measured greenhouse gas flux of marshes under different levels of inundation.
Ober, G.T. and Martin, R.M. “Effects of sea level rise and algal blooms on productivity and ecosystem effects in two salt marsh grasses.” in review, Hydrobiologia
Martin, R.M. and Ober, G.T. "The impacts of extreme inundation and algal bloom deposition on greenhouse gas flux." in prep
Evolutionary Adaptation to Climate Change: A collaborative effort with Drs. Jason Kolbe and Carol Thornber (URI) and Dr. Jason Grear (US EPA), this study investigates the evolutionary potential of mysid shrimp to climate change. Field collected mysids are cultured and exposed to different temperature treatments for more than 10 generations. Measurements of physiology, life history, and morphology are compared between baseline and post-treatment. Genetic contribution of traits are determined by comparisons between parental and offspring generations.
2017 - Ober, G.T., Thornber, C.S., Grear, J.S., and Kolbe, J.J. "Ecological differences influence the thermal sensitivity of swimming performance in two co-occurring mysid shrimp species with climate change implications." Journal of Thermal Biology 64 (2017): 26-34.
Ober, G.T. and Martin, R.M. “Effects of sea level rise and algal blooms on productivity and ecosystem effects in two salt marsh grasses.” in review, Hydrobiologia
Martin, R.M. and Ober, G.T. "The impacts of extreme inundation and algal bloom deposition on greenhouse gas flux." in prep
Evolutionary Adaptation to Climate Change: A collaborative effort with Drs. Jason Kolbe and Carol Thornber (URI) and Dr. Jason Grear (US EPA), this study investigates the evolutionary potential of mysid shrimp to climate change. Field collected mysids are cultured and exposed to different temperature treatments for more than 10 generations. Measurements of physiology, life history, and morphology are compared between baseline and post-treatment. Genetic contribution of traits are determined by comparisons between parental and offspring generations.
2017 - Ober, G.T., Thornber, C.S., Grear, J.S., and Kolbe, J.J. "Ecological differences influence the thermal sensitivity of swimming performance in two co-occurring mysid shrimp species with climate change implications." Journal of Thermal Biology 64 (2017): 26-34.