My current and recent projects are described below:
Selected previous research projects:
- Hypoxia in Marine Ecosystems: Implications for Neritic Copepods (summary here)
- Modeling the Impacts of Hypoxia on Ecologically and Commercially Important Living Resources in the Northern Gulf of Mexico
- RAPID Collaborative Research: Historic freshwater input and hypoxia effects on zooplankton populations of the northern Gulf of Mexico (summary here)
- RAPID Collaborative Research: Spatially-explicit, High-resolution Mapping and Modeling to Quantify Hypoxia and Oil Effects on the Living Resources of the Northern Gulf of Mexico (summary here)
- Predicting Striped Bass (Morone saxatilis) recruitment in the Chesapeake Bay
- GLOBEC Pan Regional Synthesis: Life histories of species in the genus Calanus in the North Atlantic and North Pacific Oceans and responses to climate forcing (summary here)
- Dynamic Stability and Particle Transformations: Tracing Pathways of Production in Estuarine Turbidity Maxima
- Forays and Foraging in Marine Zooplankton
Short Descriptions of Some Current Projects:
The effects of diatom-produced polyunsaturated aldehydes on the microbial food wed in temperate and polar waters
Funded by NSF OCE
This project will conduct a set of field/laboratory experiments to address the following hypotheses with respect to microzooplankton (consumers between 20-200 µm) and diatom- produced polyunsaturated aldehydes:
I. Aldehydes will impair microzooplankton herbivory on diatoms and non-diatom phytoplankton.
II. Aldehydes will reduce the growth rates of microzooplankton and non PUA-producing phytoplankton.
III. In the presence of aldehyde-producing diatoms, copepods will switch to microzooplankton, whereas non- (mildly)- toxic diatoms will be an important food source for copepods.
IV. The effects of aldehydes on microzooplankton and copepods will depend on the grazers' prior exposure to PUA.
The experiments will include natural plankton, captured copepods, cultured Skeletonema marinoi (SM), including its aldehyde-producing strain, and synthetic aldehydes. To gain insights into complex interactions within planktonic communities, detailed information on their composition, abundance, and dynamics will be obtained using microscopy, flow-cytometry, and cytological methods. This approach will allow the PIs to draw conclusions about the role of diatom-produced aldehydes in phytoplankton-microzooplankton- copepod trophic interactions. The PIs will coordinate efforts and exchange information with the PUA study group at the Stazione Zoologica Anton Dohrn (Naples, Italy).
Intellectual merit: Diatoms are dominant autotrophic plankton in the ocean. Recent evidence indicates that microzooplankton are the dominant herbivores, whereas copepods often rely on microzooplankton as food, except during peak diatom production. The ability of microzooplankton to feed on large diatoms and grow as fast as their algal prey leads to the question of what allows diatoms to escape microzooplankton grazing control during the initial phases of their blooms and maintain the blooms until nutrient resources are depleted? Allelopathy is wide spread among phytoplankton. The cosmopolitan bloom-forming SM produces several aldehydes and has become a model organism in plankton allelopathy studies. Most studies on diatom cytotoxicity have been dedicated to inhibitory effects on reproduction and development of marine invertebrates, whereas surprisingly little information exists on its impact on key diatom grazers, microzooplankton. Preliminary results in the Chesapeake Bay show that aldehydes may induce cascading effects within planktonic communities. The proposed study will: (1) Improve our knowledge of the critical diatom-microzooplankton-copepod links in the coastal ocean; (2) Generate novel data on the effects of allelopathy on marine food webs; (3) Contribute to our understanding of broader patterns of marine ecosystems by comparing plankton structure and dynamics in the temperate Atlantic waters; (4) Advance biological oceanography through international collaboration.
