Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher.
Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?
Some links on this page may take you to non-federal websites. Their policies may differ from this site.
While many instructors have reservations against Wikipedia use in academic settings, editing Wikipedia teaches students valuable writing, editing, and critical thinking skills. Wikipedia assignments align with the community of inquiry framework, which focuses on the elements needed for a successful online learning experience. We report on a faculty mentoring network, created by WikiProject Limnology and Oceanography, which helped 14 instructors with little to no prior experience implement a Wikipedia assignment in their classes. We found that Wikipedia assignments increase students’ motivation to produce high quality work and enhance their awareness of reliable scientific sources. Wikipedia assignments can be comparable to other writing assignments in length and complexity, but have a far wider audience than a traditional research paper. Participants in our mentoring network reported challenges with implementing this new type of assignment, and here, we share resources and solutions to those reported barriers.more » « less
Food chain efficiency (
FCE), the proportion of primary production converted to production of the top trophic level, can influence several ecosystem services as well as the biodiversity and productivity of each trophic level. Aquatic FCEis affected by light and nutrient supply, largely via effects on primary producer stoichiometry that propagate to herbivores and then carnivores. Here, we test the hypothesis that the identity of the top carnivore mediates FCEresponses to changes in light and nutrient supply.
We conducted a large‐scale, 6‐week mesocosm experiment in which we manipulated light and nutrient (nitrogen and phosphorus) supply and the identity of the carnivore in a 2 × 2 × 2 factorial design. We quantified the response of
FCEand the biomass and productivity of each trophic level (phytoplankton, zooplankton, and carnivore). We used an invertebrate, Chaoborus americanus, and a vertebrate, bluegill sunfish ( Lepomis macrochirus), as the two carnivores in this study because of the large difference in phosphorus requirements between these taxa.
We predicted that bluegill would be more likely to experience P‐limitation due to higher P requirements, and hence that
FCEwould be lower in the bluegill treatments than in the Chaoborustreatments. We also expected the interactive effect of light and nutrients to be stronger in the bluegill treatments. Within a carnivore treatment, we predicted highest FCEunder low light and high nutrient supply, as these conditions would produce high‐quality (low C:nutrient) algal resources. In contrast, if food quantity had a stronger effect on carnivore production than food quality, carnivore production would increase proportionally with primary production, thus FCEwould be similar across light and nutrient treatments.
Carnivore identity mediated the effects of light and nutrients on
FCE, and as predicted FCEwas higher in food chains with Chaoborusthan with bluegill. Also as predicted, FCEin Chaoborustreatments was higher under low light. However, FCEin bluegill treatments was higher at high light supply, opposite to our predictions. In addition, bluegill production increased proportionally with primary production, while Chaoborusproduction was not correlated with primary production, suggesting that bluegill responded more strongly to food quantity than to food quality. These carnivore taxa differ in traits other than body stoichiometry, for example, feeding selectivity, which may have contributed to the observed differences in FCEbetween carnivores.
Comparison of our results with those from previous experiments showed that
FCEresponds similarly to light and nutrients in food chains with Chaoborusand larval fish (gizzard shad: Clupeidae), but very differently in food chains with bluegill. These findings warrant further investigation into the mechanisms related to carnivore identity (e.g., developmental stage, feeding selectivity) underlying these responses, and highlight the importance of considering both top‐down and bottom‐up effects when evaluating food chain responses to changing light and nutrient conditions.