Recent changes in the growth and nutrient limitation of benthic and pelagic algae in Arctic tundra ponds
Arctic ponds are a dominant feature in Barrow, Alaska. Ponds may function as carbon sinks during the growing season from production of photosynthetic organisms like algae; however, little work has been done on this topic. Environmental changes have been occurring in the Arctic stemming from climate change and human perturbations. The focus of this study was to assess a historically studied region for changes in algal primary production that may have been produced due to increases in temperature over the past 40 years and increased human development. Additionally, this study aimed to determine nutrient limitation of algal production in the pelagic and benthic zone in order to attain a better understanding of algal primary production differences among zones. In order to do so, several methods were employed including nutrient diffusing substrate experiments, bottle incubations, and mesocosms. Compared to 40 years ago, increases in phytoplankton biomass were observed in the historically studied region. Periphyton was not significantly higher than the 1970s; however, benthic algae were more productive in sites located closer to the village of Barrow suggesting influences from anthropogenic activity. Since a human impact gradient effect on algal production at the historic site was not observed, other nutrients sources such as permafrost thaw are a likely contributor to algal growth. Nutrient limitation status of phytoplankton has changed since the original study in the historical region from phosphorus (P) limitation to nitrogen (N) or NP co-limitation. Contributions of phosphorus from deglaciation, permafrost thaw, and other sediment interactions may potentially be causing nitrogen limitation. Comparisons of pelagic and benthic experiments revealed differences among these zones with NP limitation in the pelagic zone and N limitation in the benthic zone, reflecting contrasting nutrient limitation status within the same pond. Mesocosm experiments provided support for NP limitation in the water column but, due to experimental limitations, there were no significant findings in the benthos. These findings reflect the changes occurring in Arctic ponds in light of warming temperatures and human perturbations. Further studies are needed in order to fully understand recent and future expected changes in primary production and nutrient cycling in both the pelagic and benthic zones.
Ecology|Climate Change|Environmental science|Limnology
Hernandez, Christina, "Recent changes in the growth and nutrient limitation of benthic and pelagic algae in Arctic tundra ponds" (2012). ETD Collection for University of Texas, El Paso. AAI1533229.