Broader Impacts: One post-doctoral fellow, two graduate students and several undergraduate students at the Universities of Akron and Maryland will be trained as a result of this project. The project will attract motivated minority students into the program. The research will be extended to students in grades 7-12 and teachers via an interactive distance learning series in collaboration with the WVIZ Ideastream network. The PIs will continue an existing outreach partnership with the Great Lakes Science Center, where a recent electronic presentation dedicated to Arctic change and NSF-sponsored research was seen by ca. 45,000 visitors. The PIs will also work with the Cleveland Museum of Natural History to develop public programs, and with the National Inventors Hall of Fame STEM Middle School to develop a curriculum focused on polar research. Curriculum modules will be available as free downloads from a dedicated website. Broader Impacts, LLC, will evaluate these education and outreach activities.
Products to Date:
Lavrentyev, P.J., G. Franzč, J. J. Pierson, & D. K. Stoecker. 2015. The Effect of Dissolved Polyunsaturated Aldehydes on Microzooplankton Growth Rates in the Chesapeake Bay and Atlantic Coastal Waters. Marine Drugs. 13(5): 2834-2856. doi:10.3390/md13052834 (Click here for Open Access PDF)
Franzč, G., Pierson, J. J., Stoecker, D. K. and Lavrentyev, P. J. 2018. Diatom-produced allelochemicals trigger trophic cascades in the planktonic food web. Limnology and Oceanography 63(3): 1093-1108. doi:10.1002/lno.10756 (Click here for Open Access PDF)
Novel Genomic Tools to Assess Fish Diet and Prey Quality in the Choptank River.
Zooplankton are critical food sources for marine fish, and climate-driven changes in their abundance, diversity, and quality can have profound effects on larval recruitment and fisheries productivity in coastal oceans and estuaries. Despite the importance of prey for understanding variation in fisheries recruitment, accurate identification of zooplankton species remains challenging and a lack of information on prey quality and prey selectivity by fish may hinder the discovery of relationships between zooplankton and fish productivity. In Chesapeake Bay, two copepods, Acartia tonsa and Eurytemora carolleeae, are critical components of bay anchovy (Anchoa mitchili), larval striped bass (Morone saxatilis), and other fish diets. However, the relative prey quality of these and other zooplankton species in Chesapeake Bay is poorly characterized, and current approaches to quantify zooplankton lack sufficient taxonomic resolution to distinguish known cryptic lineages in A. tonsa, which may differ substantially in prey quality. Novel approaches are needed to resolve taxonomy among zooplankton, to determine diet selectivity, and to measure prey quality, information which will advance our understanding of how the prey field affects recruitment variation in these commercially and ecologically significant species.
In this proposal, we seek to characterize how changes in environmental variables influence fish diets and zooplankton abundance, distribution, and quality (lipids) in the Choptank River, using cutting-edge genomic barcoding and lipid analysis approaches. We will quantify the diversity of zooplankton in the field and in fish gut contents, placing particular focus on the two dominant prey items, E. carolleeae and A. tonsa. For those target prey species, we will track variation in prey quality based on individual size and lipid content. By synthesizing gut contents, zooplankton composition and diversity, prey quality, and environmental data, we will produce novel zooplankton prey indices informed by the biology of the prey items and their importance in observed fish diets. These indices will be compared with fisheries productivity data from the MD DNR Juvenile Recruitment Indices, using data collected for this project and with historical zooplankton datasets (where possible) in step-wise regression models. Our goal is to determine which measurements of abundance and food quality are most important for developing useful indices for fisheries management, and to assess the efficacy of a genomic metabarcoding approach for characterizing zooplankton composition for monitoring efforts. To that end, we will specifically compare the cost and accuracy as well as the taxonomic resolution of the results of metabarcoding to more traditional microscopic identification and enumeration.
A major outcome of this project is hoped to be the implementation of these novel techniques for future monitoring efforts in the Chesapeake Bay region, which will be communicated to policymakers, managers, and stakeholders from MD DNR and NOAA through a workshop and best-practices document. Additionally, a new partnership with Chesapeake College will provide opportunities for undergraduates to engage in a comprehensive field/lab research experience, learning cutting-edge molecular techniques in zooplankton and fisheries ecology and providing college credit through an internship class.