The distribution and activity of the bulk picoplankton community and, using microautoradiography combined with catalysed reported deposition fluorescence in situ hybridization (MICRO-CARD-FISH), of the major prokaryotic groups (Bacteria, marine Crenarchaeota Group I and marine Euryarchaeota Group II) were determined in the water masses of the subtropical North Atlantic. The bacterial contributi...

Autotrophic picoplankton (APP) are distributed worldwide and are ubiquitous in all types of lakes of varying trophic state. APP are major players in carbon production in all aquatic ecosystems, including extreme environments such as cold ice-covered and/or warm tropical lakes and thermal springs. They often form the base of complex microbial food webs, becoming prey for a multitude of protozoan...

On the basis of correlative studies, picoplankton in Calder Lake, New York, are apparently unaffected by seasonal fluxes in nutrient (N and P) levels. In this small eutrophic lake, picoplankton (<2.0- to 0.2-mum size) and nanoplankton (<20 to >2 mum) predominate. Microplankton (>20 mum) are typically least important. Experiments were conducted in situ to test whether N, P or N/P ratios affect t...

We investigated whether trophic repackaging of autotrophic picoplankton by phagotrophic protists is associated with an improvement in food quality for the metazooplankton Daphnia magna (i.e., whether trophic upgrading occurs in this system). The nutritional value of the autotrophic species Microcystis aeruginosa PCC7806, Synechococcus sp. strain BO8809, Synechococcus elongatus SAG 89.79, and Ch...

Pelagic microbial food webs are structured by zooplankton through grazing and nutrient recycling. Cladocerans copepods assumed to have different effects on the loop prey sizes releasing phosphorus (P) differentially. Here, we assessed this effect of differential recycling dynamics using a combination experimental modelling approaches. We performed field incubation experiments in an oligotrophic...

The spatial variations of the picoplankton (photoautotrophic and heterotrophic microorganisms) in the Ahe atoll lagoon were studied in May and October 2008 to assess whether they were affected by human activities along the atoll. Spatial patterns were studied using 10 sampling stations chosen according to the location of the anthropogenic activities (pearl farming, harbor). Experiments were als...

Dr. George S. Bullerjahn, advisor A simple method for the optimization of the catalyzed reporter deposition-fluorescence in situ hybridization procedure (CARD-FISH) can be used to enumerate populations of cyanobacterial freshwater picoplankton in Lake Superior and Lake Erie. Here we have demonstrated that this optimized procedure can be used in the detection of the 16S rRNA sequences of cyanoba...