Tranvik, L. J.. Department of Water and Environmental Studies, lars.tranvik
Hansson, and others, L. J.. Limnology, Department of Ecology, lars-anders.hansson@limnol.lu.se

 
FOOD WEB CONFIGURATION AFFECTS THE QUANTITY AND BACTERIAL DEGRADABILITY OF DOC
 
In a long-term experiment, where all organisms, including the top predator, were allowed to respond to environmental conditions by reproduction, we tested the effects of nutrient input and food web configuration on dissolved organic carbon (DOC). Tanks with 400 liters of water were inoculated with natural assemblages of algae and small grazers (protozoa, rotifers, and small crustaceans). Some tanks also received large crustacean grazers (predominantly Daphnia magna), and some also included fish (guppy, Poecilia reticulata). Replicated tanks with the three resulting food web configurations received either low or high concentrations of inorganic nutrients. After four months, we performed a bioassay to estimate the ability of heterotrophic bacteria to utilize the DOC produced. Both nutrients and food web configuration significantly affected the quantity of DOC, as well as its potential to support bacterial growth. Our results suggest that the transformation of DOC originating in algal primary production into recalcitrant forms is dependent on the structure of the food web.
 
Day: Thursday, Feb. 4
Time: 11:00 - 11:15am
Location: Sweeney Center
 
Code: SS33TH1100S