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How does intraspecific variation shape populations, communities, and ecosystems?

We are interested in how individual variation in demography and foraging ecology scales up to influence populations, communities, and ecosystems. The fishes of Lake Turkana, Kenya, for example, differ in intraspecific diet diversity and, consequently, in their ability to adapt to ongoing massive changes to the system's hydrology. In Magellanic penguins, males show greater diet and foraging flexibility than do females, making them more likely to survive when foraging conditions are unfavorable. Accounting for individual variation and plasticity allows us to more accurately estimate population-level responses to global environmental change.



Related Resources:

  • Gownaris and Boersma. 2019. Published in Ecological Applications. Sex-Biased Survival Contributes to Population Decline in a Long -Lived Seabird, the Magellanic Penguin. Open Access.

  • Toscano, Gownaris, Heerhartz, Monaco. 2016. Published in Oecologia. Personality, Foraging Behavior, and Specialization: Integrating Behavioral and Food Web Ecology at the Individual Level.

  • Gownaris, Pikitch, Ojwang, Michener, Kaufman. 2015. Published in PLOS ONE. Predicting Species' Vulnerability in a Massively Perturbed System. Open Access.

Current Projects: 

  • Thick-billed murres in Hudson Bay, Canada vary in how they alter their foraging behavior across changing environmental conditions. This ice-dominated system is changing rapidly due to climate change, resulting in more variable foraging conditions during the breeding season. See preliminary results presented at the World Seabird Twitter Conference. 

  • Individuals of Atlantic puffins, black guillemots, Arctic terns, and common terns vary in how they adjust their chick provisioning to increasing SST in the Gulf of Maine. The Gulf of Maine is warming faster than nearly any area in the ocean, and long-term warming trends are punctuated by marine heatwaves, driving fish deeper and farther offshore. How individuals respond to this changes has implications for the growth and survival of their chicks. See preliminary results presented at the World Seabird Twitter Conference.


What scales of environmental variation drive ecosystem function?

The relative importance of different scales of variability on population, community, and ecosystem function are still poorly understood. We study how environmental variability, rather than mean conditions, influences the foraging ecology and demography of marine and freshwater organisms. For example, though lakes are often categorized using static conditions like depth, our research has shown that dynamic indicators (water level fluctuation magnitude) are better predictors of the food web structure of African Lakes (e.g. ecosystem productivity, biodiversity, transfer efficiency). In Lake Turkana, Kenya, an understudied amplifier lake undergoing extreme hydrological change, fisheries productivity is driven by water level fluctuations, but not by mean water level or fishing effort. Understanding the spatial and temporal scales that drive population dynamics is particularly important in a time of climate shifts and extremes.


Related Resources:

  • Yu-Chun et al. 2020. Published in Nature Communications. Assessing Effects of Climate and Land-Use Change on Fish Catches Across Global Lakes. Open Access. 

  • Gownaris, Rountos, Kaufman, Kolding, Lwiza, Pikitch. 2018. Published in Journal of Great Lakes Research. Water Level Fluctuations and the Ecosystem Functioning of Lakes. Open Access.

  • Gownaris, Pikitch, Aller, Kaufman, Kolding, Lwiza, Obiero, Ojwang, Malala, and Rountos. 2017.  Published in Ecohydrology. Fisheries and Water Level Fluctuations in the World's Largest Desert Lake.

  • Gownaris. Dissertation. Understanding the Impacts of Changes in Water Inflow on the Fishes of Lake Turkana, Kenya. Open Access.

  • Commito, Commito, Platt, Grupe, Dow, Gownaris, Reeves, Vissichelli. 2014 Published in Ecosphere. Recruitment Facilitation and Spatial Pattern Formation in Soft-Bottom Mussel Beds. Open Access.


How do we optimize marine spatial planning?

The United Nations has declared 2021-2030 as the "Decade of Ocean Science for Sustainable Development". Though the global coverage of protected areas has increased rapidly, we have yet to reach the Sustainable Development Goal and Aichi Target to protect 10% of the ocean by 2020. Importantly, reaching numerical targets has little conservation benefit unless marine protected areas are properly sited and managed. We are interested in informing global marine spatial planning by identifying marine priority regions and quantifying ecosystem service trade-offs in these regions. Our research also informs the role of space-based measures in conserving seabird populations.

Related Resources:

  • Gownaris, Santora, Pikitch. 2020. Virtual Presentation through OpenChannels. Gaps in Protection of Important Ocean Areas: A Spatial Meta-Analysis of Ten Global Mapping Initiatives. Recording.

  • Gownaris, Santora, Pikitch, Davis. 2020. Published in Frontiers in Marine Science. Gaps in Protection of Important Ocean Areas: A Spatial Meta-Analysis of Ten Global Mapping Initiatives. Open Access. Mapping Tool.

  • Boersma, García Borboroglu, Gownaris, Bost, Chiaradia, Ellis, Schneider, Seddon, Simeone, Trathan, Waller, Wienecke. 2019. Published in Conservation Biology. Applying Science to Pressing Conservation Needs for Penguins.  Open Access.

  • Megan Keene, Undergraduate Thesis: Quantifying Ecosystem Service Trade-Offs Within Marine Priority Areas. Environmental Studies Department of Gettysburg College.

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