Periphyton light transmission relationships in Florida Bay and the Florida Keys, USA

Light transmission was measured through intact, submerged periphyton communities on artificial seagrass leaves. The periphyton communities were representative of the communities on Thalassia testudinum in subtropical seagrass meadows. The periphyton communities sampled were adhered carbonate sediment, coralline algae, and mixed algal assemblages. Crustose or film-forming periphyton assemblages were best prepared for light transmission measurements using artificial leaves fouled on both sides, while measurements through three-dimensional filamentous algae required the periphyton to be removed from one side. For one-sided samples, light transmission could be measured as the difference between fouled and reference artificial leaf samples. For two-sided samples, the percent periphyton light transmission to the leaf surface was calculated as the square root of the fraction of incident light. Linear, exponential, and hyperbolic equations were evaluated as descriptors of the periphyton dry weight versus light transmission relationship. Hyperbolic and exponential decay models were superior to linear models and exhibited the best fits for the observed relationships. Differences between the coefficients of determination (r2) of hyperbolic and exponential decay models were statistically insignificant. Constraining these models for 100% light transmission at zero periphyton load did not result in any statistically significant loss in the explanatory capability of the models. In most all cases, increasing model complexity using three-parameter models rather than two-parameter models did not significantly increase the amount of variation explained. Constrained two-parameter hyperbolic or exponential decay models were judged best for describing the periphyton dry weight versus light transmission relationship. On T. testudinum in Florida Bay and the Florida Keys, significant differences were not observed in the light transmission characteristics of the varying periphyton communities at different study sites. Using pooled data from the study sites, the hyperbolic decay coefficient for periphyton light transmission was estimated to be 4.36 mg dry wt. cm−2. For exponential models, the exponential decay coefficient was estimated to be 0.16 cm2 mg dry wt.−1.

Boundary Effects on Benthic Microbial Phosphorus Concentrations and Diatom Beta Diversity in a Hydrologically-modified, Nutrient-limited Wetland

Water flow and flooding duration in wetlands influence the structure and productivity of microbial communities partly through their influence on nutrient loading. The effect of flow-regulated nutrient loads is especially relevant for microbial communities in nutrient-poor settings, where delivery controls nutrient uptake rates and the intensity of microbial interactions. We examined the effect of hydrologic history and proximity to water sources on nutrient enrichment of benthic microbial assemblages (periphyton) and on their diatom species composition, along the artificial boundaries of Taylor Slough, a historically phosphorus-depleted drainage of the Florida Everglades. Concentrations of phosphorus in periphyton declined from the wetland boundary near inflow structures to 100-m interior, with spatial and temporal variability in rates dependent on proximity to and magnitude of water flow. Phosphorus availability influenced the beta diversity of diatom assemblages, with higher values near inflow structures where resources were greatest, while interior sites and reference transects contained assemblages with constant composition of taxa considered endemic to the Everglades. This research shows how hydrologic restoration may have unintended consequences when incoming water quality is not regulated, including a replacement of distinctive microbial assemblages by ubiquitous, cosmopolitan ones.

Challenging ESL Students to Avoid Plagiarism and Properly Summarize and Cite Articles

Research shows that plagiarism is a problem not only for English language learners but also for students whose first language is English. With the Internet and ease of copying and pasting information into a word document, plagiarism in on the rise (Maslen, 2003). Oftentimes, students are not aware they are doing something wrong. American students come into college with the cultural conditioning of knowing (perhaps not fully grasping) American academic standards (Gu & Brooks, 2007). International students have the additional disadvantage of not knowing the conventions, traditions, and values held in academic discourse (Gu & Brooks, 2007). Within American academic circles, plagiarism is considered “one of the worst crimes” a student can commit (Wheeler, 2008). However, outside the United States, plagiarism is culturally acceptable; in fact a moral transgression would be to not copy and paste the words of an expert (Wheeler, 2008). Most of the students in English for Academic Purposes (EAP) at Miami-Dade College are planning on continuing their education once they finish the EAP program so it is essential that they are exposed to the issue of plagiarism. A number of faculty who teach in subject areas have complained that incoming students do not have the skills needed to succeed; these skills include how to cite sources and reference material. As a result of this, the focus of this action research project was on incorporating and explaining plagiarism and providing a number of writing opportunities throughout the semester.