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The Student Section of the Ecological Society of America awarded two cash prizes ($100 each) to the best undergraduate student oral presentation and best undergraduate student poster presentation. The best undergraduate student oral and poster presentations were chosen based on the same criteria as the Buell and Braun awards (see here for additional details). Awards for the 2010 recipients will be presented at the Student Section award ceremony at the 2011 annual meeting, in Austin, TX. For questions regarding the award, please contact Naupaka Zimmerman (naupaka(at)stanford.edu), ESA Student Section Chair. The winners and a brief description of their research are below.
Warmer temperatures help an invasive harmful cyanobacterium outcompete native phytoplankton
Phytoplankton are vital primary producers in both marine and freshwater communities. Rising lake temperatures caused by global climate change will alter phytoplankton community diversity. In addition, changing nutrient inputs and invasive phytoplankton may also impact community structure. How will phytoplankton communities reorganize in response to interacting global change stressors such as rising temperatures, altered nutrients and invasive species? Answering these questions can bring insight into the future structure, functioning and overall health of aquatic ecosystems.
We assembled a phytoplankton community consisting of ten different species from major taxonomic groups, diatoms, green algae, cryptophytes, and cyanobacteria typical of temperate lakes. We then subjected these replicate communities to treatments designed to reflect the projected warmer conditions of temperate lakes due to global warming along with the changing nutrients and competitive pressure of an invasive harmful nitrogen-fixing cyanobacterium (Cylindrospermopsis raciborskii). The treatments were the current peak summer average lake temperature (25˚C), projected peak summer average lake temperature (30˚C), low and high nutrient (phosphorus) availability.
At lower temperature (25˚C) C. raciborski successfully outcompetes the other species of phytoplankton, but only under phosphorus limiting conditions. At higher temperature (30˚C), C. raciborskii dominates at all levels of nutrient availability. Green algae (Chlamydomonas, Scenedesmus and Ankistrodesmus) are better competitors in phosphorus-rich conditions in low temperatures. The projected increases in temperature will likely promote C. raciborskii invasions into temperate regions.
Are you what you eat? Development times, mass, and stable isotope ratios of the mosquitoes Culex restuans and Aedes albopictus grown on different detritus types
Aedes albopictus, an invasive species from Asia, is now the most dominant container species in the southeastern United States and has been found to be a strong competitor against many resident mosquitoes. In many parts of the United States, Aedes albopictus interacts with species in the genus of Culex, including the native species Culex restuans. Past work has shown that Aedes and Culex mosquitoes show difference in feeding behavior, with Culex mosquitoes filtering the water column at the surface, whereas Aedes mosquitoes browse at the bottom of containers or on surfaces. We hypothesized that these differences may translate to differences in performance depending on detritus type. We tested this hypothesis in the laboratory by growing larval A. albopictus and C. restuans larvae in ratios of two common detritus types in containers (plant and animal detritus). We used 6 combinations of dried Drosophila melanogaster (animal detritus) and dried maple (leaf detritus). Detritus amounts used included low (0.05 g), medium (0.10 g), and high (0.50 g). Ratios consisted of low animal:low leaf, low animal:high leaf, low animal:no leaf, no animal:low leaf, no animal:high leaf, and medium animal:no leaf. Into each container we added 10 first instar larvae of either C. restuans or A. albopictus. Survival and development time were recorded for males and females for 34 days. Because feeding behaviors differ between these genera, we also investigated the contributions of detritus treatments to adult biomass of both species by using stable isotope techniques.
For Culex restuans, both male and female development time varied significantly among ratios, with the high plant only treatment producing longer development times compared to treatments containing animal detritus. Mass of females and males also was lower in high leaf environments compared to other ratios. Male mass was highest in high animal treatments, with mixed ratios being intermediate. Survival of C. restuans among ratios did not vary significantly. For Aedes albopictus, female development time varied significantly among treatments, with mixed detritus amounts producing shorter development times compared to animal or leaf only treatments. Our findings suggest that the response of each species to detritus ratios was different, with C. restuans males and females performing worse under more detritus ratios compared to A. albopictus. These results are consistent with known differences in performance under single detritus types, and suggest a more robust understanding of the performance of these species under natural food environments.