SS2.05 Phylogenetic and Physiologic Successions in Aquatic Bacterial Communities
Date: Monday, June 10, 2002
Time: 4:45:00 PM
Location: Carson C
MenezesS, Graduate School of Oceanography, University of Rhode Island, Narragansett, USA,
Hargraves, P, E, Graduate School of Oceanography, University of Rhode Island, Narragansett, USA,
A 9-day mesocosm experiment was undertaken to examine the effects of added nutrients on the abundance and species diversity of nanoplankton. Four treatments were used: a nitrogen only addition, a phosphorus only addition, a nitrogen and phosphorus addition, and a control. Temperature, salinity, and light data were collected daily, while pigment, nutrient and species data were collected every third day. Dissolved inorganic nutrients in the control mesocosms decreased to minimal values (<0.5 micromolar) by the third day of the experiment. Each of the treatments peaked in chlorophyll a values on the sixth day of the experiment. The proportion of nanoplankton chlorophyll a was maximal in all treatments on the third day of the experiment, and then reached a minimum before returning to intermediate values in the +N and +NP treatments. Photosynthetic Cryptophytes were initially abundant in all treatments, but declined in days 6 and 9. Small centric diatoms were abundant in the nanoplankton of all treatments, as were several Prasinophyte and Chrysophyte species. Pedinellids were abundant in the +P and +NP treatments. Heterotroph/autotroph ratios (H:A) were variable throughout the experiment.