Research Projects
Cost-benefits of shell replenishment
To maintain healthy oyster reefs, the Virginia Marine Resources Commission (VMRC) routinely performs shell replenishment, the addition of shell material or hard substrates, when the underlying reef falls below management thresholds. Oyster shell degrades quickly and is an expensive, limited resource; thus, optimizing repletion efforts to maximize restoration success is critical to maintain ecosystem services provided by oysters and support local economies. This project integrates long term data sets including annual oyster population surveys, shell replenishment records, and commercial harvest reports to understand both biological and economic responses to shell replenishment. In collaboration with VMRC’s Shellfish Management Advisory Committee, project findings will be used to develop a decision tool to inform management decisions and replenishment practices in Virginia.
To maintain healthy oyster reefs, the Virginia Marine Resources Commission (VMRC) routinely performs shell replenishment, the addition of shell material or hard substrates, when the underlying reef falls below management thresholds. Oyster shell degrades quickly and is an expensive, limited resource; thus, optimizing repletion efforts to maximize restoration success is critical to maintain ecosystem services provided by oysters and support local economies. This project integrates long term data sets including annual oyster population surveys, shell replenishment records, and commercial harvest reports to understand both biological and economic responses to shell replenishment. In collaboration with VMRC’s Shellfish Management Advisory Committee, project findings will be used to develop a decision tool to inform management decisions and replenishment practices in Virginia.
Fossil oyster reef dynamics
Oysters have a long history in the fossil record. Preserved shells store information and can tell us how quickly individuals grew, how long they lived and what oyster populations looked like in the distant past. Our team collected fossil eastern oyster shells from the Atlantic continental shelf, which were radiocarbon dated to ~10,000 years ago. These oysters were alive following the Last Glacial Maximum, when sea level rose around 10 mm per year! By comparison, Virginia currently has the highest rate of sea level rise on the east coast and experiences an increase of around 5 mm per year. This project provides a unique opportunity to understand how oyster reefs are maintained over evolutionary time scales and how modern populations may respond to increasing sea level rise.
Oysters have a long history in the fossil record. Preserved shells store information and can tell us how quickly individuals grew, how long they lived and what oyster populations looked like in the distant past. Our team collected fossil eastern oyster shells from the Atlantic continental shelf, which were radiocarbon dated to ~10,000 years ago. These oysters were alive following the Last Glacial Maximum, when sea level rose around 10 mm per year! By comparison, Virginia currently has the highest rate of sea level rise on the east coast and experiences an increase of around 5 mm per year. This project provides a unique opportunity to understand how oyster reefs are maintained over evolutionary time scales and how modern populations may respond to increasing sea level rise.
Post settlement life history of eastern oysters
Oysters are ecosystem engineers and provide critical services in temperate estuaries worldwide. Despite their importance, oyster populations have declined globally and in Virginia. Though many invertebrates have high mortality in their early life, there is limited information on post settlement mortality and its relationship with adult populations. Young, newly settled invertebrates are small and challenging to study. This project investigates growth and mortality in Eastern oysters (Crassostrea virginica) during the first critical months after settlement. Improving our understanding of early life history can inform and help guide shell replenishment, restoration efforts, and oyster management in the Chesapeake Bay.
Oysters are ecosystem engineers and provide critical services in temperate estuaries worldwide. Despite their importance, oyster populations have declined globally and in Virginia. Though many invertebrates have high mortality in their early life, there is limited information on post settlement mortality and its relationship with adult populations. Young, newly settled invertebrates are small and challenging to study. This project investigates growth and mortality in Eastern oysters (Crassostrea virginica) during the first critical months after settlement. Improving our understanding of early life history can inform and help guide shell replenishment, restoration efforts, and oyster management in the Chesapeake Bay.
Population status of Pismo clams
Pismo clams (Tivela stultorum) once supported a thriving commercial and recreational fishery in California. Overharvest led to a commercial harvest ban in 1947. Early clammers would use horsedrawn plows to harvest hundreds of clams! Although recreational harvest is still legal in California with the proper shellfish license from California Department of Fish and Wildlife, legal sized Pismo clams are rare and populations, anecdotally, have declined statewide. This project identified current locations, size structure, and abundance of Pismo clams throughout their range in California and made comparisons to historical records.
Marquardt, A, S Park, E Maietta, N Clark, G Waltz, L Needles, B Ruttenberg. 2023. Status of intertidal populations of Pismo clams (Tivela stultorum) across their range in California. Reg Stud Mar Sci. DOI: doi.org/10.1016/j.rsma.2023.103063
Pismo clams (Tivela stultorum) once supported a thriving commercial and recreational fishery in California. Overharvest led to a commercial harvest ban in 1947. Early clammers would use horsedrawn plows to harvest hundreds of clams! Although recreational harvest is still legal in California with the proper shellfish license from California Department of Fish and Wildlife, legal sized Pismo clams are rare and populations, anecdotally, have declined statewide. This project identified current locations, size structure, and abundance of Pismo clams throughout their range in California and made comparisons to historical records.
Marquardt, A, S Park, E Maietta, N Clark, G Waltz, L Needles, B Ruttenberg. 2023. Status of intertidal populations of Pismo clams (Tivela stultorum) across their range in California. Reg Stud Mar Sci. DOI: doi.org/10.1016/j.rsma.2023.103063
Reproduction, body condition, and growth of Pismo clams
Understanding reproduction and growth is critical to effectively manage a fishery. Information on Pismo clam reproduction and growth is at least 40 years old. Oceans are changing rapidly and this old information many no longer represent Pismo clam biology in the modern day. This project investigated annual timing of reproduction, body condition cycles as a potential proxy for management, and growth rates. Understanding the biology of Pismo clams can help generate new management actions, inform restoration efforts, and identify the time necessary to recovery Pismo clam populations or a fishery in California.
Marquardt, A, N Clark, E Maietta, S Park, B Ruttenberg. 2022. Reproduction, body condition, age, and growth of a large sandy intertidal bivalve, Tivela stultorum, Mawe 1823. Aquat Biol 31:19-30. DOI: https://doi.org/10.3354/ab00749
Understanding reproduction and growth is critical to effectively manage a fishery. Information on Pismo clam reproduction and growth is at least 40 years old. Oceans are changing rapidly and this old information many no longer represent Pismo clam biology in the modern day. This project investigated annual timing of reproduction, body condition cycles as a potential proxy for management, and growth rates. Understanding the biology of Pismo clams can help generate new management actions, inform restoration efforts, and identify the time necessary to recovery Pismo clam populations or a fishery in California.
Marquardt, A, N Clark, E Maietta, S Park, B Ruttenberg. 2022. Reproduction, body condition, age, and growth of a large sandy intertidal bivalve, Tivela stultorum, Mawe 1823. Aquat Biol 31:19-30. DOI: https://doi.org/10.3354/ab00749
