I am taking a small break from my blog tutorials on using microsatellite markers in population genetic studies to make an exciting announcement: I recently started a new 1-year Post-doc position at the University of Southern California in Dr. Dave Caron’s laboratory (more time pending funding from fellowships)!
Although it is sad that my Delta Science fellowship is over, as it was a wonderful opportunity, I will still be working/writing hard to finish up my publications from this work and I will of course share these with all of you as they are published.
In the mean time- I am moving back into marine study systems to examine the diversity and function of protists in the marine phytoplankton community! Click here to check out the fascinating research in Dave Caron’s lab. In addition to dabbling in several different ongoing projects in Dave’s lab- I am also very excited about starting up some of my own projects (pending funding) on the abundance, diversity and consequences of parasite-host interactions in the phytoplankton community. As some of you might already know- I am an extreme parasite enthusiast, and only recently have researchers started to examine the potential abundance and importance of parasites in the marine phytoplankton community!
Recently, researchers in the Tara-Oceans Expedition found that parasitic interactions were the most abundant pattern in the global marine phytoplankton interactome (Lima-Mendez et al. 2015). Results from the V9-18S tag-sequence processing revealed parasite-host associations that included the copepod parasites: Blastodinium (Dinophyceae: Blastodiniaceae), Ellobiopsis (Marine Alveolate Group I: Ellobiopsidae), and Vampyrophrya (Ciliophora: Oligohymenophorea: Foettingeriida) and alveolate parasitoids of dinoflagellates and ciliates (Lima-Mendez et al. 2015). The alveolate parasitoids in particular were recognized for their top-down effects on zooplankton and microphytoplankton (Lima-Mendez et al. 2015).
Parasitoids are parasites that kill their host in order to complete their development (Lafferty and Kuris 2002) and increased abundance of alveolate parasitoids have been linked to declines of dinoflagellate blooms (Coats et al. 1996, Coats 1999, Chambouvet et al. 2008, Mazzillo 2011, Jephcott et al. 2016) and have been shown to regulate their dinoflagellate host populations in laboratory experiments (Noren 2000, Coats and Park 2002). The most researched alveolate parasitoids include several strains of Amoebophrya ceratii (Marine Alveolate Group II: Syndiniales) . These parasitoids have small flagellated infective stages that penetrate and multiply inside the dinoflagellate host cell, and produce numerous infective flagellates after killing and exiting the host (Cachon & Cachon 1987; Jephcott et al. 2016). For example A. ceratii can produce 60-400 new infective dinospores from its host in less than 48 hours (Chambouvet et al. 2008; Mazzillo 2011), and the generalist parasitoid, Parvilucifera sinerae, can produce 170 to > 6000 zoospores per sporangium, depending on the species and size of its host (Garces et al. 2013), with zoospore release within 72 hours of infecting a host (Alacid et al. 2015).
Below for your viewing pleasure is an example of these parasitoids- the life cycle diagram and life-cycle stages from Alacid et al. 2015, and Alacid et al. 2016 (respectively) of the generalist parasitoid Parvilucifera sinerae, in its host dinoflagellates.
So now of course the question you might have is: “why do we need to research these parasites/parasitoids further?” Well, we simply do not know enough about these amazing parasite-host interactions, and most of our knowledge is currently limited to the photic zone of the ocean, and concentrated on just a few of these parasite species (there are many parasites out there just waiting to be discovered!). For those of you that don’t think ‘not knowing enough’ merits more work- my reply to this is that: mortality rates in the phytoplankton community have an incredible significance regarding the total primary production and biogeochemical processes in the ocean. However, how can we account for the mortality rates in the phytoplankton community and consequences for primary production if we are not accounting for a large % of contribution to mortality due to parasites that have not yet been characterized? And this folks.. is the reason why this research should be funded (aside from the obvious fact that parasites are absolutely fascinating, and the evolution and ecology of parasites can tell us a lot about related free-living species as well (that is another blog topic I will save for the future).
Of course my new Post-doc research in this field is still a bit tentative as it depends on gaining further funding- but in the mean time I am posting some lovely photos of parasites (Euduboscquella spp.) in tintinnid ciliate hosts (Eutintinnus spp.) that I have been finding from some local net tows (marine sampling nets that concentrates organisms of different size classes). So exciting- it is like a treasure hunt every time!
References (highly recommended reads also!)
Alacid E, Rene A, Garces E (2015) New insights into the parasitoid Parvilucifera sinerae life cycle: the development and kinetics of infection of a bloom-forming dinoflagellate host. Protist 166, 677-699.
Alacid, E., Park, M. G., Turon, M., Petrou, K. & Garces, E. (2016) A game of Russian roulette for a generalist dinoflagellate parasitoid: host susceptibility is the key to success. Front Microbiol 7, 769.
Cachon J, Cachon M (1987) Parasitic dinoflagellates. In: Biology of dinoflagellates, pp. 571-610. Blackwell, New York.
Coats DW (1999) Parasitic life styles of marine dinoflagellates. Journal of Eukaryotic Microbiology 46, 402-409.
Coats DW, Adam EJ, Gallegos CL, Hedrick S (1996) Parasitism of photosynthetic dinoflagellates in a shallow subestuary of Chesapeake Bay, USA. Aquatic Microbial Ecology 11, 1-9.
Coats DW, Park MG (2002) Parasitism of photosynthetic dinoflagellates by three strains of Amoebophrya (Dinophyta): Parasite survival, infectivity, generation time, and host specificity. Journal of Phycology 38, 520-528.
Chambouvet A, Morin P, Marie D, Guillou L (2008) Control of toxic marine dinoflagellate blooms by serial parasitic killers. Science 322, 1254-1257.
Garces E, Alacid E, Bravo I, Fraga S, Figueroa RI (2013) Parvilucifera sinerae (Alveolata, Myzozoa) is a generalist parasitoid of dinoflagellates. Protist 164, 245-260.
Jephcott TG, Alves-De-Souza C, Gleason FH, et al. (2016) Ecological impacts of parasitic chytrids, syndiniales and perkinsids on populations of marine photosynthetic dinoflagellates. Fungal Ecology 19, 47-58.
Lafferty KD, Kuris AM (2002) Trophic strategies, animal diversity and body size. Trends in Ecology & Evolution 17, 507-513.
Mazzillo FFM (2011) Novel insights on the dynamics and consequence of harmful algal blooms in the California Current System: from parasites as bloom control agents to human toxin exposure PhD dissertation, University of California, Santa Cruz.
Lima-Mendez G, Faust K, Henry N, et al. (2015) Ocean plankton. Determinants of community structure in the global plankton interactome. Science 348, 1262073.
Dr. Julie V. Hopper 
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