Calanoid copepods are among Earth’s most abundant animals, and they play a key role in moving energy from the base of the food chain to higher consumers. Some copepods, such as Calanus finmarchicus, can undergo a dormant period (diapause) during their juvenile development. It is not well understood how copepods “decide” whether to undergo diapause, or when to enter or exit diapause.
Metabolic adaptations of Antarctic Copepods
In December 2018-February 2019, I spent six weeks aboard the ARSV Laurence M. Gould during a cruise along the West Antarctic Peninsula. Antarctic copepods have developed particular feeding and behavioral strategies to survive in their very seasonal environment, it is not known how each of these species will respond to environmental change. The overall goal of this project is to examine and compare these adaptations across species and to understand how each species responds to short-term changes in food availability. The project contains three main objectives: the first objective is to compare the sets of genes across species, especially looking at genes related to storage of energy from food. The second objective is to measure and compare the responses of copepods to changes in food availability. The third objective is to determine how variation across the western Antarctic Pensinsula habitat affects the feeding condition of the copepods. This field work will be conducted through a collaboration with an existing sampling program (the Palmer Long-Term Ecological Research Regional Grid). See also my recent blog post about this project (and look forward to more soon!). At time of writing (June 2019), we have sent RNA samples out for high-throughput sequencing and are eagerly looking forward to analyzing the data. This project is funded by the Office of Polar Programs at NSF.
Circadian metabolic rhythms in migratory zooplankton
In 2019 we also started a new project, led by Dr. Amy Maas at BIOS that focuses primarily on the migratory copepod Pleuromamma xiphias. We are using a suite of techniques (respirometry, proteomics, transcriptomics, enzyme activity assays) to study how the physiology of these animals changes over daily cycles and in relationship to diel vertical migration. As these small animals move into deeper water each day, they continue to respire, excrete, and sometimes they even die and may sink into deep waters. We know in general that metabolic rates vary over daily cycles, but it’s not clear how these cycles interact with the temperature changes and activity bursts that the copepods experience while migrating. Measuring these processes is important to understanding how migratory zooplankton contribute to the vertical movement of nutrients and carbon through the water column. We completed major field sampling during a 4-day cruise in May 2019. We’ll be returned to Bermuda in July for additional field sampling and lab-based experiments. This project is funded by the Biological Oceanography Program at NSF.
Work in progress and recent(ish) results:
In 2015, I participated in a cruise in the Bering Sea aboard the NOAA Ship Oscar Dyson. I was sampling Calanus copepodids and conducting experiments to identify molecular and physiological signatures of food deprivation. This work was funded by the WHOI Access to the Sea Program. Link to a blog post describing this work.
We have compared transcriptome-wide gene expression patterns at two times during development in the fifth copepodid stage. We then conducted detailed qPCR-based expression profiling of a subset of the genes. We anchored these molecular measurements with observations of molt stage progress, oil sac volume and gonadal development. This project was funded by the Biological Oceanography Program at the National Science Foundation. (Tarrant, Baumgartner, et al. 2014. Frontiers in Zoology).