Current lab members and volunteers
Tim Davidson (PI)
Dr. Davidson studies marine ecology, conservation biology, and human impacts in the marine and aquatic environment. He received his BS in Environmental Science at Oregon State University, MS in Biology from the Oregon Institute of Marine Biology, and PhD in Environmental Sciences and Resources at Portland State University. Davidson also completed post-docs at the Smithsonian Tropical Research Institute in Panama and University of Hawaiʻi at Mānoa. When he is not exploring wetlands, reefs, or the intertidal, he enjoys surfing, travelling, and practicing Judo as an assistant instructor at the Sacramento State Judo Club.
​Hannah Ciffone  (MS student)
Hannah received her BS in ecology, evolution, and biodiversity from UC Davis in 2020. She is now an MS student investigating combined effects of copper and salinity on the behavior and survivorship of an invasive burrowing isopod. She enjoys her job at an aquatic toxicology laboratory and likes cooking, climbing, and language learning in her free time. 
Katie Karpenko (MS student)
​Katie earned her B.S. in Biology with a concentration in Ecology, Evolution, and Conservation from CSUS in 2015. She is interested in conservation and ecology, with a particular focus on how molecular tools can be applied in ecological research and natural resource management. She explores these interests in her current position as a Senior Research Associate at the Cramer Fish Sciences – Genidaqs lab, where she specializes in environmental DNA (eDNA) research and application. For her M.S. research, Katie is using eDNA to map the distribution of the invasive New Zealand mud snail in the San Francisco Estuary. Her work aims to understand how the estuary’s salinity gradient shapes the species’ distribution and reproductive output. This research is supported by the COAST Coale Graduate Scholar Award. Outside of her professional and academic pursuits, Katie enjoys exploring nature, gardening, and working on her many creative hobbies.
Rebecca Pilakowksi (MS student)
Rebecca is an MS student studying the effects of low salinity events on bioerosion and survivorship of an invasive burrowing isopod. She currently works at the California Department of Pesticide Regulation, Certification & Licensing Program.
Ericka Rosen (MS student)
Ericka graduated from Oregon State University in 2024, obtaining a BS in Zoology. She is interested in studying the ecology and behavior of aquatic invertebrates, and hopes to potentially research the impacts of New Zealand mud snails. 
Jack Morgan  (undergraduate researcher)
Jack is an undergraduate research studying how the burrow microhabitats created by the invasive boring isopod Sphaeroma quoianum may provide a refuge for intertidal invertebrates. He received funded through the CSU COAST Undergraduate Research Support Program and are a co-author on a paper currently in review.
Volunteers & new research students:
  • ​​Andre Martinez
Former lab members & volunteers at Sac State:
Former MS students
Amanda Croteau (MS student; 2024, dual advised with Dr. Amy Wagner)
​Amanda used coral carbon isotopes to reconstruct past climate, understand the biochemical effects of coral disease, and predict future ocean conditions of the Flower Garden Banks National Marine Sanctuary (FGBNMS). Her research was funded by the NOAA Office of National Marine Sanctuaries through the Dr. Nancy Foster Scholarship Program. Amanda is also a proud Cherokee Nation tribal citizen. 

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Carla Cruz Medina (MS student; 2024)
Carla investigated the impacts of invasive pond turtles using a global meta-analysis. She also was a research assistant for the Bushy Lake Restoration project ​where she helped sample aquatic invertebrates and measure water quality at the lake. She received several university and outside scholarships including the prestigious CSU Trustees Award.  


