Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Sampling and analytical procedures:

Spat and adult samples dredge-collected from the James Joseph research vessel were based on standard operating procedures for the Haskin Shellfish Research Laboratory annual dredge survey to monitor the natural oyster (seed) beds on the New Jersey side of Delaware Bay. Annual stock assessment workshop reports related to these samples (Rutgers oyster SAW reports) are available at https://hsrl.rutgers.edu/documents/delaware-bay-oyster-stock-assessment-reports/ and should be consulted for dredge method details and definitions for spat versus adult life stages. Additional published reports describing aspects of the oyster population are given below.

In general for transect analysis samples, sample collections for the SEGO project piggy-backed on Haskin monthly monitoring program collections. The Haskin program consistently samples oysters from the same grids every month (see SAW reports for a definition of grid). Dredge contents were hand sorted to find spat if present. All spat were collected. A sample of 50 adult oysters from each site was haphazardly (without size selection) culled, cleaned of fouling organisms, measured for shell height (hinge to longest dimension), and shucked for tissue dissection and preservation in ethanol. For challenge experiments, many more dredge hauls were required from the same area to find sufficient numbers of similar-sized adults. They were processed by cleaning them of fouling organisms and arranging them in four ambient-salinity and room temperature raceways and fed frozen shellfish diet according to manufacturers protocols: 0.18 mL per animal based on 10g meat weight. Feces and pseudo-fences were siphoned out every day and water was changed approximately every 4th day throughout the challenge experiment. Challenge experimental protocols will be reported in conjunction with genomic analyses.


- Dates converted from mm/dd/yyyy format to yyyy-mm-dd format
- Latitude and longitude fields rounded consistently to 5 decimal places
- Temperature and salinity fields rounded consistently to 1 decimal place
- Dissolved oxygen field rounded to 2 decimal places

NSF abstract:

Many marine animals have a bipartite life cycle consisting of a stationary bottom-dwelling adult stage and a mobile larval stage. The flow of water transports these larval offspring, and their genes, to different habitat patches. It is thought that animals from nearby patches will be more genetically similar than animals in patches that are further in proximity, but these patterns of genetic similarity may not be maintained if the nearby patches have different habitat characteristics. This idea is fundamental to our understanding of adaptation and evolution, but it has not been adequately tested with respect to the effects of rapid selection. This study applies new technologies to test if the genetic signatures of marine animals change even when patches with different environmental characteristics are closer together than the dispersal distance of larvae. This research focuses on eastern oysters (Crassostrea virginica) in Delaware Bay, and their ability to withstand variability in the amount of salt in the water. This study will provide new insights on factors that control oyster survival and growth in estuaries with different salinity profiles. The three investigators are sharing study results with resource managers and stakeholders to improve shellfish restoration and oyster stock management in Delaware Bay, Chesapeake Bay, and New York. A postdoctoral scholar at Cornell and graduate student at the University of Maryland are being trained and mentored during the project. The investigators are also working with teacher training programs in New York and New Jersey to develop and disseminate new curriculum materials on oyster ecology for middle-school students.

The project will investigate whether hyposalinity tolerance of oysters is a function of viability selection during larval dispersal and after settlement. Gene flow across salinity zones within an estuary is expected to be high enough that adaptive differentiation will not result from Darwinian multigenerational processes. Instead, recurrent viability selection in each generation is expected to generate spatial variation in this trait at small spatial scales. This type of recurrent within-generation adaptation has been referred to as phenotype-environment mismatches and has been hypothesized to generate balanced polymorphisms, but it has never been studied beyond single gene cases. The project team is testing for spatially discrete patterns of selection by first collecting oysters from different salinity zones, measuring variation in their tolerance to low salinity and then testing for associations between this trait and genomic variation using whole genome sequencing. Experimental hyposalinity challenges enable within-generation, before/after genomic comparisons to identify DNA variants that change as a result of strong viability selection. Candidate genes and selectively neutral control loci will be assayed in larval, juvenile, and adult samples from the same salinity zones to test for an association between variation at candidate loci and lifetime hyposalinity exposure. Two years of environmental data will be collected and added to an existing long-term data set to map salinity variation. The observed spatial distribution of hyposalinity tolerance and genomic variation associated with it provide a test that could definitively reject the prevalent assumption that all larvae have similar capabilities. If larvae differ by parental source for traits that differentially affect their viability in the plankton, then phenotype-environment mismatches can have profound consequences for population connectivity. This project improves understanding about mechanisms that shape realized larval dispersal and recruitment variation in oyster populations.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.