BACTERIOPLANKTON: DISTRIBUTION AND ECOLOGY

Role of bacteria in the carbon cycle

Recall

How to determine numbers of cells and biomass Direct count Culture Fluorescence microscopy ATP Identify environmental microbes by PCR, RFLP, and sequencing

SEM micrograph of bacterioplanktonFluorescence micrograph of bacterioplankton

ASSUMPTIONS Growth of bacteria substrate-limited Thus, bacterioplankton most common in layers where primary production highest (epilimnion) Low biomass in metalimnion A second maximum in the hypolimnion Numbers lowest in winter

Thus, bacterioplankton should vary according to season and depth

Co-occurrence of phytoplankton and bacterioplankton

Numbers and relative occurrence of bacterioplankton in a Michigan Lake from October to July

Numbers and production rates of bacterioplankton through the seasons

Lake Hancza, the deepest lake in Poland

Gotkowska-Płachta A., Niewolak S., Korzeniewska E VERTICAL DISTRIBUTION AND SEASONAL CHANGES IN THE NUMBER OF BACTERIOPLANKTON IN THE WATER OF LAKE HAŃCZA, PARTICULARLY IN THE PERIOD OF RESERVOIR SUMMER STRATIFICATION. EJPAU 6(2), #10. Figure 2. Vertical changes of temperature, oxygen saturation and number of planktonic bacteria (thousands of cells/ 1 cm 3 of water) in the water of Lake Hańcza (at station 1) during summer stratification of the lake in 1997 and A temperature, B oxygen, C planktonic bacteria

Gotkowska-Płachta A., Niewolak S., Korzeniewska E VERTICAL DISTRIBUTION AND SEASONAL CHANGES IN THE NUMBER OF BACTERIOPLANKTON IN THE WATER OF LAKE HAŃCZA, PARTICULARLY IN THE PERIOD OF RESERVOIR SUMMER STRATIFICATION. EJPAU 6(2), #10. Figure 3. Vertical changes of temperature, oxygen saturation and number of planktonic bacteria (thousands of cells/ 1 cm 3 of water) in the water of Lake Hańcza (at station 1) during summer stratification of the lake in the years 1999 and A temperature, B oxygen, C planktonic bacteria

Also controlled by Temperature (as you have seen, usually highest in warm months) pH (grow best in circumneutral pH) Often restricted by nutrient availability, especially phosphate

Model of seasonal control of bacterioplankton

DOC: Amino Acids and Carbohydrates Concentrations low Assimilated faster in aerobic water than in anaerobic water Assimilation faster in warmer water than in cooler water Humic acids degrade very slowly and may be linked to other organics

Uptake of DOC As cells die, 5-35% released as DOC Extracellular release of DOC by primary producers a major source Most DOC released by primary producers in the euphotic zone Bacterial assimilation peaks after peak release of DOC by phytoplankton

Distribution of carbon fractions versus rates of uptake

The microbial loop

Idealized daily fluctuations of various parameters that impact bacterial uptake

Organic content of suspended particulate matter (POC) through the seasons

Phytoplankton production relative to rates of sedimentation of POC

Rates of turnover by large and small bacterioplankton

Bacterioplankton in riverine and lacustrine systems De Araujo, M.F.F. and M.J.L. Godinho Seasonal and spatial distribution of Bacterioplankton in a fluvial- lagunar system of a tropical region: density, biomass, cellular volume and morphologic variation. Brazilian Archives of Biology and Technology. 51(1): doi: /S

Bacteria in Rivers and Lakes, a Study De Araujo, M.F.F. and M.J.L. Godinho Seasonal and spatial distribution of Bacterioplankton in a fluvial-lagunar system of a tropical region: density, biomass, cellular volume and morphologic variation. Brazilian Archives of Biology and Technology. 51(1): doi: /S

Summary for bacterioplankton. See Table (p. 523) RIVERSRESERVOIRSLAKES Bacterioplankton abundance High to very highModerate to highLow Bacterioplankton production Low but increasing with stream order Low to moderateLow Bacterioplankton respiration HighModerateLow Bacterioplankton Mortality HighModerateHigh