Another 1st author paper for Sarah:

Princiotta, S.D. and R.W. Sanders. 2017. Heterotrophic and mixotrophic nanoflagellates in a mesotrophic lake: abundance and grazing impacts across season and depth. Limnology & Oceanography 62: 632-644.

The last bit of Erin’s Ph.D. work is: Graham, E.R. & Sanders, R.W. 1916. Species-specific photosynthetic responses of symbiotic zoanthids to thermal stress and ocean acidification. Marine Ecology 37: 442-458.  Here’s a link.

Temperature-dependent phagotrophy and phototrophy in a mixotrophic chrysophyte by Sarah DeVaul Princiotta, Brian T. Smith and Robert W. Sanders has been published in the Journal of Phycology (52:432-440) and can be found here.

Defining planktonic protist functional groups on mechanisms for energy and nutrient acquisition: incorporation of diverse mixotrophic strategies by Aditee Mitra and 22 co-authors (including R.W. Sanders) was published in Protist (167:106-120) and is available online at  http://www.sciencedirect.com/science/article/pii/S1434461016000043

Sanders, R.W., S.L. Cooke, J.M. Fischer, S.B. Fey, A.W. Heinze*, W.H. Jeffrey, A.L. Macaluso*, R.E. Moeller, D.P. Morris, P.J. Neale, M. Olson, J.D. Pakulski, J.A. Porter, D.M. Schoener*, C.E. Williamson. 2015. Shifts in microbial food web structure and productivity after additions of naturally occurring dissolved organic matter: results from large-scale lacustrine mesocosms. Limnology & Oceanography. 60: 2130-2144. DOI: 10.1002/lno.10159

Cooke, S.L., J.M. Fischer, K. Kessler, Craig E. Williamson, R.W. Sanders, D.P. Morris, J.A. Porter, W.H. Jeffrey, S.B. DeVaul*, J.D. Pakulski. 2015. Direct and indirect effects of additions of chromophoric dissolved organic matter on zooplankton during large-scale mesocosm experiments in an oligotrophic lake. Freshwater Biology. 60:2362-2378.  DOI:10.1111/fwb.12663

*Current or former graduate students in the lab.

Erin’s final paper from her Ph.D. work was published: Graham, E.R., A. Parekh, R.K. Devassy and R.W. Sanders. 2015. Carbonic anhydrase activity changes in response to increased temperature and pCO2 in Symbiodinium-zoanthid associations.Journal of Experimental Marine Biology and Ecology 473:218-226.  Here’s a link.

Amy Parekh and Roni Devassy were undergraduate researchers in the lab.

Congrats to them all!

McKie-Krisberg, Z.M., R.J. Gast and R.W. Sanders. 2015. Physiological responses of three species of Antarctic mixotrophic phytoflagellates to changes in light and dissolved nutrients. Microbial Ecology 70:21-29.

Abstract: Antarctic phototrophs are challenged by extreme temperatures, ice cover, nutrient limitation and prolonged periods of darkness. Yet this environment may also provide niche opportunities for phytoplankton utilizing alternative nutritional modes. Mixotrophy, the combination of photosynthesis and particle ingestion, has been proposed as a mechanism for some phytoplankton to contend with the adverse conditions of the Antarctic. We conducted feeding experiments using fluorescent bacteria-sized tracers to compare the effects of light and nutrients on bacterivory rates in three Antarctic marine photosynthetic nanoflagellates representing two evolutionary lineages: Cryptophyceae (Geminigera cryophila), and Prasinophyceae (Pyramimonas tychotreta and Mantoniella antarctica). Only G. cryophila had previously been identified as mixotrophic. We also measured photoautotrophic abilities over a range of light intensities (P vs. I) and used dark survival experiments to assess cell population dynamics in the absence of light. Feeding behavior in these three nanoflagellates was affected by either light, nutrient levels, or a combination of both factors in a species-specific manner that was not conserved by evolutionary lineage. The different responses to environmental factors by these mixotrophs supported the idea of tradeoffs in the use of phagotrophy and phototrophy for growth.

“Species-specific photosynthetic responses of symbiotic zoanthids to thermal stress and ocean acidification” by Erin R. Graham and Robert W. Sanders is accepted for publication in Marine Ecology.

ABSTRACT: Increasing sea surface temperatures and ocean acidification (OA) are impacting physiological processes in a variety of marine organisms. Many sea anemones, corals, and jellies in the phylum Cnidaria, form endosymbiotic relationships with the dinoflagellate Symbiodinium spp., which supplies the hosts with fixed carbon from photosynthesis. Much work has focused on the generally negative effects of rising temperature and OA on calcification in Symbiodinium-coral symbioses, but has not directly measured symbiont photosynthesis in hospite or fixed carbon translocation from symbiont to host. Symbiodinium species or types vary in their environmental tolerance and photosynthetic capacity, therefore, primary production in symbiotic associations is directly related to symbiont type. However, symbiont type has not been identified in a large portion of Symbiodinium-cnidarian studies. Future climate conditions and OA may favor non-calcifying, soft-bodied cnidarians, including zoanthids, over coral species. Here we show that two zoanthid species, Palythoa sp. and Zoanthus sp., harboring different symbiont types (C1 and A4), had very different responses to increased temperature and increased pCO₂/low pH. Thermal stress did not affect carbon fixation or fixed carbon translocation in the Zoanthus sp./A4 association, and high pCO₂/low pH increased carbon fixation. In contrast, both thermal stress and high pCO₂/low pH greatly inhibited carbon fixation in the Palythoa sp./C1 association. However, the combined treatment of high temperature and high pCO₂ increased carbon fixation relative to the treatment of high temperature alone. Our observations support the growing body of evidence that demonstrates that the response of symbiotic cnidarians to thermal stress and OA must be considered on a host-specific and symbiont-specific basis. In addition, we show that the effects of increased temperature and pCO₂ on photosynthesis may change when these two stressors are combined. Understanding how carbon fixation and translocation varies among different host-symbiont combinations is critical to predicting which Symbiodinium associations may persist in warm, acidified oceans.