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Jessica Nichols (MS student, 2023)
​Jessica graduated with an MS in Biological Sciences in June 2023. Her thesis was titled "Bioeroding effects of wood boring ecosystem engineers alter habitat complexity and community structure."  She completed her BS in Biology from California State University San Marcos.  Nichols studied how wood-boring ecosystem engineers alter wood habitat structure and invertebrate community composition in the Florida mangroves. She now works as an Environmental Scientist for the Yuba Water Agency.
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Sarah Albright (MS student, 2021)
Sarah graduated with an MS in Biological Sciences in Dec 2021. Her thesis was titled "Impacts of body size and water movement on fragmentation in three temperate estuarine algae." She received her B.S. (Honors) in Marine Biology from the University of Hawaiʻi at Mānoa, and worked for NOAA's National Marine Sanctuaries, Papahānaumokuākea Marine National Monument as a scientific communications intern during her time in Hawaiʻi. Her Master’s thesis investigated the vegetative fragmentation and dispersal of algae in the San Francisco Bay. When she’s not working or adventuring along shorelines of the Pacific, she is doing science outreach and education, camping in the Sierra Nevada mountains, or writing fantasy novels and leading games of Dungeons and Dragons with her friends.​ She recently published a paper with Davidson investigating potential biotic resistance by urchins on invasive algae. Sarah now works for the Army Corp of Engineers.​
Former Undergraduate students
​Lexie Cepeda (undergraduate researcher)
Lexie was an undergraduate researcher with a concentration in General Biology (graduated 2025). She received an NSM SURE award (2024-2025) to examine how burrows of an introduced ecosystem engineer (Sphaeroma quoianum) reduce desiccation stress for intertidal invertebrates using lab and field desiccation experiments. She gave several poster presentations and an oral presentation at the BIO 186C seminar series on this work. We are currently collaborating with current student Jack Morgan and former research student (now professor) Ethan Roberts to publish these results.  

​Alivia De Luze  (undergraduate researcher)
Alivia was a student in the Ecology, Evolution, and Conservation concentration at Sacramento State (graduated 2022). Her interests are in conservation ecology, natural resource conservation, and wildlife biology. She is currently conducting research investigating the impact of marine wood borers on introduced and native mangroves. She also helps measure water quality and sample aquatic organisms with the Bushy Lake restoration project.  Her marine borer work was funded through the CSU COAST Undergraduate Research Support Program.
​Cassandra Rodriguez (undergraduate researcher)
Cass completed her final semester at CSUS and now pursuing graduate school at UC Davis. Her primary interests are in Conservation Biology and Wildlife Conservation. She is a mother and an 8-year veteran with the United States Air Force, where she served as an Aerospace Medical Service Technician/EMT. Cass conducted a meta-analysis on the feeding and burrowing effects of the globally invasive species, Myocastor coypus (nutria) and received research funding through the CSUS COAST program and SEE program at CSUS. ​
Ethan Roberts (undergraduate researcher)
Ethan graduated from our EEC program (BS, 2020) and completed an MS (McDonald lab, 2024) at Sacramento State. He investigated how burrows formed by an invasive ecosystem engineer affect intertidal invertebrate communities, which is currently being prepared for publication. During his MS, he focused on biology education with Dr. McDonald. While much of his time is spent between school and research, Ethan moonlights as a science illustrator, portrait artist, jazz pianist, and piano instructor. Ethan received several research awards at CSUS including COAST awards and an NSM SURE project award.  He now works as a professor at Sierra College.  
Anthony Ziba (undergraduate researcher)
Anthony is a graduate of our evolution ecology and conservation program (BS) and an LSAMP Award recipient. He studied patterns of leaf herbivory and predation in Florida mangroves using field and lab experiments.  
Other former volunteers & lab members:
  • Jackie Elston - Helped with desiccation experiments with invasive isopods (2024)
  • Mary-Frances Kantola - Helped with the Bushy Lake Project & teaching assistant for Bio 167; Received Bio Sci student of the year (2023)
  • Eric Weston - Helped sample water quality & aquatic macroinvertebrates with the Bushy Lake Restoration Project  (2021)
  • Jane Simeon - Creating biological illustrations for an educational plant ecology game (2018-20)
  • Jenna Grossman - Studied the impacts of invasive marine algae (2019-20)
  • Catlinh Nguyen  -  Helped gather and compile data for a meta-analysis of invasive Nutria impacts (2020)
  • Alyson Bender - Researched methods to quantify microplastics & impacts (2020)
  • Erika Ornouski - Researched mangrove ecology connectivity (2020)
  • Jessica Agajan - Analyzed patterns of leaf herbivory in native and invasive mangroves (2019)
  • Danielle Nestler - Analyzed patterns of leaf herbivory in native and invasive mangroves (2017-2019)​
  • Allyson Bricker - SURE Award recipient - investigated how ecosystem engineering isopods affect predation rate in the intertidal (2018-19)​
  • David Boelen - MS student from OSU - studied the biogeography of marine wood boring crustaceans and mollusks (2018)
  • Aliyah Penn - Examined marine debris and plastic pollution abundances in the intertidal (2018)
  • Jonathan Semkiw - ​Examined marine debris and plastic pollution abundances in the intertidal (2018)