One of the reasons I haven’t posted for a bit besides the normal-busy routine is that it is Spring Time! What’s that got to do with anything you ask?
BLOOMS! BLOOMS OF EVERYTHING!
Besides blooms of flowers in the desert (such as those in the Anza-Borrego Desert), we also get blooms of phytoplankton along the coast in Southern California.
Here, in the spring we get very high winds that can result in upwelling events in the coastal ocean, pushing waters offshore and bringing up cold, nutrient rich water from the bottom ocean layers to the top layers.
This increase in nutrients (such as nitrogen, phosphorous, iron, etc.) can result in massive ‘blooms’ or increases in specific phytoplankton species (diatoms, dinoflagellates, etc.), since typically their densities are limited by nutrient availability. During these blooms, whoever wins the space and resource competition will dominate… until they get run down by grazers, parasites or viruses.. or run out of their limiting nutrient. Once these species decline this then provides space/resources for the next dominating species.
These upwelling events also offer AWESOME opportunities for scientists to examine the species dynamics, and the mechanisms that result in some species or functional groups of phytoplankton to dominate over others.
This year, our laboratory (the Caron Laboratory at USC) decided to start our sampling period after we noticed strong winds on April 9th.. and I mean Strong! I was biking to my circus class that evening, and a branch literally flew and hit me.. luckily I was wearing a helmet 🙂 During lab meeting that week, we were all telling each other the horror stories of the strong wind, and realized.. ‘woah!’… we should start our spring sampling asap! So we quickly contacted the amazing Santa Monica Pier Aquarium (Heal The Bay) and received permission to use some of the space there to do our sample processing for three weeks. Then we finalized our schedules, rotating each daily to sample and process the water off of the Santa Monica Pier. Each day at 8:30am, we get to the aquarium, load up our cart with the RBR (an oceanographic instrument that measures temperature, salinity, chlorophyll and dissolved oxygen), a bucket and container for loading up sea water, and a 20 micron plankton net to collect a concentrated water sample. Then by 9am, we are loading up water into our collection container, and then rolling the water back to the aquarium to filter some of it down as fast as possible onto filters that we flash freeze for DNA/RNA extractions. We also preserve some of the whole sea water for relative abundance counts of the different organisms via microscopy, and we sample the water for extraction of chlorophyll and domoic acid (toxin produced by some diatoms). Once we get back to the lab, we inspect the concentrated samples from the plankton net to get a quick overview of who is in the water, and who is the dominating species.
This year the sampling has been super interesting! It started off with a diatom and dinoflagellate bloom, and it looks like the diatoms have been CRUSHED by a parasitoid, Cryothecomonas spp.! Once the diatoms crashed, the dinoflagellates increased more, in particular two species are currently dominating: Akashiwo sanguinea and Cochlodinium spp. (species will be determined after we get our molecular sequences back). I also found some tintinnid ciliates parasitized by Eudoboscquella parasitoids.. so beautiful.
In addition to using molecular sequences for identification of the different taxa, our laboratory also analyzes the RNA sequences (using bioinformatics) to examine gene expression of the different taxa that are increasing and decreasing during the bloom. These methods can help us determine when species are taking up specific nutrients, when they are multiplying, when they are stressed, and even if they are being attacked by parasites. Lastly, my work in particular during this spring bloom will examine the dynamics of these species and their parasites through time using qPCR (quantifies the relative number of the hosts and parasites by comparing samples to standard curves).
We have five more days left of daily sampling, and I will be sure to follow up with another blog on the results of this spring bloom sampling period. I will also post soon about the exciting results from a massive laboratory experiment that I just finished. Stay tuned!
Dr. Julie V. Hopper 