Oral Presentation Freshwater Sciences 2023

Seasonal changes in phytoplankton community structure, stoichiometry, and nutrient dynamics of Central Arkansas ponds (#338)

Felicia S. Osburn 1 , Aidan P. Patton 1 , Halvor M. Halvorson 1
  1. University of Central Arkansas, Conway, ARKANSAS, United States

In Arkansas, USA, small bodies of water such as ponds cover over 156,000 acres of the state. While aquatic systems such as lakes, reservoirs, streams, and rivers are somewhat well studied for this state, ponds have been overlooked. This knowledge gap becomes more prominent when considering the limited work done on urban ponds, specifically. With harmful algal bloom events becoming more prominent in freshwater systems due to increasing eutrophication and increased temperatures, understanding the changing nutrient dynamics and phytoplankton community structure of public ponds is essential to better protect both the aquatic life in these systems as well as the public who utilize them for various recreational activities. In this study, we were interested in exploring how urbanization influenced the seasonal nutrient dynamics of ponds as well as how the phytoplankton community responded to these changes. We selected 25 ponds in central Arkansas, comprising a gradient of total urban land cover in the watershed that ranged from 0 - 99%. These ponds were sampled seasonally in 2022-2023 (encompassing Summer, Fall, and Winter sampling events) for phytoplankton and total, dissolved, and particulate nitrogen (N) and phosphorus (P). Water quality parameters were also taken at each site, including: pH, specific conductivity, air and water temperature, pressure, and dissolved oxygen (mg L-1 and %). In preliminary results, for ~75% of ponds the total N:total P increased in the Fall compared to the Summer values. With this change in nutrient ratios, it is expected that the phytoplankton community will shift seasonally, both in response to changing nutrient dynamics as well as other environmental conditions such as temperature.